mjr46

do a compression test again but if the turbo seals aren't leaking, which most likely would be visible inside the turbo, it's possible an oil control ring/s have issues

19stang88

A compression test does not determine a bad head gasket. A leak down test will tell you if you have a blown head gasket. When you performed a compression test, did you crank the engine over three time and then got your reading?

mjr46

not true my friend, blow between cylinders = adjacent cylinders will be lower than the rest also if it blows near a coolant passage =remove radiator cap and watch the level rise or see air bubbles, leakdown test is for locating where loss of compression is = valves, rings ect ect

nacanitihs

well if the oil seal in the turbo is bad you would notice a coat of oil inside the cold side piping. is there any shaft play in the turbo?

ARod's 01GT

Well I did take the turbo and down pipe off and saw nothing out of the ordinary as far as built up oil residue or anything. Could you explain more about the oil control rings as I have never heard of these before?

I also looked at some of the piping and again saw nothing that shouldn't be there. As far as shaft play the is a very small, I'm talking a minute, amount of play, left and right, with the shaft but as I understand that is normal. And there is no in/out play with the shaft so I'm thinking the turbo and seals are good. Not that this matters much but the turbo does only have about 1000 miles on it and is clocked the right way as far as the feed and return lines go, so its is a fairly new turbo.

What are your guy's thoughts as far as the thinning cheap oil just squeezing by the seal during load?

nacanitihs

well the only way that would happen is if the seals were bad. the seals are designed not to let anything through. plus 10w-30 regardless of brand will only get so 'thin'. thats what the rating is for, its a measure of viscosity. and again there would be oil in the piping, which you say there isnt any


could there be anything dripping on the downpipe? i know in my SHO my crank seal is bad and it dripps oil onto the cat causing it to smoke after driving it for a little while. where abouts is your downpipe located?

what brand turbo do you have?

ProTrickVic

with my limited turbo experience, i have never seen shaft play, not even a minute amount. so if it moves, my bet is that its on its way out. i've heard nothing but bad reviews from On3 in the long run results.

have you checked you coolant? are you still running pcv, breather, evac?? your car can still run hard with a turbo even with a blown head gasket or really bad blow by cause you're ramming air down the throat of your motor.

does your oil smell like gas? i bet you're having some fuel leakdown into your oil.

19stang88

From how a learned it, A compression test won't determine a blown head gasket. If compression is below the 15% of the highest cylinder than that gives you the cylinder to perform a leak down test.

mjr46

I understand what your saying and like I said two adjacent cylinders with low compression due to a burnt firing ring can be determined with only a compression test, in such a scenerio all a leakdown would verify is yup we have leakage, now I have used the tester to just pump a cylinder up to watch coolant level rise..... I have case after case of such, just did a 94 mustang with such , I don't often need to go any further when searching for blown head gaskets. do it however you want but a skilled tech can form an accurate diagnosis on a head gasket with only a compression test often depending on where it is blown, firing ring in the thin area = low compression adjacent cylinder, blow elsewhere, you can pump air in the cylinder or crank the motor over and use compression to watch the coolant level rise...case point on that, my 81 jetta diesel..when it popped the head gasket, all I had to do was crank the motor over on a cold motor and watch the level rise quickly.. to each his own

19stang88

I get what you're saying. I am not a tech, but I learned from auto class with a good teacher. I'm always willing to learn. Techs have been there and done that, so like any experienced technician, they would know tricks here and there.