Coolant overheating

[Dano41]

Hi my 1999 406 diesel has started overheating at times 95c and when I turn the heater to warm air it progressively got cooler and cooler until now only cool air comes out.I have had to top up the coolant regularly recently because there is a small leak at water pump.Any ideas what it might be,could the water pump have failed completely,how do I test that the water pump is working?

[steve_earwig]

You'll have to investigate the water pump leak, it may be finished, it may just need a gasket (although it would be silly not to replace the pump while it's off. And timing belt, obv.)

The overheating/cold heater is almost certainly air locks in the system, caused by the drop in coolant due to the leak. You could bleed the coolant but it'd only be bailing out the leaky canoe.

[PeterN]

Not wishing to be pessimistic but the low water level could have caused the head gasket to fail unless you have always kept it topped right up, this will cause the system to pressurise and blow the coolant out of the filler/overflow pipe. If its been running for any length of time without antifreeze this can corrode the gasket and also cause it to fail.

Peter

[mjb]

Could also be a failed thermostat

[Dano41]

Thank you for the replies.The problem was the thermostat.

[PeterN]

Good, pleased for you.

Peter

[steve_earwig]

Heavens, so mjb was spot on And this makes the water pump leak??

Ah well, good news it's fixed without being something major.