oily residue in header tank

[rainydays]

I have a berlingo 800D LX 1.9 Diesel and have noticed an oily residue in the header tank.
The vehicle seems to drive ok with no loss of power and the temperature gauge sits just under half way, could this be a head gaskett issue?
There is no signs of water in the oil and no yellowy sludge on the oil filler cap.

Thank`s: Sean

[citronut]

it could be the oil cooler is on its last legs leaking oil into the coolant,
i would think it is a DW8 engine so not sure how they differ from the XUD lump in that area,

regards malcolm

[rainydays]

Is that a big job to replace?

[rainydays]

Looked over a few previous post and found similar issues.
Does anyone know if the oil cooler just screws off once you have removed the filter/hoses etc?
Also what would be the best way to remove the oil residue from the cooling system/header tank if i replace the cooler?
Do you need any gasket sealant when fitting another cooler?

Much appreciated to all who take the time to reply

[Lighty]

When you remove the filter, there is a big nut, that screws onto the filter thread, this holds it all on, cant remember about the gasket, pretty sure its a rubber O ring type of thing.

[citronut]

i think the nut withdraws the threaded tube theat the filter screws onto, the tube goes right throught the cooler and screws into the crank case,
and i think Lighty is corect it has a large O ring between it and the engine

regards malcolm

[citroenxm]

Ive just taken in a HDi 110 Xantia on 285k, with awfull grey sludgey water in the header tank ONLY!!

Ive already tried an oil cooler on the car from an XUD.. Yes they DO fit and the differences was only the coolant outlet pipes.

Anyway, the car was pressureising the cooling system and leaving grey oily sludge in the expansion bottle, BUT there was no "mayo" under the oil cap, and the oil in the sump was perfectly fine!!

After swapping coolers the car still did it, so it has to be a failure between the oil and water passage way on the gasket.

[rainydays]

I have bypassed my oil cooler today and drained the coolant system. After leaving it running for at least twenty minutes there was still no sign of oil from the oil cooler stubs. Think my problem may be elsewhere.
There is no obvious signs of water in my oil. The car temperature gauge never got above half way. Will probably have to take it to a garage to check for the head gasket side of things

[Lighty]

I would take it for a blast, oil leaks are much worse when the engine is worked, often not leaking at idle speed.

[rainydays]

would you take it for a blast with the oil cooler still bypassed?

[citroenxm]

considering the oil system runs at a few bar id guess even at idle oil would soon be spewing out the coolant pipes that are open because of the bypass and theres no need to go for a blast..

[addo]

No, it's a weep.

Water (coolant): 14PSI hot
Oil: 80PSI hot/revving

With that difference in pressure, even a pinhole will allow decent flow rapidly. You only need a fine level of corrosion, and ingress of oil will take several days/weeks/months to be seen.

Testing is better done with the cooler off, water gallery pressurised to 100PSI (air) in a bucket of water.