Overheating

[wattfield]

My 1994 Rav has been overheating - the heater air doesn't warm up for a long time, then the engine overheats. Once the temperature gets almost into the red, it starts to cool down again. I'm not sure if the fans coming on when it's meant to; I tried to test this but the engine wouldn't get up to temperature while stationary. My other thought is that the thermostats faulty. How do I figure out which is faulty?

Cheers, Watty

[igormus]

My 1994 Rav has been overheating - the heater air doesn't warm up for a long time, then the engine overheats. Once the temperature gets almost into the red, it starts to cool down again. I'm not sure if the fans coming on when it's meant to; I tried to test this but the engine wouldn't get up to temperature while stationary. My other thought is that the thermostats faulty. How do I figure out which is faulty?

Cheers, Watty

Hi Watty

It seems the cooling system must be examinated.

- be sure a head gasket is in order;

- the thermostatic valve is about or already died;

- be sure the coolant level is in limits.

Cheers/Igor

[bothwell_buyer]

Just as igormus says. Simple checks like making sure the coolant level is ok. Things like an air lock in the system would spring to mind, but Ive not heard much about airlock problems on the RAV4. Worth a check.... you can try loosening clips/hoses to check there is coolant there for example. That would be the first solution....

You could try draining and flushing the cooling system then add a anti-freeze.... does the coolant in the system seem more like sludge?? If it is a bit like sludge then that would account for slow heater operation and cooling problems. Remember the car is almost 17 years old !!

Moving on, things like the heater valve sticking are not unknown - the valve is under the dash and there have been some posts on this in the last few months.

The thermostat might be worth changing anyway - no harm.

The pressure cap for the cooling system (ie the old radiator cap thingy) might just be worn out and causing coolant leak??

Theres some cheap things to look for first of all. If the engine is otherwise running ok - pulling ok etc - then a head gasket failure is less likely.

I didn't check your profile... but if you were in Scotland I would have a look for you.

[wattfield]

Thanks all for your help!

Last night I managed to stop when it overheated, chacked under the bonnet, and the fan wasn't turning, so I think that's probably where the problem lies.

I DO live in Scotland - sunny Ayrshire! Think I'll manage, but your offer's much appreciated!

[anchorman]

If it overheats while you are going along I doubt it is the fan (although that should run when the vehicle is idling). You can always take the plug off the fan switch and short it to make the fan run then see if it comes down. If not check the radiator is hot all the way down - if not it could be blocked.

[bothwell_buyer]

I did travel down to Troon to help fix a members RAV and the sister-in-law lives in Prestwick so I don't need an excuse....