GTA header tank pressure cap

After an hour of spirited dirivbing today, I noticed a bit of coolant bubbling from the pressure cap.

Water temp didn't get to 90 (its cold outside) coolant was on max when cold. Do I need to worry about anything? The pressure cap is pale blue, I have a new rad and new Renault type D coolant.

From the 'blue' bit or the threads ? They do sometimes weep a little bit from the threads dependent on fit ... .If temps are normal and hoses not hard then all OK I would say ..

After an hour of spirited dirivbing today, I noticed a bit of coolant bubbling from the pressure cap.

Water temp didn't get to 90 (its cold outside) coolant was on max when cold. Do I need to worry about anything? The pressure cap is pale blue, I have a new rad and new Renault type D coolant.

check to see if the pipes are hard to squeeze when hot and pressurising ?If they are make sure you bleed the cooling system properly and get all the air out it can be a bit of a pain. If the system is pressurising it could be exhaust gases leaking into the cooling system; you don't need to overheat for a head gasket to have failed. I have been through this at least thrice with my Renaults

Next step to see if there are any minute bubbles appearing in the header tank, bad symptoms can cause frothing. Minute bubbles coming up in the header tank in my experience will indicate that there are probably head gasket issues.


I hope that's not the case and it is just a weak cap

Si21

From the 'blue' bit or the threads ? They do sometimes weep a little bit from the threads dependent on fit ... .If temps are normal and hoses not hard then all OK I would say ..

From the blue bit, as iff the system was over pressure. Odd though as it wasnt at boiling temp.

(OT, got lots of positive comments at the PH Southwest Breakfast club meet today)

(OT, got lots of positive comments at the PH Southwest Breakfast club meet today)[/quote]

The GTA does get a lot of attention I am always getting youngsters telling me "Yes man the car is dope or sick" when translated I think this means I dig your wicked car sir ..Yo! .Clee bredrin can you confirm?

A good sign if youngsters and adults a like can bring themselves to comment

I always get a lot of attention at motor sport events; more so than car shows TBH. People always coming up to ask questions etc it makes the reliability issues encountered through ownership seem a little more worthwhile.

si21

I had this once - though quite some time ago and from memory, my original cap was green in colour. Replaced it with a blue cap and it was fine.

I guess if you dont have any of the other symptoms mentioned, then probably just the cap gone faulty.

Silly question but how far up the header tank is it filled when cold?

Filled to just below max when cold

So thinking out a loud, the system is a pressurised type so the coolant should be under pressure and drop slightly when up to temperature; if its not doing that then the pressure is escaping; so hopefully a new cap will sort it.

si21

So thinking out a loud, the system is a pressurised type so the coolant should be under pressure and drop slightly when up to temperature; if its not doing that then the pressure is escaping; so hopefully a new cap will sort it.

si21

Not in my book Simon, due to the expansion of the coolant when heated by the running engine, the level rises in the header tank,..... it is the air trapped at the top of the reservoir that is under pressure. This in turn, raises the boiling point of the coolant to above 100 degrees C. When the engine cools down, the coolant returns to normal. Well that's what happens in my Alp.

So thinking out a loud, the system is a pressurised type so the coolant should be under pressure and drop slightly when up to temperature; if its not doing that then the pressure is escaping; so hopefully a new cap will sort it.

si21

Not in my book Simon, due to the expansion of the coolant when heated by the running engine, the level rises in the header tank,..... it is the air trapped at the top of the reservoir that is under pressure. This in turn, raises the boiling point of the coolant to above 100 degrees C. When the engine cools down, the coolant returns to normal. Well that's what happens in my Alp.

Ah reverse physcology...I was thinking it would work the other way round expecting the air to expand more than the coolant with the boiling temp of coolant being dropped by the antifreeze.

Live and learn, thanks John I am now a little older and wiser..I hope.

Simon

I am going to bleed the cooling system.

Do I do it engine running? Workshop manual says no, but on other cars I have done it with the engine running?

Also do I do it cold or hot?

What's your max? I assume you mean to the top of the tube in the middle of the expansion tank?

I am going to bleed the cooling system.

Do I do it engine running? Workshop manual says no, but on other cars I have done it with the engine running?

Also do I do it cold or hot?

My car is an Atmo, but I assume the water pump is the same a the turbo and bleeds in the same way. I always bleed the front at the rad as I fill system and it helps if you tilt the car a little to the rear to make it the highest point. Once the rad is filled i then close the bleed valve and then fill the system and continue bleeding from the pump; I usually do this with the engine running. Once all the air has escaped from the pump bleed fully run it up to temp with a brief gentle drive let it cool down for 30 mins and then go and check the level and top up if necessary. I am not sure TBH if the Turbo has a different bleed screws maybe someone more familiar with the Turbo can confirm.

also when running up I leave the cap off until I take it for a drive.

This method appears to work for me.

I hope this helps

SI21

Bleed screws are on the rad and the thermostat housing