Hi All,
I'm on the slow boat to getting my zero cost Barn Find back to respectability.
History
Car is a 1998 4.0 X100 It's currently suffering from rough idle but once it's warmed up it Idles well at 650prm.
While I was waiting for the car to warm up I got a low coolant warning. On investigation I found a thick pool of coolant by the drivers (RHD) front wheel.
The Coolant is orange ish in colour but seemed to feel oily. Waited for the car to cool down and checked the expansion tank.
Once I got the cap off I could see it was almost empty and bits of the cap O rings where in the tank. Picked the bits out I again noticed that the coolant had an oily feel to it.
Filled the expansion tank up with just over 1 litre of 50/50 coolant, stated car and noted that the coolant warning had gone.
Took the car for 1/4mile spin seemed to drive ok but when parked up I could see coolant dripping from the overflow pipe.

Today.
Took the drivers side (RHD) Wheel and wing liner off to see why the Coolant overflow was dripping.
Didn't take long to find that the atmospheric tank was full!! After removing the tank from the car it was very clear that what was in the tank was not what I'd class as Coolant,
more like a sludge mix of thick coolant and oil. I've cleaned the tank out with white spirits and just put it back empty for now.
My next step will be to give the coolant system a full flush out.
For now I'm ruling out the head gasket as the dipstick was showing the engine oil at the right level and colour (no coolant in the oil)
I will be doing a compression and leak down test and will be guided by the results.

Question.
What would cause the coolant system to become contaminated with Oil?
I'm sure the car is not fitted with an engine oil cooler also couldn't visually see one.
Is there a route in from the gearbox??

Thanks for any advice.
XKRT

 

I suspect someone mixed different coolant types resulting in a gel. Hopefully a system flush will remove the mess, but you may have to backflush the heater core and maybe even have the radiator steam cleaned. When you get it cleaned out use the red coolant, which is the currently approved one.

 

Thanks RJ237,
once it can be shown that there is no other reason for the gunk in the coolant (engine/gearbox oil contaminate)
then full flush out and new recommended coolant fill-up will be on the list of job to do.
XKRT

 

As you pointed out, there is an off chance there is a leak of transmission fluid into the cooling system. The left side of the radiator houses the transmission cooler, and it occasionally fails. My understanding is that coolant ends up in the transmission as well.

FWIW, keep in mind the reservoir cap is a critical part in the cooling system and is known to fail pretty regularly. I assume a leaky cap would allow the coolant to be pushed to the overflow tank. Cheap part to buy, and stock a couple extra.