engine overheating

[CMF_andy]

my radiator and condenser fan is intermittent.
both cut off suddenly and temp. start to raise.expansion tank is boiling.
have to stop the engine to let it cool off,play with the fan connectors.then it is ok.
but works fine all the time.plays me out at least once a week.checked fuses and wiring connections ok.
could it be relays,thermostat,engine temp.sensor?
can i tap a earth wire direct to the fan so that fan starts when i on the ignition?
please help me it is driving me nuts!

 

[CMF_Yom]

I don't see why you cant tap it so the main fan is on constantly when the ignition is on.

Could be a random relay problem, I had an issue the other weekend where the aircon compressor was turning on by itself. This causes nasty power drop and a pressurebuild up inside the system. It meant i had to have the blower fan on constantly.

It stopped though. Hasn't done it again either.

But as for your problem, other thing to check could be the ecu temp sensor (there's 2 of them, one for the dash gauge and one for the ecu). These are apparently a common problem in the UK?

Goodluck

 

[CMF_mrh]

I had this problem when I replaced my motor with one from the wrecker.

It kept over heating all the time so I changed the engine temperature sensor to my old one from the original engine.

Had no hassle once I did that and has not over heated yet. Could be a loose connection on the temp sensor?

In the meantime what I did until I resolved the problem was locate a switch inside the car so I could run the engine on cooler days. Once the car was running at normal engine temp I flick on the switch for the fan.

Good luck with it mate.

 

[CMF_andy]

thanks bros for the replies.
i will change both aircon and radiator fan relays and see how it goes.if it does not solve the problem it has to be the engine temp. sensor.right?

 

[cisco]

Hmm weird. And the thing is, that the fan should be intermittently coming on and off when everything is working properly. If you need to hack something to get it to stay on all the time, then that's just really hiding the true problem..

 

[CMF_andy]

the fan should come on intermittenly i agreed.but sometimes it don't come on when it should be.what do you suggest,cisco?i too do not wish to add a switch to cover the problem.that is my last thing i would do.

 

[CMF_jay85]

hey i am an auto elec....... are you saying that both fans play up? does it happen both when the a/c is on and off? basically both fans will come on when a/c is on and pretty much stay on constantly...... if a/c is off then only the radiator fan will work, it will cut in and out as it is needed. dependin on the temp...... its hard to say wat it is..... pull apart the plugs and check for any burning.... i would be leading towards a wiring problem or relay.... not and engine temp sensor, cause they should still both work when ac is on because it is basically just bypassing the engine temp sensor. it is a hard problem without havin the car in front and playing up to diagnose though

 

[CMF_nz_aj]

If it's a faulty temp sender it will be telling the ECU that the engine is cold. In that case you will be using a lot of petrol. If you're getting around 30mpg or worse I'd be looking at it.

 

[CMF_andy]

i am getting 13km/ltr.
70%highway,30%city.
is it normal?

 

[CMF_nz_aj]

13km/ltr = 7.69L/100km = 36.7mpg
It's on the heavy side but may reflect your driving style or terrain you're driving over.

 

[CMF_EVLGTI]

Try bleeding your cooling system, if you have any air in the cooling system it can cause the overheating.

 

[CMF_andy]

is there a bleeder like the bmw?

 

[CMF_Madrabbit]

It could be the temperature sensor, the one one at the front end of the head above the water pump. This one tells the ECU the coolant temperature and the ECU switches the fan on at the appropriate temperature.

 

[CMF_Alex_B]

here is a page of the haynes. i'd test as many of these specs as you can,

Alex