Those little checks you can do regarding overheating?

[Acheron]

I recall something about radiator pipes being soft or hard, and something about the heater blower.

I know about the oil cap being white and gunky is bad news but cant remember the others.

The car lost about an inch of coolant the other day but i dont know where and it was running a littl lumpy which makes me think it was burning coolant. However after running it again for a few days the level has stayed the same but still running a bit lumpy and a little white some out of the back :S

Head gasket was done about 50 miles ago.

[Rawwr]

Have you been checking the level at the same temperature each time (i.e. cold)?

Does the underside of your oil cap look like it's being sponsored by Hellmanns?

[Big Rod]

It's possible there was an airlock left after your HG job was done and the discrepancy you see in the water level is the airlock dispersing.

I would say it's maybe a little early for any 'mayo' to form on your filler cap so if it's stayed level since then just keep an eye on it for a bit. You should be ok.

[Sam_68]

If it is a blowing head gasket, many garages can do a cheap chemical test that detects combustion gasses dissolved in your coolant.

They can also do a pressurised test of your coolant system, as one of the common causes of coolant loss is pinhole leaks in perished coolant hoses that can be a bugger to detect normally since they only start to leak when the system is hot and therefore pressurised... and in that case the coolant can be lost as vapour (steam) which is very difficult to see in warmer weather (though you can often smell it, if you are used to the smell of hot antifreeze).

A dodgy seal on the waterpump is another favourite for gradual coolant loss.

Paying a garage with the appropriate testing equipment a few quid to do these quick checks might save you a lot of grief in the long term.

[varsas]

Sam_68 said:

If it is a blowing head gasket, many garages can do a cheap chemical test that detects combustion gasses dissolved in your coolant.

Paying a garage with the appropriate testing equipment a few quid to do these quick checks might save you a lot of grief in the long term.

I had this test done on my Stag, and performed a compression test myself (also duplicated by the mechanic)

The car passed both tests.

A few days later this was the result:

http://www.youtube.com/watch?v=bi0TlUwZK0A

Pulling the head showed head gasket failure. If the car fails the tests you have HGF. If it passes the test it might be OK, it might not.

The hose thing is to see how hard the top hose gets, if it's stiff you have a pressurised coolant system, which suggests HGF. You can see the same thing by looking into the expansion tank with the car running, if you see bubbling it suggests HGF.

ETA: you can get the white mayonnaise on the underside of the oil filler through condensation, it doesn't really mean too much but if it's on the bottom of the dip stick you have a problem (water in the oil). Burning coolant has a sweet smell, you should be able to sniff the exhaust.