Thought it was a boost leak but could it be a vacuum leak?

Good Evening Everyone,

I am hunting for a pressure leak somewhere under the hood and I think I may have found it but am unsure if what I found relates to the symptoms. The symptom is as follows and can be seen in the video links. When the car is approaching idle (lower RPM) a lower pitched whistle can clearly be heard. I made a boost leak detector and attached it to the hard intake pipe after the intake flex hose. I clamped the EGR to intake hose shut and plugged the small vacuum hose just before the hard intake hose curves vertical into the turbo. I uncapped the oil cap and didnt notice anything. I was using a bike pump with a gauge on it and removed the valve stem from the valve to the boost pressure tester. I then put the oil cap back on and gave it a couple of pumps and the only hissing I could hear was coming from the plastic housing coming from the bottom front of the block to the CCV on top of the engine. There is a crack in that housing where air is leaking from but am unsure if that would be the cause of the winding sound. Are there any other hoses I should be plugging between the turbo and intercooler? It would make sense that this is the cause of the problem since it may be allowing extra air to go into the turbo from the CCV.





https://flic.kr/p/rE1W7t

https://flic.kr/p/qZtevy

And a little something for the help http://vwts.ru/engine/aaz_1z_ahu/1z_ahu_diesel_tdi_servicing.pdf

Thanks,
Justin

Mine whistles like that too. I've never looked much into it though. Interested to see what you come up with.

That doesn't sound overly abby-normal. If anything, I'd say it's an exhaust leak. Maybe check the downpipe flex for cracks. Getting more and more common as those B4s age.

The photos youve pictured are from the PCV oil drain back to the block. Those should never be under pressure. You stated you pressurized from the turbo inlet pipe. Please remove the TIP and pressurize at the compressor inlet. That'll isolate the pressure track. Pressurizing at the turbo inlet pipe is going to put pressure into the PCV and into the block, so you won't find a boost leak that way if you have one.

Ill do that this weekend. I think I would like to do a turbo rebuild sometime down the road so as to avoid this catastrophic failure you were speaking of Anuthee, I found a G15 rebuild kit that should work if a G15 is a G15 is a G15 no matter what kind of car it's in. What do you think? http://www.saabperformanceparts.com/item245.htm

Justin

New turbo. Never seen a rebuilt turbo on a TDI perform properly.

Why not do you suppose? Just out of curiosity.

Because the components are not matched and balanced.

Would it be worth it to build the cartridge and send it out to get balanced? I have done that before on a 1.8t build I did. But I didn't have that car long term so I couldn't tell you the outcome.

Try it and let us know how it goes. You don't mind your car being the guinea pig, do you? After all, what could go wrong?

Okay you win this round sir

jhax said:

Okay you win this round sir

Click to expand...

Actually YOU win because you're not going to waste time and money on a poor value turbo rebuild kit.

Oh HOORAY I win!

Hey All,

Took the boost piping off and I'm going to clean it out. Turns out one of the bolts holding the intake pipe onto the turbo was MIA which is what I suspect was causing the whistling. The turbo has no play laterally and very little play in and out. I cant remember which is good and which is bad? There was also oil in the boost piping which I know is normal, but how much is cause for concern? Photos attached.

Justin

That looks like a normal amount of oil to me, and the real check is the intercooler.

The spot on the ground is the oil from the intercooler.

jhax said:

The spot on the ground is the oil from the intercooler.

Click to expand...

That's it? That's nothing....

Steve

No kidding, mine used to generate 5-6oz per 1,000 miles. I drained it often. Now it generates 1oz per 4,000 miles. I'm hoping that lessens with the new turbo.

So how much oil should I expect in how much time to be concerned about my turbo? What about your guys' axial shaft movement?

Minimal movement still at 440,000 miles but I've seen them go at 1/2 that. It all depends on driving styled oil used. If you're accumulating 5-6 ounces per fillup, I'd say you're close but there is no hard and fast rule.

Well I just changed the oil yesterday and used Liqui Moly full synthetic 5w-40. I drive it on I70 every day 35 miles for work at 65 mph on cruise control. No ventectomy (did that today) from full and am at 825 miles and just got to the line above the red zone. Once you hit that point on the fueel gauge how many gallons are left?

It's different for every car, but usually about 2 gallons. I've known some to run out when 1/2 way down the red zone and some to still have 4 gallons left.

Owners manual says it's supposed to be a couple gallons when you hit the orange.

On my Mk3 when the low fuel light comes on it typically takes about 11 gallons to fill, which means that the remaining contents should be roughly 3.5 gallons. The light comes on too soon IMO.

Steve

Well Steve ze Germans probably designed that because us Americans only have driven gas cars and dont know any better.

jhax said:

Well Steve ze Germans probably designed that because us Americans only have driven gas cars and dont know any better.

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I wouldn't doubt it...

I think the Germans thought it odd that Americans wanted cup holders, at least that's what a couple German friends I know told me.

That's just one of the many aspects about these cars that I like actually, they were made for driving, both hands on the wheel, driving. I was watching a documentary about Ferraris and how they were made. The plant manager took the crew through the entire process and at the end he showed a finished product, he specifically pointed out that that particular car was for an American customer because it was built with cup holders. Looks like Ill put the boost pipes back on since it doesnt seem like the turbine is rubbing on any of the housing at all. So besides excessive oil in the boost pipes, what should I be looking for when a turbo begins on the slippery slope to faildom? I was talking with Anuthee who informed me that when these turbos fail, they fail catastrophically. What does that look like? Feel like? Sound Like? Im driving to vegas for Wuste at the end of the month and I just want to be absolutely sure everything is alright, especially since I plan on not using any interstates to get there.

So I know things have been done to prevent oil build up in the boost piping, I was thinking of taking pieces of a t shirt and wrapping them around the "male" barbs on the top of the CCV system (one on the passenger side of that hockey puck gig and one on the drivers side of the intake pipe. What does that goofy little sensor on the intake from the CCV measure? oil vapor haha? From what I have read, that little guy does not like to be blocked off right?

The build up is just condensed vapor from the CCV. The sensor is a heater. You don't have anything to worry about with your "build up"

I would like to keep the build up in the engine part of the engine bay if I can help it, I have it registered in a non-emissions county, If I could plug the intake and get a canister for the CCV without it screaming faults at me I'll do it.

Your engine is a diesel. Diesel fuel is an oil. Using the proper engine oil in your car makes the pretense that it too is made to be burned. Emissions regulations were taken into account when this vehicle was made and how it is operating is unlikely to be illegal. That and given how little oil vapor is being deposited in your intercooler, you won't be affecting your emissions by leaving it stock, as it was sold in the US, as it currently is.

You sir and your emissions morals...