Fluctuating water temp - K series

[Tim S]

Hi

The water temp on the gauge has started fluctuating recently. It always sat at 86 degrees in normal conditions. Now it sits at 86 when I'm moving, but goes up to about 91 when stationary - even for a minute, at traffic lights and the like. It then returns to 86 when I get going again.

Engine is running fine, there's no coolant loss or sign of oil in the water.

So, what could it be??

Might the water pump be on the way out??

Cheers

Tim

PS - all this on a VVC K series

[robin]

How long has coolant been in there? It might be an idea to flush the system and refill? Failing that water pump or airlock in the radiator. If you bleed it carefully then you can eliminate airlock. Robin

[Tim S]

Hi Robin

Most of the coolant's been there for ages - I'll give that a try before going down the water pump route.

Thanks for that.

Cheers

Tim

[robin]

Yeah, it's not so much the age of the coolant as the time there has been for it to degas - even if you have a tiny leak somewhere or you trapped some air in the system when filling you will accumulate gas and it tends to pool in the radiator, as I understand it. So actually you might find that just brimming the expansion tank with the engine cold and running at 2K might be enough to put some pressure into the rad such that when you open the bleed nipple the gas can escape. It's PITA though as the bleed nipples are never in the right place, so you need some creative jacking/levelling to encourage the gas to run to the bleed nipple.

Cheers,
Robin