Noise from engine bay at 80C (HDI 90)

[cheesemaker]

Hello, New to this forum, some advice please.
Got a clean 2000 406 HDI with 126500miles on the clock, drives well and economical (compared to my previous 3L petrol car)

Noticed a knocking noise from the engine bay, loudest in the cabin with aircon off and windows up. sounds like some sort of pump. No such noise when engine is cold, but as soon as temp reaches 80, the noise appears. It is not related the engine speed, I wonder if its the water pump? but i thought it runs continuously regardless of water temp. any ideas?

cambelt changed at 92K, but not sure if the pump been changed.

any help is appreciated.


also need CV joint changed, will tackle that soon.

[teamster1975]

Welcome to the club!
Any chance you could record the noise and stick it on youtube?
The Hdi's suffer with knackered crank shaft pulleys, may be worth getting the car up to temperature, removing the aux belt and see if it still happens?

[cheesemaker]

cool, will give that a go over the week end.
thanks again.

[cheesemaker]

funny thing happened, haven't heard the noise since i posted.... maybe it's all in my mind.

[teamster1975]

These things are sent to try us!!

[cheesemaker]

here's my logic.....
at 80"c (ish) the thermostat opens.... so the noise could be related to the opening of the thermostat....
could it be an air lock that finds its way to some sort of pump mechanism causing the noise?
I forgot to mention that I did top up the coolant a little, although it wasn't low at all, I thought that it might help, and touch wood, since then no more noise, we'll see when the weather and air temp picks up...