Expansion Tank keeps boiling over

[Catfish]

Basically dad and I thought it was down to the fan not engaging, but It seems not.

We thought we had everything bar the temp gauge working. Put a thermostat in, when there hadn't been one in before.
Took it for a drive today, around 14 miles, to get fuel.

Got back, lifted bonnet, coolant was boiling Shut off the engine, and the expansion tank went nuts, boiling over and bubbling like no tomorrow
Seems to get worse once the engine is shut off. Turns out radiator and pipes had no water in them.
Radiator is still getting water circulated, water pump is still pumping everything around, there's no leaks. But then take it on a drive and coolant boils.

Any ideas? Seems to be getting airlocks quite a lot, but we can't figure out what is wrong Please help!

[SUPERCHARGEDGTA]

could be headgasket, often shows as pressure in cooling system pushing coolant out and causing airlocks then boiling over

[Catfish]

bugger, hoped that wouldn't be the case - apparently they haven't been long replaced!
would that cause oil/water mix in the radiator/expansion tank? Because at the moment it doesn't look like water and oil are mixing. Water is a bit orange and mank, but no sign of oil there. But then again, i'm new to these cars, and dad hasn't worked on them for a long time lol

[Rocky]

I posted on your other thread but water and oil doesnt always mix on these cars. Where the gaskets done properly?

[Catfish]

Its anybodys guess if they were done properly, I'm guessing if they have failed so quickly, then not so much!
Guy I bought it off, turns out he was quite a con man it seems, I had no one with me whilst looking at this one, seems I picked a doozy

[SUPERCHARGEDGTA]

if it is leaking from combustion chamber into cooling system (most common) then it will not let water into oil or oil into water, just pressurise the cooling system
(been there with mine, fine ticking over, take it for a run (especialy a hard drive) it was bubbling /boiling in the header tank

shame temperature gauge isnt working

only other thing is blocked or wrong radiator. had one in once that had a single core radiator (V6?) fitted.
that was ok driving but overheated a bit after a few miles and boiled if turned off, but was ok as long as you let it idle for a few minutes before turning off

[Catfish]

Sorry to sound dim, but how would I do that? I imagine my dad would know, but to be fair he'd rather not touch the car much now
We will check the rad, seems like water isn't staying in there, so might be possibility it's blocked, perhaps ! The rad seems big enough for the car, reaches across most of the engine bay, but it could may be wrong
Sounds like you had something similar to me, did the radiator solve it?

[banker]

has your Dad done a sniffer test to check for head gasket failure yet, worth ruling stuff out before venturing down a particular path.

[Newcastle knight]

Worth flushing the entire system out for sure as its a hell of a lot easier than doing the head gaskets, mine ran quite hot a few years ago and i got home from knightcon one year and about 5 minutes from home the temp gauge kept creeping up, and by time i got home the coolant was just starting to bubble in the expansion tank so i undone my bottom rad hose the following day and flused the whole system with the hose pipe and was amazed out the cruddy brown water that came out. After i filled the coolant back up its ran really cool ever since, but if i run the car and get stuck in traffic it still heats up quite quick so i knock the fans on to keep it cool

Has your car got the airdamn fitted ? if its not there then that wont help either as it deflects cool air up onto the radiator

[Catfish]

James - not yet no, but he doesn't think it is hgf!

Scott thanks for tip, I think we are going to flush the system first, get all the gunk out, get it filled up and try again. The expansion tank on my car is full of cruddy brown water which isn't great! Have a spare expansion tank so might whack that in loo
Sounds like exactly what mine is doing, though it will do it after a run, rather than traffic!
It has got the air dam, looks similar to banker's front in his sig above, but just isn't a gta!

[SUPERCHARGEDGTA]

James - not yet no, but he doesn't think it is hgf!


It has got the air dam, looks similar to banker's front in his sig above, but just isn't a gta!

the air dam is under the car, about 18 inches from the front (under the rad)
it is a good idea to flush cooling system anyway
if it still boils up then get the HC check done on the header tank

[Newcastle knight]

Yeah its like a rubbery plastic shroud that bolts under the rad support so its worth sticking your head under there to check its not missing.

This is what mine done, it was fine all the way home on the motorway because the engine was mostly being air cooled, but once i got off the motorway and was coming home thats when the temp starting going up, and that was with both my fans going, so by time i pulled up outside my house the temp gauge was hovering at the 220 mark on the gauge and when i turned the engine off i could hear the coolant just starting to bubble. That was quite a hot day though i remember, in stop start traffic coming home etc

[Catfish]

Ah right, gotcha! I'm not certain my car has an air dam then, there's a space under the bumper I can just reach my hand up into, and I don't recall there being something behind the rad either? I would have to have a look at the car and double check for sure!
Can this affect air flow to the rad as well? Might have to get one of those then!
I only have a single fan on the rad as well I believe, wondering if that doesn't help?
Thanks for the info so far guys, I really appreciate it!

[Mikey V8]

Could this not be a thermostat problem?

[Rocky]

Could be stuck just check top hose is hot

[SUPERCHARGEDGTA]

dose say new one fitted in first post
possibly a faulty one (though I have never had one)

[ccckeeper]

Did it overheat with no thermostat fitted. Hope you never put it in upside down.

[SUPERCHARGEDGTA]

trouble is its at the top, so if air/gas in system it is no longer immersed in water so closes stopping circulation

[G20BlazerTA]

dose say new one fitted in first post
possibly a faulty one (though I have never had one)

I had a faulty thermostat once - made in Canada. I got about 5 miles down the road before my TransAm boiled over.
Heres a pic of the offending item

As you can see the brass bit at the top broke allowing the pin to pop up through the hole meaning the thermostat couldn't open. Never seen this before or since but proves it can happen

[Catfish]

You'll have to bear with me, typing this on my phone so easier said than done!
the top hose was hot, but had no water in.
it didn't have a thermostat previously and overheated when i got it home for the first time. I got a spare - presumably new unused thermostat with the spares in the trunk, so we decided to put it in see if it made any difference.
dad definitely put it in the right way, he doesn't like working on my car, but he will do it right!
we might take it out again, dad says the cars tend to run cooler without them.
he had a look yesterday, and he believes it could be little more than a blocked radiator, but we cant do much more until the weather warms up!

[SUPERCHARGEDGTA]

to check rad and coolant flow/circulation leave rad cap off, suck out about 3 inches of water out and start the engine
you can see the water coming through the matrix
there is a picture of this on another thread in tech section

[SUPERCHARGEDGTA]

here it is, 3rd post down is picture

http://www.poc-uk.org.uk/forum/viewtopi ... &start=450

[Catfish]

Cool thanks for that! We will probably get onto it next week now, it's not been nice enough this week, and no garage to work in
I will ask dad to do this when I speak to him next

[Jabra07]

I just wanted to post a response on this thread as someone who has had exactly the same problem via 2 different issues. Having looked to this thread for help i found it rather doom and gloom and thankfully was not as serious... First of all don't panick there are 2 easy fixes to this problem. Here are my resolutions to it...

1. You could have a belt missing that drives the water pump. If there is no water going through the top radiator hose when the engine gets warmish then the belt that drives the pump may be loose or completely not there (like mine). If the belt is there and driving the pump then the waterpump itself may be faulty, but again only if it is not pumping the water through the top rad hose. You will know the water is flowing through it as it will feel spongy when squeezed you should feel the coolant going through and it will be very hot.

2. It could also most likely your radiator cap!! Yes, thats all. (common problem) if it is not fitted properly or is old and is letting air in then it it will be loosing pressure from the cooling system which reduces the boiling temp of the coolant to 100degrees when it should be about 130degrees when pressurised, which gives the engine enough time to get hot without boiling before the cooling fan kicks in to cool the rad. The cap is easy to thread if not put on carefully, so get a NEW proper 16ib radiator cap its about a tenner online. fleabay etc. and try this after you have made sure coolant is going through the top hose and you have the pump belt in place.

Try the above 2 first but make sure the coolant is going through the top hose before you even check the cap. As that should happen wether the cap is faulty or not. If the pump is working and the rad cap is fine then you ay have an air leak or coolant leak which is letting air in, my bottom hose popped off too when the belt was not connected as the boiling water had no where to escape from.

[cowboy1sf]

Had this twice in the past both on a 3rd gen. 1st time it was the radiator cap, 2nd time it was the plastic bottle cap. Cost both times under £10 quid