Yet another cooling problem

[P2daz 0]

Ok, where to start..

 

I have been using coolant and have had to top up weekly but apart from that my car has been running ok and the temperature has been stable.

 

Then today i drove for about 4 miles (not normally enough to have moved the temp guage)and parked up - on my return i saw a pink puddle under the car.

 

Water had blown out of the expansion tank and the tank was almost full - well over the MAX line.

 

I just thought i must have overfilled it but when i drove home the car overheated and the oil temp shot up.i pulled over and the tank was still full and all hoses were hot.

 

I had no heat out of the vents either, i had the car towed home and there it sits until tomorrow morning.until i and the car have cooled down!! :lol:

 

My first thought is an airlock - can they just happen out of the blue?Is it possible that i've always had one and it's just moved along the system?

 

There is water flowing back into the expansion tank - does that mean the water pump is ok?

 

What is the best way to re-fill to prevent airlocks - i have searched and there seems to be numerous schools of thought here ( i topped up from the top hose last time)

 

Any ideas folks ?

[dr_mat 0]

Sounds like your heater matrix is stuffed. There's a bypass valve to prevent water flooding inside the car when it fails.

[P2daz 0]

I should have mentioned that i replaced the valve at the start of winter due to lack of heat .Thats when all my problems started, the car boiled over a few days after following a good 40 mile trip on the A1 and since then has needed to be topped up on a regular basis.

I haven't noticed any coolant on the carpets or steaming windows though but then again i can't see any signs of leaking anywhere around the engine.

 

If the safety valve has gone due to the matrix going am i right in thinking it should be blocked if i blow through it? Does it remain blocked and need replacing or can it be reset somehow?

 

I think maybe i'll be bypassing the matrix tomorrow morning :cry:

[P2daz 0]

I drained the system down this morning and flushed through with nothing evidently wrong.

I refilled through the top hose slowly and ran the car up to temp and topped up at the expansion tank.

 

It seemed to be settled at 90 so i took it for a spin (to buy a bucket to wash the bloody thing as a treat! :? )

I slowly watched the needle rise to 110 as i reached my drive.

the expansion tank was full and leaking past the cap(new by the way).

The top hose was so hot i could barely touch it the bottom hose was only slightly warm and i could hear the coolant bubbling away in there (boiling?)

I am pretty sure the heater matrix is ok though as i had heat from it (although not hot) and the carpets are dry.

 

I am thinking maybe thermostat or still an airlock?

 

Is the thermostat a big(expensive)job?Because i would probably get a garage to do it as i have limited workspace.

 

Anyone any further ideas?

 

Cheers

[P2daz 0]

I should have mentioned it's a valver :oops:

[Goldie 2]

Sounds like an airlock to me... I refilled mine yesterday and to avoid airlocks pour the coolant in slowly, run the car up to temperature and "massage" the hoses to encourage any air in the system to leave...

 

Has you thermostat been in the car long?

[P2daz 0]

I did exactly that to fill up, i don't know about the stat, i have had the car about 8 months now and haven't changed it, the previous owner gave a folder full of receipts so i'll have a look through that but i can't remember seeing it as being changed before.

 

I have also had a leak where i have top up every week so maybe there's a crack in the thermostat housing as well?

Do you think that the fact that it happened 'out of the blue' would suggest the stat had jammed shut? Can an airlock suddenly appear? If there is a leak could that let air into the system as well?

 

Edit - just checked the comprehensive history folder and can't see any mention of stat being changed.

[P2daz 0]

Can anyone confirm that this is most likely to be thermostat?

[mic_VR 3]

Sounds like thermostat to me I'm afraid mate.

 

The boiling over is probably occuring because the stat isn't opening up enough. Get it out of the car and test it in some hot water. Should start to open at about 80c and be fully open be fully open about 110c? (someone on here will know for certain).

 

If you're really not sure try running the car without the thermostat in at all and it'll run cold all the time, this isn't a good idea for too long but is a definite way of proving the stat is faulty

[P2daz 0]

Cheers for that, i've literally just ordered a thermostat, o-ring and housing so fingers crossed.

 

Cheers

[Paul B 0]

Oh No! Sorry to hear she's not being nice to you. Hope you get it sorted mate :)

[P2daz 0]

Heyup Paul, hows it going?

 

Yeah she's being a bitch alright but thats part of the joys of a corrado in a twisted kind of way isn't it?

 

Wanna buy it back :lol:

 

Daz

[Paul B 0]

If it's any consolation the Bora's had a few dramas too lol....

 

How's it lookin these days? sorted the body work out at all?

 

I reckon it does sound like the Thermostat is sticking closed, hope that sorts out your cooling worries

[Rob Heath 0]

Think you need to change your sig paul buckley, lol

[P2daz 0]

It's looking pretty much the same matey although If i get chance i will sort the body work out but right now i just got to sort out this cooling issue.

 

The car has been greta really with the only problems being cooling related so it will be nice to get it sorted once and for all.

 

What's been happening with the Bora?

[P2daz 0]

Tonight I started the car up, took of the resevoir cap and let the car run up to 90 degrees whilst massaging the upper hose as suggested.The top hose got hot as did the bottom this time.

 

After a while i felt a lot of bubbling in the top hose and the coolant level rose until it overflowed and the settled down again to well below the minimum level, i topped it back up again and waited and it did this once more, again topped it up and waited for about ten minutes, then it settled down, the temperature remained stable at 90 and the fan kicked in every now and again, so i fitted the cap again and waited some more and all seemed fine.

 

I then took it for a spin and two minutes into the drive the temp shot up to 110 :x

There was not heat from the heater vents either.

The resevoir had filled up again, the top hose was solid and hot , the bottom hose was a lot cooler, i released the cap and the pressure was unbelievable.

 

So i am none the wiser but am thinking Head Gasket?

[P2daz 0]

Tonight i changed the expansion tank cap bought from VW and bypassed the heater matrix, i THINK that thats sorted it but i'll have a drive tomorrow and know for sure.

 

Trouble is i don't know what has caused the problem i think it's the cap (a massive difference in the quality between it and the one I bought from G+S).

 

Is there an easy way to test the matrix?

[P2daz 0]

I have noticed that the hoses are under a lot of pressure, not so hard that they can't be squeezed, but i am still concerned.

 

How hard are yours? I can squeeze mine in about 20mm- if that makes any sense?