5 replies to this topic

[Deeppockets]

I have a persistent aux belt squeak which I can't shift on an MPI and would welcome ideas. I have changed the belt twice and it keeps squeaking.

Could one of the pulleys be out of alignment? Anyone else had similar?

For reference the water pump was changed for a high capacity version and the tension pulley replaced just before I got it back on the road a couple of years ago.

[Deeppockets]

Further on this topic I posted some time ago, I have found my alternator pully is 5mm offset (towards the engine) from the water pump and crankshaft pullies, which are roughly in alignment. Poly-v belts are more sensitive to pulley alignment and this could well be the root cause of my belt squealing.

 

I think the alternator has been replaced at some time in it life. From what I can gather the alternator on an MPI is fixed so the only other option is to remove the pulley and pack it somehow.

 

Anyone else with/had a similar issue? 

Edited by Deeppockets, 30 April 2023 - 04:23 PM.

[sonscar]

Does the alternator have a floating bush at the rear still?if so space the front with washers.Just a thought as I am not familiar with MPI,Steve..

[Deeppockets]

(Some time later...)

 

Thanks Sonscar, that was a good suggestion. The alternator did have a floating rear bush which would have allowed the front mounting points to be packed forward with washers.

 

In the end, however, I obtained an original Marelli alternator (in really god condition) which I have fitted - and squeak gone! The removed alternator is an aftermarket unit but with no identifying markings.

 

Putting the two units together on the bench the aftermarket unit's brackets-pulley distance is shorter than the OEM. 

[Java_Green]

If I remember it correct Continental's recommendations is within +-0.5 deg misalignment in-between pulleys (for Poly-V belts). I doubt that there is many MPI's fulfilling that. Anyhow, the motivation is -except for wear - that they are likely to squeak.

[Deeppockets]

There was ~5mm offset on the alternator which gives 5-10 degrees deviation. It isn't surprising that every belt would squeak,