PCV Catch Can

[Dutch]

I’m looking at installing a PCV catch can.

I’ve done some research and it could boost performance and keep the engine cleaner. Has anyone have any experience doing this? The reason I’m looking into his is:

After having owned my delorean for a few months now and having tried to get it running right (issues from bad wiring, vacuum leaks, ruptured fuel lines), I’ve decided to do a full engine rebuild.

engine vin1729.jpg

I took the dissembled engine to a local performance shop (for the Tampa Bay area I would recommend Ray's Performance Machine Shop). They hot dipped the engine to clean it, honed the piston liners, reseated the valves, and resurfaced the headers (with valuable insight from John at SpecialTAuto). As they completed the work they mentioned that my headers and block had been modified (enlarged ports, upgraded racing studs etc).

When I bought the car the PO advertised it with DMC California performance cam shafts and Special T automotive performance headers, I initially to no notice of it (I was a happy new delorean owner). However now I wanted to know more about it. After using my best friend on the net Google looking for the performance cams I discovered the following post:

http://www.projectvixen.com/dmcnews-.../msg79587.html

Well, that’s the car I have now.

I’m still in the process of the rebuild and currently buying all new seals, gaskets, bearings, fuel lines, master slave, clutch (looking at stage III clutch from specialTauto because of the performance, does anyone have any experience) and other parts.

So when I took the engine apart I noticed that all the vacuum lines where lined and filled with smudge and oil, the rest of the components too, so there is definitely contamination. I was hoping that perhaps installing a catch can eliminate this. Below is a youtube of how and what:

https://www.youtube.com/watch?v=3KrSn3BoeLE

Also any advice on the next part, the reassembly, would be greatly appreciated.

Thanks

Dutch

[sdg3205]

Interesting.

We don't have PCV's though. Would you tap each valve cover and somewhere on the intake to create a system?

[DMC5180]

Interesting.

We don't have PCV's though. Would you tap each valve cover and somewhere on the intake to create a system?

Not the kind most people are familiar with. The oil fill cap is the PCV. That's why the hose is connected to the air cleaner.

[sdg3205]

Ah yes, of course. Does it work properly as a pcv for both cylinder banks? I have always felt the seal to be a little lacking.

[DMC5180]

Technically, yes. The oil drain passages in the head and timing chain cover area are equalized crankcase pressure areas.

the O-ring seal does seem marginal at best. I installed a new o-ring in the past and even then it wasn't what I would call seal tight. Positive Crankcase Vent just means the negative pressure created in the intake of the running engine draws positive crankcase blow by gases in the engine for recycling. There is a slight vacuum in the crank case. So maybe that's why the simple o-ring seal on the cap works.

On a piston aircraft engine the CrankCase vents to atmosphere overboard.

Dennis

[sdg3205]

I don't recall ever seeing any oil in the tube to the intake. Either the filter on the cap is really good at doing its job or the system doesn't operate like a modern pcv.

[DMC5180]

There is the other small vacuum hose that connects to the CS brass tube. On my engine it definitely has oily crankcase gases going through it. My Blue silicone hose has turned brown and seems like it oozes engine oil through the material. Probably incompatible material for the application.


Dennis

[Bitsyncmaster]

There is the other small vacuum hose that connects to the CS brass tube. On my engine it definitely has oily crankcase gases going through it. My Blue silicone hose has turned brown and seems like it oozes engine oil through the material. Probably incompatible material for the application.


Dennis

Mine does the same. I was considering not using silicone hose on that one hose. By the way, I did try to use PCV via tapping the passenger side valve cover. It ended up pulling to much oil into the intake and the exhaust would burn your eyes. So if you do a PCV, make sure you have a really good baffle to limit oil flowing.

[Dutch]

In doing some additional research if found the following post on PCV (http://dmctalk.org/archive/index.php/t-7246.html - Credits to David Teitelbaum)

According to information on this PCV system air is drawn from the air cleaner through the oil cap and then routed into the intake manifold (using its vacuum).

Although vacuum in the intake manifold is used to create a flow from the air cleaner via the oil cap to the intake manifold, it doesn't mean there's a vacuum inside the crank case.
The air flow created by the intake manifold vacuum is only used to draw (blow-by) vapors from the crank case.
If there was a vacuum inside the crank case, the vapors would stay inside the crank case.

So, there is a vacuum.

In the strictest sense the crankcase is not under vacuum. There is air flow, enough to keep the crankcase at atmospheric. Air is going in to replace the air being removed. Positive Crankcase ventilation means the air is being forced (directed) as opposed to the earlier type of ventilation, an air tube usually coming off of the highest point of the motor, generally a valve cover and any pressure being expelled to the atmosphere. In PCV that air is run through the motor so any hydrocarbons can be burned. Most manufacturers use a calibrated orifice AND a check valve to prevent any blow-back from a back-fire. The Delorean only has the calibrated orifice. Too much vacuum and you suck oil in from the valve stem seals.

In my case the contamination might have been just the whole system not taken care of. I'll look in to the vacuum hose that connects to the CS brass tube and see what goes on there.

Again any suggestions, advice I can get on the rebuild would be appreciated.

[dn010]

My original engine had 70K+ miles on it and did not have any kind of deposits or build up/sludge, however as mentioned; my once blue silicone hose changed color due to residue and that is about all. You are more than likely correct in that the poorly maintained system caused your issues, I'm sure vacuum leaks diminish the amount of air being pulled from the crankcase which would lead to sludge.

In my case the contamination might have been just the whole system not taken care of. I'll look in to the vacuum hose that connects to the CS brass tube and see what goes on there.