My 4.0L 1998 X308, has developed a problem.

1. I noticed fumes coming from the oil filler, when opened, after a very short jouney. (Electronic temp gauge shows normal temp.) Thought It might be BLOWBY, but did a quick exhaust check, no obvious sign of Blowby.

2. Oil appears to be very dark. When put onto a kleenex, it seperates into a dark patch and a normal oil patch. Had an oil and filter change about 1000 miles ago. Mechanic said the old oil was very dark/black.

3. Small amount of fluid on the Thermostat Housing Cap. Not flowing out, no obvious cracks. (Plastic Housing)

4. Engine hoses feel incredibly hot. No sign of radiator fan cutting in.

5. No obvious loss of coolant.

6. When looking in the oil filler cap, very dark deposits just inside.


Any thoughts, would be appreciated..

Thx.
Stu.

 

What brang and grade oil are you using? Some motor oils are prone to make deposits and burn in the combustion chambers.
Check if the radiator fans are faulty, they must kick in when an AC is on. If not - check the cooling fan control module and wires.
The smoke and the dark oil colour may be caused by an oil overheat, which may be caused by a faulty cooling system.
Also it may be caused by a liner damage. There's no point in checking exhaust system for a blowby. Do a compression and leakdown tests. Check PCV for a leaks and excessive blowby. Check for a coolant temp. with an OBD-II scaner.
Give us a picture of an engine oil on a kleenex. Remove the spark plugs and check for oil deposits on an electrodes, give us a pic.

 

Thanks for quick reply, I will check the bits you mentioned and will post some pics, as you suggest.

Cheers,

STU.