Got home from this morning’s run and noticed a knock/rattle sound coming from the engine at idle.
It was a deep heavy sound like that of a stuffed conrod big end bearing but it was emanating from the front of the block, too far forward for the crank/rod. It was also inconsistence with the engine timing/mechanical sequence if you know what I mean.
Whilst listening, the thermo fans kick in and the noise disappeared??? Once the fans dropped off the rattle returned and got worse when I dropped the idle a touch.
So I pulled the fan belt off and immediately the sound was gone no matter what I did with the idle. (Don’t worry I ran it only for a few seconds).
This is the second genuine GMH water pump gone to the dogs. The belt is not that tight in my opinion, just enough to stop slippage when the fans, lights and battery charge load is on. I pulled the spare new GMH pump off the shelf and opened it up and had a good look. I notice that the anti-cavitation plate was floating loose but prevented from dropping out by the impeller arrangement. However if I shook it side to side it made a sound not unlike what I was hearing?
Has anyone else got a new genuine pump and does the plate float in it too? Do I have a dud?