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Discussion Starter · #1 · (Edited)
So, after searching and reading several threads concerning the expected life of a stock TD04 and the symptoms of a failing turbo I'm beginning to draw the conclusion that I may be due for a replacement or upgrade.
First, some history and a rundown on my car and the symptoms it is displaying. I have an '06 fxt with 166k miles, the only mods are a stromung cat back and a Cobb stage 1 ecu reflash. About two years ago I experienced what seemed to be a boost leak, my turbo would spool well initially for a second or two then there would be a noticeable drop in boost and acceleration. No real whistling noise like it was hemorrhaging boost and unfortunately I don't have a boost gauge but it was definitely down on power. Also no CEL, no smoke, no untoward noises and car would rev to high rpm with no issue, just took longer to get there. I pulled the intercooler and inspecting all duct work for leaks to no avail, I then reinstalled the intercooler, duct work and tightened all clamps. This did not fix the issue. It did however miraculously disappear a few days later and ran like a champ up until a couple days ago when...you guessed it...the same symptoms have reared their ugly head once again.
My question is aside from a boost leak, what is a probable cause for this issue? Malfunctioning/worn BOV, EBCS or is my turbo getting tired? I know 166k miles is a boatload of miles for a stock turbo and TD04'S are cheap but before I start throwing parts at it I wanted to get some opinions from the fine folks on this forum. Thanks in advance.
 

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2011 turbotek tuned fxt 4eat paddle shift
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If you have a cobb ap you can moniter your boost level with that by either live logging or data logging i would try that and see what it says.
 

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'21 ISM Crosstrek Limited
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You have an Accessport, so you have a boost gauge, along with many other gauges.

Having an AP, you also have excellent logging ability... which is the path to knowledge about your car. Providing logs is part of asking for help. Otherwise all you are asking for is guesses.

EDIT:
Nate was quicker on the draw :)
 

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2001 Forester 4EAT
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842 Posts
If you don't mind wasting a few hours you can always pull the down pipe and check for shaft play. But I think you're right, turbo's on it's way out.
EDIT: but yes, some logging would be much easier and faster :)
 

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Discussion Starter · #5 ·
Thanks for the reply guys. Using the accessport to data log didn't even dawn on me, I'll have to pull out the book and see what that involves, I have the old version 1, I'm sure it's not too difficult. I'm also gonna pull the intercooler and inspect the BOV. I came across a post of Peaty's on scoobymods that more or less outlined my symptoms and the culprit was a torn diaphragm on the BOV.
 

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Discussion Starter · #6 ·
Just pulled some live boost readings from my accessport, which is just about the only live data my ol' version 1 will provide. Results are as follows:
All these readings were acquired in 3rd and 4th gear. As mentioned in my initial post when I applied a liberal amount of throttle (not violently stomping to the floor but a swift depression to full throttle) boost levels would climb and spike quickly at between 17-18 psi (which seems high for a TD04) only for a fraction of a second then settle down into the high 3's psi and pretty much stay there, if I let off slightly and then rolled on it again it would go to 7-8 psi. The curious thing is if I rolled onto the full throttle position painfully slowly I would get a gradually increase in boost all the way to 12 psi where it would be sustained and pull very hard until I was ready to lift.
I'm clearly no expert but given this info it would seem that my turbo has no issue producing boost and my BOV has no issue holding it. There does seem to be an issue with boost control however. Perhaps an issue with my BCS? This is were I'm pretty ignorant.
Any thoughts?
 

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Discussion Starter · #7 ·
Got a chance to pull my intercooler and inspect all the hoses. Everything looked kosher and surprisingly was pretty clean. There was a light film of oil but no sludge. I then disconnected the BOV and tested it per Peaty's instructions and it was tight with no leaks. I cleaned the lot of it and reinstalled.
To be honest after driving it for a bit today it seems to be performing as normal. I'll have to get some boost reading to be sure. Perhaps simply cleaning the intercooler, hoses, etc was helpful. None the less I believe my next step will be to test/clean the boost control solenoid. I've read plenty of posts on how to do such a thing buy had a difficult time finding a post that stated the exact location. Maybe I'm just that clueless. Is it the small box mounted to the inner passenger fender well and strut tower? That has an electrical connector and two lines running to it from the area of the turbo.
 

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'21 ISM Crosstrek Limited
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Got a chance to pull my intercooler and inspect all the hoses. Everything looked kosher and surprisingly was pretty clean. There was a light film of oil but no sludge. I then disconnected the BOV and tested it per Peaty's instructions and it was tight with no leaks. I cleaned the lot of it and reinstalled.
To be honest after driving it for a bit today it seems to be performing as normal. I'll have to get some boost reading to be sure. Perhaps simply cleaning the intercooler, hoses, etc was helpful. None the less I believe my next step will be to test/clean the boost control solenoid. I've read plenty of posts on how to do such a thing buy had a difficult time finding a post that stated the exact location. Maybe I'm just that clueless. Is it the small box mounted to the inner passenger fender well and strut tower? That has an electrical connector and two lines running to it from the area of the turbo.
This is in no way meant to be anything other than a follow-up, and firm, suggestion to datalog... all the highlighted will disappear and be replaced by definitive statements then.

I'll admit the V1 AP is a, relatively speaking, kludge. However, it's all I had when I had my '05 LGT and it served me just fine. Datalogging answers ALL your questions and more. It takes away guessing about direction. You are wasting your time without it.
 

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Discussion Starter · #9 ·
Appreciate the suggestion. I can also appreciate the importance of data logging as a tool the only issue is I don't really know how to data log. I read my accessport manual and saw nothing pertaining to it. Perhaps the problem is that the closest thing I have to a laptop is the android phone I'm writing this on. Not soliciting instructions on how to data log, just stating facts.
None the less my car is performing as it should at this point. When I removed the intercooler and related plumbing the only issue that indicated a problem was that one of the vacuum hard lines that runs across the front of the intercooler was almost blocked completely with a gelatinous ooze that I effectively blew out with carb cleaner. Seemed to do the trick and unless the returns I will consider the problem solved.
 

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2001 Forester 4EAT
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Glad to hear its back to acting normal! I've had 2 TD04s fail (both with significantly less miles than you're at) and they both had different (and odd) symptoms during failure. But with that many miles on the original unit it's not a bad idea to start collecting parts for the inevitable... (Time to upgrade! :))
 

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1999 Forester S Turbo 5MT
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When this first appears on the horizon many of us start to wring our hands as if the end of the world is coming. Turbo failure is not actually as big a deal as some folks in the trade would have you think. Are you in any way mechanically inclined? I have removed, swapped, rebuilt and modified my turbo many times now to the point where I can do it in around 90 minutes. There are many excellent tutorials online to how you how to rebuild the TD04, and also how to remove it. I don't have any specialist tools either. The other alternative is to buy a s/h unit or a recon if a new one is out of reach although personally, I wouldn't pay the kind of retail that the TD04 comes at.

If the front/compressor side was breaking up you would have found either small pieces of alloy or an oil/alloy paste in the turbo to IC pipe as well as the back/entry area in the IC. I think you have a cat in the up pipe/pre turbo? If that has/is broken/breaking up then the debris could have interfered with the turbine wheel. One of my early rebuilds was using a donated side entry TD04 cartridge which had a clockwise thread for the compressor wheel nut (now they are all anti clockwise because the shaft spins clockwise, in effect a safety/self locking device). I failed to thread lock the nut and it came undone causing the compressor wheel to destroy itself and the housing, but still mangaged decent boost. The clean up took ages but in the event of this happening know that the IC basically acts like a filter so little if anything finds its way through to the throttle body. Whatever does get through will be a fine soft alloy paste that will likely do little harm but I'm open to correction there. Cleaning the IC out is a time consuming PITA but ultimately satisfying 'man' operation. It might be as simple as your bearings failing and as I said above, lots of good picture tutorials to be had as well as service kits by the bucket load.
 

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Discussion Starter · #12 ·
Shef: My thoughts exactly. Although I'll probably just go with a garden variety TD04 in the interest of cost effectiveness, I'll replace a few "while I'm in there" things and perhaps a downpipe and custom tune. That is unless a killer deal on a VF** and STI intercooler presents itself.

Bassmaker: Thank you for all yhe very useful info. At the moment the culprit for my inconsistent boost seems to be a gummed up hard vacuum line. I will however be on the hunt for a replacement turbo in the near future and tackle the task myself. Although I can assure you I won't complete it in 90 min. :)
 
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