Coolant Pressurising/boiling Up

[Sinbad 16]

Having totally lost interest in my 1.6 gti,yesterday i pulled it out the garage after my recovery home a month ago after the mot where it dumped its coolant out.

Yesterday i found out i had the throttle body pipes on the wrong way round so swapped them,ran it up and the same thing happened again,got hot,turned off and then removed cap and it all erupted out.

There is no head gasket symptoms,its a rebuilt engine with new gaskets,belts,pump-the lot-even some new hoses.

The liner seats were in excellent condition and i used brand new seals,quality ones.

Any ideas why its doing this??

I just want it sorting so i can get rid now tbh,just want some of my money back on it.

[Anthony 1,003]

ran it up and the same thing happened again,got hot,turned off and then removed cap and it all erupted out.

If you take the cap off an overheating engine then it will boil over as you're depressuring the cooling system.

 

Are you sure that it's not airlocked somewhere, and is the thermostat new or known good?

 

Does it overheat when driving along, or only when stationary? If it's the later, it could just be the fan isn't coming on, which is a very common issue and easily remedied.

[Sinbad 16]

new stat yes,temp gauge shown halfway when it happened but it felt very warm.

I bled it up ok,the right top pipe on the bottle returns,the left doesnt,and the rad is warm in all areas and i get hot air out the blowers all the time.

It didnt overheat when driving the 55miles i managed before it boiled over the last time,which is when the cap was half on (i hadnt put it on right after topping up coolant before i set off)

[ian010778 21]

Mine was doing exactly the same thing earlier this year after I replaced the expansion tank and gave it all a good clean. I had also managed to get the TB pipes on the wrong way around after cleaning it. I did a number of things at one time and it's been fine for about 4 months now - here's a run down.

 

1. I swapped the TB pipes back around - make sure you don't put one on the 'spare' inlet that is only used on the 1.9 - this could be easily done but it's a blind hole and not used on a standard 1.6 according to the advice I got from other forum members at the time.

 

2. I put the original expansion tank back on.

 

3. Before I refilled it I got a hose pipe and flushed it all through. I kind of did it in sections in that I took the pipes off near the firewall and flushed the heater matrix through, I then did the same with the rad' and the rest of the system.

 

4. I was really careful when refilling it - especially making sure the fluid coming from the bleed near the thermostat housing ran clear as the first time I filled it I think I missed this and got an airlock too. I also used the top of an old coke bottle and some spare hose to make a header tank and filled it really slowly.

 

5. I replaced the thermostat - wasn't too expensive from Halfrauds (they had one on the shelf!) and it came with the rubbers too.

 

You could also try running it up without the thermostat in - although not a long-term solution as it'll use more fuel it will tell you if your new stat' is faulty or not but as far as I know, if the pipe from the stat' housing to the rad' is getting warm as well as the rad' then that is a sign that the stat' is opening.

 

My thoughts are that it was the expansion tank that was affecting mine but I still can't explain why as all the inlets/outlets on the replacement are clear - the only thing it could be is if the cap wasn't sealing well against it but I think that cap issues are usually related to the cap/spring rather than the tank itself.

 

Hope this helps.

 

Ian.

[S@m 156]

I also used the top of an old coke bottle and some spare hose to make a header tank and filled it really slowly.

 

 

That is a good trick.....on a 306 or xsara. But on the 205 you can slightly undo the expansion tank nuts and then lift the whole thing up (with all hoses still attached) then find a way to hang it up on the open bonnet - i use bungee cord - that way it becomes by far the highest point in the system and bleeds well.

 

Sam