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Hello I bought this car yesterday, seat ibiza 1.9 tdi 2001 AGR engine, fixed geometry turbo, GT1544S with 290.000km.
The owner told me that it has an air leak from the turbo into the crankcase ventilation port.
Anyway the car runs fine with lots of power, no noises, but notice a little rough on idle and a low continuous whistle when accelerating past 3000 rpm. Today I decided to do a boost leak and really find out that it really exists a pressure leak from the air intake into the crankcase with the air intake hoses disconnected from the engine. I made a drawing of what I did to test it. Does this mean I really have to replace my turbo? or it is normal that this GT1544s leaks air into the oil side, back through the crankcase?

Thank you


teste_boost_eng.jpg
 

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How can it? The ccv is on the intake before the turbo, I don't see how it could leak that way at all.

Blown turbos generally leak oil, a lot of oil, either into the intake in which case the engine revs by itself or into the exhaust in which case there's a lot of white smoke. Some whistle is normal, with stock it sounds a bit like an owl but with a modified exhaust or boost pipes it can be louder. Obviously the faster the turbo spins the higher the pitch.
 

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How can it? The ccv is on the intake before the turbo, I don't see how it could leak that way at all.

Blown turbos generally leak oil, a lot of oil, either into the intake in which case the engine revs by itself or into the exhaust in which case there's a lot of white smoke. Some whistle is normal, with stock it sounds a bit like an owl but with a modified exhaust or boost pipes it can be louder. Obviously the faster the turbo spins the higher the pitch.
Yes believe me, I'm lost on this, I disconnect everything that goes into the engine and the only way pressure could go inside crankcase is through turbo (compressor side). I'm thinking it could be bad shaft seal on the compressor side. In fact if I just apply 3 psi this pressure goes to crankcase. I don't know if it's normal with this fixed geometry turbo this air leak? Today I've done a smoke test leak, and smoke come out through the same place, the hole in the engine where ccv fits. I found some reports of people doing boost leak test and the oil start bubbling!
 

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Are you sure that pressurized air does not flow through the cylinders with open valves into the crankcase, and appears again at the crankcase ventilation?
There is no possible path from the turbo housing into the crankcase, both are connected with bulk material.
 

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Are you sure that pressurized air does not flow through the cylinders with open valves into the crankcase, and appears again at the crankcase ventilation?
There is no possible path from the turbo housing into the crankcase, both are connected with bulk material.
Hello audi1z, yes i'm sure, if you look closely to the picture above I disconnect all pipes connecting to the engine, all except turbo. I even disconnect all hoses connecting to N75 so the only way pressure could go inside the engine, into the crankcase, is through the oil connection on the turbo, or the way you said but through the hot side of the turbo. If the pressurized air travel to the hot side of the turbo it won't create pressure in the crankcase because the exaust pipe is open, or am i thinking wrong?

But today I tested again and I also hear the oil bubbling!! like other people report on other forums. I don't see another possible way of this happening, only with bad turbo seals. :(

found this exemple:
https://www.dsmtuners.com/threads/oil-bubbling-during-boost-leak-test.445658/

thank you
 

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All I can think is the air is going past the turbo seal and then in through the oil system, there's a feed and a return. But is there oil coming out the seal? I'd have thought there would be if there's enough room for air to get in.

Maybe the system just isn't designed to be tested like that. The impeller is like an odd shaped fan so forces the air in the opposite direction.

If you really think the turbo is to blame though you could check out turbo rebuild in the UK, they're a good company and sell good parts to repair turbos. See if they would ship a rebuild kit to Portugal.

They're very simple when you open them up but you have to very careful about marking the turbo impeller and the nut in relation to the shaft or it will definitely need rebalanced. All has to line up exactly as it came apart.
 

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Hello seatman, yes that's what I'm believing turbo seals. I'm waiting for some tools to remove the turbo hoses and see if the turbo is leaking oil through the compressor side. I've been reading about turbo rebuilding replacing only the full cartridge for about 120€ it's already assembled and balanced and since my turbo housing is in good condition I think it will be better than, a more expensive, complete turbo. I will contact that company and see what they have to say to me about prices and delivery, but I think it will be quite expensive because of the brexit thing, customs started to apply taxes :(
 
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