Got the donor car bottle (Ford Sierra)fitted in near to the rad and when running the engine in the garage as soon as it gets hot and the pressure builds up it pushes the water out of the lid. Its got a new washer on and its screwed down tight.
What do i do to fix it please?
Steve

Try a replacement pressure cap. It was a fairly regular problem with sierras.

(1) Check the bottle isn't over filled -- you need to leave room for expansion.
(2) Check you don't have an airlock in the system.

If none of the report back -- as it could be a lot of things.

I could be wrong, but does it not also need to be at the highest point in the system. You mention it's down by the rad somewhere..

Bottle is filled to the max mark.
Not sure about air lock.
It is mounted as high as i can get it and the top part of the bottle is above any other part of the system.
New lid sounds most likely at this time, i didnt know they had probs.
Cheers

From your description cap is the least likely especially if you are only half filling the tank nothing should come out unless the car is actually boiling --- from your description ounds very much like either an airlock or local boiling, which begs the usual question do you have a by-pass connection pumbed up ?



[Edited on 10/8/08 by britishtrident]

I dont know is the honest answer. Im not running a heater so its just in and out of the rad and the engine.
The pressure seems to build up within a minute or two from starting from cold and push water past the cap.

You need to have some sort of bypass connection. On the donor tin top this was formed by the heater pipe work --- you need to run a smallish bore hose from the engine side of the thermostat housing to the water pump inlet (or the bottom rad hose). The bypass connection bypasses both the thermostat and the radiator and allows warm coolant flow to recirculate around round the engine block and head before the thermostat opens.

[Edited on 11/8/08 by britishtrident]

I do recall there being a plugged outlet on the thermo' housing but not lower down. Ill be out there in a bit and report back.
Steve.

British Trident,
I think ive found the problem. I have the top pipe from the bottle going to the top of the Polo rad. Ive got a Haynes manual for an older Sierra than my donor but i can see that the top pipe should go to the higher outlet on the thermo housing.
The bottom pipe go's to the water pump.
Does that sound right?
Steve.

That should be fine.

Its better but when it got hot and just before the temp gauge hit the red and the fan should have cut in, the lid gave way again
Will try a new lid and or bottle next if the plubing is right.

Remove the thermostat and very carefully drill two 2mm holes in the valve plate and refit.

Ill try anything

Did the thermo. mod and plumbed as per Flak Monkeys instructions and pics and its sorted.
Cheers,
Seve.