water pump or thermostat?

[Andrew (UK)]

I've not driven this car more than a few miles at a time so far.
It had a new thermostat when I was doing the initial sort out on it.
I have not been happy with the way the coolant system was working and it
seemed to be loosing coolant sometimes and the area under the reservoir
bottle would be wet as well.
Today I gave the whole system a good flush out and got rid of a lot of
debris out of the system and I thought that would cure it.
So I started the car and let it run to warm up, then noticed that the
heater hoses were hot so I shut the heater valve. A few moments later it
started to eject coolant out of the reservoir bottle drainange holes -
the ones at the top - so I shut the engine off at that point.
The top radiator hose was hot at this point but the bottom hose was
barely warm.
So does anyone think this is a bad water pump ie shaft not turning the
impeller? Or did I get a duff thermostat? I am not happy with the fit of
the thermostat in the seal. The seal seems to fit the housing OK but the
thermostat seems to be a bit small for the seal, if you push it to one
side of the seal, you get a gap on the other side, so you have to try
and get it to sit in the middle. Hmm a thought just struck me, maybe I
got the thermostat upside down? Anybody got pictures of it going in?

Thanks,
Andrew
67s

[classicswede]

It is quite possible the thermostat is upside down - it is easy to check remember that when under presure the spring compresses. It will be easy for you to suss out with that in mind. I cant see the pump being the problem.
It is also possible that it is head gasget failure but check out the stat fully first. You can check the operantion by placing inmto a kettle.

[Andrew (UK)]

I really hope its not the head gasket but I guess we'll see in due course. I think I have the stat in the correct way, at least it sounds like it. With all the sludge there has been in the coolant system, I am wondering if there is a port into the water pump that is still blocked that is only important once the stat opens. As I have a new pump I will swap the old one out and flush the system out again.
This car sat for a few years and I think suffered from it. The bottom radiator hose was almost solid with sludge when I got the car.

Thanks,
Andrew

Lotsa de goopin needs a dooin' & shove the thermostat in the kettle wiv the lid off & see if it opens

Then burn ya fingers picking it up whilst its still warm...... Carefull which way round you plonk it & try & get that loose silly looking thing thats thro the side pointing straight up ..... & don't go mad with the RTV/Gasket sealer....... Slowly fill so as not to trap air ............... Try that then drain the ferker again & start with about 2.5 Litres or so of antifreeze & topp up ....... Adding salt & pepper to taste

Spose you could change the water pump ........... Probably better have a few beers before starting/during doing that ....... They rarely go to plan

[mike gilbert]

I recently had an identical problem with a new thermostat that did not seem to fit in its new seal properly - it seemed too small. I dug an old thermostat out of my 'just in case' collection and put that in the new seal. It fitted perfectly and the overheating problem disappeared. I bet that is your problem.
Mike

[Andrew (UK)]

Yes I am now leaning towards the thermostat. I will get another and see if it is any better.

Thanks,
Andrew