Oil in expansion tank!

[Ritch]

We shortly celebrated ticking over 200k in our 06 D5 equipped V70. It has unfortunately developed a worrying fault!

I noticed a thick sludge of engine oil on the top of the expansion tank which all posts seem to have led to the oil/water heat exchanger being the culprit! I’ve swapped that out and am currently running a dishwasher tablet flush through.

I’m on my second proper flush but when I top off with clean water it quickly gets an oily slick in the expansion tank again.

How many times should it need flushing like this? The majority of the coolant that came out was a lovely newish colour and the T stat housing was 100% clear of oil.

If i’m unlucky and it isn’t the oil cooler, is it then only the HG left as possible culprit?

Cheers

[VOLVOBOY]

Hi.
Definately engine oil ?
Is the car an automatic ? Could be transmission fluid.
Headgasket failure on a D5 is very rare.
Could be EGR failure.

[Clan]

Originally Posted by Ritch

We shortly celebrated ticking over 200k in our 06 D5 equipped V70. It has unfortunately developed a worrying fault!

I noticed a thick sludge of engine oil on the top of the expansion tank which all posts seem to have led to the oil/water heat exchanger being the culprit! I’ve swapped that out and am currently running a dishwasher tablet flush through.

I’m on my second proper flush but when I top off with clean water it quickly gets an oily slick in the expansion tank again.

How many times should it need flushing like this? The majority of the coolant that came out was a lovely newish colour and the T stat housing was 100% clear of oil.

If i’m unlucky and it isn’t the oil cooler, is it then only the HG left as possible culprit?

Cheers

The oil has seeped into all the rubber hoses long before you discovered it . The only safe way of preventing this and other hoses hose blowing one after the other just when you have forgotten all about it is to replace every rubber hose in the system . not far off £ 500 last time I did one about 10 years ago .

The D5 headgaskes cant blow unless you have seriously overheated it and warped the head .... they are multi layer stainless steel sheets ..hence their cost

[Ritch]

Originally Posted by VOLVOBOY

Hi.
Definately engine oil ?
Is the car an automatic ? Could be transmission fluid.
Headgasket failure on a D5 is very rare.
Could be EGR failure.

Hi VolvoBoy, i’m 99% it’s engine oil, very black and tar like, seems just like dirty diesel oil. I’m very familiar with the tranny oil in these having swapped out the valve body a few years back.

Tell me more about how the egr could fail and get oil in the water? Not massively familiar with them on these but aware on other engines how an egr can fail and pressurise the coolant or burn it out the back.

[Ritch]

Originally Posted by Clan

The oil has seeped into all the rubber hoses long before you discovered it . The only safe way of preventing this and other hoses hose blowing one after the other just when you have forgotten all about it is to replace every rubber hose in the system . not far off £ 500 last time I did one about 10 years ago .

The D5 headgaskes cant blow unless you have seriously overheated it and warped the head .... they are multi layer stainless steel sheets ..hence their cost

Clan, thanks, your wisdom comes up on many a search!

It can only be a matter of weeks/months since this began as I regularly check the old girl over as my wife commutes in it. I almost have a sense of pride in how clean and new looking the coolant has always been in this car! Often isn’t in others lol!

I don’t doubt you at all but it won’t be getting £500 on it at this stage in life…

[VOLVOBOY]

Hi.
When i mentioned the EGR i was thinking diesel oil vapour and not engine oil.