Sucking oil through the PCV?

[UncleDave]

OK, here's the background: A long time ago, when my '84 GN was still a Hot Air (actually, 3 months ago), it would blow smoke on startup. It would be worse if it sat for a while after running for a long time. Only smoked at startup, never anything noticeable while driving. The engine had 70k on it, so I figured either turbo or valve guides.

Fast forward to the present. Engine has been rebuilt, heads have been refreshed, new valve guides, brand new turbo, but still smokes on startup exactly as it used to before the rebuild. Now I'm pi$$ed that I spent all that coin on a new build that's fubar'ed, I feel like a fool and the car looks like an embarrassing turd because it smokes when I start it up.

Since I am loathe to spend any more money fixing what should have been a proper head job to begin with, I decide to go hunting for where the oil is coming from. Easiest thing first, I check PCV hose and lo, the hose was wet from oil. I wondered if the oil is being sucked into the TB and intake, so I checked the plenum and sho 'nuff, oil in the plenum. I'm guessing that oil is being sucked into the intake and is draining down into the intake runners, hence the puff when starting up. Might still be poor head work, but I need to rule out the easy (and cheap) stuff first.

Search results indicate that this is common with these cars.

Is anyone here still running a catch can on their PCV? Most of the posts I found were from 3 - 5 years ago. Any recent info would be appreciated.

Thanks!
~Dave

 

[TurboBuRick]

Yep, I run one on the pcv and one off the valve cover.

Some pics here

 

[meanchicken]

RJC makes a inexpensive PCV substitute that does a better job than the OE type...

 

[Scott87]

I use one of these moisture seperators from eastwood as my catch can. I did order both the oil and moisture seperator. The oil seperator has too much of a restriction to it so I am not using it.

Eastwood Air Compressor Water Moisture Separator Filter: eBay Motors (item 360302951653 end time Sep-28-10 07:12:35 PDT)

THen I have a few of the 3/8" kynar check valves from us plastics.
Check Valves | U.S. Plastic Corp.

The whole setup for short money works well. My exhaust used to smell pretty rank due to the vapors and mosture being sent out, now 90+ percent of it is captured. Pretty happy considering the cost of it was less than $100.

I will have to take a few pics of it, since I havent done so since installing it but here is a drawing of it I had done when brain storming on how to get rid of possible blow by.

 

[BEATAV8]

I just run open breathers. No PCV.

Works just fine.

 

[TurboBuRick]

I just run open breathers. No PCV.

Works just fine.

Damn Steve, how do you deal with the fumes in the cabin?

 

[TurboBuRick]

Interesting set up. Does this lower line here go to the intake pipe?

 

[Just a Six??]

Damn Steve, how do you deal with the fumes in the cabin?

I dont smell any fumes like that?
I do have a catch can I throw on if going where there may be inspectors handing out tickets like car shows etc. VC to catch can to before turbo sort of like factory setup. Stock VC breather drivers side. Used it once so far & worked decent enuf.
A good proper working Delco PCV for the average driver is a must for any GN
(asides from the custom setups)

 

[BEATAV8]

Damn Steve, how do you deal with the fumes in the cabin?

I can smell E85 exhaust more than anything. Once upon a time the cowl seal weatherstripping was missing and the fumes would get into the cabin, but with the seal in place it's not smelly.

 

[Scott87]

Lower line dumps to atmosphere. It is after the moisture seperator so incase of any possible blowby it will have a chance to bleed. I took pictures earlier will post one.

Rick it doesnt alter my blms if any. The pressure difference with the moisture seperator is negligable. I tested both the oil seperator and the moisture seperator by exhaling through them the oil seperator is way too restrictive but the moisture seperator is doing just fine.

These kynar check valves from us plastics open on check very easily (half a pound) when I tested blowing through them. Unlike the overpriced brass POS I ordered from K____N that when I tested trying to blow through it almost gave me an aneurysm.

So far I like the function, the secondary check valve for blow by was an after thought. I figure if by chance I happen to have any blowby I want to get rid of it under long durations of being in boost. Example would be driving up a mountain or a very long incline.

Interesting set up. Does this lower line here go to the intake pipe?

 

[Scott87]

Here you go rick.

Sigh, rusty radiator detracts from the stainless wire I use to tie everything up with. :smile:

 

[UncleDave]

OK... So, RJC and Kirban sell valves that are supposed to be PCV replacement, and/or check valves that restrict vacuum. I thought about defective PCV and tried blowing through it from the top; can't do it, so figure it's working correctly. Not sure if a simple restriction would make a difference in my case, but it's cheap and easy enough to try first. Thanks for the info guys.

 

[UncleDave]

Multiple causes?

OK... So, I installed a catch can this morning and drove the car out on a job, which was a pretty good ride. After letting it sit, I started it up and wouldn't you know it, there was smoke! Except, this time, it wasn't blue and did not smell at all like burning oil. Instead, it was grey and smelled only like a rich fuel mixture. The idle was also a little rougher when warmed up and BLM's are up to 137; again, not too bad but not perfect.

So, it's possible that the smoke issue was two-fold. It might be too early to know whether I resolved the oil smoke issue, I'll have to test it further, but there is definitely a rich fuel smoke at startup. I still think there is a vacuum leak somewhere, and it's kicking my butt and being very elusive.

One more thing: after a fuel pump & hot-wire upgrade, I now notice a raw fuel smell after getting into boost. Could this possibly be related to the charcoal canister? How would I go about testing that to make sure it's working correctly?

Thx
~Dave

 

[Scott87]

Take a few hoses off one at a time, roll them around in your fingers squeezing them, look for cracks and dry rott, bend the vac lines on a 180 degree bend look for the same thing if you see dry rott and cracking replace the line.

Chances are good you will need to replace the check valves in your system. I ended up replacing all my check valves with the ones from US plastics. Make sure to buy the kynar seal valves they resist chemical exposure and the seal wont leak due to exposure.

The vapor canister could be seeing boost indicating a faulty check valve. There should be a check valve just before the vapor can. You should check to make sure it is not leaking, and make for certain it is installed in the correct orientation. It should pass vaccuum but should slam shut when the lines become pressurized under boost.

OK... So, I installed a catch can this morning and drove the car out on a job, which was a pretty good ride. After letting it sit, I started it up and wouldn't you know it, there was smoke! Except, this time, it wasn't blue and did not smell at all like burning oil. Instead, it was grey and smelled only like a rich fuel mixture. The idle was also a little rougher when warmed up and BLM's are up to 137; again, not too bad but not perfect.

So, it's possible that the smoke issue was two-fold. It might be too early to know whether I resolved the oil smoke issue, I'll have to test it further, but there is definitely a rich fuel smoke at startup. I still think there is a vacuum leak somewhere, and it's kicking my butt and being very elusive.

One more thing: after a fuel pump & hot-wire upgrade, I now notice a raw fuel smell after getting into boost. Could this possibly be related to the charcoal canister? How would I go about testing that to make sure it's working correctly?

Thx
~Dave

 

[vacuum 6]

I still use one. Made one for ~$40.00 with all parts.



Since then I've designed a PCV BOV and the engine no longer sucks oil via PCV. I still run a catch to keep all crap out.

 

[vacuum 6]

IMO - I would not worry about the startup puff. Put a catch on it and forget about it. Not using oil and still making power?

 

[Mark E.]

Are you running valley pan style intake gasket?

 

[UncleDave]

Are you running valley pan style intake gasket?

Yup, the blue FelPro with the integral valley pan... Do you think it may have become compromised?

 

[Mark E.]

Nope, but with no valley pan there can be extra splash against the pcv port. Then it can really suck oil.

 

[UncleDave]

IMO - I would not worry about the startup puff. Put a catch on it and forget about it. Not using oil and still making power?

Doesn't use oil, just leaks oil (but don't they all? ). Misses at idle, seems to run fine under load. WOT seems fine, but the tranny can't handle it...

The startup puff just bugs the heck out of me. After installing the catch can, she still puffs at startup, but to me it looks & smells like fuel. Haven't been able to really test it out though. We've been having crappy weather, otherwise I'd be out shaking her down some more.

Speaking of weather, she runs different one day to the next. The old girl's a bit finicky... Maybe if I massage her quarters and compliment her differential, she'll run better. :tongue: