Overheating

[John]

I'm struggling to resolve my overheating problems, and hoping for a few ideas where to investigate next...

The radiator seems to be fine, but I reverse flushed it through off the car anyway. The thermostat is new and opens and closes at the appropriate temperatures. With the thermostat installed, the temperature goes up to within an eighth of an inch of the red line and sits there relatively happily, but eventually the engine cuts out and won't start again until it has cooled off for a while. With the thermostat removed, the guage doesn't get past about a quarter inch from cold. My only thoughts are that the water pump isn't pumping too well, but given that it is a purely mechanical affair, I can't see how it can pump "just a little bit" unless most of the fins are missing. In which case, I'd expect a fair amount of noise where the bits of metal are flying round the pump.

Anyone got any suggestions?

Thanks

[stagstr]

imported post

Hi John,

From the info you have supplied it sounds thermostat-related to me. It begs two questions:

What inlet manifold do you have?

Do you havea blanking disk on the thermostat?

The cooling system changed circa Mk1-Mk2 and you cannot have a veryearly (Mk1-ish) inlet manifold with a blanking disk thermostat. My notes tell me that the thermostat will not open because there is no recess in the early manifolds to accept the blanking diskwhich moves outward as the thermostat opens. Conversely, a non-blanking disc thermostat in a Mk2 manifold will not blank off the by-pass circuit and will allow water to bypass the radiator - potentially leading to raised temperatures.

I hope it's as simple as that for you.:dude:

regards

Ray

[John]

imported post

I thought about that a few hours ago, and popped out to get a thermostat with a disk (the current one doesn't have one). It's a '72 model, with the later type radiator - not sure about the manifold - I've not seen both types to compare, but I suspect it is the later type. On the other hand, it is a Mk1 in other respects - I think it was made in the 'hybrid' period. Either way, I'll try out the new thermostat tomorrow! Thanks for your help.