Overheating - Where do I start?

There are many, many threads on here relating to this issue....but
1.check coolant level.
2.pull drivers side luggage compartment trim and check two maxi fuses nearest firewall.
3.put a finger through the bumper side-vent(engine off!!)and spin the cooling fans either side. Stiff/siezed fans are common.

Let us know what you find!

 

I had the same problem. My fix was the both the Thermostat and fan relay needed replacing. Easy fix.

 

Odd complaint indeed!

On the basis that the temperature is fine when driving and only gets over-hot when idling one would of course suspect that the cooling fans are not working, but you've confirmed they work.

Both? First fan comes on at about 90c and the other one should come on at just under 100c.
On mine, the second fan will only come on if I block the inlet to the first one as the one fan prevents the temp from getting high enough for the second fan to come on.

Maybe your first fan is not working and it's only when the temp hits the higher level that what should be the second fan comes on? This scenario would produce pretty high indicated temp value on the dash.

On a RHD car it's the driver side that comes on first, I think it's the same on LHD.

 

1. 40 mm from neck when cold.
2. Sounds good
3. The RHS is normally used a lot more frequently - mine is real loose but my LHS is somewhat tight to rotate by hand but runs like a good'un when I force it into operation as above.

Possible that your temp sender has failed and is sending incorrect information? They are relatively prone to doing so.

 

Question for Eddie........

Is there an electric re-circulation pump in the system somewhere (other than the main mechanical pump)? I seem to recall reading somewhere that there is one but I've never come across it. Possible contributor?

 

Yes, secondary electric pump for the heater, mounted on the front bulkhead.

I agree with FerrariDublin, you could well have a fan switch issue, mounted on r/h radiator. Check the internal resistance of the r/h motor too, if it's higher than the left (take a couple of readings, turning the blades slightly between readings) when the motors wear, high IR can burn out the high speed sense signal of the r/h fan. You should have the r/h fan spinning at a higher speed than the left when the temp approaches 3/4.

 

so the fans turn, are getting power and it still overheats?

I would think thermostat no opening or water pump if this Is the case...

 

Not always. If speed 2 on the r/h radiator doesn't cut in (compounded if its being driven with the a/c on) then it will overheat. A poor sealing cap or a small coolant leak will also cause it. Water pumps have so far been very,very non-problematic, as have 'stats...

 

I know Eddie... I've just had to run the logic..

 

Yes, 40mm from top of neck to fluid level when cold is correct filling level.

If you had very low coolant your fans wouldn't come on at all and also you've said that your car is fine once you're moving, so, no, I don't think your problem is severe lack off coolant but of course you could still be low. You could also have air in the system.

Given that the temperature is fine when driving and not fine when idling one has to look to the operation of the fans. Your car is doing much more work when driving than it is when idling so there's even more heat being generated. The radiators must be doing their job which means there must be coolant etc.

If the problem only happens when static that is when the fans should kick in pull air over the radiators. Just how high does your temperature go at idling? You posted a picture of a perfectly normally low temperature!

 

As Greg states above.

I missed/skipped reading the "when moving it's fine" part. If thermostat or pump it would overheat even when moving. Agree with fans. I'd clean connections, then consider perhaps poor relay contact or fan motor is getting worn.. I'll pull my fan relays and check resistance across the contacts tonight if I remember on my 99..