Overheating - coolant problems

[russ3161]

I posted previously believing I had a blown head gasket. Fortunately I don't think it is that now as I've found a leak (or a couple of leaks) that would explain the overheating.

Unfortunately I can't see where the leak starts. Looking from behind the car it drips down this side of the sump on the right which makes me wonder if it's the water pump. Problem is when I back the car up on to two ramps to get a good look it stops leaking! Does that sound familiar to anyone.

The radiator is also dripping but at a much slower rate so I'm more concerned about leak at the back. The radiator also stays cold when it's ticking over up to temperature and the water there is cold when I use that bleed point.

Any suggestions? Does the leak sound like it's in the water pump region? I should explain I have no mechanical knowledge whatsoever!

[russ3161]

Also, if it is the water pump (and it's started dripping while on the ramps now so I'm fairly sure it's something in that area) what sort of labour time should I expect to be paying out for to replace it?

[greglebon]

Sounds to me like your thermostat is jammed shut: the leaks won't help, and need fixing......but check the 'stat operation.....

[russ3161]

Thanks. What's making you think that then? Is there a guide somewhere here to removing/checking the thermostat?

[greglebon]

The thermostat restricts the flow of coolant round the engine coolant channels when the engine is cold.
This enables the engine to heat up to optimum temperature quickly.
When this temperature is reached, the 'stat opens, allowing the coolant to flow through the radiator, and for heat to be taken from the coolant / engine.....

As your radiator is cold, then the stat is not opening to allow this.
This means that the coolant flowing through the engine has no way to dissipate the heat, leading to overheating......

It is also possible to have the 'stat jam open: this manifests itself as the engine taking a much longer time to reach optimum tepm, even though the car still runs fine in this state.

It is also crucial to have the system sealed, as the pressure increases the boiling point of the coolant.
So test the stat, fix the 2 leaks, and take it from there.....

Testing is easy: there is a guide on here somewhere...but it basically involves removing the stat, placing it in a pan with boiling water, and checking whether it opens.
It should also close again when removed from the water....

(Not the most scientific description of how to do it...but in a nutshell.... )

[NDR008]

Replacing the thermo is not a hard job, can help you out with it if you want. As regards to the water boiling test, I would only use it as an indicator. I've replaced working thermostats with new ones and engine temp was different. The thermostat's wax' properties change, and it is the exact temperature opening point shifts. The boiling water test makes it hard to tell if it is just not opening at the right temp. But I guess it serves the purpose of figuring out if it is gone completely.

Anyway thermo's ain't too expensive, and on such an old engine, no harm in replacing it anyway.

[Tony jinxy froude]

I believe i mentioned thermostat in your last post , very easy to replace to be honest, also it does sound like a water pump problem too, but check the area where it joins the large bore pipe at the rear of the engine, it could just be that one of the seals is leaking, mind you if this is the case you may as well replace the pump as there is quite a bit of dimantling to do anyway just replacing the seal , Jinxy