Aftermarket Valve Covers - Missing a PVC Hole?

Chris-Nelson · Post by **Chris-Nelson** » Thu Jul 03, 2008 5:58 pm

My '85 Fiero came with aftermarket valve covers from Edelbrock and I have a feeling that they are causing an issue and I'd like your opinion on this issue.

The valve cover closest to the firewall has one hole in it for the PCV system in the normal spot on the fiero.

The valve cover closest to the trunk only has one hole in it for the oil fill cap.

I think my engine has a little blow by so I have ditched the PCV valve with a recirculating catch can instead. But it is only hooked up to the one valve cover.

I replaced both valve cover gaskets last night and this morning I started it up and it was doing great. Later I went for a drive and when I came back and opened the hood I found that both valve covers had begun leaking oil again...

Could this be caused by the fact that only one of my two valve covers is venting crankcase pressure?

I'm considering using a hole saw to make my own PCV system hole in the cover that has the oil fill cap on it and making sure both sides are venting.

Shaun41178(2) · Post by **Shaun41178(2)** » Thu Jul 03, 2008 6:04 pm

those valve covers use the cork or the rubber gaskets?

Chris-Nelson · Post by **Chris-Nelson** » Thu Jul 03, 2008 6:10 pm

Here's a little story that I think will help.

When I assembled the top end of my engine last time (to fix a leak at the LIM) I used new Fel Pro rubber gaskets for the valve covers.

At the same time I was using a hollow tube to bypass the PCV valve in to my catch can setup.

The cover nearest the trunk began to develop a small leak, but it was big enough that I wanted to fix it so I tore it all apart last night and replaced the gaskets with cork gaskets. When I tightened the valve covers down I used a torque wrench and followed my Haynes manual with torque specs.

At the same time that I replaced the gaskets I also installed a new PCV valve because it fit better than my hollow tube bypass method. The new valve still went to the catch can.

This time around both valve covers began to leak profusely and I can't even hardly drive it because so much oil is being pushed out.

So what is the culprit? Cork gaskets suck? Is the PCV valve not letting enough pressure out and it blew out the gaskets?

IDK. I'm going to try and do a leakdown & compression tests next week to see what the condition of my engine is.

whipped · Post by **whipped** » Thu Jul 03, 2008 8:30 pm

did you overtighten the valve covers? If you warp them, they won't seal.

Aaron · Post by **Aaron** » Thu Jul 03, 2008 8:55 pm

Having the breather line only hooked up to one valve cover will not cause any problems, the 3.4l DOHC had it setup this way from the factory in 96-97 (And mine is setup this way).

However, this should be a breather line, not your PCV. The PCV should come from the crankcase somewhere near the intake manifolds, not from the valve covers.

Atilla the Fun · Post by **Atilla the Fun** » Fri Jul 04, 2008 3:21 pm

The easiest cheap solution is to simply install the valve covers from a Camaro, Firebird or S-10 with a 2.8 or 3.1

THE PUNISHER · Post by **THE PUNISHER** » Fri Jul 04, 2008 3:56 pm

Preferred performance sells a HP increasing PCV block off plate.

Aaron · Post by **Aaron** » Fri Jul 04, 2008 4:03 pm

Don't say that--he'll believe you.

lucky · Post by **lucky** » Sat Jul 05, 2008 1:00 am

I've been drooling over those edelbrock VC's myself. But if this is what I'm in for......
Seems to me a simple test to determine if its a pressure or sealing issue at the gasket would be to just run the car without the oil cap and the pcv.

Chris-Nelson · Post by **Chris-Nelson** » Sat Jul 05, 2008 2:29 am

Aaron wrote:Don't say that--he'll believe you.

actually no I wouldn't. Thanks though! :thumbleft:

Chris-Nelson · Post by **Chris-Nelson** » Sat Jul 05, 2008 2:30 am

lucky80 wrote:I've been drooling over those edelbrock VC's myself. But if this is what I'm in for......
Seems to me a simple test to determine if its a pressure or sealing issue at the gasket would be to just run the car without the oil cap and the pcv.

They are nice, but this situation kinda stinks.

When they vent there are minimal problems. The problem came back (leaky valve covers) when I switched back to a functioning PCV valve.

I believe my main issue is too much blowby creating too much pressure and because of a bottleneck effect in the stock PCV valve system it went to the next weakest link which was the new valve cover gaskets and blew them out.

Fixing it all tomorrow.

Shaun41178(2) · Post by **Shaun41178(2)** » Sat Jul 05, 2008 2:53 am

when you had it hooked up to a breather system with no valve, how much smoke was coming out of the valve covers? There will always be some but was there a lot coming out? If not then its not blowby.

Atilla the Fun · Post by **Atilla the Fun** » Sat Jul 05, 2008 9:18 am

based on all that, I suspect your engine has higher miles on it. Then your best solution for blowby is to bore and hone for new pistons and most importantly, rings. Neither Childs and Albert nor Total Seal lists a gapless ring set for any of the GM 60 degree V6s, so you're out of luck there.

Chris-Nelson · Post by **Chris-Nelson** » Sat Jul 05, 2008 12:49 pm

The engine supposedly had around 60K on it when I bought it (more than the car...) but I know that both previous owners drove it hard a lot. Lots of racing and general hot rodding. ...I do to...

I'd love to pull it all apart and rebuild it with the intent of running nitrous and fix the little issues with it.

Aaron · Post by **Aaron** » Sat Jul 05, 2008 12:57 pm

Well what if you had it setup correctly, would it work right then?

There should not be a PCV valve on any of the hoses to your valve covers. The hose from your valve cover should go directly to the air intake, before the throttle body. This system is the breather, not PCV.

The PCV valve should be in the line that goes from your crankcase vent to your intake, after the throttle body.

Series8217 · Post by **Series8217** » Sun Jul 06, 2008 3:17 am

Aaron wrote:Well what if you had it setup correctly, would it work right then?

There should not be a PCV valve on any of the hoses to your valve covers. The hose from your valve cover should go directly to the air intake, before the throttle body. This system is the breather, not PCV.

The PCV valve should be in the line that goes from your crankcase vent to your intake, after the throttle body.

I don't think the 2.8 has a crankcase vent. You have to use one of the valve covers. The PCV valve goes into one valve cover, and the breather line onto the other.

lucky · Post by **lucky** » Sun Jul 06, 2008 4:26 am

series is right, no crankcase vent on the 2.hate. IIRC that car has a 3.4 tho.

Fastback86 · Post by **Fastback86** » Sun Jul 06, 2008 1:01 pm

lucky80 wrote:series is right, no crankcase vent on the 2.hate. IIRC that car has a 3.4 tho.

Doesn't matter, the 3.4 is set up the same way. Series is correct.

The Dark Side of Will · Sun Jul 06, 2008 5:53 pm

The PCV system allows engine vacuum to pull oil vapor laden air from one valve cover. The air to replace that comes from the other valve cover's connection to filtered air.

Kohburn · Post by **Kohburn** » Mon Jul 07, 2008 8:54 am

yeah, even if the pcv was clogged completely is shouldn't increase the pressure in your case because the other valve cover is supposed to be a fresh air supply to the atmosphere.