Might be time to fix 5-speed leaks

[Stainless]

Hi all,

Long time owner here. The only maintenance I've had to do for my 5-speed manual up to this point is replace the gear oil, slave, and master cylinders. The clutch line was already a SS braided line, thanks to the PO. While under the car recently, as I prepare to replace the original accumulator, I noticed the 5-speed is looking really crusty, meaning there have been unaddressed leaks occurring for a long time.

645876458864589

I am mentally preparing to drop the tranny and address this long-neglected piece of equipment. I'd like to address all possible issues while I have it out, including anything that should be done internally. I'm confident that the rear main seal is contributing to some of the crustiness, as well as the seals for the output shafts. I'm looking to do it all, but not sure of all the issues or maintenance items I should address while I'm in there.

For context, the transmission performs very well. It shifts a little rough from 1st to 2nd when cold, but if weren't for the visible leaks, I would have no other reason to do this. The clutch is likely original. The car has around 53k miles.

What all should I plan on addressing?

[Mark D]

Looks like your transmission is doing an excellent job of incrementally disbursing rust preventative solution to your engine crossmember :D

Mine was doing the same when I first bought the car and the first thing I was told to check was the breather/vent on top of the transmission. It is known to get plugged and cause positive pressure to build inside the trans case when operating. After cleaning out the plugged vent the amount of gear oil leaking seemed to decrease, and after giving the transmission a good degreasing I was able to diagnose the leak as coming from one of the output shaft seals.

Before committing to pulling the entire trans out you may want to start with checking the vent and cleaning everything off really well to help pinpoint the leak.

If you end up pulling the trans it would make sense to replace the clutch while you're in there if it hasn't been done before. Same goes with the usual stuff you'd replace with the clutch like the throw out bearing, and possibly the shift fork/shift fork boot if they are deteriorated. With the trans pulled it may also be worthwhile to replace the 2nd gear selector shaft roll pin with a reinforced pin since they like to shear off and leave the trans with a spongy feeling downshift from 3rd to 2nd.

There is also a large nut on the end of the transmission for 5th gear that has been known to back itself off slowly and machine itself a hole through the end of the cover. Might be worth checking that as well and adding some red loctite.

[David T]

Unless you have other issues with the transmission, I would not pull it to fix some minor leaks. Get some Gunk and wash it. Even after you pull it and "fix" the leaks, you may still have some leakage.

[Josh]

Im no expert but it looks like you need new axle flange seals and a rear main seal for the engine. Both are common failure seals.
David, If you call this a minor leak I am scared to see what a major one is.

You do not need to disassemble the transmission to get to these seals but if you are taking it apart, It is common to replace all the internal roll pins and check over the bearings syncros. If you are planning for more power install a input shaft coupler. Inspect the 5th gear retaining nuts and re-install with red lock tite and stake the nut. Put the box back together with all new seals. This would also be a perfect time to replace the clutch, pressure plate, throw-out bearing, slave cylinder, and resurface the flywheel.

[FABombjoy]

rear main seal for the engine. Both are common failure seals.
It's worth cleaning the flame trap & ensuring PCV isn't blocked before figuring on replacement of the rear main seal.

Rear main seems like the first place excess crankcase pressure is noticed. For some reason the dipstick holds CC pressure better.

Years ago my trans looked a lot like the above, including the rear main leak. After new lip seals, flange repair, and improved PCV, all is dry!

[powerline84]

I had the same results as Luke. After converting to efi and modifying the pcv system and actually adding a pcv valve my leaks went down. I was pretty surprised.

[82DMC12]

It's worth cleaning the flame trap & ensuring PCV isn't blocked before figuring on replacement of the rear main seal.

Rear main seems like the first place excess crankcase pressure is noticed. For some reason the dipstick holds CC pressure better.

Years ago my trans looked a lot like the above, including the rear main leak. After new lip seals, flange repair, and improved PCV, all is dry!

Sorry to resurrect but what do you mean by the "flame trap" and the PCV? I know what a PCV valve is but didn't think our cars had anything like that. Does it have something to do with the hose that that connects the oil filler cap to the CSV? Or the hose that connects the black air filter cover to the oil filler cap?

[FABombjoy]

Sorry to resurrect but what do you mean by the "flame trap" and the PCV? I know what a PCV valve is but didn't think our cars had anything like that. Does it have something to do with the hose that that connects the oil filler cap to the CSV? Or the hose that connects the black air filter cover to the oil filler cap?
The oil cap contains a stainless or brass metal matrix. It's not on the maintenance schedule but should probably be cleaned at each oil change. It's really an air-oil separator that's not particularly effective, and even worse once it builds up junk. Volvo calls it the "flame trap" so backfires don't enter the crankcase.

Not my pic but a great example of what these can look like under the worst of circumstances
66748

DeLorean PCV is a fixed orifice type system rather than PCV valve. A small orifice in the cold start tube provides best PCV at or near idle and light engine loads, and the big rubber hose to the airbox during medium & high load. The big tube is sometimes called the "fresh air inlet" but I'm skeptical that you can have anything resembling air move in to the crankcase with vacuum on the opposite side of the cap. You'll notice that your air filters get oily just above the plastic tube internal to the filter box.
66749

Fixed orifice types are K-jet compatible as they are a consistent "leak" downstream of the meter plate and the CO adjustment can be made around them. A traditional PCV valve would be preferred but K-jet can't compensate for the variable flow rate of a valve. Carburetors and EFI installations can.

[82DMC12]

The oil cap contains a stainless or brass metal matrix. It's not on the maintenance schedule but should probably be cleaned at each oil change. It's really an air-oil separator that's not particularly effective, and even worse once it builds up junk. Volvo calls it the "flame trap" so backfires don't enter the crankcase.

Not my pic but a great example of what these can look like under the worst of circumstances
66748

DeLorean PCV is a fixed orifice type system rather than PCV valve. A small orifice in the cold start tube provides best PCV at or near idle and light engine loads, and the big rubber hose to the airbox during medium & high load. The big tube is sometimes called the "fresh air inlet" but I'm skeptical that you can have anything resembling air move in to the crankcase with vacuum on the opposite side of the cap. You'll notice that your air filters get oily just above the plastic tube internal to the filter box.
66749

Fixed orifice types are K-jet compatible as they are a consistent "leak" downstream of the meter plate and the CO adjustment can be made around them. A traditional PCV valve would be preferred but K-jet can't compensate for the variable flow rate of a valve. Carburetors and EFI installations can.

Interesting and thanks for the education! I assume the metal mesh could be cleaned with mineral spirits and the fixed orifice cleared out with some compressed air. I'll have to take a look at these (as well as the breather hole on my manual trans).

[Azar]

Hello, I am new to this please accept my ignorance. I have a similar picture and leaks as the thread starter. The Gearbox is dismantled and we are planning to change all the seals but also the front and back cover gaskets.
I was trying to find more information on the PCV bit couldn't. I presume it is Pressure Control Valve? Can someone pint me at the article which explains it exactly or probably point at the pats schematic so I can check it? The engine is disassembled, too. Thank you!

Gesendet von meinem Mi 9T mit Tapatalk

[Bitsyncmaster]

Hello, I am new to this please accept my ignorance. I have a similar picture and leaks as the thread starter. The Gearbox is dismantled and we are planning to change all the seals but also the front and back cover gaskets.
I was trying to find more information on the PCV bit couldn't. I presume it is Pressure Control Valve? Can someone pint me at the article which explains it exactly or probably point at the pats schematic so I can check it? The engine is disassembled, too. Thank you!

Gesendet von meinem Mi 9T mit Tapatalk

I'm pretty sure PCV stands for positive crankcase ventilation. Back in the old days all engines just used a pipe that extended down under the engine which was cut to draw a very slight vacuum from the air flowing past the pipe as you drove the car.

[FABombjoy]

Interesting and thanks for the education! I assume the metal mesh could be cleaned with mineral spirits and the fixed orifice cleared out with some compressed air. I'll have to take a look at these (as well as the breather hole on my manual trans).
Spirits, brake cleaner, anything like that should work. The orifice is just a hole in a tube and normally maintenance free. There are two of these in the cold start tube, one for PCV and one for the vapor canister. If you remove either small vacuum hose you can see inside and IIRC both have the same orifice diameter. It's a pretty simple way to allow engine vacuum to draw out blowby gasses without burning excessive quantities of oil vapors.

[82DMC12]

Spirits, brake cleaner, anything like that should work. The orifice is just a hole in a tube and normally maintenance free. There are two of these in the cold start tube, one for PCV and one for the vapor canister. If you remove either small vacuum hose you can see inside and IIRC both have the same orifice diameter. It's a pretty simple way to allow engine vacuum to draw out blowby gasses without burning excessive quantities of oil vapors.

Oh, OK so the orifice is actually on the CSV tube. Is there anything to clean inside the air filter box cover?

[David T]

Oh, OK so the orifice is actually on the CSV tube. Is there anything to clean inside the air filter box cover?

Just wipe it out and if necessary replace the air filter. It usually gets oily where the small hose connects in at the top. Also inspect the air sensor plate and venturi. If it is dirty, wipe it clean. Make sure the air sensor plate is not touching the sides as it moves and it should move freely after the fuel pressure drops.

[Azar]

Hi, can someone post the part numbers of PCV and the tube with CSV, I will then find them in the catalogue. I am still lost :) Thank you!

Gesendet von meinem Mi 9T mit Tapatalk

[Ron]

Hi, can someone post the part numbers of PCV and the tube with CSV, I will then find them in the catalogue. I am still lost :) Thank you!

Gesendet von meinem Mi 9T mit Tapatalk
A PCV valve goes in the valve cover on some cars, they are NOT used on a Delorean.

See #1(CSV) and #6(tube):
https://store.delorean.com/parts/fuel-emissions/2-2-1-cold-start-valve-thermotime-switch.html

See: Workshop Manual (http://dmctalk.org/showthread.php?2866-Searchable-Workshop-Technical-Bulletins-and-Volvo-Engine-Manuals) pages D:06:02-D:06:03
(Has a sealed crankcase, and uses CCV Closed Crankcase Ventilation.)

[David T]

A really quick and simple test of the ventilation system is to take a piece of paper and place it over the oil fill while the motor is running. If it doesn't stay put, either the system is not working or you have very worn piston rings. If the motor isn't burning oil it isn't the rings. Rare for anything to go wrong with the ventilation system unless someone modified it (it's SO simple!). On cars with boosted induction (a turbocharger or supercharger) it isn't unusual to find broken piston rings and piston lands creating excessive crankcase pressure.

[Ron]

A really quick and simple test of the ventilation system is to take a piece of paper and place it over the oil fill while the motor is running. If it doesn't stay put, either the system is not working or you have very worn piston rings.
Doesn't it quit working when you remove the oil fill cap??

[Azar]

A PCV valve goes in the valve cover on some cars, they are NOT used on a Delorean.

See #1(CSV) and #6(tube):
https://store.delorean.com/parts/fuel-emissions/2-2-1-cold-start-valve-thermotime-switch.html

See: Workshop Manual (http://dmctalk.org/showthread.php?2866-Searchable-Workshop-Technical-Bulletins-and-Volvo-Engine-Manuals) pages D:06:02-D:06:03
(Has a sealed crankcase, and uses CCV Closed Crankcase Ventilation.)Thanks! Since the parts are lying here in my house I checked them all, they are good.

Just struggling to link this all to the 5 Speed Gearbox oil issues.

I was in the workshop today and inspected my gearbox (it is not disassembled yet). I did not find any valves or breathers on it. May be I am searching wrong?

Also the mechanic replaced the rear crankshaft seal and said that there was a wrong one installed, smaller than should be (it was a black colour). The new ones are brown.https://uploads.tapatalk-cdn.com/20210710/0427cf6e48f6574a060d912b37d923c2.jpg

Gesendet von meinem Mi 9T mit Tapatalk

[Ron]

Just struggling to link this all to the 5 Speed Gearbox oil issues.

I was in the workshop today and inspected my gearbox (it is not disassembled yet). I did not find any valves or breathers on it. May be I am searching wrong?
There is a vent hole in the top of the transmission that Mark mentioned that needs to be clean -- That's all there is for it.
The crankcase ventilation, valves, vacuum, etc. have nothing to do with the manual trans.

[Azar]

Thanks Ron, as usual, for clarifying patiently to me :)
Next time I am in the workshops will inspect.

Gesendet von meinem Mi 9T mit Tapatalk

[Azar]

Hello, we have searched for the breather hole in the gearbox but did not find it. Perhaps someone can point in the right direction? Thanks!

Gesendet von meinem Mi 9T mit Tapatalk

[DMC-81]

Hello, we have searched for the breather hole in the gearbox but did not find it. Perhaps someone can point in the right direction? Thanks!

Gesendet von meinem Mi 9T mit Tapatalk

Hi there,

Here is where it is located (red arrow):

http://dmctalk.org/attachment.php?attachmentid=66958&d=1627930597

Here is the part number:
http://dmctalk.org/attachment.php?attachmentid=66959&d=1627930671

and breather installed:
http://dmctalk.org/attachment.php?attachmentid=66960&d=1627930708

[Azar]

Many thanks! Will check tomorrow, hopefully he did not mount the gearbox in the car yet...

Gesendet von meinem Mi 9T mit Tapatalk

[DMC-81]

Many thanks! Will check tomorrow, hopefully he did not mount the gearbox in the car yet...

Gesendet von meinem Mi 9T mit Tapatalk

You are quite welcome.