Better O Ring for Oil Filler Cap

[content22207_2]

Just replaced the round O ring on #5939's oil filler cap with one of these square profile O rings -- what a difference: http://www.mcmaster.com/#4061t293/=13h9552

I am a big fan of square profile O rings. They are what I provide with my carb conversions now. Round O rings actually have very little contact area -- just the crown of their round shape. Square O rings contact from edge to edge, providing much more sealing area.

Bill Robertson
#5939

[David T]

Just replaced the round O ring on #5939's oil filler cap with one of these square profile O rings -- what a difference: http://www.mcmaster.com/#4061t293/=13h9552

I am a big fan of square profile O rings. They are what I provide with my carb conversions now. Round O rings actually have very little contact area -- just the crown of their round shape. Square O rings contact from edge to edge, providing much more sealing area.

Bill Robertson
#5939

You must be careful substituting square for round. The groove will still be round and when using a square ring there is a high chance it may twist as it is inserted making it leak badly. A new, proper round "O" on the oil filler works just fine.

[content22207_2]

I use square O rings on the A/C compressor too: http://www.mcmaster.com/#4061t233/=13h9i5h

O ring grooves have square profiles -- shouldn't their O rings be square too....

David's theoretical objections notwithstanding, in real world use I have had excellent success using square profile O rings.

Bill Robertson
#5939

[content22207_2]

Just added a bag of these to my next McMaster order for the Volvo's coolant distribution pipe (Y pipe): http://www.mcmaster.com/#4061t239/=13h9pdh

I will report their fit in a week or two.

Bill

[content22207_2]

The groove will still be round

How did I miss this?

Better look at your engine again -- groove on the oil filler cap is flat bottomed/sided, not round. Same with grooves on the back of the A/C compressor. And in the heads (intake ports). And the coolant distribution pipe (Y pipe). I'm pretty sure every O ring groove on the PRV is square.

Square O rings fill grooves completely. Round O rings leave gaps (you're only sealing with the crowns of the round shape):

44898

Bill Robertson
#5939

[Ron]

FYI- According to that link, the o-ring has a temperature range of -30° to 212° F.
Since engine oil is typically 200F hotter than radiator temps, this o-ring is not a good choice.

[content22207_2]

Knock yourself out: http://www.mcmaster.com/#1182n211/=13ha0hx

I sincerely doubt the oil filler tube gets hot enough to melt rubber -- it would melt the plastic screen at the bottom.... The cap itself is made of plastic, for crying out loud.

But rest assured: if my engine blows up and kills me because of a substandard oil filler cap O ring, I will post a warning message (giving you and David full credit of course).

Bill Robertson
#5939

[Ron]

But rest assured: if my engine blows up and kills me because of a substandard oil filler cap O ring, I will post a warning message (giving you and David full credit of course).

Bill Robertson
#5939
I have no doubt, if it was possible to post a warning after death, that you would blame someone who warned you when it was your hardheaded, face saving, stupidity...

:rolleyes:Typical Bill Robertson

[David T]

I have no doubt, if it was possible to post a warning after death, that you would blame someone who warned you when it was your hardheaded, face saving, stupidity...

:rolleyes:Typical Bill Robertson

Actually I applaud Bill for continuously looking for places and things to improve. In some cases a square "O" ring may make sense. Replacing an old, hard, shrunken round "O" ring with a new square one is an improvement BUT so is replacing that old round "O" ring with a new round one. I have seen cars where the oil fill was so loose it was like the "O" ring wasn't even there, that's how bad they get. At that point anything, round or square would be an improvement. I don't always agree with what Bill does but he is trying hard!

[content22207_2]

For the sake of science I just warmed the engine up to operating temp (radiator fans on) and took a temperature reading on the oil filler neck: 131 degrees:

44899

Thank you Ron ever so much for your great concern about my motoring welfare, but in this instance at least I'm good.

Bill Robertson
#5939

[Ron]

Actually I applaud Bill for continuously looking for places and things to improve. In some cases a square "O" ring may make sense. Replacing an old, hard, shrunken round "O" ring with a new square one is an improvement BUT so is replacing that old round "O" ring with a new round one. I have seen cars where the oil fill was so loose it was like the "O" ring wasn't even there, that's how bad they get. At that point anything, round or square would be an improvement. I don't always agree with what Bill does but he is trying hard!As do I! ...It is the personal attacks, however subtle, one must put up with when making a comment or suggestion about them. E.G. I point out that the part suggested would be used very close to its advertised temp limit (even at radiator temp) and that somehow winds up with engines blowing up, people dying, and posting after death...!?! -- Typical Bill Robertson.


For the sake of science I just warmed the engine up to operating temp (radiator fans on) and took a temperature reading on the oil filler neck: 131 degrees:

Thank you Ron ever so much for your great concern about my motoring welfare, but in this instance at least I'm good.

Bill Robertson
#5939Seems there is some sort of contradiction to your posts about our alternators burning up due to heat in the engine compartment and being oriented backwards here. (Maybe you should investigate which way the fans actually direct air in the first place...).
Try again after a long trip. Only 81 degrees to go...

P.S. You are most welcome.

[content22207_2]

I'm pretty sure the OEM O ring is Buna as well. McMaster sells Viton and silicone alternatives if you're truly concerned.

Personally I think if you get your engine hot enough to melt the oil filler cap O ring, you're going to have a lot bigger problems than a melted O ring....

I use Buna O rings for my intake ports as well -- they work just fine.

And the A/C compressor (how hot does that high side hose get, eh?).

Bill Robertson
#5939

[Ron]

And almost EVERY stock one I've seen leaked (including new ones), causing an unmeasured vacuum leak!
...Of course that only matters to someone who hasn't went backwards with there fuel delivery technology...

I suggest you spend another quarter... and find someone else who is amused buy your senseless arguments.

CYA!

[FABombjoy]

Unmeasured vacuum leak from the oil cap? That is not really possible. The cap is open to fresh air from it's breather tube in the intake. The orifice ensures a constant predictable leak from that location.

Worse case scenario, missing that O ring you would have oil vapors escape and mess up the place, and your substandard psuedo-PCV system would become an open air unfiltered breather system.

[DMCMW Dave]

Unmeasured vacuum leak from the oil cap? That is not really possible. The cap is open to fresh air from it's breather tube in the intake. The orifice ensures a constant predictable leak from that location.

Worse case scenario, missing that O ring you would have oil vapors escape and mess up the place, and your substandard psuedo-PCV system would become an open air unfiltered breather system.

And you want to worry a bit about rainwater as that cap is sort of under the vent screen under the louver.

[content22207_2]

And almost EVERY stock one I've seen leaked (including new ones)

Perhaps it's time to start using square ones?

Trust me -- the fit is *TIGHT*. The cap comes off, but you've got to pull like you mean it. About as hard as pulling a barbed vacuum hose off.

Bill Robertson
#5939

[content22207_2]

I've got 24 more of the things -- anybody want to render an independent assessment? I'll sell them for cost plus postage (and the envelope).

Bill Robertson
#5939

[bytes311]

My oil filler cap doesn't seat all the way down, and I had no idea about the o-ring because it's missing from my car. I also don't see it mentioned on the 1-4-0 diagram?

[novadmc]

I've got 24 more of the things -- anybody want to render an independent assessment? I'll sell them for cost plus postage (and the envelope).

Bill Robertson
#5939

I'll take one off your hands. you want me to paypal you the money? shoot me a pm.

[Ryan King]

I've got 24 more of the things -- anybody want to render an independent assessment? I'll sell them for cost plus postage (and the envelope).

Bill Robertson
#5939

I'll take one. PM me. I hope my car doesn't explode. Bill will you buy me a new DeLorean when my car dies from this o-ring?

[Chris 16409]

I've got 24 more of the things -- anybody want to render an independent assessment? I'll sell them for cost plus postage (and the envelope).

Bill Robertson
#5939

I'll take one, send me a PM. My original o-ring was hard and cracked. I am currently using one off a Volvo from the Junk yard. I'll try one of the square ones. Heck, send me two!

[Patrick C]

I'll take one! PM me how much you want and what address to send PayPal to.

[content22207_2]

Let me buy a package of manila envelopes and get a weight/postage quote. Should be the same price nationwide.

Bill Robertson
#5939

[Ron]

Unmeasured vacuum leak from the oil cap? That is not really possible. The cap is open to fresh air from it's breather tube in the intake. The orifice ensures a constant predictable leak from that location.

Worse case scenario, missing that O ring you would have oil vapors escape and mess up the place, and your substandard psuedo-PCV system would become an open air unfiltered breather system.
The port on the cap toward the front of the engine/car connects to the breather, which is under vacuum, not open to fresh air (when running ;-), measured, since it passes the plate. [Which is why you should plug it if playing with the CO with the breather off....]
But, the port toward the rear connects to the CSV's auxiliary air pipe, not measured. And the large port, on the bottom, has LOTS of vacuum (put your palm over it when the engine is running and you will see) for the crankcase (PCV), not measured either.
[FWIW, I doubt it would totally defeat the purge system, but it wouldn't be good.]
No?

[Ron]

Perhaps it's time to start using square ones?

Trust me -- the fit is *TIGHT*. The cap comes off, but you've got to pull like you mean it. About as hard as pulling a barbed vacuum hose off.

Bill Robertson
#5939I didn't say anything about the shape, Bill (although I agree with David). It was the material...and the fact that, if you take the old one to most any auto parts and ask for a larger one, a dollar would pay for both, WTH!

I still love ya', Bill.


I've got 24 more of the things -- anybody want to render an independent assessment? I'll sell them for cost plus postage (and the envelope).

Bill Robertson
#5939
:rofl: A stamp and envelope would cost more....

[content22207_2]

[FWIW, I doubt it would totally defeat the purge system, but it wouldn't be good.]
No?

No.

The oil filler cap is connected to the air filter -- that's where PCV is supposed to breathe.

Pulling unfiltered air into PCV (around an ill fitting O ring for example...) is not part of the design -- not on a PRV, not on any engine.

Bill Robertson
#5939

[content22207_2]

:rofl: A stamp and envelope would cost more....

I am not giving away envelopes and postage.

Apologies.

Bill Robertson
#5939

[Ron]

No.
The oil filler cap is connected to the air filter -- that's where PCV is supposed to breathe.
I didn't say any different. Only that the port was not open to fresh air.
It IS under vacuum...and the only port there that could leak and the air sill be measured.

I meant for the "No?" to apply to the whole thing, fwiw.


Pulling unfiltered air into PCV (around an ill fitting O ring for example...) is not part of the design -- not on a PRV, not on any engine.

Bill Robertson
#5939Of course not...Nor is the unmeasured air via an ill fitting o-ring to the auxiliary pipe.

[content22207_2]

Then stop working against my efforts to find a better fitting O ring.

I will get some envelopes and a postage quote tomorrow. After other owners have a chance to evaluate the O ring there will be a larger data set. Obviously my word alone doesn't count for much.

I humbly suggest putting hostilities on the back burner until then.

Bill Robertson
#5939

[Ron]

I am not giving away envelopes and postage.

Apologies.

Bill Robertson
#5939No apologies needed -- My mistake! Let me rephrase that:

Why pay more for an envelope and postage than a superior part costs (the next time you pass an auto parts store w/o the wait....)?

[content22207_2]

Because parts houses only sell round O rings....

If you find a suitable size (and apparently suitable material) square O ring anywhere, please feel free to post info and pricing.

McMaster stocks nearly half a million products -- that's the inventory I purchased from.

Bill Robertson
#5939

[Ron]

Then stop working against my efforts to find a better fitting O ring.

I will get some envelopes and a postage quote tomorrow. After other owners have a chance to evaluate the O ring there will be a larger data set. Obviously my word alone doesn't count for much.

I humbly suggest putting hostilities on the back burner until then.

Bill Robertson
#5939
And again, I said nothing about the fit!

I think it is obvious to anyone, but you, that I was not working against your efforts to find a better fitting O ring. In fact, I was trying to persuade you to continue and choose a better one than the one you found...due to its temp rating, which kicked off your typical shitty sarcasm etc.
It's all still there -- Read it! YOU started the hostilities, in a personal manner, yet. I had comments on the product/idea, not one word about the one presenting it....until you started the typical Bill BS.
Does "tit for tat" remind you of anything?

Ignore ON.

[content22207_2]

If you have a better O ring, please feel free to post the info.

I posted a link to my O ring in the very first post.

Bill Robertson
#5939

[Ryan King]

And again, I said nothing about the fit!

I think it is obvious to anyone, but you, that I was not working against your efforts to find a better fitting O ring. In fact, I was trying to persuade you to continue and choose a better one than the one you found...due to its temp rating, which kicked off your typical shitty sarcasm etc.
It's all still there -- Read it! YOU started the hostilities, in a personal manner, yet. I had comments on the product/idea, not one word about the one presenting it....until you started the typical Bill BS.
Does "tit for tat" remind you of anything?

Ignore ON.

:popcorn:

You done Hijacking Bill's thread yet?
Bill always gets crap from everyone when he simply said he found something that fits better then the stock O-Ring
Better sure it was you, Ron, who came blasting in here fully loaded ready to take Bill down.

Sounds to me like youre the one spouting "Typical Shitty Sarcasm"

-Ryan

[Ryan King]

Just in case you forgot Ron....


I have no doubt, if it was possible to post a warning after death, that you would blame someone who warned you when it was your hardheaded, face saving, stupidity...

:rolleyes:Typical Bill Robertson

Youre the one coming in and starting shit.

[Ron]

Just in case your forgot Ron....
Youre the one coming in and starting shit.
No, no. I came in with:

FYI- According to that link, the o-ring has a temperature range of -30° to 212° F.
Since engine oil is typically 200F hotter than radiator temps, this o-ring is not a good choice.
Where is the ""Typical Shitty Sarcasm" in that???

To which he replied:

Knock yourself out: http://www.mcmaster.com/#1182n211/=13ha0hx

I sincerely doubt the oil filler tube gets hot enough to melt rubber -- it would melt the plastic screen at the bottom.... The cap itself is made of plastic, for crying out loud.

But rest assured: if my engine blows up and kills me because of a substandard oil filler cap O ring, I will post a warning message (giving you and David full credit of course).

Bill Robertson
#5939I didn't say it would melt...and who needs the rest of that sarcastic shit??

[Ryan King]

No, no. I came in with:

Where is the ""Typical Shitty Sarcasm" in that???

To which he replied:
I didn't say it would melt...and who needs the rest of that sarcastic shit??

You started off by saying Bill is "Hard Headed" and Stupid. He simply proved you wrong by showing the engine temp...

Why youre still here...I dont know.

[Nicholas R]

For what it's worth, there is a lot of science as to why O-ring grooves are square while O-rings are round. One of the main design assumptions when designing a seal is: "The cross section of a squeezed O-ring is rectangular."

I regularly have to spec out o-rings, and I live and die by the Parker O-Ring handbook. Flip through it; you'll notice that nearly every groove shown is a square groove with a round o-ring. In some cases, you'll see a small radius to the corners of the groove, or a dovetail (trapezoidal) groove, but its almost never full round. I wont go into the details, but in a nut shell, the groove and O-ring are sized accordingly such that when compressed, the round o-ring deforms and fills the groove shape just enough to seal, but not enough to be damaged. A lot of factors go into how it deforms, such as the hardness and durameter of the o-ring, tensile and compressive strength of the material, the poissons ratio of the material (ratio of compression vs expansion), expansion and contraction due to heat, loading type, environmental conditions, and much much more.

I have no opinion on this specific application, but in a case where an o-ring was under pressure, I would certainly not be replacing a round o-ring with a square one, just because it 'seemed to fit better'. I will say however that the oil fill tube on the valve cover seems like a pretty low risk area, as do the intake ports, since your only real risk is a potential vacuum leak

If you too are interested in the O-Ring Handbook, it is linked here: Parker O-Ring Handbook (https://www.parker.com/literature/ORD%205700%20Parker_O-Ring_Handbook.pdf) :wrenchin:

[Bitsyncmaster]

This brings up a good question. Why do some applications use a square O-ring? I agree the "oil cap" on our D does tend to not hold fully seated.

[FABombjoy]

The port on the cap toward the front of the engine/car connects to the breather, which is under vacuum, not open to fresh air (when running ;-), measured, since it passes the plate. [Which is why you should plug it if playing with the CO with the breather off....]
But, the port toward the rear connects to the CSV's auxiliary air pipe, not measured. And the large port, on the bottom, has LOTS of vacuum (put your palm over it when the engine is running and you will see) for the crankcase (PCV), not measured either.
[FWIW, I doubt it would totally defeat the purge system, but it wouldn't be good.]
No?
No.

Port facing rear of car connects to CSV tube, under vacuum through fixed orifice, that is correct. Actually this is the only piece of intelligent design because any accumulated oil vapor in the CSV tube will be gasoline flushed when the CSV activates. Nice touch!

Port facing front of car is unmetered air separately provided by the air filter. This is the source of "fresh air". What you'll find is that stray oil vapor will still make its way down this tube which is why one corner of the air filter is always a bit grungier than the rest.
44928

From a fueling standpoint you cannot really have an unmetered vacuum leak at the oil cap. Depending on load / MAP / blowby you might even see crankcase gases flow through the air filter and back into the metered air stream.

[content22207_2]

FWIW:

High side on the A/C compressor is under a lot of pressure (more than 300 PSI on a hot day). And the groove is square. I have used one of these O rings in that application for many years no problem: http://www.mcmaster.com/#4061t233/=13hqpyj

Bill Robertson
#5939

[Ron]

No.

Port facing rear of car connects to CSV tube, under vacuum through fixed orifice, that is correct. Actually this is the only piece of intelligent design because any accumulated oil vapor in the CSV tube will be gasoline flushed when the CSV activates. Nice touch!
But if the o-ring is bad, air can go past o-ring>bottom of cap>forward port>aux pipe>manifold, which connects downstream of the air plate, so not measured.
No?
(I sold 1669 so I can't look and see if/where I have it wrong...)


Port facing front of car is unmetered air separately provided by the air filter. This is the source of "fresh air". What you'll find is that stray oil vapor will still make its way down this tube which is why one corner of the air filter is always a bit grungier than the rest.
...I with you...similar to carbed systems that have a tube going to a 2nd little filter mounted inside the the breather. Flow direction depends on blowby...as I assume you know the crankcase pressure can go positive on a severely worn engine and blow the PCV valve out of the valve cover....

I think we are together, except the part about the CSV's auxiliary pipe being downstream of the measuring plate...
Maybe I should say, yes, the one would be metered, but not measured by the plate... (And yeah, it would be small;-)

[David T]

One of the main reasons you see square grooves for round "O" rings is that it is just easier to make a square groove. If a round "O" ring should twist as it is installed it doesn't affect the sealing as much as if a square ring was to get twisted. A properly sized "O" ring should be compressed and is no longer round but oblong when actually sealing. Age and temperature tends to shrink them so they no longer seal as well. They also get hard and are no longer as resilient. Remember the Space Shuttle? As loose-fitting as the fill may become with an old "O" ring, I don't see them leaking much vacuum and even it they leak the orifice in the cold start tube maintains a constant vacuum from the motor so it doesn't affect idle as Bill said. The only problem I have seen is when you have turbos and you blow the piston lands, when the turbos kick in it blows the oil fill right out with a LOT of oil! I doubt Bill's rings are going to fix that! As for temps, it does get hot there. In fact, when we inspect Deloreans we look inside and if the plastic screen is missing or melted we know the motor got overheated and probably needs head gaskets.

[FABombjoy]

I think we are mostly together :D

The fixed orifice present in the CSV tube vacuum port is always consuming unmetered air. If you pinch that hose while running the idle will change.

If the oil cap has no O ring, some of that unmetered air may be slightly fresher than normal and some oil vapor may escape the cap. And as Dave pointed out earlier, rain (or car wash) water could enter the valve cover and that is probably the best purpose it serves.

Some crankcase vapor may enter the metered air stream depending on MAP and crankcase pressure.

If the fresh air inlet connected to the passenger side valve cover, this system would be improved. Then you would have bona-fide fresh air circulation throughout the block and it would start to resemble a modern PCV system.

[Nicholas R]

FWIW:

High side on the A/C compressor is under a lot of pressure (more than 300 PSI on a hot day). And the groove is square. I have used one of these O rings in that application for many years no problem: http://www.mcmaster.com/#4061t233/=13hqpyj

Bill Robertson
#5939

FWIW, 300psi is not considered a lot of pressure in the o-ring world.

[Ron]

You started off by saying Bill is "Hard Headed" and Stupid. He simply proved you wrong by showing the engine temp...

Why youre still here...I dont know.
No, as a reply to HIM starting off with his sarcasm, I reacted in kind that he "would blame someone who warned [him] when it was [his] hardheaded, face saving, stupidity... Big difference than the way you paint it!

Since you didn't show where you feel I was sarcastic etc in my first post, as asked, and his reply was nothing but false implications (...melting) and sarcasm (blowing up, dying, and posting after death, 'for crying out loud'), we'll have to agree to disagree, because I think his typical unwarranted sarcasm started the BS. That's the way it has been for years, and not just with me, but with anyone who makes any comment about anything he posted for years. One can politely ask for clarification on something that seems confusing, come right out and say they don't mean to step on toes, use "IMO", "IMHO", "$.02", etc... and off he goes. (Why do you think he has been permabanned from so many sites???) I happen to be one who doesn't care to ignore it, not over and over (although I probably should ;-)

P.S. FWIW, he only showed that a just warmed up engine was only 80 degrees away from the temp limit near the o-ring...too close for what it would actually be on a long trip already, imo --- all over pennies.

======

I have no problem with a little tit-for-tat, but I think it is past time for the off topic discussion to go to PM.

[Ron]

I think we are mostly together :D

The fixed orifice present in the CSV tube vacuum port is always consuming unmetered air. If you pinch that hose while running the idle will change.

If the oil cap has no O ring, some of that unmetered air may be slightly fresher than normal and some oil vapor may escape the cap. And as Dave pointed out earlier, rain (or car wash) water could enter the valve cover and that is probably the best purpose it serves.

Some crankcase vapor may enter the metered air stream depending on MAP and crankcase pressure.

If the fresh air inlet connected to the passenger side valve cover, this system would be improved. Then you would have bona-fide fresh air circulation throughout the block and it would start to resemble a modern PCV system.

Yes! Actually, totally agree, if I read correctly:devil:

======

Now that's the way discussions should go...

[content22207_2]

Box of 50 envelopes costs $5.31 (5 cents per).

Postage is two stamps (94 cents).

O rings are $8.36/25 (33 cents per).

Penalty for everyone giving me a bunch of crap is 68 cents.

If you want one of these O rings, put $2 in an envelope and mail it to:

Bill Robertson
909 W Scotsdale Road
Laurinburg, NC 28352

Make sure a correct return address in on the envelope -- that is where I will mail the O ring back to.

Bill Robertson
#5939

[krs09]

I've got 24 more of the things -- anybody want to render an independent assessment? I'll sell them for cost plus postage (and the envelope).

Bill Robertson
#5939

These are the ones for the oil filler cap right?? I odered some of the o rings and they sent me the ones for the ac compressor (ugh). If they are right but me down for one.. Can I get a link for the correct size o-ring? Pretty please.

[Ron]

...
Penalty for everyone giving me a bunch of crap is 68 cents. I'll send you a $1.00 if you want :smile:.
...or we can call it even and end ALL of he BS once and for all.
What ya say Bill?

[content22207_2]

Penalty for everyone giving me a bunch of crap is now 69 cents.

Bill Robertson
#5939

[Ron]

:rofl:

[Chris 16409]

Box of 50 envelopes costs $5.31 (5 cents per).

Postage is two stamps (94 cents).

O rings are $8.36/25 (33 cents per).

Penalty for everyone giving me a bunch of crap is 68 cents.

If you want one of these O rings, put $2 in an envelope and mail it to:

Bill Robertson
909 W Scotsdale Road
Laurinburg, NC 28352

Make sure a correct return address in on the envelope -- that is where I will mail the O ring back to.

Bill Robertson
#5939

Shall I send you $3 for two o-rings?

[content22207_2]

Should be 3-4 stamps for 2 O rings.

At $3 you will be getting a tremendous discount on the crap penalty.

Bill Robertson
#5939

[Chris 16409]

Should be 3-4 stamps for 2 O rings.

At $3 you will be getting a tremendous discount on the crap penalty.

Bill Robertson
#5939

Mailed you my money for the o-rings. Thanks Bill.

[DMCMW Dave]

Penalty for everyone giving me a bunch of crap is now 69 cents.

Bill Robertson
#5939

Most businesses would call that profit. It's not a dirty word.

I'm surprised nobody has complained about Bill selling a 33 cent o-ring for $2 (without analyzing the costs).

[content22207_2]

Post #48. Envelope and postage are 99 cents alone.

Why in the world does everybody expect me to work for free?

And with all due respect, DMC Midwest isn't exactly in the charity business -- you all just charged me $18 to ship about $30 of parts (*THAT'S* one major reason why I xRef so much of my car from Autozone...).

Bill Robertson
#5939

[mluder]

For what it's worth, there is a lot of science as to why O-ring grooves are square while O-rings are round. One of the main design assumptions when designing a seal is: "The cross section of a squeezed O-ring is rectangular."


Sure... the o-rings on the intake are round but the machined grooves are square as another example.

Cheers
Steven

[mluder]

I agree the "oil cap" on our D does tend to not hold fully seated.

If I recall correctly it does once the engine starts up... There's a pretty good vacuum there that tends to suck it down.

Cheers
Steve

[content22207_2]

So much controversy over a simple O Ring. Thank goodness nobody mentioned it at either of the political party conventions.

If you all want to continue using round O Rings, knock yourselves out. I like square ones, but I appear to be a minority on this forum. Obviously somebody somewhere feels the same way I do otherwise McMaster wouldn't sell them.

A couple of owners have PM'd me that they're sending a couple of bucks to try themselves, but nothing's showed up in the mail yet. No sweat -- O Rings and envelopes are sitting on the shelf. They won't go bad. Envelopes are an odd size (like for a wedding invitation, but I don't plan on getting married anytime soon) -- I'll find a use for them eventually.

Bill Robertson
#5939

[Bitsyncmaster]

If I recall correctly it does once the engine starts up... There's a pretty good vacuum there that tends to suck it down.

Cheers
Steve

But the large hose is just open to the air cleaner.

[DMCMW Dave]

And with all due respect, DMC Midwest isn't exactly in the charity business -- you all just charged me $18 to ship about $30 of parts (*THAT'S* one major reason why I xRef so much of my car from Autozone...).

Bill Robertson
#5939

Never said it was a charity. . .

BTW shipping is probably close to break-even, definitely a loss if you figured the hourly cost of Suzy/Julee. We recycle about 99% of the shipping materials (which is why sometimes you get stuff in Amazon boxes, and usually with DMCH tape on them). UPS and FedEx have had some pretty astounding rate increases in the past year, especially considering fuel is cheaper.

[Ryan King]

Mailed you my money for the o-rings. Thanks Bill.

My money is in there too! I bought one.

[DMCMW Dave]

I can't believe this o-ring generated 62 (now 63) posts. The internets at its best!

[content22207_2]

61 posts were people telling me square O Rings don't work.

May I humbly suggest the lowly Post Office. My order would have fit into a small flat rate box for $6.80. You can print postage at the office and schedule a pickup just like UPS.

Bill Robertson
#5939

[refugeefromcalif]

I need to get my head around what seal type is actually being discussed. Are we talking about actual Square seals or, what are known as Quad rings?
Here's the cross section of a Quad ring.

http://daemar.com/wp-content/uploads/2013/09/dmr-o-rings-quad-rings-render-profile.jpg

George

[content22207_2]

http://images1.mcmaster.com/mvB/contents/gfx/large/j05-oring-square-dark-c1l.png?ver=1409840408

(McMaster illustration)

Bill Robertson
#5939

[DMCMW Dave]

61 posts were people telling me square O Rings don't work.

May I humbly suggest the lowly Post Office. My order would have fit into a small flat rate box for $6.80. You can print postage at the office and schedule a pickup just like UPS.

Bill Robertson
#5939

All you have to do is ask for it and accept the risks and the time delay.

Cost depends on what is shipping, the post office is more expensive when stuff gets bigger. They also lose a lot more shipments.

[Ron]

I'm surprised nobody has complained about Bill selling a 33 cent o-ring for $2 (without analyzing the costs).
Seemed he thought I did both (but I wouldn't call it complaining since I did't want one) to no avail.:deviltail:


...and the fact that, if you take the old one to most any auto parts and ask for a larger one, a dollar would pay for both, WTH!

I still love ya', Bill.


:rofl: A stamp and envelope would cost more....


Let me rephrase that:

Why pay more for an envelope and postage than a superior part costs (the next time you pass an auto parts store w/o the wait....)?

[Ron]

But the large hose is just open to the air cleaner....and the engine is pulling a few hundred CFM through the air cleaner.
Lots of vacuum...you know, Dave?!?

[FABombjoy]

...and the engine is pulling a few hundred CFM through the air cleaner.
Lots of vacuum...you know, Dave?!?
No, I even posted a picture of how the air cleaner assembly is set up internally! The fresh air tube is fed from a separate portion of the filter element :tongue2:

Under very high load, a draw-through turbo (BAE/Island) car may outflow the air cleaner/distributor assembly and draw the air inlet tube into vacuum assuming a low amount of blowby combined with a check valve on the vacuum line. None of the kits came with a check valve and they work to pressurize the crankcase & fresh air tube. I suspect that under high load CC pressure is actually flooding the fresh air tube and feeding oil vapor/blowby gasses (OR fresh, clean compressed air) into the engine air intake.

See attached log snip from my own draw-through turbo car. MAP values on this recording are taken at throttle edge tap. You can see MAP drop about .1 bar over atmosphere at higher load (about 6psi at peak) and under these circumstances the fresh air inlet could be drawn into mild vacuum if the CC isn't pressurized (which is extremely unlikely) or if the O ring was left out.

The O ring keeps vapor in and water out.

[David T]

No, I even posted a picture of how the air cleaner assembly is set up internally! The fresh air tube is fed from a separate portion of the filter element :tongue2:

Under very high load, a draw-through turbo (BAE/Island) car may outflow the air cleaner/distributor assembly and draw the air inlet tube into vacuum assuming a low amount of blowby combined with a check valve on the vacuum line. None of the kits came with a check valve and they work to pressurize the crankcase & fresh air tube. I suspect that under high load CC pressure is actually flooding the fresh air tube and feeding oil vapor/blowby gasses (OR fresh, clean compressed air) into the engine air intake.

See attached log snip from my own draw-through turbo car. MAP values on this recording are taken at throttle edge tap. You can see MAP drop about .1 bar over atmosphere at higher load (about 6psi at peak) and under these circumstances the fresh air inlet could be drawn into mild vacuum if the CC isn't pressurized (which is extremely unlikely) or if the O ring was left out.

The O ring keeps vapor in and water out.

CC pressure/vacuum depends a lot on how much leakage there is from the valve seals and the rings. The CC is supposed to be kept under constant vacuum so oil fumes and blow-by do not go right out to the atmosphere, instead getting drawn into the intake and burnt up in the motor. You are correct, there is no check valve, only an orifice, even in the commonly available turbo kits. Pressurizing the induction does all kinds of things like negating any vacuum advance, pressurizing the vapor canister, raising line pressure in the automatic, deactivating the vacuum actuators for the A/C system (good thing it has a reservoir to operate for a while!). Same goes for the power brakes but I don't think you will be using the brakes when you have boost pressure! Anyway, if you do have excessive leakage it should only be for a short burst. On one car, whenever he went into boost he would blow that cap right out and shoot motor oil all over the engine! He had blown the lands on the pistons from too much boost and had excessive blow-by. That pressure also tricks the CPR into enriching the fuel too. I doubt the people who put the turbos on in the first place considered the turbo's effects on all of the vacuum systems.

[content22207_2]

Just mailed two O Rings to an owner in Idaho (let me know if they don't show up by next weekend).

What I thought was additional postage due to weight is actually a thickness surcharge. Two O Rings cost the same to ship as one -- 68 cents at the Post Office or two stamps from the house (94 cents).

That means I just made an obscene $1.66 profit. Oops. But I don't feel too bad because DMC Midwest has the audacity to charge $3.45 for a single A/C compressor O Ring (plus their hefty UPS shipping charge). No telling how much they'd want for one of these O Rings because they don't offer them separately, just as part of a $65 oil cap assembly. Midwest wants $1.56 for an intake manifold O ring, so it doesn't bode well (intake manifold O rings are 1/8" thick -- these are 3/16").

Bill Robertson
#5939

[Ron]

No, I even posted a picture of how the air cleaner assembly is set up internally! The fresh air tube is fed from a separate portion of the filter element :tongue2:
LOL Sorry. But the pic only shows the hose's tube removed and only half of the breather... Maybe it's staring me in the face and I can't see it, but I just don't, and don't have a D at the moment to look at.
My thinking, in what I see as a common sense approach is: I know that crankcase fumes are not allowed to be turned loose into the atmosphere, they are drawn, along with fresh air and burned...and that the hose in question carries them to the breather. The breather is virtually sealed up, except the inlet, so anything (including the hose) connected to the breather will be under (some) vacuum, no matter where it terminates inside. Depending on where, I can see it not being as much as I think it is (If so, SORRY, Dave! ;-).


The O ring keeps vapor in and water out.

All this drove me back to the question of whether a bad o-ring at the oil fill cap can cause an unmeasured vacuum leak or not. (I wasn't sure if metered/measured might be what you meant by " we're mostly together" and when I saw this post, I look another look in the manual.) You were right about a metering hole, but, there would be unmetered air:

"An air leak in the engine crankcase will cause a lean running condition since the crankcase is connected to the intake manifold. Possible air leaks could be the oil dip stick not installed completely, oil filler cap not sealing properly, or leaking engine gaskets." (WSM D:06:03, b.)

===========

(Dang, I hate not having a D now, second guessing myself:frantic:, so just in case, I like Tabasco sauce and salt with my crow ;-)

[Ron]

Just mailed two O Rings to an owner in Idaho (let me know if they don't show up by next weekend).

What I thought was additional postage due to weight is actually a thickness surcharge. Two O Rings cost the same to ship as one -- 68 cents at the Post Office or two stamps from the house (94 cents).

That means I just made an obscene $1.66 profit. Oops. But I don't feel too bad because DMC Midwest has the audacity to charge $3.45 for a single A/C compressor O Ring (plus their hefty UPS shipping charge). No telling how much they'd want for one of these O Rings because they don't offer them separately, just as part of a $65 oil cap assembly. Midwest wants $1.56 for an intake manifold O ring, so it doesn't bode well (intake manifold O rings are 1/8" thick -- these are 3/16").

Bill Robertson
#5939Pardon me for asking, but will the $1.66 be credited toward any penalty for the next bunch of crap someone gives you??

[DMCMW Dave]

But I don't feel too bad because DMC Midwest has the audacity to charge $3.45 for a single A/C compressor O Ring (plus their hefty UPS shipping charge). No telling how much they'd want for one of these O Rings because they don't offer them separately, just as part of a $65 oil cap assembly. Midwest wants $1.56 for an intake manifold O ring, so it doesn't bode well...


You're lucky we don't add the "giving me crap" charge.

[FABombjoy]

You were right about a metering hole, but, there would be unmetered air:
It's all unmetered. It's a controlled vacuum leak compensated for by the idle system and CO setting. The O ring has no bearing on the metering.

For it to be metered air the fresh air supply would have to be below the metering plate.

[content22207_2]

I know that crankcase fumes are not allowed to be turned loose into the atmosphere, they are drawn, along with fresh air and burned...and that the hose in question carries them to the breather.

Other way around. Air passes from the breather, through the oil filler cap, thence into the cold start tube (where the calibrated nipple is -- PRV's substitute for a proper PCV valve).

Imagine normal PCV condensed into the oil filler cap. Normal engine pulls air from the breather into one valve cover, then from the other valve cover into the engine. PRV does the same thing on one side of the engine.

Bill Robertson
#5939

[content22207_2]

You're lucky we don't add the "giving me crap" charge.

Kind of hot in the kitchen?

You were the one who questioned my costs (already accounted for in Post #48, thank you very much).

Then I looked at the price of your O Rings....

Bill Robertson
#5939

[Soundkillr]

Yeah bill, clearly a dmc vendor is the problem....:dunno: