Serpentine Belt Coming Off

[Tendaimwari]

On the way home last week an " alternator not charging" warning flashed up. A quick look under the bonnet revealed that the serpentine belt had come off and coolant was over the front off the engine. It had happened before about 6 months ago. The belt just got put back on.

So again, I re-installed the belt on Friday and it has just come again with coolant all over the front RHS of the engine. Anyone have any ideas where and what is causing the fluid to be expelled? Could it be the thermostat sticking and the built up pressure being relieved and subsequently making the belt slip and come off?

[FrenchAudi]

Possibly the engine overheated because the belt came off and was no longer turning the water pump.

It is posible the belt tensioner may not be keeping the belt tight. Also, the tensioner pivot may be worn, so that its pulley is twisted in relation to the belt, or another pulley may not be correctly lined up, or even loose.

If any of the components driven by the belt has been replaced, the fore and aft position of its drive pulley could have been altered.

[Tendaimwari]

Possibly the engine overheated because the belt came off and was no longer turning the water pump.

It is posible the belt tensioner may not be keeping the belt tight. Also, the tensioner pivot may be worn, so that its pulley is twisted in relation to the belt, or another pulley may not be correctly lined up, or even loose.

If any of the components driven by the belt has been replaced, the fore and aft position of its drive pulley could have been altered.

Thanks for the reply. There was no overheating, temp stayed at 90C. The fact that the car has done several 1000km since the first instance does not make me suspect misalignment. The water pump was changed approx. 1yr ago, 6 months before the first instance so any misaligment would have caused the belt to come off sooner and more regualr. Although 3x times is far too many.

I personally think the root cause is linked to the coolant tbecause everytime it has happened there's been coolant in or around the alternator. I will it check out.

[FrenchAudi]

I don't think the teperature sensor is actually in the cylinder head, so it will not immediately show an increase in head temperature if the pump is not running.

Three times in six months sounds a bit too regular to me. Just a suggestion.

The belt coming off could be related to engine rpm.

[Artiglio]

If your car has an “alternator clutch pulley” see if it is in good condition and working correctly.