giday i have a 98 el xr6 that is over heating when we put it under load either by towing the trailer or just having a bit of fun. about a year ago we replaced the radiator with a xr8 one and a new thermostate and the only other thing we did is put in a j3 chip .when we first found out the car was over heating we then replaced the 3 relays and the temp sensor but that did not fix the problem of the fans not kicking into there second speed and they wont do that even when the aircon is on full ,the only way we can get them to run top speed is to disconnect the temp sensor my last resort is to now replace the ecu any other ideas would be great or somwhere we can get the ecu checked on the goldcoast would be great
thanks .

when driving the fans do bugger all actually, the air speed is greater when you are moving than what the fans are capable of generating. I would be looking at the cooling system and not the fan side of things if it were my car.

starting with a complete system flush.
Also check/replace your thermostat. once they get overheated a few times theytend not to work the best.

I hope you have not put a stop leak treatment in at any time as that stuff is pretty much just sawdust anyway and is pretty bad long term.

Why was the rad replaced with the XR8 one? still trying to hunt down the cooling issue?

But I would start with a complete flush and a new 92 degree thermostat. Then move forward from there. Next I would be looking at the water pump. there is bugger all to the cooling system if it is not loosing any coolant its more a matter of finding out why the system is not flowing as it should.

At the end of the day, you can cool the radiator all you want but if the system cannot circulate or circulation is poor, there is little you can actually achive.

thanks for the info the reason the radiator was changed was the tanks on the sides both split and i was advised that the xr8 one was bigger and better suited to the conditions in qld as for the fans shouldn't they turn on to full speed when the aircon is switched on full because they arn't doing that and thats why i thought that could be the problem .
thanks for the help will get a gasket for the water pump and flush the system and try that to.

The tanks usually don't split, the o-ring just comes out, making a huge leak. This is usually caused by too much heat, as in low water levels in the tanks.
Make sure the system is pressure tested, and has NO leaks, before you worry about the rest. If it's loosing water, there's the problem.
Good luck.

I'm not sure if you guys can read or not but overheating isnt the actual problem here!!!
Problem is the fans not kicking in properly.

I'm guessing you replaced the relays in front of the airbox? I thought there were 4, unless thats only with EFs as I know the thermos are actually different.

Also side tanks do split, 2 out of 2 that I've replaced were split end, neither cars were ever run low of water or over heated.

hello yes all three relays have been replaced in front of the air box and the sender on the side of the thermostate on the front of the motor, it has all so had a temperature probe put in the water and the thermostate seems to be opening when surposed to even when all of this has been checked i still cant get the fans to turn on the second or there fastest speed unless i disconnect the sender on the front of the motor so thats why i am now thinking it may be a wiring problem or a computer issue.

Have u done an ECU self test. If it can it will run the fans. Start the engine, warm it up then with an alligator clip jump the last two terminals of the diagnostics plug [nearest the steering wheel]. Other than that get someone to scan the ECU codes, and run a self test. Regards TPVM.

Maybe it's like this????.....this is from an EL......was doing the same thing.....got hot towing a trailer, or very hot days......and there was nothing wrong with the fans....or t'stat.

 

 

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Try pulling the relays in and out a bit, and a bit of CRC down the terminals, might have some corrosion built up in there.