Bunging The Expansion Tank

[dobboy 231 2 Cars]

Anthony, it doesn't explain why the 1bar is ok up to 90 odd degrees before releasing.

 

Maybe the 1.3 bar just didnt fit at all, and was only .8bar.

 

Got another now, a GTI6 version, which doesn't have tabs. Will see how this one goes when the car cools down and I fit it.

[Anthony 1,003]

You should be able to start it from cold without a cap fitted at all and it not chuck coolant out until hot.

 

Indeed, that's how I (and I imagine most people) bleed them - run it up to temperature without the cap on, bleeding air out of the system using the bleed points and squeezing the hoses. It shouldn't start chucking coolant out until it's at 90+ degrees where the coolant is starting to boil because of the lack of pressurisation.

 

With the expansion cap fitted a quick test is to squeeze the hoses with the engine running but still cool - they shouldn't be hard. If they are, the cooling system is prematurely pressurising and that usually points at HG failure. The hoses being harder to squeeze when hot is normal.

[dobboy 231 2 Cars]

Anthony, I've just let the car cool down, then opened 1bar cap, the water level was still pretty high even though been out for a spin earlier.

 

So, temp when I started was just under 60deg, I let it run, felt top pipe go hot, opened bleeding nipple and a few bubbles, let it run again, then seen water expanding, put 20psi cap on, closed nipple.

 

Let it run on, and my fans kicked in, and no leakage.

 

Although the pipes are hot I can squeeze them fairly easily.... They don't feel particularly pressurised.

 

I think my HG is ok, there are no other warning signs etc.

 

I can't remember exactly, but maybe when the water gushed out after 30sec with the other cap, the car was still fairly warm.

[dexter1002 4 1 Cars]

have you had the car running for a length of time with the correct cap fitted?

[dobboy 231 2 Cars]

Deter, yeah, has a couple of hrs last night at all sorts of speeds etc, and all is well.