Morris Minor Owners Club

When I drive away with moggy the fan belt slips for a second or so
I have tried to firm it but I wrote that you should not tighten it to much because of the waterpump
So I left 1 cm of slack on the long side of the belt

Is this common for the Morris or is it just mine

Quick comment - if you are driving away how do you know it slips ? Are you getting a squeal when driving off that you think is the fan belt ?
Check the belt for ‘ glazing ‘ - that might make it slip but I’m still uncertain how you have attributed the noise to the fan belt .

The belt is New
I hear it when the engine goes a bit faster than Idling
When I push the gas pedal a little bit all down it is gone

Maybe I have to check if the alternator is in line because that is the part that I renewed

If the belt is old replace it , if it is new spray it with Belt Dressing .
That will possibly solve the problem .

As said earlier, it should be nothing to do with driving - just engine accelerating the alternator.

The squealing should be greater when all the ancillaries are turned on and then the engine revved quickly from a very slow idle. It would also occur more if the battery is poor.

The belt must be tight enough to prevent slippage, or it will wear rapidly. The effects of an over-tight belt is usually found with the drive end bearing of the alternator, before the water pump, but if either is faulty that, too, can cause an overload on the drive belt.

We are assuming, here, that your pulleys and belt are of the correct section? A belt of too-small section may well ‘try’ to drive on the bottom of the pulley groove.

Make sure there is no oil on the pullies - that will cause slippage.

A common fault when alternators are fitted.
The fan belt has to be very tight so as not to allow the belt to slip. The alternator has a resistance to turn when putting power back into the battery especially after starting so causing the belt to slip.
To check that the tension is correct apply a load of 8lb at right angles to the belt mid way between pulleys. The belt should deflect by no more than 6mm.
There is no need to worry about the water pump if the fan belt tension is set as above. The pump has ball bearing not plain bearings and is well able to cope with the additional tension/loading of the belt when an alternator is fitted.
A tip - apply talcum powder to the belt so as to remove any greasiness from the belt and/or pulley.

Is there a washer between the dynamo and the metal bracket?

it seems that the dynamo is not completely in line

Do you have an alternator or a dynamo fitted?

Normally there is no need for a washer between the water pump dynamo/alternator mount and the alternator/dynamo. If the pulleys are not in line you may have to fit a sized washer to align the pulleys.

I think I have a Dynamo
The old one (better said a new one but the old model)

My translation wrote that the dutch word for dynamo is dynamo.....

Better said

Should there be a washer between the bracket and the dynamo
or shouldn't there be one in between

You have a dynamo fitted.
If removing the washer the pulleys are aligned remove the washer. There is a washer also fitted to the rear mount bracket. The rear mount bracket has slots so that the correct alignment can be achieved without resorting to fitting a washer. Tighten the rear mount bracket after getting the front mount correct.
If you have a dynamo the belt tension is adjusted to give a max 25mm movement of the belt halfway between the pulleys on the longest run.
If you can move the fan blades without turning the engine the belt is not tight enough.

Maybe it s more clear when you see and hear it
so I made a small clip on YouTube

https://www.youtube.com/watch?v=uAKlgu06wWU

To me the dynamo looked mis-aligned and insecure? I’m hard of hearing but that seemed not to be a particularly loose-belt noise.

Dynamos can tolerate less belt tension because they do not make as much power at slow speed, as would an alternator.

I have tightened the fan belt but that didn’t make any difference.
I have made it as it says in the book and the noise stays the same

Check that the crankshaft pully is not coming apart. The failure of the multi-part crankshaft pulley is quite common.

In the Youtube clip — is it my imagination or is the dynamo / coil moving more than the engine when the engine is revved ?

The dynamo is not moving
I think my hands are not so steady

Can it be the water pump
However that has been replaced recently

Remove the fan belt and check the bearings of both the water pump and the dynamo for roughness. Closely examine the crankshaft pulley for damage.

I will try that tomorrow
Keep you informed