help with an odd issue

[barndawgs91]

right at a month ago the turbo started loosing power and smoking at high boost and it finally let go and dumping oil into the downpipe .I did pull the exhaust Mani back and check for oil nothing but carbon ,separated turbo housing and the exhaust side was soaked bad turbo seal so got the problem with that settled. tried another 14b turbo and it was locked up with a little persuading and oil i got it free but the bearing lasted about 40 min with a 30 min idle and less than a 10 min drive it was smoking.so searched for another turbo found a 16g with minimal shaft play but the charge side was different slightly so onto the custom oil and water inlet , outlet lines and charge pipe. primed the turbo and fired it up noticed a leak on the oil return so oil was circulating tried to fix the problem but made it worse the oil return hose had split and fired out about 3qts of oil shut it off . Went and got new line and replaced it no leaks and everything looked fine as far as temps and oil pressure but instead of running at 15# of vacuum I'm at 10 # but everything is matched up and where its supposed to be .but its not boosting and i have extreme crankcase pressure blowing the dipstick out and runs better with the oil cap off and the idle is rough . I took it for a test drive around my complex it was on and off again power but no boost .
Data log of problem and that was driving around the complex .

compression numbers
#1-65
#2-130
#3-130
#4-120


and there is no milky oil so its not a water leak .With the new turbo it is spinning but not spooling and building boost could the different exhaust housing make it not spool right ? just to clarify 91 talon tsi fwd turbo , straightline specialties UICP and elbow, 16g turbo off of a starion i used my hotside , walbro 190,blitz boost controller .

 

[Old Mitsu Tech]

The cylinder with 65 psi most likely is a valve. You can squirt oil into that cylinder and see if the compression comes up. If it does, it's rings. If not, it's valves or valve related.

Either way, you probably are going to pull the head. Have everything done. Grind valves, resurface, check for cracks, etc. This should be done by a competent machine shop as they have all the tools necessary for such a repair.

Good Luck

 

[barndawgs91]

hmm vlaves but there was no issue with them and it isnt smoking at all anymore out the exhaust just exccessive crankcase presure and light smoke out of the breather vent

 

[oldman]

Then it's most likely the rings but not limited to. I strongly suggest performing a leakdown test before you pull the head so you can get a better idea of what's in play.

 

[oldman]

hmm vlaves but there was no issue with them and it isnt smoking at all anymore out the exhaust just exccessive crankcase presure and light smoke out of the breather vent

My suspicion is

Excessive blow by from #1 => Excessive crankcase pressure => Backed up/poor oil return capacity => Blown turbo/turbo seals.

 

[barndawgs91]

My suspicion is

Excessive blow by from #1 => Excessive crankcase pressure => Backed up/poor oil return capacity => Blown turbo/turbo seals.

replaced with a good turbo the other 2 that i used were bad but not this one and believe me with the amount of oil that was comming out of the turbo return line it wasnt a capacity issue.