Air pressure at valve cover breather/PVC

[OB1]

I just finished installing a 1G head on my 95 block and noticed that at idle, there is a significant amount of air pressure leaking from both the PVC valve (less that 1year old) and the vented valve cover breather vacuum port.

What would be causing this? Bad rings?

 

[oldman]

I just finished installing a 1G head on my 95 block and noticed that at idle, there is a significant amount of air pressure leaking from both the PVC valve (less that 1year old) and the vented valve cover breather vacuum port.

What would be causing this? Bad rings?

What was the reason for the head swap? Have you done a compression test yet after the swap? How is the PCV valve (not pvc) leaking? Is the pcv routed back to the intake manifold? That should do it for now.

 

[OB1]

The reason for the head swap was because I was pushing coolant at 25psi and decided to do a 1G head, ARP head stud swap while I was in there.

I have not done a compression test since the swap. The last compression test was a year ago, results were 145-150 accros.

The PCV valve is just vented because of my JMFab intake. So is the valve cover nipple for now.

 

[oldman]

So you have the stock pcv valve (not a straight fitting) on the valve cover but just vented? Same on the breather side? Did you even compression test or leakdown prior to pulling the old head or did you just assume it was the HG? Did you resurface the replacement 1G head? Lastly, Do you feel pressure gushing out of the VC or is it smoking out of the two vents?

 

[OB1]

Correct, I have the stock PCV valve vented.

On the breather side there is just the stock hose hanging off the valve cover, vented.

No compression test prior to pulling the head beacuse the car was running great, just pushing a little coolant after hard runs.

No, I did not send the head out for resurfacing, it came off an engine that had burned a piston. I did clean it off with a rubber cleaning disc and some acetone.

No smoke, just air pressure at the two ports. I can block the air off with the tip of my finger, so its not really bad, just noticable.

Car runs and drives fine, just seems a little slow.

 

[oldman]

So the so called "pressure" = you can feel air pulsing through both vents?

If so, it's normal. All cars have blow by (fuel mixture escaping through piston rings during a compression stroke) but un-healthy motor will have more. You should perform a wet and dry compression test to see where they stand.

More importantly though is your crankcase ventilation setup. I strongly suggest that you reroute the pcv back into your intake manifold by welding an extra 1/4" fitting to the IM and install a internally filtered catch can, same for the breather routing back to the intake pipe. The stock crankcase ventilation setup serves an important and specific purpose but if you must vent, at least do the folllowing.

1. Replace the pcv with a straight fitting.

2. Change your oil more often than regularly scheduled.

 

[OB1]

So the air pulsing is normal then, thats good news. I never noticed before I guess.

I don't run any emission components what so ever. The only vacuum ports being used are the brake booster, BOV, and FPR. All else has been removed.

I'm also running DSMLink.

I will pick up a strait fitting, tee both the PCV nipple and Crankcase vent nipple together and run them to a vented catch can.

Thanks alot for your input, really appreciated.

 

[oldman]

I don't run any emission components what so ever. The only vacuum ports being used are the brake booster, BOV, and FPR. All else has been removed.

I understand that, I just want to make sure that you understand there are other ways, proper ways, to keep your intake tract free of oil besides disabling the stock crankcase ventilation system, not to mention emmissions is just a small part of what a pcv is design to do. Venting is a short cut and there are consequences, it's important that you understand what those consequences are and take preventive actions so the price you pay for a clean intake tract do not exceed the cost of doing it right in the first place. ie. Blown engine, turbo...etc.

Thanks alot for your input, really appreciated.

You're welcome.

 

[OB1]

After 10 minutes of driving I blew my 1G coil pack. One side sort of melted.

I swapped my 2G coil back in a she fired right up.

Is there any harm in running a 2G coil pack with a 1G CAS?

My car seems to run just fine.