911ego

Hoping for a little help... I have a Mk1 Gt3. It has just started overheating in traffic. The thermo fans do not start until the temperature is way too hot. Along a highway, it is cool. The dealer advised me that a new DME is needed at a cost of $12k Aussie dollars. I need some help in understanding what triggers the thermo fans. Are there sensors at the radiators or does the engine temperature sensor do the job? Could there be another answer before I dig deep??

plima

I have a 2004 GT3 and found that the resistor that provides for the "low speed" fan operation failed. This meant that when the DME called for the fan (low speed at first) nothing happened. When it got hot enough, the DME called for full speed, and the fan came on. Simple fix: just wire around (bypass) the resistor, and the fan will come on when requested (but it will only run full speed). No cost, and less than an hour's work ( the resistor is right at the fan, and can easily be identified) Reply if you need more info.

bobsan

what test was performed by dealer to reach that conclusion , 'cause that wont be a cheap fix ??

also, if the fan is working regardless of speed, engine shouldn't O/H

when was last time front was off and debris between the rads removed ??

911ego

The fan on the right side of the car comes on first (low speed) when the car is starting to get over normal temperature. The left fan does not come on at all (yet). If it continues to sit in traffic, it will continue to heat up until both fans eventually kick in (high speed) but the temperature gauge inside the car is touching the red zone before this happens.

I do not know what test the dealer did to come to this conclusion but I think the idea of bypassing the resistor is worth a shot. Do I bypass one or both resistors???

911ego

Forgot to mention the radiators were cleaned of debris about twelve months ago, so that should not be the cause.

bobsan

6.3 mkII only has one fan, could be same for mkI. also years worth of debris could be substantial, whats it look like inside front intake in back corner ??

911ego

The dealer said the engine temp sensor that gives the DME (or ECU) the temp signal checks out fine. The fans can be started by the system tester manually...so the DME is not giving the fans the signal to turn on.

I am hearing that the DME can be repaired by SPECIALIZED ECU REPAIR in Florida. Has anyone had their ECU repaired here? Would it be worth sending the unit there before buying a new one?

ninerguru

Might be cheaper to install a switch to manually turn fans on when stuck in traffic... Is the wire from the eng temp sensor to the ECU broken? If the ECU is not getting the signal from the sensor, the ECU won't know when to turn fans on.

911ego

The dealer is going to put a loan ECU, alarm unit and key fob from another car into mine to test that the ECU is the problem....if so, I either have to isolate the fans with a switch or dig deep and buy a new ECU. I don't know which result I am looking forward to.