Overheating!

[427james]

Came back from a long run the other day (luckily without ay traffic). When I pulled up I noticed it was at around 100 and climbing.

I have since run the car and the fans just dont come on.

I have checked the plugs at the front to both fans and cleaned them with some WD40 and a toothbrush. Also checked the fuses which are fine.

It doesn't seem to matter if you disconnect the ECU temp sender or not!

ANy one have any ideas?

I am fast running out of love for the car! I have had it actually working for around 600 miles in 5 months and spent 5k on it!

James.

[Far Eastender]

Do you need one of these?

www.clever-trevor.net/part/131/radiator-coolant-temperature-fan-switch-tvr-part-no-tvr006.html

[jbvipercerb]

I thought if the ecu has an out of limits signal from the temp sender it would put the fans on. If they still aren't working have you checked the fuses and relays in the fuse box, or if they're ok is there power to them and a signal from the ecu to switch the relay?
Don't give up hope!

[TT Tim]

If you want to check the fans themselves, pull the lead off the temp sensor on the hard pipe under the front engine cover, with the ignition on the fans should come on when the sensor is disconnected. i.e. the system fails 'safe' with the fans on.

HTH

Tim

[jensena]

If you have air in the system the fans wont come on and it will overheat, so bleed the system to make sure there is no air in it.

[JohnSW20]

Hi

Sorry to jump on the end of this; but how big a job is it to bleed the system??

Cheers

John

[Steve_T]

Pull the connection to the temp sender, to force the fans on, then get a multimeter and check for a voltage across the connections to the fans. I'm assuming that you only need to switch the engine on, but not start it for this to happen (can't remember). If you find there's a voltage across the terminals, then the likely cause is that the connectors are sufficiently corroded to prevent enough current flowing to start the fans. Clean up the connectors and try to switch the fans on again. If there's no voltage to the fans, then your problem is upstream of this point - a problem the ECU or a wiring fault most likely.

Steve.

[jensena]

JohnSW20 said:

Hi

Sorry to jump on the end of this; but how big a job is it to bleed the system??

Cheers

John

Easy Job - 2 Bleed screws on the coolant pipes each side of the engine - big ugly large wing nut type things. Make sure the collant is topped up to maximum, then get the engine warm, unscrew then and allow the air to escape until only liquid is being expelled, then tighten up and repeat for the other side. Then repeat again to check.

[427James]

Thanks guys,

The fans do not come on when the temp sender unit is disconnected and I have cleaned up the terminals.

I will bleed the system, but the fans should still come on when the temp sender unit is off.

All fuses are OK, so I am a bit frustrated with it (again). Why is the wiring so utterly poo on these cars????

James.

[TT Tim]

Stupid question - it isn't your gauge that's knackered is it?

I ask as my gauge reads over 10 degrees over.

Try plugging in the laptop and watch what happens, can't remember the temp for fan1 - have a feeling it's mid 90s.

Good luck

Tim

Edited by TT Tim on Monday 22 January 19:12

[keithyboy]

TT Tim said:

. . . I ask as my gauge reads over 10 degrees over. . . .

So does mine apparently as do many others - it's to do with the routing of the capillary tube alongside the manifolds allegedly. Overheating is also often caused by an airlock in the system - I had a similar problem a while back - all sorted now. Make sure the filler cap on the reservoir is good and tight too - this can also cause similar symtoms.

[thegreengoblet]

jensena said:

JohnSW20 said:

Hi

Sorry to jump on the end of this; but how big a job is it to bleed the system??

Cheers

John

Easy Job - 2 Bleed screws on the coolant pipes each side of the engine - big ugly large wing nut type things. Make sure the collant is topped up to maximum, then get the engine warm, unscrew then and allow the air to escape until only liquid is being expelled, then tighten up and repeat for the other side. Then repeat again to check.

I also found that undoing the rad nut ever so slightly (top right hand side of rad - you'll have to remove the engine cowling if you have a 4.5) expelled some air.

Oh , and thanks for the help when I needed to bleed my system Jensena