Overheating Problem

[BlackRam]

Now that you guys have sorted out my paint issue (thanks all!), I have a far more serious problem. Whilst driving the coolant system works fine and the temp guage fluctuates between say 80 and 90 (can't remeber exactly). HOWEVER, when I stop for any reason, the temperature starts to rise. I switch the twin fans on and this does nothing but slow down the rise....but it does keep rising and eventually water seeps out of the overflow at which point I switch off. I have replaced the radiator cap which I assume is working correctly and creating a pressurised system. The engine has just been serviced and is running well (ie not lean etc). Have you any ideas what I can do?
I know there is also a product called Wetter Water but would rather not have to use that. HELP PLEASE....as I cannot go anywhere where there might be a traffic jam which fairly restricts you nowadays!

[TINKA]

sounds like you have a circulation problem. If I switch off my heater matrix I get exactly the same problem. Also worth checking that your radiator is not blocked as this sounds like a strong candidate.

[maxGD059]

There's posts on 'Wetter water' if you do a search. I've used it & it does help a tad, but it won't if you have an underlying problem such as a blocked rad or air lock

[Philip]

Could also be timing too advanced at tickover or too lean at tickover?

Phil

[stevee8]

It maybe a circulation problem though given that the cooling system is coping when on the move (adequate air and water flows) might throw that in doubt.
Do you have any more info such as how old the rad/engine/water pump might be?
If it is circulation then a drain down and flush through would be easy to do.
This might sound obvious but are you sure the fans are both running at full speed and moving air in the right direction - if you have "suckers" mounted on the front of the rad they will be drawing warm air from the engine compartment, likewise "blowers" mounted on the back of the rad. A dirty connection or similar may be slowing the speed.

[BlackRam]

Do you think that the water pump may be only efficient when the engine is above idle? Have you heard of this before? It might make sense. I do not know how old the water pump is but a clue might be in the fact that the plugs have just been changed for the first time since 1998! Yes I couldn't believe it either. They were so coked/fouled up that only five of them had gaps and were therefore working correctly (or at all!) I think i need to completely drain the system, replace with a new water pump and possibly use Wetter Water as well (belt and braces). What would you do now?

[robert]

Personally, I would give it a complete going over, oil, fluids, leads, etc. Barrs and Water Wetter in the rad.

Rob

[TonyD]

1. Check that your thermostat is opening fully.

2. Check that your radiator cap is the right pressure for your engine.

3. Check that your hoses are not collapsing or slowing down the flow.

4. Check that your radiator gets hot everywhere, not just at the top. If its just the top of the rad that is really hot and the rest of the rad is cold you have a flow problem.

5 Check that the expansion tank is in the correct place for the water flow and is connected to the correct point in the system.

6. If the water is circulating and the radiator is big enough to cope ie 3 core or above, you should have no need of water wetter or the likes.

7 Make sure you have a heater bypass hose fitted.

8 Make sure you use antifreeze/summer coolant at the correct concentration ( you could have rust scale blocking some water channels.)

9. Back flush the radiator.

Cheers,
Tony

[SimonP]

Originally Posted by BlackRam

Do you think that the water pump may be only efficient when the engine is above idle? Have you heard of this before? It might make sense. (edit) What would you do now?

This is very common. If your top hose exits the engine at a 45 degree upward angle, then has a 90 degree bend to send it back down towards the radiator, you WILL have problems - especially if the bottom of said 90-degree bend is above the level of coolant in the header/expansion tank.
The pump just hasn't got enough "oomph" to push the water over this hill at idle.
As soon as the revs increase, the pump has sufficient "oomph" to push the water over, but it's still impeding the circulation a bit.

Circulating water is easy, but pumping it uphill is not!

Best thing to do, is obtain a 90-degree horizontal outlet 'stat housing, and ensure that the coolant level in the top hose is at least 1/4 of the way up, the higher the better.
That will circulate enough coolant at idle to keep your engine happy.
But, don't over-fill your header/expansion tank - half full is the correct level for most systems.
If you cannot get the top hose more than 1/4 full with the header/expansion tank half full, you will need to locate the tank higher up.

As for the rad fans - if there's no coolant circulating, they are useless.
Fix the circulation and all will be fine. You may find that with proper circulation, one fan will do!

Simon.

[BlackRam]

Thanks guys for all the suggestions and boy do I feel stupid !

I went through all the suggestions, checking for airlocks in the top hose, tested the thermostat in the kettle (wife was out at the time!), had quotes for electric water pump, new ali radiator custom made, etc., etc.

Sat the car on the drive having topped up the header tank, squeezed the top hose to blow any air out and replace it with coolant, started the engine, waited on idle for it to heat up until the thermostat cut in and temp dropped (excellent!) water temperature rose again and then I switched on the fans......it stopped rising and held steady ! SORTED !
Took the car for a celebratory run of a couple of miles.....got home left it running, switched on the cooling fans again......but the temperature carried on rising... back to square one . Suddenly remembered that sometimes the fuse for the indicators works loose (always meant to sort out but never have!), looked at the fans ....NOT WORKING.....LOOSE FUSE......WHAT A BLITHERING IDIOT ! :angry: Sorry to have wasted all your energy on this guys but thanks for again for all your suggestions.