Haywire

OK...1999 A4, completely stock, 150,000 miles. AEB engine. All parts appear to be original to the car based on factory clamps, etc.

I'm new to turbos...learning as I'm doing. Read many threads on many forums.

I'm getting 2psi max per my vac/boost gauge (also per Torque). Peaks to 4-5 psi during shifting.

New diverter valve 06A 145 710P, new PCV. Zero change.

Did pressure test with homemade PCV fittings etc. Got the pressure up to ~20psi (to the point where the hoses were ballooning) and fixed one small leak. The only other noise was gurgling from crankcase.

Verified wastegate actuator by applying mild pressure directly to the line. Seemed OK...shaft moved. There is no play in the shaft though, it's snug.

Removed the line to the wastegate actuator to eliminate actuation and test drove; no change, so I think that indicates that N75 isn't the cause.

I did an exhaust using Seafoam. Wasn't sure what to expect because I had never used Seafoam with the intent to look for leaks. Didn't really see much coming from under the hood, but I did realize that I had parked my rear to the wind so I had a little bit of stray smoke from the tailpipe.

Question: What does an exhaust leak look like when an engine is Seafoamed? Is it extremely obvious?

So, I'm down to actuator or wastegate itself...I think. I tired to access the wastegate actuator rod with the turbo in situ, but no way I'm getting my hands in there. I assume the turbo has to come off.

In winter, I had occasional P0422s, none lately...still I have a hunch I might have a clogged cat.

What did I miss, and what else could I test?

TIA,

Ron

Prospeeder

Its probably the wastegate flap has worn away or fell off. Remove the 3 bolts holding the cat to the turbo, and the 13mm bolt and spring on the bottom of the cars exhaust and pull it back, look inside and inspect the wastegate flap. Also inspect the catalytic converter, if its plugged up there wont be much boost happening if the exhaust cant escape. It cant be a control problem, like the N72 because the wastegate spring is set to 4 psi, so it must be a mechanical failure, IE turbo wastegate, clogged exhaust ect. There is no repairing the wastegate flap, you must replace the turbo.

If the car is cold, and you have a little snake like optical camera for looking down holes, take out the o2 sensor and have a look inside.

Haywire

Thanks for a great answer.

I'll remove the O2 and sneak my scope in. Will post pics if I can.

Thx,

Ron

Haywire

So what do you make of this?

Prospeeder

hahahaha my Passat had the same exact thing, no boost at all, and thats what I found. You need a new turbo. I tend to just try and find a good used one from like ebay for 100-150 bucks as long as its an original KKK (now borg warner) And the wastegate is in good shape, and minimal shaft play it should live many years. Or spring for a genuine new Borg Warner turbo. But dont waste your time on that 150-300$ ebay new turbo junk. I tried one on a subaru, dead in a month, tried one in a 99 A4 for an older lady who did not drive hard, put in friday, car towed in smoking like hell on monday.

Haywire

The local yard has several to choose from for $50/each, one car already has the front clip off and cat pipe cut, so removal will be a snap...have to figure out what engine codes have compatible turbos to my AEB...have read somewhere that the 2001 and newer are slightly better. Input is welcome...and thanks again for the spot-on guidance.

Prospeeder

Any Passat or A4 1.8T turbo will bolt on and work fine, no modifications regardless of engine code. Of course be sure the wastegates are in good shape, not wearing away, melting, or super loose, as well as be sure shaft play of the impeller are not excessive.

Haywire

Sooo, is this too much play?

I'm in no hurry...I can wait a few weeks to do a rebuild (I have a pretty well equipped shop at home and work). I'll just driving without power for awhile longer.

Prospeeder

That looks about normal. I would run it. Sometimes they feel alittle looser if they havent been used in a long time. I will dribble some oil into the feed hole and spin it, then feel it.