01 ALH NO TURBO BOOST... SOUNDS LIKE A STEAM LOCOMOTIVE...

[FLASH1970]

as the title states, i have a 2001 Golf ALH manual. 456k miles. recently it lost all turbo boost. i can hear it whistiling at lower RPM (1200-1500), but when going over 1650ish RPM, it starts to sound like an 1880's steam locomotive. in cold weather after about 5 minutes or so of driving, the chugging would stop all of a sudden and itd pick up a tiny bit of power, but can tell theres still no turbo boost. i have ran the codes with VCDS which took about 5 minutes and came back with...

17964 - Charge Pressure Control
P1556 - 35-10 - Negative Deviation - Intermittent
16764 - Glow Plug/Heater (Q6) Circuit
P0380 - 35-10 - Malfunction - Intermittent

I cleared the codes a couple weeks back and no check engine light has come on since.

reading through this forum i got some ideas. So, I checked for boost leaks, none. Checked the turbo actuator using a vaccuum pump, it held vaccuum. Checked to make sure the actuator is moving, it is. Replaced the N75 solenoid, no change. I already replaced the vaccuum hoses a few years ago and did not find any leaks or ripped or cracked hoses.

Any ideas? Thanks all.

 

[P2B]

when going over 1650ish RPM, it starts to sound like an 1880's steam locomotive.

This noise plus the P1556 underboost code is a clear indication of a boost leak. It's possible the leak only opens up under pressure so was missed when you checked for boost leaks. I once found a cracked pancake pipe which only leaked above about 10psi.

 

[FLASH1970]

thanks for the suggestion. ill redo it. not sure how much pressure was in it when i did the test. i just know the intake tube from the air filter to the turbo started expanding like an accordion and held for 30 seconds or so. ill see if i can get a gauge on it and put 15psi through it.

 

[FLASH1970]

Well, I tried re-doing the boost leak test and didnt come up with any leaks... i even took off the intake hose so it wouldnt balloon up and absorb pressure.

 

[IndigoBlueWagon]

How's the oil level? Any oil in the intercooler?

This sounds like a turbo on its last legs to me. If it's original, it's way past its intended service life.

You might want to take off the airbox to turbo pipe and check for shaft play. Also, get a mirror down there and check if you can see any damage to the compressor blades.

 

[shoebear]

I have one of these boost leak testers that attach to the hard plastic intake pipe (after the accordion hose) and allows pressurization to 30 PSI (the limit of the gauge). You could probably piece one together for half the cost, but the kit makes it convenient.

VW 1.9TDI Diesel TURBO BOOST LEAK TESTER - 30 PSI Gauge w/ PCV Block '95-2007 | eBay

This boost leak tester will install pre-turbo on the inlet pipe to make testing very easy. (see photos) No need to cap the throttle body. Turbo Boost Leak Testers, Inc is dedicated to making boost leak testers – Thats it!

www.ebay.com

I do think you have a boost leak, based on your description and codes. I also agree with IndigoBlueWagon's comments about checking the turbocharger itself. Remove the intake pipe to the turbocharger compressor (the outboard side of the turbo) and check the shaft. You should have slight radial (side-to-side) movement and no axial (in and out) play. Also use your phone to snap photos of the intake impeller and the housing around it to look for possible impeller / housing contact and also for impeller blade wear. And check your charge air cooler (intercooler) for oil pooled inside.

 

[J_dude]

allows pressurization to 30 PSI (the limit of the gauge

The real psi limitations are the stock constant tension clamps, and the fact that there's no lip or anything to grab on the turbo inlet.

 

[shoebear]

The real psi limitations are the stock constant tension clamps, and the fact that there's no lip or anything to grab on the turbo inlet.

Yes, I know this from experience! I have upgraded all the clamps to T-bolts, and I haven't tested past 25 PSI.