308 GTB COOLING SYSTEM HEADER TANK

Could anyone advise if they have experienced leaks in the cooling system header tank.

I've just replaced the pressure cap due to constant coolant loss via the overflow, and the increase in pressure has blown two holes in the tank, which turns out had been filled with silicone by a previous owner, so it was an old problem.

I've ordered a replacement tank made in heavy aluminium, but would like to hear of any stories you may have related to this problem.

Pretty common if the coolant isn't changed regularly or the cars sit around.

Ethylene Glycol reacts with air to form organic acids. So if the cars sits there the acids build up in the tanks an rots it out. Buffers in the antifreeze slow this acid formation but they get depleted neutralizing the acid. Annual changes of the coolant will keep the buffer level up.

The earth friendly antifreeze uses Propylene Glycol which does not have this problem.

My header tank on our old QV had many holes it it. I took it to a local machine shop and had them fill in the holes until I could get around to replacing it (which I never did). After almost two years the current owner has not had any issues.

brass and copper work harden, which means with thermal expansion and contraction from heat cycles the metal becomes harder and brittle. thus holes and cracks develop, not sure what the material is on the older tanks but a majority of European cars used copper or brass and thus the problem.

just last night I had to 'fabricate' from scratch a new rubber grommet for the tank level sender on the mondial for the expansion tank. there is no replacement for some odd reason, so I chucked a rubber suspension bushing into the lath and turned one out, works perfect. now I don't have to worry about boiling water

Many thanks to you all for your advice.

I replaced the header tank with the new aluminium tank, but unfortunately lost almost half of the coolant when she reached running temp. It was probably an air lock that caused such expansion, but I then realised the new tank was supplied with a cap rated at only 7 lbs, which is way below the recommended 12.8 lbs.

I have the 1.1 BAR rated cap supplied by the Ferrari specialist who serviced the car and I am told that this should be OK to use, although it is equal to approx. 15 lbs pressure rating.

I'll let you know how I get on, but keep your fingers crossed for me that I do not start blowing pipes etc. elsewhere in the system!

Just finished trying the car out and everything seems to have held together pretty well. She ran normal temperature all the way and whilst idling in my garage, she got nice and hot, with no obvious problems - and more importantly, no loss of coolant.

I did notice a slight fuel leak on the right hand rear carb, so I guess I need to check this out next.

Took the car for a spin on Sunday morning and she ran well, then again whilst parking in the garage she blew some coolant out. I left her to cool down and checked the level, to find she had lost almost all her fluid again and therefore had been running much hotter than I thought, as the temperature sender was not recording the true temperature in the engine! The general concensus seems to be she has blown a head gasket on the exhaust side, which is pressurising the system.
I have a mechanic visiting tomorrow evening to test the cooling fluid for exhaust gases being present, which will tell us if our fears are correct. It seems unlikely to be a simple air lock, so we just hope the damage is not too bad 'financially', but it does seem likely it will sting quite a lot!

Trevor,

Did you bleed the air out of cooling system after re-fueling it?

Hello Milton, I have drained and refilled the system a total of five times now, with fluid obtained from the bleed points on both the thermostst and radiator.
I have just had the cooling system chemicaly analysed for exhaust gases, and thnkfully none seem to be present.
The engine and header tank all got hot during the testing, but the radiator stayed cold, so it now seems I have got away with the head gaskets, but could have a faulty thermostat or blockage in the cooling system somewhere, that is stopping or badly restricting the flow of the coolant allowing it to overheat and force it's way out of the header tank, which I guess would allow air into the system and double the effect?
Any thoughts?

Trevor, pull the thermostat out, its an easy job. To test the thermostat, place it in cold water, and check to see if it is fully closed. Now, bring the water to boiling and observe to see if it fully opens. Let me know what happens.

Regards,

Milton