OK then random problem alert.

I took my car out today for the first time since saturday (the problem was not present on saturday). It obviously takes a few minutes and a few more in the cold weather for the car to get to temp.

So as I was driving along I was thinking that I was a bit cold and looked down to notice the the temp gauge was just about past the second marker.
Strange me think as it has always sat between the 5th and 6th markers on the gauge.

I think that it might be because I haven't long set off. So I look back at it after around 35minutes driving its still in the same palce and the heaters aren't that warm either.

I get where I'm going then on the way back it gets up to around 4 when sat in some trafiic. So when I get home I leave it running and check all the pipes are warm which they are so think it might be the thermostat has failed open and so the water is passing through the rad all the time.

So check the rad that not warm so then leave it to get up to temp and see if the fans come on. Which they do.

So everything seems fine just a random case of car not appearing to get warm?

Any checks that I might be able to do without dropping all the water out?????

Could the temp switch be faulty? I'm guessing

Yeah could be.
What does it do?
Any idea where it is located?

Im no mechanic, but could it be a sticking thermostat? Had similiar thing happen a car a few years back that caused the same problems.

Sounds like your thermostat - as already been said.

The fans on the IS200 come on when the coolant gets to 80C, so if your rad is cold when the fans cut in there may be something else wrong.

Ok thought that the thermostat opened when the fans kicked in like my older cars.

Didn't check the rad when the fans where on so will try that tomorrow, to see if the water is circulating.

The fans kick in at 93c, might have to get a new stat

any updates mattc

Yeah.

Today its all back to normal????????????

The stat could have stuck open and now it has been heated up again may have closed and is working again as it should, I would monitor the situation for now and see how it goes.

Its all ok again today.

Will get a new stat anyway and when I cahgne my cambelt in a few weeks will change the stat as well, for peace of mind

Just to say that my car has been fine for ages and its now started this random problem again. Think its new stat time

Are you sure its not just due to the air being so cold?!

It does it on my van, but ive noticed its only when its real cold outside!

Get an OEM one. pattern part thermostats have been known to jam open.

Time for a new stat then, I think its wedged open from time to time

matt did you get round to your heater matrix flush ? did it help ? if so it might be worth flushing and reverse flushing your whole system as a build up of crud can accumulate at the thermostst and prevent it from closing properly hence overcooling- i think you would need to reverse flush as that usually moves build up by virtue that the water is going in the opposite direction to normal

[quote name='lexynik' post='712914' date='Mar 10 2010, 09:56 PM']matt did you get round to your heater matrix flush ? did it help ? if so it might be worth flushing and reverse flushing your whole system as a build up of crud can accumulate at the thermostst and prevent it from closing properly hence overcooling- i think you would need to reverse flush as that usually moves build up by virtue that the water is going in the opposite direction to normal[/quote]

No not yet, but think I need to do it now