Technical Oil temperature warning light?

[willendure]

The oil temp warning light (and temperature indicator needle) has been coming on. I have been doing quite a bit of towing recently, and I am wondering if it is something to do with that? Does anyone think changing the oil/coolant might help? I've only had this car a couple of months, but as it is second hand I don't really know when they were last changed.

Also, sometimes the temperature will rise quite easily, other times it takes some acceleration up a hill with the trailer on to do it. Is this something to do with DFP cycles and the excess temperature associated with that?

 

[ourmark]

I think you're on the right track. I'd change the oil and filter first and then look at a coolant flush if no better.

Also check the outside of the radiator in case the front has got blocked up with debris. I had that on a Landrover after deep wading (mud), but it could also be other things like dried grass that got sucked in and stuck, restricting air flow.

Can't really add much on the DPF point, as mine is a petrol.

 

[willendure]

On further investigation it seems that that the main cooling fan is not running. Its electrically powered, I guess due to the engine being transverse.

 

[willendure]

Turns out the fan is working - it just doesn't come on until the engine is hot, so is stationary when idling.

Car is behaving better after not towing for a while. I guess the towing clogs up/stresses the exhaust gas cleaning system too much. I'm going to change oil/coolant and try some diesel fuel flush too, and see if that helps it.

 

[Ralf S.]

Is your beast a diesel?

When was the water pump last changed? These can get "loose" so the pump is being turned by the cam belt but the impellor inside the head is not turning at the same speed.

This needs a new pump.. but it's best done at the same time as a cam-belt change to avoid extra work... unless it's failed, obviously (in which case do it asap... but also fit a new cam-belt so it's all done for a few years).

Also.. try bleeding the radiator (stone cold engine). If there is a screw on the back (left or right side) unscrew it slowly until either air or coolant comes out (don't take it out completely as it will be tricky to put it back in when coolant is leaking out ) Tighten it back up when coolant comes out. Repeat after a few days,

If you keep getting air in the rad' then that could be a head gasket problem but the diesel isn't particularly prone to this.

The thermostat should begin to open when the beast gets to 86C and be fully open when it reaches 90. 90C is usually the "big" or "mid" mark on the temperature gauge. The cooling fan should come on at 92C and stay on until the temp drops to 90C. If your temperature creeps up towards 90.. drops a bit just before it gets there... then rises until just over, when the fan comes on.. the thermostat and fan are working properly.

If the radiatore is in good condition and the pump is new and there is no air in the cooling system and the fan comes on when the temp gets to 92.. then the beast should stay cool (that is below 92C).

Towing up hills will make it run "hot" more of the time than when you're not towing but the beast should never usually overheat so that the light comes on... so check all of the above. I only ever saw the overheat light when I lost a head gasket once (air in the rad' was preventing cooling).


Ralf S.