Coolant Fans Not Working

[mickthevick]

Hi, i have a is200 and its started overheating at slow speed, ive noticed neither of the fans are kicking in even with the ac on, all the fuses seem to be ok, also when its overheating the heaters start blowing cold has anyone got any ideas what this could be.

[ColinBarber]

really overheating, or the gauge showing it is overheating?

The fans work from a temperature switch via a relay, so either the switch or relay could be faulty.

[clifton 94]

hi check your water level in the rad not just the header tank if its low in the rad start the engine and top up the rad while its running this will expel any air then check for any leaks and see if the fans kick in

[sjrainsford]

Possible symptoms of an air lock there.

[mickthevick]

thanks for the replies, its really overheating (blowing steam from just under the rad cap). checked water level in the rad it looks full, top hose and bottom hose both hot, will try running it with the cap of to expell any air locks in the morning, p.s should it blow steam from just under the rad cap ? and thanks

[sjrainsford]

If its over heating it will blow steam from the rad cap as they also combine as a pressure relief valve.

If the cap has failed the water can boil and cause things like air locks.

First off though, I'd be keen to run it with the cap off and give all of the hoses a good squeeze to try and expel any possible trapped air. It's also not uncommon for water pumps to fail.

[ColinBarber]

p.s should it blow steam from just under the rad cap ?

Normally no, but the cap has a pressure valve in it to do exactly that if the system gets too much pressure. A faulty cap can make it vent before it should do.

[mickthevick]

Bled the air out o the system this morning and the fan kicked into life, took it a spin round the villiage got back home with steam yet again coming from the bonnet, it looks like my rad is leaking on the seam below the rad cap, is this because the cap is faulty or is my rad shot at,

[clifton 94]

If its coming out of the seam the rads finished and will need replacing don't use it till you replace it or the next thing will be head gasket

[mickthevick]

Thanks for that, going to get it stripped down, is it normal for it to pressurise and blow out of the rad though or should i be looking at the water pumo too.

[mickthevick]

*pump lol*

[ROYT]

also check if the thermostat is stuck shut or otherwise faulty

[mickthevick]

Thanks will check, radiator is now off and looking for a new or second hand one

[sjrainsford]

Yes it's normal for there to be pressure there. Too much is bad though and that's why the cap has pressure relief.

[mickthevick]

Nice one, had the thermostat out tested it in a jug of boiling water and it did'nt move at all so i know thats gone just the rad to source now, is there anywhere to buy lexus parts at lower prices also how do i check to see if the water pump is working as it should.

[ColinBarber]

there are third party radiators and thermostats available for the IS200 if you want to save some money. Eurocarparts for example list parts for the IS, no idea on the quality - hopefully others have some direct experience.

[mickthevick]

thanks for that.

[clifton 94]

hi there's a rad on eBay that's new with fans