Oil in coolant reservoir?

**5pot** · 02-04-2012, 04:16 PM

Hey guys,

Not sure if this is the right place to post this...

I have a MKV 2.0 TDI (2005). I had my car in the workshop on friday to have the major 105km service, cambelt, waterpump, etc, etc. What they noticed while they were doing all this was that there was oil in the coolant reservoir.

They're not sure how it got in there but I can see black/dark brown build up above the waterline in the reservoir.

I haven't done any oil changes on my own since buying the car in Nov 2009. The two services I've done so far were done at VW Essendon.

The only time I had to top up the oil was on a return trip Melbourne-Sydney. The oil light came on, but I had a spare 1L bottle of Approved VW 507 in the boot (Castrol) which I emptied into the engine and carried on back to Melbourne. Other than that, I have never noticed excessive consumption of oil. The car seems to boost well and doesn't overheat, even during summer with the A/C going, etc. There is also no visible evidence of oil in the sump (there's no mayo-looking stuff on the oil cap) If it has any relevance, i don't think it smokes excessively, except for a good puff when I nail the go-pedal in 2nd gear. The coolant, from memory, has always been pink in colour. I know about this from previous VAG ownership.

Not really sure how this happened?? Is it possible the previous owner had it serviced elsewhere and they used non-approved oil? Is there an oil cooler that's cooled with engine coolant which is now leaking and oil is getting into the coolant? If so, why is there no water/moisture in the sump??

that's all the detail I can think of at the moment...

---------- Post added at 04:16 PM ---------- Previous post was at 10:10 AM ----------

No-one willing to tell me that it might be the headgasket?

**Transporter** · 02-04-2012, 05:06 PM

It could be the oil cooler.
Did you ever changed the coolant? Did you top up with no OEM coolant or tap water?

**buzuki** · 02-04-2012, 06:03 PM

oil coolers a common problem.

**5pot** · 03-04-2012, 08:55 AM

I've never changed the coolant myself and never had to top up. All servicing has been done by a VW dealer in my care and as far as I know, in the previous owner's care too. The coolant has always been the VW pink/red stuff.

Is the oil cooler built into the radiator or is it a separate cooler else where in the engine bay?

**buzuki** · 03-04-2012, 05:06 PM

bolted to the engine with the oil filter housing in most cases.

**Umai Naa!!** · 03-04-2012, 06:34 PM

The engine oil cooler has had an internal failure. It's a common problem with the early Golf 5 TDIs.

Here's hoping they do a thorough job of it.

**gldgti** · 03-04-2012, 06:36 PM

Indeed - you're not looking for a traditional oil cooler but rather its a coolant/oil heat exchanger that serves to quickly warm the oil and keep its temperature stable. Its integrated into the oil filter empennage.

If there is a small crack/separation internally within the HE, some oil could leak into the coolant circuit.

If it was a mk1 diesel I would have suggested headgasket, but VW have pretty much eliminated head gasket problems since the 90's by using incredibly big bolts with lots of threads into the block with lots of meat, and metal headgaskets.

**Transporter** · 03-04-2012, 07:09 PM

Wow, 3000th post, congratulatons.

As for the oil in coolant, I see a lot of earlier MK5 TDI owners in CZ forum Dieselpower forum :: Zobrazit frum - drba/problmy VW group posting the headgasket failures (made before 2005) , if they're right? I don't know (they're very high mileage engines), but I always recall it when someone has the issue with the oil in coolant.

..and as always eliminating the oil cooler first is a good idea, especially if it's a common fault.