Crank case blow by

[03CL55AMG]

So I was at a performance shop yesterday, checking my startup voltage on my 87 conquest, which has been modified quite a bit ,the batteries in the back, and the owner of the Performance shop told me to go ahead and turn it over. Well it did start, but it was kind of hard to start. That’s another subject. But it was smoking, a fair amount. Not pouring smoke, but definitely noticeable. So, haven’t really seen that before with this car, except the last time that the motor was hurt a little bit. So while it was idling, we opened up the valve cover oil fill cap and you could feel the blow by coming out of that oil fill hole. Also, the breather cap on the back of the valve cover also was puffing a little bit.

 

So, I’m thinking to myself I must’ve hurt the rings or something along those lines, for it to have crank case blow by like this. So this morning, I ran a compression check when it was dead cold. And the compression was 138 on number four, 130 on number three, 133 on number two, and 137 on number one. So now I’m a little bit confused, because the last time my Engine broke some rings and scuffed a piston up a little bit. Three of the pistons checked out and one was like 75-80pounds. So I thought I’d post this up with some of the experience on this forum being extensive, and see if somebody else could give me their thoughts as to how that could happen, by the way, the plugs were all lightly tanned and looked really good. So now I’m not sure if my rings are hurt or not. and when I started it today, it didn’t smoke at all. One guy mentioned to me, possibly turbo seals, or the intake going into the turbo is got a lot of oil in it. Not sure… any help is gonna be appreciated.
 

 

 

 

 

[GoldStar]

Very similar symptoms to mine (albeit I still have my oil-air separator), and this is my cause. All 4 cylinders look like this:

My symptoms were quite a bit of smoke on startup and loosing an abnormal amount oil, but otherwise ran great. In my initial digging, I found that there was oil pooling up in the intercooler. Cleaning out the intercooler temporarily fixed it, but the next time I got it into boost, oil would get caught in the intercooler again, leading to smoking on cold starts. After confirming my PCV valve was good, I cleaned out my oil air separator, its associated lines, and even got a new turbo core to eliminate that; made no difference.
Digging a bit further, I found that compression test readings were great, and adding oil to the cylinders made no difference. The test that really prompted me to get in there with a borescope was a leak down test. I've forgotten the readings at this point, but they were definitely out of spec. Never got to the bottom of what caused this damage, but I suspect it was one of the previous owners; the old turbine was chewed up like it had eaten debris.

[kev]

Do a leak-down test.   It will tell you if you really do have a blowby issue.   

Don't assume the worst from the start.   Valve seals will have the same symptoms and are easily replaceable...especially if you have a leak-down tester (if not, buy one, they are cheap nowadays)  to hold the valve up without tearing down the engine.