Help! Oil In Coolant?

[Luey]

Hey everyone.

I'm having some issues with my Audi A3 2.0 TDI Quattro... again!

I really hope someone can help! I have a tiny amount of oil making it's way into my cooling system.

I have provided details below and done a lot of testing and thinking on the matter.

I have had the issue for about two to three months, but I haven't used the car a lot in that time. 1000 miles tops.

What I know so far:

• There is a tiny amount of oil floating on the top of the coolant in my expansion tank
• There is less than a 10p coin size amount of oil floating on the surface
• The oil is not mixing with the coolant, there coolant otherwise is fresh and clean
• The car is not loosing any noticeable amount of oil or coolant at this point
• When running the car with the expansion tank open there are no bubbles indicating there are no exhaust gasses escaping into the cooling system
• There is no sign of any moisture entering the oil system whatsoever, no froth, sludge, nothing
• There are absolutely no signs there is anything wrong with the car and no performance issues
• I first noticed this issue about three months ago and it's seemingly not gotten worse

My thoughts

• Wherever this leak is it has to be astoundingly tiny
• I believe if the head gasket had cracked I would not still be able to drive the car
• My guess is either the oil cooler has a tiny fracture or there is a leak in the rubber oil cooler gasket
• I'm not even certain it is oil if anyone has any other guesses, but I am fairly sure it is... 

If anyone has any ideas or thoughts please let me know! 

[Magnet]

Hello Luey,

CIn the absence of any other replies to date, I would be tending to follow your 3rd. possible point under "My thoughts" in this case.

There are a lot of misconceptions about head gasket failures, since this gasket protects not only combustion pressure to combustion pressure, but this pressure to a coolant channel or the oil way. It can also protect links between (high) oil pressure and usually (the lower pressure) the coolant channels. 

If this oil was entering the coolant via this gasket, then there has to be the start of a failure between the oil gallery and an adjacent waterway. 

Not sure of how much this might help pending other replies. 

Can you extract the oil?? Using a srynge or similar, so you can check that it is indeed oil. 

Kind regards,

Gareth.

[Luey]

4 hours ago, Magnet said:

Hello Luey,

CIn the absence of any other replies to date, I would be tending to follow your 3rd. possible point under "My thoughts" in this case.

There are a lot of misconceptions about head gasket failures, since this gasket protects not only combustion pressure to combustion pressure, but this pressure to a coolant channel or the oil way. It can also protect links between (high) oil pressure and usually (the lower pressure) the coolant channels. 

If this oil was entering the coolant via this gasket, then there has to be the start of a failure between the oil gallery and an adjacent waterway. 

Not sure of how much this might help pending other replies. 

Can you extract the oil?? Using a srynge or similar, so you can check that it is indeed oil. 

Kind regards,

Gareth.

Thanks for the reply. 

Quick update: I called Audi this morning and got a quote for £320 for diagnostics. Obviously I won't be taking them up on that offer. I have called up an independent garage and got a quote for £39 for diagnostics and £119 for labour fitting a new oil cooler, which I would supply myself as I can get it for just £50 from Eurocarparts. They quoted me over £250 for the same part but said they'd happily allow me to supply it. Still making up my mind what I want to do but welcome any more suggestions.

Magnet in response to your post. 

I really appreciate any help and advice. 

I have already fished out some "oil" with my finger. It's very hard to tell if it's actually engine oil. I can't think otherwise what it could be to be honest. 

I've also been trying to work out if I could have accidentally introduced oil into the system myself by accident. Which again I don't think is the case.

 

 

[Luey]

Anyone know if there is any chance I exposed any coolant veins when I took the manifold off a couple months ago? 

I have attached a picture of the work. I would have expected if I exposed a coolant vein to have see coolant at some point. 

This is the only thing I can think of where I could have allowed oil into the coolant system somehow.

[cliffcoggin]

The most likely source of oil to my mind is the oil cooler. A pressure test should settle the matter.

[Luey]

Quick update:

I decided to give "Holt's Radweld Plus" a go this week to see if it would seal up the leak.

It very well may have done the job and been a quick temporary fix to help me isolate the problem. 

I drained the coolant today and flushed the system through with clean water before refilling with fresh coolant.

So a couple points:

• There was only a small amount of oil in the coolant that I drained not at all a concerning amount
• As mentioned on several occasions I'm trying to fix the problem before it gets worse
• The Holt's Radweld left an unsettling amount of sediment and I would advise everyone stay well clear of these products
• I flushed the system repeatedly to ensure none of it was left in the system
• We will see however now if any more oil appears in my coolant
• If none does either the Rad Weld work's and it's a small low pressure leak somewhere or the oil entered the system via mechanic error
• ...and by mechanic error I mean I used a dirty funnel or spilt a drop in the system unknowingly at some point in time

I will update everyone when I know what's going on.

I'm likely going to replace the oil cooler and the seal between the cooler and the block regardless as I suspect that's the problem. 

While I'm at it I'm going to also replace my boost hose seals and I will do a tutorial for the site!

[Fel]

Hi, 

Have you changed the oil cooler and did it fix the problem? 

I have the same problem on my A3 1.8 TFSI. 
 

Thanks

[Magnet]

Hello Felix,

I would suggest you send Luey a PM, since this thread is 5 years old. Having said that, he did revisit the forum a couple of years ago. 
Perhaps you could let us know how you get on. 
Kind regards,

Gareth.