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-   -   Audi Q7: Coolant has mixed with engine oil & triggered a plethora of issues (https://www.team-bhp.com/forum/technical-stuff/213568-audi-q7-coolant-has-mixed-engine-oil-triggered-plethora-issues-2.html)

I echo Jeroen's comments here. It may not be as bad as a leaking head gasket. If you are lucky, it could be something much more simpler like a failed oil cooler.
You mentioned that initially there were signs of oil and coolant mixing. During the same, do you recall if the overall fluid level of the engine oil and coolant where within the limits or not? And was there noticeable difference in the color of the exhaust? If exhaust color was normal, it is quite unlikely that there are failed cylinder head gaskets. Usually modern VW TFSI/TSI are pretty reliable there with some basic regular maintenance.

I do not know the precise schematics of the ancillary component layout of this 3.0TFSI, but if you are lucky, current issue could quite possibly be:
a) A faulty coolant pump (I think layout is such that mixing can occur, Eg: 1.6TDI mixing can happen at coolant pump side also, but impossible in case of 1.8TSI).
b) Faulty Oil Cooler (most common point that fails and creates oil/coolant mixing)

And as already mentioned in the thread, the default universal coolant color for VAG engines is Pinkish (not green).

I am attaching a SSP of the particular engine and I think it might be useful for other members also on this thread to provide advice or possible weak points that could lead to this fault.


This particular 3.0L TFSI utilises a supercharger which has integrated liquid to air cooling unit. If I'm not mistaken, there isn't a probability for mixing of coolant with engine oil at this location:)

Cars are generally very cheap in the middle east. Just because he bought it that cheap does not mean he got a lemon.

Maybe his Q7 is savable, he can better decide after he gets the report from Audi Mechanics.

+1

Even though he got it cheap, he has used it for more than 80K kms without any major issues. That itself justifies the purchase.

Some what related thread given below, please read through to check for suggestions:
https://www.team-bhp.com/forum/techn...30-000-km.html

I was taking this to BOSCH or Arya. I found Bosch guys to be incompetent though.

Considering that only 75K of happy life is left, ny suggestion would be to let it go. Plonking $$$ now and then again after 300K doesn't seem to be a good idea.

Received the details from German experts garage. They are saying that the cleaning was not done properly. So the coolant again mixed with engine oil and was circulated throughout the system. This has caused damage to engine.

Currently, the cylinder 1 and 2 are showing severe compression losses and there is a leakage in few pipes which were damaged due to overheating. As per the mechanics, the engine needs a complete overhauling which will be costlier than total price of the car.

I have asked them to provide this on a paper and will be taking car to previous garage today to check what could be done since it is clearly a human error.

Any suggestions of what could be an alternative to engine overhauling?

Find a used engine, which should be easy in a place in Sharjah and swap it in. No stress of rebuilding the engine, which will probably BE more expensive than buying one from a scrap car.

But it must also be noted that the car also served him well for 80k odd Kms before this issue. So it not fair to blame the previous owner.

The location is Abu Dhabi sir, not India. The price dynamics there are considerably different. The typical price for 2010-11 Q7 is 6-7 lakhs. So he only got a slightly better deal. And he has already covered 80K. So no point blaming the guy who sold it.

any problems expected with the car’s electronics when you swap an engine? Mechanically, electrically it is all very straight forward. The challenge could be whether the electronics will work correctly once everything is in place. On quite a few high end cars, you need access to a proper Manufacturing specific programming unit. Even on my Jaguar XJR 2002, when swapping the engine, it’s getting the electronics up and running properly which is the main challenge.

I don’t know about Audi, but it’s worthwhile checking. There are of course those guys that will just disable the CEL and call it a successful transplant never the less.

Jeroen

If its just the physical bits of the engine being swapped, then there will be no programming needed. The electronics are a bother when you are changing things like control modules, etc. If he manages to get an engine with the same 4 digit engine code, which shouldn't be a problem - then it will simply be a matter of removing the existing engine, putting in the new one, and connecting up all the electronics.

Even if the control modules are retained, I would imagine there could be some learning / adaptation required for the new engine, for components like throttle body, intake manifold flaps (this engine has one on either cylinder banks), fuel pressure related calibrations etc during an engine swap. Nothing major, and do not require a factory tool for it, something like VCDS / OBDeleven can also do the job.

An update on the situation. I took the car to 2 more workshops and all of them had the same conclusion. Leaking head gasket allowed the coolant and engine oil to mix slowly. This led to partial loss of engine capacity in cylinder 1 and 2. Overhauling was the only option to save this engine. The cost for overhauling was almost exceeding my purchase price.

Went to Sharjah to look for engines. Found one after a lot of search and the cost of engine was close to overhauling cost.

So with no option to save the engine which was now randomly losing and gaining power, I had to sell the car. Selling this to an individual was not an option and dealers were asking this at a dirt cheap price.

So took this to an auction where the auction house did a preliminary check and pasted their report on the car. Somehow, they thought that check coolant level warning light was not an issue and can be fixed quickly. No questions were asked to me about the car condition or the issues. The car did not misbehave during a 100 meters test drive that they did within their own parking. Had a thorough cleaning and polishing done before I went to the auction.

The auction went on for few minutes and luckily, lots of dealers were interested. Sold the car at approximately 65% of the purchase price. It feels bad to let such a beautiful machine go but considering the circumstances, had no other option.

Back to used car market for a Q7 or X5 or a Cayenne now.

Same thing happened with my sisters brand new Ford Endeavour. Luckily Ford replaced the entire engine and all pipes free of cost under warranty.