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Discussion Starter · #1 ·
My XC90 2.5T has 128K mi and I'm the second owner. Last weekend to my surprise I got an low oil light after which I immediately shut down the motor. I added almost 4 qt of oil but when I checked the dip stick I noticed exhaust coming out. My first thought was that it may be the PCV valve but looking at the amount of exhaust gas escaping plus the fact that it was burning so much oil my suspicion is worn piston rings.

In my defense I always use synthetic, oil chg interval ~6-7K mi but unsure of the previous owner's maintenance discipline. Is ~130K about right for ring replacement on these turbo inline 5? I always hear these motors are bulletproof
 

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No it's not, and don't assume your rings are bad. Do a compression test, it's super easy!
 

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+2 PCV , its almost the right time for that to get clogged up
 

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volvofla, i recommend you to check the compression first, easy way to do it, dont remember how much compression on the 2.5T is normal, but you need to see no more than 10% difference on each cylinder.

There is a few test that you can make, if you car is running at idle after a normal driving warm up, remove the oil stick, if you see smoke coming out you NEED the new pcv crankcase system, that includes, pcv pipe, oil trap, elbow:

pcv pipe:
http://www.fcpeuro.com/products/vol...il-trap-to-intake-hose-genuine-volvo-30650578

vent hose from valve cover:
http://www.fcpeuro.com/products/volvo-crankcase-vent-hose-valve-cover-to-oil-trap-long-hose-8692217

Oil trap:
http://www.fcpeuro.com/products/volvo-oil-trap-c70-s60-s80-v70-xc70-xc90-8692211

elbow:(inspect yours for any cracks).
http://www.fcpeuro.com/products/volvo-crankcase-vent-hose-inlet-from-engine-to-oil-trap-30677388

This needs to be done asap, you dont need over pressure in your engine, or you will kill your cams seals, or something worse, if you have your pcv system clogged you will burn more oil than normal and also you will kill a lot of parts in your engine.
 

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Discussion Starter · #7 · (Edited)
Had the compression test done and the pressure range from 130psi to 110psi (cylinder #3). I believe normal is 140psi. Will a clogged pcv account for a loss of 4 qt of oil over 7000mi. How is the oil being burnt (i.e. pressure from crankcase forcing oil through piston rings?). I see no visibly sign of oil leaks either around the dip stick, oil filer cap or otherwise. I need to make a decision quick as I've already paid for a salvaged 2.5T long block but can still cancel by today.
 

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do you see this in your car?.


maybe not that much...but any smoke.
 

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If you only see smoke on startup and it goes away when the catalytic converter gets hot it could be several things but we had a bearing/seal go out on the turbocharger and it was dripping into the exhaust and being burned by the hot cat. Car (850) ran great but was consuming lots of oil, with little to no smoke when everything was hot.

Good luck.

P
 

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Discussion Starter · #11 · (Edited)
Well the verdict is in and I just got off the phone with the mechanic after doing a leak down test. I have 70% leakage at TDC, dropping down to 20% along the bore. The best cylinder (#5) only sees 9% leakage at TDC. Our guess is that the piston rings are pinched and there is some damage to the bore which accounts for the variance in leakage along the length of the cylinder wall. I guess this sounds like a new engine. For what it's worth I upgraded the stock 14T with a 16T angle flange turbo and an OBX catted downpipe but no software yet. Wonder if the combination of these mods contributed to the engines early demise. It's not like I drag race this thing and I only put 8K mile with all these mods.
 

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so you did a leak down test?. If you are getting more smoke than the video def. you have a problem on the PCV. You mention before that the compression gave you values of 110 and 130 correct?.
 

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Discussion Starter · #13 ·
so you did a leak down test?. If you are getting more smoke than the video def. you have a problem on the PCV. You mention before that the compression gave you values of 110 and 130 correct?.
Yes a leak down was performed. Compression test did result in a range of 130 - 110psi between the banks.
 

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well if you did a leak down test, you should find where the leak downs comes from? valves exhaust, admission? headgasket? rings? thats why is important to know where the leaks comes from. 130-110 is not that bad.

The 16T makes good power, the 2.5T engine produce a lot of torque on low rpms 1500 rpms so having a bigger turbo without the correct tune def. will damage something there. You should consider send your ecu to ardideas.com with Lucky.

Before open your engine, let me know where the leak came from.

regards,
 

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Discussion Starter · #15 ·
Before open your engine, let me know where the leak came from. regards,
There was no leak from the valve guides or head gasket. Seems like most of the leakage (50%-70%) was coming from top dead center. Going down 5mm from TDC, the leakage was 20% which indicates worn rings or even bore damage. Ironically I was planning on upgrading the ECU with Lucky this month. Guess it'll have to wait.

In terms of the bigger turbo I was under the assumption that the stock knock sensor and ECU will prevent detonation or overboost conditions even without Lucky's tune.
 

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The stock ECU can do it, but the 16T + low rpms torque of the 2.5T can make things a little bit difficult for the ECU to hold. I think you will have a broken piston, i hope the cylinder walls are intact so you just need to get a new set of pistons.
 
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