Turbo failure wiki

[Scruit]

Given that you're getting those AVCS-related trouble codes and getting a "hooo" sound from the turbo it sounds like an oil issue, either sludge, weak oil pump, or poor oil flow into the turbo. I'd fully change the oil and replace the oil feed system. Might be getting a clogged artery in the turbo oil feed system because if the turbo is getting under-oiled it can make that sound you described.

 

 

Thanks for the reply.

 

After the AVCS OCVs were replaced I changed the oil. I'll remove and clean/check the oil lines this weekend.

 

I'm also planning on checking the pistons with a borescope to look for scoring or an indication of ringland issues.

 

Logging this morning's commute showed the turbo topped out at 15.98psi, which is my tune - but only after 20 mins of driving. The hooo sound is greatly diminshed when the engine is at full temp, but will come back when cold again). During the time when the engine is cold the turbo topped out at 12psi. (That was from freeway merging - I don't want to so a actual pull until I know the car's safe to do it...)

 

I only got 1 misfire in the entire commute - and I got 34 knocks detected during the 30 minute drive. I'll have to examine the logs in greater detail to figure out where the knocking happened.

 

IAM never came off 1.000

Edited May 1, 2015 by Scruit

[fahr_side]

You should not be pushing hard at all until the engine is fully warmed up.

[keenster]

I broke a ring land on two Pistons and my cylinders were not showing any signs of failure. All my cylinders had no scoring on them and the crosshatches were still there. Better do a compression test too. That will tell you a little more about possible ringland failure.

[Scruit]

Compression good. If ringlands just let go when they feel like it then I can't do anything else to predict ore prevent.

[fahr_side]

Borescope also tells you nothing about how oval your cylinders are. My #4 showed no scuffs or scores, had crosshatching all around, but was out of spec for roundness.

[Scruit]

Sure, there's a limit to what I can see - but it's better than nothing. I was hoping to (NOT) see evidence of blown head gasket (really clean piston) or evidence that one cylinder is significantly different in terms of carbon buildup etc. Possibly visible damage, that kind of thing.

 

Save for taking the engine apart, there's not much more I can do. I'm going to "run what I brung" at this point. If the engine goes tits-up next then the upgraded oil line should spare the turbo and I'll stick a built engine in there. Luckily I have a couple options for alternate transport.

[fahr_side]

Leak-down test is the best way I know of to diagnose a bad ring land. Compression numbers can be fine, bore can look clean, piston crowns can look perfect.. but if you have a bad ring land the leak-down will be poor and usually oil consumption will either be high or is headed that way real soon.

[Scruit]

Another question: I see a lot of discussion of how a "failed" turbo usually takes out the engine with it. Ok... but...

 

What is a "failed" turbo? Mine has bad bearing and a lot of slop, with the tips of the impeller blade folded over - however it was still functioning normally and the only symptom was a "hooo" sound under boost that nobody noticed until I pointed it out.

 

When I think of failed turbo I think of something that makes some kind of noise that would make your average driver stop and call for a tow.

 

So, is a turbo "failure" that causes engine death the kind of thing where a the turbo looks like it tried to ingest a handful of pocket change? Or is a mild "hooo" sound with loose bearings considered to be a failure that necessitates a teardown of the engine? Does the metal in the engine come from the bearings being worn away? Or the blades coming apart?

 

Starting to worry that I may be pulling the pan on mine to check for debris. Intercooler has zero debris visible in it. The oil is coming out of the car tonight after the leakdown test is completed. I figure if the oil has any flecks in it I'll pull the pan.

[keenster]

Do it ASAP or this...

http://images.tapatalk-cdn.com/15/05/08/07c58e9d63d5e0a63de863721db883bd.jpg

 

Failure is loose shaft. Exploded turbo anything that can make the turbo not function the way it was built to do.

 

The metal come from the turbo. Then the metal goes in the intake. Then the small metal particles wear down engine components and then bye bye short block.

 

I would PM JMP.

Edited May 8, 2015 by keenster

[Scruit]

Failure is loose shaft. Exploded turbo anything that can make the turbo not function the way it was built to do.

 

I would PM JMP.

 

I have the replacement turbo in hand and will install it in the coming days - my question was about whether a turbo with loose bearings that has not suffered a *catastrophic* failure poses a risk to the short block.

 

Where does the metail inthe oil come from? Turbo shaft bearing material making it down into the sump through the oil return line? Or bits of broken blade going into the cylinders via the air intake?

[fahr_side]

It's explained in the first post in this thread. When the turbo's bronze bearings wear, this causes the extra clearance that allow the wheels to contact the housings. This lost bearing material is then suspended in the oil as fine particles which come down the turbo oil drain into the pan. Since they are fine and light they stay in suspension long enough to be picked up by the oil pump and pressurized. The oil filter is not 100% efficient. The filter can become clogged to the point the bypass opens and the oil is sent to the galleries unfiltered. It's contaminated oil being pushed into the main and rod bearings that causes the real damage. Go back and read the first posts.

[Scruit]

Gotcha. Thanks. My car has not exhibited any of the 5 listed symptoms (smoke, squeal, metal in oil, *catastrophic* turbo failure or oil system failure - as far as I can tell)

 

I'm going to cross my fingers that I caught it early enough. I'm going to pull and clean the oil pan and then put it all together again. If I need a new engine then I need a new engine. Time to start saving up I guess.

[fahr_side]

I'd drop the pan and take a look. It's not fun having the motor come to a rattling, clattering, screeching stop and it always happens at the most inconvenient time.

[Scruit]

I'd drop the pan and take a look. It's not fun having the motor come to a rattling, clattering, screeching stop and it always happens at the most inconvenient time.

 

I hear that. Good advice.

 

Leakdown numbers: (all cold - don't want to run engine right now)

 

#1 135psi 20% LD (sound from oil filler)

#2 130psi 27% LD (sound from oil filler)

#3 130psi 25% LD (sound from oil filler)

#4 120psi 30% LD (sound from oil filler)

Edited May 9, 2015 by Scruit

[turboconcepts]

I have the replacement turbo in hand and will install it in the coming days - my question was about whether a turbo with loose bearings that has not suffered a *catastrophic* failure poses a risk to the short block.

 

Where does the metail inthe oil come from? Turbo shaft bearing material making it down into the sump through the oil return line? Or bits of broken blade going into the cylinders via the air intake?

 

Could be rod bearings, but if your turbo has a radial play (side to side wobble) that means that it's on its out. When it's starved of oil and you lose the oil pressure bubble in the turbo then metal makes contact with metal, could be shaft against journal bearings, journal bearings against bore, thrust collar against thrust bearing, etc, either way it will gall and you'll lose material, metal particles then start clogging the oil passages and causing abrasion from the particulate (think sand paper), thus further decreasing the lubricity and causing more wobble, until the wobble is so bad it galls the piston rings then you lose the seal, leak oil, smoke out, then total catastropic turbo failure, as in it's spinning at 130k rpm one minute then CRUNCH it stops spinning, wheels break and lodge into the housings and the whole thing goes to hell. So if you're getting shaft wobble that usually indicates turbo is going, most likely due to oil starvation, as in clogged oil supply in most cases with these units, replace turbo and oil supply system and you might be able to save your motor. And do a full oil change, every drop you can, and clean the oil pan. Feel free to call us up for advice 800-298-8726, ask for Nick.

 

~tc

[Scruit]

So if you're getting shaft wobble that usually indicates turbo is going, most likely due to oil starvation, as in clogged oil supply in most cases with these units, replace turbo and oil supply system and you might be able to save your motor. And do a full oil change, every drop you can, and clean the oil pan. Feel free to call us up for advice 800-298-8726, ask for Nick.

 

~tc

 

 

Understood. New turbo is sitting here waiting to go in. The car is on stands and the engine is not being run until I'm sure I've saved it. I am going to drop and inspect/clean the pan, then run two more complete oil changes though it (replace turbo/oil line, clean the OCVs and oil lines, do an oil change, run the engine to full op temp, do another oil change, then start driving it and cross my fingers. I'm hopeful I can save the engine, but also not going to be too surprised if the engine goes south vary soon. I'm going to look at installing an oil pressure gauge to keep an eye on things for now.

 

Thanks!

[Markbo]

When my turbo blew (cracked is more accurate I guess) among the many, many things I did was 3 full oil changes within the first 100 miles. Did it help? I dont know but i havent had to replace the small block. Yet.

[Scruit]

When my turbo blew (cracked is more accurate I guess) among the many, many things I did was 3 full oil changes within the first 100 miles. Did it help? I dont know but i havent had to replace the small block. Yet.

 

How long has it been? Miles/Months?

[Markbo]

18 months. Not sure on the miles, but daily driver.

[StkmltS]

Understood. New turbo is sitting here waiting to go in. The car is on stands and the engine is not being run until I'm sure I've saved it. I am going to drop and inspect/clean the pan, then run two more complete oil changes though it (replace turbo/oil line, clean the OCVs and oil lines, do an oil change, run the engine to full op temp, do another oil change, then start driving it and cross my fingers. I'm hopeful I can save the engine, but also not going to be too surprised if the engine goes south vary soon. I'm going to look at installing an oil pressure gauge to keep an eye on things for now.

 

Thanks!

 

You should make a turbo replacement video for Youtube like the one you did for the clutch replacement. Watching your clutch video a few times beforehand is probably the biggest reason I was able to successfully change my clutch without having anyone there to help. I'm sure the world would be a better place if you made a similar one for replacing a turbo.

[RuhRoh]

Read through the first few posts and the last few pages, and have a few questions.

 

I have a 2005 Legacy GT 5MT with about 146k and no major drivetrain issues. I've purchased a new car and will be selling the GT shortly, and want to be sure I'm not selling a time bomb to the new owner.

 

It's on its original turbo and has never been modded.

 

A couple of months ago, when it was still my daily driver, I got a check engine light that stayed on for a few days and didn't go away when I filled it with gas and retightened the cap. Took it to my local indy shop, which doesn't specialize in Subies, but is generally quite competent.

 

Here's what the is written on the service order:

 

"Computer diagnostics, check engine light on. No drivability issues, had codes P0011 camshaft bank 1 over advanced and PO302, cylinder 2 misfire. Due to prior history working on similar vehicles the tech checked for oil level and found no oil on dipstick. The camshaft is operated partially from oil pressure and with no oil the cam position was incorrect, which can also cause a misfire. No sign of any oil leaking, possible turbo issue. Completed BG decarbonizing oil service, cleared codes and turned off light. Ran vehicle and light remained off. Performed BG decarbonizing oil service."

 

What the service writer told me was that one bank was oil starved with no oil on the dipstick. I had been out of the country for a couple of weeks but I know I had checked the oil level at least in the week or two before I had left and had found it fine. So that was a new issue. He also said the oil might have been going out the tailpipe or the turbo, but I had seen no smoke, nor heard any unusual noises from the turbo.

 

The writer also said that performing the oil decarbonization process -- flushing the engine oil and decarbonizing it -- might help. And if the check engine light doesn't come back on, then we might be in the clear.

 

It has been more than 1,000 miles, the check engine light has stayed off, and the oil level is ok. My new car is here so the GT is no longer my daily driver.

 

Questions:

 

-- do I need to be worried about turbo being ready to fail on the new owner?

-- have people done turbo replacements before they go bad, and if so, how much does that generally cost?

--what other signs should I be looking for?

 

Thanks!

[fahr_side]

I'd get that passenger side turbo feed and AVCS line replaced ASAP.

 

 

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[Soarin]

I've read the entire thread and couldn't find if this was asked.

If there is metal in the oil pan and even if things like the pan, oil cooler, oil pick up lines, banjo bolts, AVCS solenoid are replaced and the motor is flushed out; would it be a good thought to replace the rod bearings anyways?

My 06 LGT turbo died while I was on the road to pick up a new aluminium radiator and since this is my daily I want to know what would be the best way to not have issues post new turbo.

[Scruit]

Some people get away with replacing the oil a few times over the next few hundred miles. Some people aren't that lucky. You won't know which you are.

 

If you don't plan on replacing the SB, then I'd do this:

 

- FP filtered oil line to feed your new turbo.

- Stick a big magnet inside the oil pan (will catch most debris, but notably not turbo bearing material)

- Add an oil pressure gauge

 

Keep a close eye on oil pressures. Low oil pressure at cruising speed is a sign of severely worn bearings. "Low" is a matter of opinion, with some folks claining 75-100 psi warm cruise pressures. I get 60psi cold, 55psi hot - new SB, blueprinted heads.

 

 

EDIT: oil pressure gauge is also a source of stress as you drive because any blip in the reading makes you pucker up a little.

Edited December 30, 2015 by Scruit

[fahr_side]

The big question here is do you want to risk the heads to find out if the bottom end is going to live. If you strip the motor at the first sign of debris in the oil you'll likely save the crank and heads from damage. If you roll the dice you risk the cam bearing surfaces and crank journals being scored beyond rescue for the prize of not having to build the engine. Only the owner can really decide if it's worth the risk.

 

 

Sent from a device using some software.