I got stuck in an 8 mile stop-start traffic jam heading to Poole the other day. The air temp was probably 20+ degC, and the oil temp was creeping up. Once it went just above the top white line (10'o clock) the oil light came on together with the ! central warning light.



My hot oil pressure is usually 1 bar at tick-over and at this oil temp it dropped slightly below the 1 bar marker picking up as usual once I started moving forward again. The (v hot) oil level was showing full at tick-over (while rolling slightly downhill) and once home and on level ground, was 3/4 on the dip stick. (No engine undertray fitted.)

Some air flow through the cooler extinguished the warning light rather than a rise in oil pressure. So I pulled over onto the verge a couple of times during the 40-50 minute queue to allow the oil to cool a bit. This helped and as the oil temp went upto and over the top mark again the oil light came on again.

Once through the jam and driving again, no problems.

Is this normal or does anyone think the oil cooler fan might need checking? Or some thing else?

 

I would check your oil cooler for dirt and debris. I would also make sure your oil cooler fan is running at both low and high speeds. Have you ever replaced the oil cooler resister? I changed mine out as part of my engine rebuild and the resister's ceramic body was badly cracked. It was merely a matter of time before it failed. Also, my oil cooler was full of dirt and dead insects.

Do you have access to a Hammer of Scantool? You can test the oil cooler fan with them.

 

From your advice Rob, it sounds like the fan and cooler are not working as they should. I'll check the ceramic restistor. Last time I looked the cooler was clear, could be a bit cleaner though. I've got to fix the front grille sometime too as a 100mph pheasant ran through it. It could be that bits of it are still in the cooler somewhere out of sight.

No Hammer available.

Many thanks.

 

IIRC there is something in the handbook to suggest that in very hot conditions the oil pressure may drop to trigger the warning lights. This is normal.

My understanding even if the ceramic ballast resistor is knackered the fan defaults to high speed so I'd test the operation by shorting the two pins across the fan relay - Cant remember which two but someone will be along to tell you....................

 

You can also install a manual override switch that forces the fan to run high. I have one and sometimes to resort to it when I am stuck staring at the oil temp gauge in traffic.

 

Confirmed.

 

Yup, with a defective CCU my oil cooler fan speeds are having none of it. Been like this for a couple of years (will send CCU off to Tore B at some point). However, never had over high temps so far, even when in the M25 parking lot for 2 hours one time last summer.

I keep a small jumper lead in the glove box to bridge (marked) relay points just in case the worse should happen in traffic. Try bridging the relay connections for low and high speed to check fan operation (don't need ignition on). If low speed bridge gives nothing then check/replace ballast resistor already mentioned by Zingari. If both speeds work fine but fan not playing ball when engine hot (drive around without the arch liner for a bit to observe/hear out for the fan), then likely to a CCU fault.

Your gauge reading though shows roughly the temp the high speed fan would kick in - 115oC / 239oF (the upper graduation being 120oC / 248oF).