Disco 2 Disco 2 Td5 - Layer of oil at top of coolant header tank

Okay,

Original head gasket and original oil cooler (270,000km) - 2003 Discovery 2 Td5 ("facelift" model). Everything has been great, and still running with no issues at all, EXCEPT...

Checked fluids yesterday as I usually do most days and noticed there was a thin layer of engine oil floating at the top in the coolant header tank. Previously I had a very small coolant occasional drip/leak at the top front hose and someone suggested that was a sign of a blown head gasket (presuming exhaust gases in coolant and increasing pressure on hoses?). Anyway, I checked this same hose when running to see if it was rock hard as was suggested - it wasn't really - it would give when pressed (I used a rag so as not to get a burn).

So, runs fine - notice no difference when starting or running, but I obviously want to fix whatever problem I'm having! Original head gasket and original oil cooler. There is some coolant underneath the oil cooler and I believe there is a small coolant leak there.

Checked dipstick several times - oil is very clean, with no discolouration or no non-oil smell.

What do you think?

Any further checks I can do to narrow down the problem?

Once I think I'm on the right track then I'll need to order parts and work out what tools I will need to do either job - oil cooler or head gasket, or both?

Any thoughts?

Get a gas check on the expansion tank, if your head gasket has gone it will put combustion gasses in the coolant , it only takes a few minutes to have a gas check, and it could save you a lot of pain and pennies

Assume I'll have to take it to a mechanic then? Assume they'll take the expansion tank cap off, screw something on there and analyse for CO2 and/or CO whilst running?

There's always a chance that the cylinder head could be cracked but it sounds to me that the issue is with the engine oil cooler. If you still running the original at that mileage, the O-rings might have perished or the heat exchanger could have corroded, From what I read, it seems that it is not very tolerant to incorrect coolant type or mix. Check this good write up here - https://www.landyzone.co.uk/land-rover/td5-oil-cooler-repair-oil-in-coolant.201097/

Intestinalworm said:

Assume I'll have to take it to a mechanic then? Assume they'll take the expansion tank cap off, screw something on there and analyse for CO2 and/or CO whilst running?

Click to expand...

NO, you don't need to. Get one of these, https://www.ebay.co.uk/itm/312746279910?ssPageName=STRK:MEBIDX:IT&_trksid=p2060353.m1438.l2649
and you can check for yourself. Very simple to use and accurate.

99% oil cooler issue. Just done mine after same symptoms.

NPG said:

There's always a chance that the cylinder head could be cracked but it sounds to me that the issue is with the engine oil cooler. If you still running the original at that mileage, the O-rings might have perished or the heat exchanger could have corroded, From what I read, it seems that it is not very tolerant to incorrect coolant type or mix. Check this good write up here - https://www.landyzone.co.uk/land-rover/td5-oil-cooler-repair-oil-in-coolant.201097/

Click to expand...

Replaced fuel cooler o-rings - profile went flat, so likely the same thing, not much oil but it is there. Also notice a bit of coolant weeping from oil cooler area so will be able to clean it up nicely. Kit also includes gasket for turbo and I notice little bit of oil around that area - it's amazing what you find when you get some stuff out of the way!

Hellastony said:

NO, you don't need to. Get one of these, https://www.ebay.co.uk/itm/312746279910?ssPageName=STRK:MEBIDX:IT&_trksid=p2060353.m1438.l2649
and you can check for yourself. Very simple to use and accurate.

Click to expand...

Thanks for the link to that analysis kit!