Topic

My F overheated on the way from the shops today about half a mile from home. At first I thought it was because I forgot to refit the pressure cap after I topped up the coolant.

I let the car cool down, topped up the coolant and went to drive away. There was a loud crack form engine bay. I wondered if the pressure cap had been forced off but it was ok when I checked. I then decided to drive home keeping an eye on the water and oil temperature gauges. The temperature remained normal but the charging light came on. When I got home I checked the drive belts and discovered both the alternator and water pump drive belts were missing.

I went back to where I stopped (in my other car) and looked for the missing belts. I couldn't find the water pump belt but found the alternator belt. The belt is in one piece and appears undamaged with no signs of wear.

What I'm wondering is what could have caused both belts to come adrift or snap (perhaps).

Have you checked if the alternator has seized?

The water pump is driven by the cam belt, if that snapped the engine will stop. Check the alternator mounting bolts, these sometimes come loose allowing the alternator to move and the belt coming loose. Youa re very lucky, sometimes the alternator drive belt comes loose and breaks the cam belt which will trash the engine.

I was wondering if the aircon compressor (?) had seized as the aircon hasn't worked in the 2 years I've owned the car.

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Did you turn the a/c on when you heard the bang? If so that's what caused your belt to come loose.

I just checked and the a/c is off and has been all day. I just tried to turn the a/c compressor by hand but it wouldn't budge.

Red face time.

I now realise that the MGF only has one drive belt to drive the alternator (and aircon compressor if fitted) and that the water pump is driven by the cambelt. What confused me was that other installations of the K Series, such as my Rover 25, have a second belt to drive the power steering pump. As the F has an EPAS system this isn't required although the crankshaft pulley is the same and has provision to drive 2 belts.

This still doesn't explain why the overheating should cause the alternator drive belt to come adrift or is it just a coincidence?

From the Official MGF Workshop Manual


I find it interesting that this picture clearly shows a second drive belt. Presumably it was reused from a different K Series engine models manual. This is also part of the reason for me thinking there were 2 belts

I've found out why the drive belt came off. On examination I found the tensioner pulley has sheared off.

alanrt54 wrote: wrote:

From the Official MGF Workshop Manual

I find it interesting that this picture clearly shows a second drive belt. Presumably it was reused from a different K Series engine models manual. This is also part of the reason for me thinking there were 2 belts

The only good thing about the AC compressor pump fitted to MG's in the UK is that it shields the alternator from water splashes.

Hope you get it fixed for next Sundays run down the Wye Valley

alanrt54 wrote: wrote:

I've found out why the drive belt came off. On examination I found the tensioner pulley has sheared off.

Any major damage?