confusing overheat problem

[quarryman]

Now, a few weeks ago I jumped to conclusions about the state of my (sierra) engine. Having replaced the battery, adjusted and cleaned the plugs, and generally just had a good root around the engine bay the van started and seems to run fine.
Took it for a spin - and its cold outside today. After about 10 miles the engine was running very warm, temp gauge for coolant was showing a good 95-100 degrees with a lot of pressure in the system.
Released the valve on the coolant tank after a while and tonnes of steam came pouring out.
Also, I can't get any heat out of the blowers - but I could until I started getting problems.

As for general running, the van seems ok, doesnt want to stall, pulls ok - its just getting very hot somewhere.....

Still - I got my christmas tree in one piece so that's a start - these vans have their uses!

[Zebedee]

Sounds like it could be an airlock in the cooling system.
Had the near exact same problems with my passat a few months back after flushing the system and adding new water/anti freeze.

[Ian Hulley]

Is this the Pinto or the DOHC ? I had both (in Sierras) and the Pinto has a high point bleed spigot which has a cap over it (these used to perish and blow coolant everywhere ) you may need to have the asre-end in the air with that part raised to bleed it properly.

Ian.

[quarryman]

Think you could be on the button there. I overfilled the coolant, then drained through - airlock could be the culprit. I'll try and bleed it at the weekend.

[Mr Bean]

Released the valve on the coolant tank after a while and tonnes of steam came pouring out.
quote]

Exactly right! If it doesn't boil when you remove the cap on a hot engine the chances are you themostat is duff or misssing - i.e not closing. (Just like an astronauts blood would boil if his space suit sprung a leak.) Your cooling system is like a cross between a plumbers store and a pressure cooker. As for the heater not working I agree that you probably have an air lock. The amount of furum space used on heating and bleeding must tell us something about the design of the T25 cooling system...
Cheers
Wolfie