Lots of air coming from the oil cap

[Benshooter]

This is a bit of an extension on to my post about my low compression numbers...

I had the car warm and at idle this morning and I pulled off my oil cap and noticed a very good amount of air was being blown out of it. Not just a little, a lot.

It's not blow-by, my rings are fine... And it doesn't smoke unless I'm hard on the boost, and even then, it only smokes a tiny, tiny amount and not all the time. I couldn't even notice it until I had someone drive the car in front of me as I followed, so I'm guessing it's not the exhaust valves...

Could it be the intake valve seats? Possibly even the seals or stems? It seems like I've narrowed it down to that but I don't want to perform any unnecessary work since I'm on a budget for the next month. Maybe the big web cams weren't ground properly?

And yes, I have a new OEM PCV valve installed...

 

[ramsack]

yea a leakdown test will tell you more than a compression test in this quest for finding the issue.

 

[Spoolin18]

I hate to hijack an old thread, but I'm having similar problems. I recently had a t-belt job done with compression, the results were as follows. in this order 1234

110-137-145-142

It holds excellent oil pressure, holds about 18-20 inch hg vaccumm at idle, has plenty of power. Doesn't smoke. Has some air pushing out the oil cap lid, the dip stick pops out slightly. Its the original. Its an all original car, I have a oem pvc valve to put on. The mechanic was stumped. Its a little hard on gas. I can blow through the crankcase vent and feel it out the dipstick tube and some through the oil cap hole. The timming looks slightly off to me, not sure., its been raining so much here. boost 10 psi. Any ideas? No mechanic close knows jack shit, I'm highly pissed at the mechanic, he did several test, but couldn't pinpoint the problem.

 

[Benshooter]

I hate to hijack an old thread, but I'm having similar problems. I recently had a t-belt job done with compression, the results were as follows. in this order 1234

110-137-145-142

It holds excellent oil pressure, holds about 18-20 inch hg vaccumm at idle, has plenty of power. Doesn't smoke. Has some air pushing out the oil cap lid, the dip stick pops out slightly. Its the original. Its an all original car, I have a oem pvc valve to put on. The mechanic was stumped. Its a little hard on gas. I can blow through the crankcase vent and feel it out the dipstick tube and some through the oil cap hole. The timming looks slightly off to me, not sure., its been raining so much here. boost 10 psi. Any ideas? No mechanic close knows jack shit, I'm highly pissed at the mechanic, he did several test, but couldn't pinpoint the problem.

Wet test that low cylinder. That is WAY out of spec.

Oh and if I had to take an educated guess I would say your getting quite a bit of blow-by on that low cylinder, which is leading to the extra crankcase pressure.



If anyone cares about my OP, it was the valve seats...

 

[bring_1]

ok, i agree with you on some points, but oil seals in the turbo would have nothing to do with his problem. that is a LOT of air to be leaking by them which is impossible. i would be looking at your rings then you have pretty crappy compression numbers.

check ## rings, just tore down a motor one of the cyls was 120 ish others were 135 or better and the #1 compression ring on the hole was in like 6 pieces.

Cam has nothing to do with blowby.Your compression seems a little low. By any chance does your dip stick work itself out? if so you might have excess blow by.This is caused by worn rings. What you might want to check is your plumbing to your intrcooler.You might have oil in all the piping as well as your intercooler. What causes this is the vent tube coming from the valve cover to the intake hose having to much crank pressure. You can solve this problem by installing a catch can off of the valve cover. Depending on how much oil you use it might not be a big problem BUT you wil eventually need a ring job and if thats the case you might as well freshen up the whole engine..

also there is a line that runs from your valve cover to a sert on the intake, to vent crank case gasses, on my car when i bought it they were runnin the wastegate off that sert and had the line off the VC ran to the intake, oil all over the IC pipes and intake and it was a smokey sunuvabitch driving it. check that thats plumbed properly

 

[400hp93talon]

ok, i agree with you on some points, but oil seals in the turbo would have nothing to do with his problem. that is a LOT of air to be leaking by them which is impossible. i would be looking at your rings then you have pretty crappy compression numbers.

COMPRESSION TEST!!!! Do you have a catch can? If so and it keeps filling up when your just driving you have horrible blow by which is caused by your rings or even bent valves(along with bad valve seats) leaking pressure out of your cylinders. Whith the cap off and running you should be able to pour oil into your head the cams will throw a little of it around but there shouldnt be that much moving air I wouldn't think!!

 

[Spoolin18]

Wet test that low cylinder. That is WAY out of spec.

Oh and if I had to take an educated guess I would say your getting quite a bit of blow-by on that low cylinder, which is leading to the extra crankcase pressure.



If anyone cares about my OP, it was the valve seats...

Yea, I know. The service limit is 121. I don't understand what the hell could be going on, if it was rings, it should smoke? Headgasket, should smoke white. It don't. No oil is built up in the intake track, no oil comes out of the crankcase vent. I don't know, just stumped.

With all the great minds on here, No one can point me in the right direction without wasting money?