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changing fan belt

Posted by wolfe 
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Lisa Wolfe
Vancouver, Canada   can
Hello mgb enthusiasts,

My husband typically handles my repairs for my 1974 1/2 mgb however he is out of town. I'd like to impress him by changing the fan belt and was hoping to get some basic instructions on how to do this.

My question:

-do I have to remove the alternator to change the fan belt? and if so how do I do this?

thanks for your help.


PaulM Avatar
Paul McLaren
Lower Mainland BC, Canada   can
1968 MG MGB
1970 MG MGB "Miss Lou"
1970 MG MGB "Dolly"

You have to loosen two nuts one to let it pivot and the other onr is the adjuster to tighten it up snuggly. Have a look at it is very easy to do.

Paul McLaren

1969 MGC GT
1970 MGB Roadster
1970 MGB Roadster

Derek up North Avatar
Derek Nicholson
Sherbrooke, Quebec, Canada   can
1961 MG MGA
I'll just flexh-out what Paul said.

No need to remove the alternator. Just loosen the 2 fasteners on the alternator that are easy to see (probably a 1/2" wrench/socket) and the the fastener for the adjuster (harder to see). This will allow the alternator to pivot down enough so that you can remove the old and install the new belt. Then swing the alternator back up to tighten the belt and re-tighten all 3 fasteners. You don't want the belt too tight. From 1/4" to 1/2" deflection if you push/pull the belt between pulleys.

You might find this link useful:-


If you go to page 92 of 417, there's a picture showing the fasteners, even though it shows a dynamo/generator. They're the same for the alternator.

Edited 2 time(s). Last edit at 2007-05-30 09:40 AM by Derek up North.

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rbgos Avatar
Richard Gosling
Aberdeenshire, UK   gbr
1973 MG MGB GT "Sammy"
Hi Lisa,

No, you do not need to remove the alternator. It is held on by two bolts - it pivots around the upper bolt, and when tight the lower bolt holds it in place. Loosen both and this will be clear.

With the bolts loosened the old fan belt should be loose enough that it comes off easily. Fit the new fan belt, and then move the alternator so that the belt is tight. Tighten the lower bolt, then test for belt tightness. A firm push on the longest span of the belt should deflect it by around 1/2 to 1 inches. It may help to use some sort of lever to push on the alternator to get it tight enough. Once it is tight enough, tighten both mounting bolts.

It's not worth over-tightening the fan belt, it will reduce the life of the water pump.

Which reminds me, my fan belt has been sqealing a bit of late, I really need to get it tightened a bit...

Richard & Sammy ('73 Black Tulip BGT)

Derek up North Avatar
Derek Nicholson
Sherbrooke, Quebec, Canada   can
1961 MG MGA
A couple of other thoughts:-

The belts will stretch with use. Check and adjust again after 100 miles of use.

If the old belt isn't broken, throw it in the trunk as a spare. Unless you want to keep a new one as a spare (either for yourself or another MG owner).

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