Overheating - Top Hot, Bottom Cold

[hacky]

Alright,

Was through in Lochgoilhead at the weekend, coming back was giving it some eventually came up to gridlock as soon as I got to the traffic my car started overheating. Water temps were rising, once it got to 100 i pulled in as soon as i could. As soon as it cooled down it would be overheating again by the time I started moving.

When driving at 50mph or more it would be fine (86/87) but as soon as I slowed down rising quickly. Highest it reached was 115.

Anyway the top pipe on the radiator was very hot, the radiator itself was stone cold, the bottom pipe was cold and the fan was working. There was no steam, no leaks, no overflows from expansion tank. Does this point towards a thermostat problem?

Ironic that only 2 weeks ago Squiggle was recommending I bought a zero/sports cool running thermostat! Anyway, what do you think it is likely to be? Faulty thermostat, air lock, etc?

Thanks guys

[cullenmin]

Have you done a coolant fluid change lately? If this was done incorrect then you could get an air lock, squeeze the rad hoses (when cold) and you'll hear any air pockets in the system. If so keep squeezing and keep topping up the header tank. If system is definately full then I'm not too sure what it could be.

Thermostat or faulty water pump maybe, someone on here may know better.

Rich

[hacky]

A coolant change is on the cards mate, replaced all fluids recently other than the coolant. Was planning on doing it this weekend then this happened. Only reason I left it was because I couldn't find out which coolant I should be using! Loads of folk saying you can't use this and can't use that but no-one actually says what you CAN use! I have been suspecting an air lock recently but was just leaving it as I would sort it when doing the coolant flush.

What coolant can I use then? Is Halfords stuff OK? Would prefer just to be able to go and pick some up today rather than wait on delivery.

Graham

[scoobymark]

Is your fan working?

the fan should kick in at 95 - 96 degrees, if the fan can not get the temp back down then you may have a leak

[cullenmin]

My '98 type R kicks in the fan at 92-93 degrees C as indicated on the Apexi water temperature reading.

It should never go above that.

I've topped mine up using one of the halfords coolant in the past, I havnt heard of any reason not to use the halfords stuff.

[hacky]

Is your fan working?

the fan should kick in at 95 - 96 degrees, if the fan can not get the temp back down then you may have a leak

I couldn't tell you when the fan kicked in but I can tell you that it didn't get the temp back down. Only way to get the temp down was to go fast or turn off the engine.

But as I said there was no hot water in the radiator so thats why the fan wasn't getting the temps down. Something is stopping the hot water going through the radiator to cool it down. I was thinking thermostat, waterpump or air lock.

I'll do the coolant change first, rule out the air lock. Once that is done, I will run it and see what happens.

To check if there is a leak is there a compression test I can do? Sure I read something about it. And I would guess do a test like that I would need to drain the coolant therefore it might be worth doing it before I do the coolant change?

[cullenmin]

A garage can do a pressure test, I think they connect a pump to the header tank then jack up the pressure to locate leaks.

AWD done this to mine to locate a leak I had, ended up being a very fine hairline crack on the radiator that was even hard to locate with the pressure test but evertime I drove it, I'd get the steam from the engine bay. New radiator and all sorted. My symptoms were different to what you have though.

[the squiggle]

Initial impressions are air trapped in system, duff water pump or thermo jammed shut

Checking the thermo is easy by putting it in a pan of boiling water and seeing if it opens

Air trapped in system described above

Water pump would need checked out by a competent garage

[cusco kid]

I couldn't tell you when the fan kicked in but I can tell you that it didn't get the temp back down. Only way to get the temp down was to go fast or turn off the engine.

But as I said there was no hot water in the radiator so thats why the fan wasn't getting the temps down. Something is stopping the hot water going through the radiator to cool it down. I was thinking thermostat, waterpump or air lock.

I'll do the coolant change first, rule out the air lock. Once that is done, I will run it and see what happens.

To check if there is a leak is there a compression test I can do? Sure I read something about it. And I would guess do a test like that I would need to drain the coolant therefore it might be worth doing it before I do the coolant change?

hi bud if your heater went cold you got an air lock

sounds like thermostat failed ,take it out and boil water put in a cup and insert thermostat if it opens its ok if it stays shut its fooked

geo

[hacky]

Hi guys,

Ordered a thermostat along with some coolant from Subaru. Waiting on it arriving, hopefully tomorrow. Get it replaced and the system flushed and see where that takes us!

I think it might be a combination of air lock and faulty thermostat. Heres hoping anyway!

Cheers so far, will keep you updated!

Graham

[hosstheboss]

Hi guys,

Ordered a thermostat along with some coolant from Subaru. Waiting on it arriving, hopefully tomorrow. Get it replaced and the system flushed and see where that takes us!

I think it might be a combination of air lock and faulty thermostat. Heres hoping anyway!

Cheers so far, will keep you updated!

Graham

I was just going to say ALWAYS replace the thermostst if you have these kind of issues. They can work then fail so it's not worth taking the chance!

[hacky]

Well, got the thermostat out yesterday and dunked it in some boiling water, no movement what so ever. So that solved that one!

New thermostat and coolant from Subaru and its sorted! The coolant I was told to get was phosphate free.

Simple fix, cheers for the help!

[hosstheboss]

Well, got the thermostat out yesterday and dunked it in some boiling water, no movement what so ever. So that solved that one!

New thermostat and coolant from Subaru and its sorted! The coolant I was told to get was phosphate free.

Simple fix, cheers for the help!

Good news mate, you must be relieved.

[hacky]

Tell me about it. Just lucky I noticed it beginning to overheat and not letting it get too hot. Carried out the head gasket test for exhaust gases in the coolant anyway and no issues there.

Just a pain but its an old car, got to expect to do some work on it every now and again.

[cullenmin]

Good to see you got it sorted mate

[fuji0030]

Maybe a coolant change is on the cards mate, replaced all fluids afresh added than the coolant. Was planning on accomplishing it this weekend again this happened. Only acumen I larboard it was because I couldn't acquisition out which coolant I should be using! Loads of folk adage you can't use this and can't use that but no-one in fact says what you CAN use! I accept been apprehensive an air lock afresh but was just abrogation it as I would array it if accomplishing the coolant flush.

_________________

Thermostat

[Jazmac]

Tell me about it. Just lucky I noticed it beginning to overheat and not letting it get too hot. Carried out the head gasket test for exhaust gases in the coolant anyway and no issues there.

Just a pain but its an old car, got to expect to do some work on it every now and again.

how did or were you get the head gasket test done, i have the exact same problem, however i have re-newed rad, collant and thermostat which results in the same problem overheating, was ordering new head gaskets along with inlet manifold gaskets today but i missed the dealer planning on doing it tommorow.

Edited May 19, 2009 by Jazmac

[green_goblin]

new head gaskets along with inlet manifold gaskets today but i missed the dealer planning on doing it tommorow.

Why are you replacing the inlet manifold gaskets??

[Jazmac]

Why are you replacing the inlet manifold gaskets??

Well i thought while i had the inlet manifold striped off i better renew these gaskets as well as there can tare, had a problem with these on my last scooby when i removed the manifold, so i thought if i have them there if i need them i have no down time on the swap over.

cheers

[david_richards]

Great to here everything is ok. I have a similar problem with my classic. I think it is the thermostat as the temperature has suddenly gone through the roof compared to is usual steady self. Could you tell me where the thermostat is on a 94 wrx? I can't find any info on it at all!

Cheers