I've had an issue in HaHa for a couple of weeks- when started from cold there were chirping/growling noises coming from the front of the engine.
Sounded bloody terrible idling at the lights.
If you put a screwdriver against the pump or the (new) alternator body, it did indeed sound like some bearings on the way out.
These noises went away from 1500rpm up.
I fitted a NEW alternator a couple of weeks ago, but this made no difference to the noise.
Hmmm...
First I took the Bosch fan belt off, ran engine, no funny noises.
I then spun the fan by hand, smooth as silk. No water leaks (usual cause of water pump bearing probs).
Ditto the alternator, no noise when spun by hand.
Fan belt? It looked OK, no cracks and not worn to look at.

OK- so I put the belt back on, started it, noise reappeared.
I had a `drylube' stick used for doorlocks etc, so I rubbed it on the sides of the belt. NOISE GONE...
New belt time. I fitted a new Quinton Hazell belt, no more noises.
So... what caused the noise? The belt wasn't worn, it was still level with the top of the alternator pulley. It just looks like any other s/h belt.....
It's the first time I've used a Bosch belt on a Mini, I guess it may be the last- as I've never had noises like this from any other fan belt in the last 40+ years. And Bosch belts ran fine on my EA Ford.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

slightly different V shape on one of the pulleys

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Mine squeels to about 1500 rpm's too but only at night when I turn the lights on.
I think this would be alternator though.

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I have seen a lot of different belts make different noises. The noise can sometimes be cured by taking the belt off and turning it around.

TimB, When you turn the lights on is causes more load on the alternator and therefore more load on the belt. Try tightening the belt. Or it could need a new belt. If the belt is tight and it is still noisy squirt WD40 on the belt when it is making the noise and see if the noise stops, if the noise stops you know it is the belt.

Cheers Morris 1100

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Doc,
I would check that the belt that you have fitted isn't tracking awkwardly (make sure it's all straight)

also if you are running the car with a large ammount of electric's I have experienced a shorter life from them occasionally

this I came to the conclusion that the rubber surfaces had become hot enough to burn just a little on the surface and this means the surfaces are ont quite as grippy in parts and eventually as a whole.

otherwise a slightly bad profile on the bosch may have reduced grip

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-doing a Degree in Mechanical Engineering,
and a few conversions:
13B Extend in a 1600
4EFTE in a mini ute (all slowly)

All 3 pulleys are aligned properly, I had to do this 12 years ago when I fitted the Triger belt drive kit.
Tension was OK too.
I reckon it's the belt composition, maybe the rubber dried out or something.
It's the type that has serrations on the inside, but many belts are like that now. Including the new Quinton Hazell one I fitted.
I did notice that this new belt is narrower than the old... it sits below the top of the NEW alternator pulley.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

Cheers Kev..I expect you have the Chock going buy now and itting back enjoying your Cintra

Maybe try one of the the Wider profile belts as yours is sitting down low on the Alt...As you know know when I changed mine the come in three sizes...maybe you need one of the next two sizes up

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Stop Licking the Dog...I Don't Care Who Started It

Well this new belt is made for a Mini, it's a Quinton Hazell QBA825, came from Karcraft.
If it stays quiet it's all good.
Maybe the Bosch belt was too wide...

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

Must say I didnt hear any noice when you Left Kev

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Stop Licking the Dog...I Don't Care Who Started It

My squeeky belt is a Quinton Hazell but 'Morris 1100' was correct, it just needed re-tensioning. Doesn't squeek when I turn the lights on now

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Thinking back now, what may have contributed to the Bosch belt's demise was the run to Kangaroo Valley a few weeks ago. The heavens opened, they got 157mm or so of rain in a few hours, the 18 Minis drove through it for what seemed like hours. The fan belt got so wet, it was slipping and screeching, even with just parker lights on.....

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

Just throwing this out there but if the fan was unevenly worn or damaged, would it cause a vibration from a balance issue? Could that replicate a bearing sound through
the pulley?

I don't think so. My son's Clubby fan was missing a blade for a while, but it ran fine.
Unbalanced things play up at high rpm, not idle.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

This is even more unlikely, but you cancelled out the bearings early on.
By spinning the parts by hand it wouldn't add the side loading on the bearing
that the belt tension would do.
Okay, so it's not there now, but if it returns go back to bearings.