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Discussion Starter #1 (Edited by Moderator)
Hi,
OK I need some help with a 1998 RAV4.1 overheating problem.

I have looked at a lot of threads and it seems to be a common problem.
I have yet to see a thread that says "here is a fix". Most just fizzle out with no result.

My problem started about 2 years ago. I noticed the temp gauge getting hot as I got to work. (20 km)
As it is just a to and from work car I rarely do more than 20km.
Shops, rubbish trip etc are all under 20km.

Now, over 20km is a different story.
At about 30km the temp touches the red.

So, I read the codes.
O2 sensor and ECU temp sensor faulty.
Replaced both with genuine Toyota parts.
Now I have no codes but no change, still getting hot.

So, then I replaced all the usual suspects.
Thermostat, Gauge sender unit, Radiator, Hoses, Water pump, Coolant, Cap, ECU sender again.
Co2 sniffer shows nothing. Radiator pressure test OK. Compression test OK.
No change, still getting hot.

IR thermometer shows the thermostat opens at around 84c.
Cooling fans come on at around 104c and off at around 92c
Way too hot I think.

Now, from what I have worked out the fans are controlled by the ECU through a relay.
I have been told by Toyota that the ECU settings can't be reset.
(It was suggested that I pull the thermostat and sell the car)

My current thinking on a fix is an aftermarket thermostat fan switch to control the fans and leave the relay connected to fool the ECU into thinking the fans are still connected.
The only problem I can see is with the A/C.
If the A/C is turned on the fans should come on at half speed.(through the same wires but a different relay)

I am open to all suggestions.

1998 Rav4.1 manual 3FSE with 250000 km

Thanks

Sinner
>:D
 

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Welcome!
I may be wrong but it don't think the ECU has anything to to with controlling the fans. That's usually done by a sensor switch on the radiator which must be defective if the fans aren't turning on until boiling temps are reached.
 

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Hi,
OK I need some help with a 1998 RAV4.1 overheating problem.

I have looked at a lot of threads and it seems to be a common problem.
I have yet to see a thread that says "here is a fix". Most just fizzle out with no result.

My problem started about 2 years ago. I noticed the temp gauge getting hot as I got to work. (20 km)
As it is just a to and from work car I rarely do more than 20km.
Shops, rubbish trip etc are all under 20km.

Now, over 20km is a different story.
At about 30km the temp touches the red.

So, I read the codes.
O2 sensor and ECU temp sensor faulty.
Replaced both with genuine Toyota parts.
Now I have no codes but no change, still getting hot.

So, then I replaced all the usual suspects.
Thermostat, Gauge sender unit, Radiator, Hoses, Water pump, Coolant, Cap, ECU sender again.
Co2 sniffer shows nothing. Radiator pressure test OK. Compression test OK.
No change, still getting hot.

IR thermometer shows the thermostat opens at around 84c.
Cooling fans come on at around 104c and off at around 92c
Way too hot I think.

Now, from what I have worked out the fans are controlled by the ECU through a relay.
I have been told by Toyota that the ECU settings can't be reset.
(It was suggested that I pull the thermostat and sell the car)

My current thinking on a fix is an aftermarket thermostat fan switch to control the fans and leave the relay connected to fool the ECU into thinking the fans are still connected.
The only problem I can see is with the A/C.
If the A/C is turned on the fans should come on at half speed.(through the same wires but a different relay)

I am open to all suggestions.

1998 Rav4.1 manual 3FSE with 250000 km

Thanks

Sinner
>:D
I have to ask a stoopid question, is the Car actually overheating or is just the guage.
I had a problem for a couple of years with my 96 Camry stalling, heat guage in the Red Zone, and no fix.
Mechanic checked engine temperature and it wasn't overheating, just the guage issue and stalling.
Mechanic went out and hooked up some instrument, went for a drive and found that the car was stalling because it was getting too rich a mixture, because a guage was telling the car it was really cold out.
They googled and I went to Camry forum and found out it was the CTS, (Coolant Temperature Switch).
Changed that little thingy and car went back to normal, and the guage worked normally after that.
I went out and bought that neat little gun you point at the engine to check temperature, and use it for meat on the Bar-b-Q.


Ott.
 
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