Alternator Belt Adjustment

[ab2cv]

Apologies if this has been asked before (I have tried searching), but I am looking for advice / tips on how to tighten up my alternator belt.

In principle it looks easy but I don't know how to gain access to get a socket on the end of the bolts I need to loosen / tighten. In fact, the bolt on the adjuster bracket doesn't even feel like a normal bolt head (it feels round). The main alternator mounting point has a bolt on each end but I can't get a socket on either end due to lack of space.

So far I've only tried attacking this from the top, but peering down it doesn't seem like there would be any better access from underneath.

Does something else need to come off to make space? Any tips or photos of how to tackle this? (I think my car has air-con so there is also what looks like the compressor for that underneath / next to the alternator)

Thanks

[jonwat]

This diagram may help 

[ab2cv]

Definitely, thanks 👍 The nut (number 18) is  what I need to aim for! I’ll have another go tomorrow…

[ramjet]

I've done mine before. I can't exactly remember how I did it, but I seem to remember doing it from underneath.

[jcslocum]

I recall there is some loosening to be done on the bottom and the top, then prying from the top to get tension on the belt. That I recall takes 2 hands, and then you need a 3rd to tighten the slid bolt. A real PIA!!! I have to this on my '84 because the belt is now screeching when I put on the headlights.   

[ab2cv]

Thanks both. Yes mine is so loose that it's screeching under normal load. It goes away when I declutch but as soon as I try to accelerate it get's somewhat loud and attention seeking but not in a good way !

Off to see if I can even get a spanner or a socket on the end of a nut - that will be an achievement at this point in time...

[ab2cv]

I now know why folk probably can't remember how they did this... the brain only tends to store happy memories...

 

Loosened the pivot rod nuts (number 5 and, er 5) holding one end and loosening the other so it doesn't spin. 13mm ring spanner on each end.

Loosened (sneaky hidden) nut (number 18), again 13mm ring spanner did the job.

Now the alternator wobbles around, but, can I get it to pivot in such a way that it put's tension on the belt? Ehm..no

It's like it just doesn't want to slide on the plastic slider. Maybe it's somehow rusted itself on in such a way it's binding?

Either way, I think I have found one of many Lotus positions...

[ramjet]

Also check the depth that the belt is sitting in the grooves of the pulleys. The belt top surface should be just above the pulley groove walls. If the belt sits so deep that the inner diameter of the belt is running on the bottom surface of the groove, you won't be able to tension it enough.

The other thing is that a slipping belt 'polishes' the groove walls which in turn can affect the friction between the belt and the groove. I have seen pulleys polished to a very smooth shine. No new pulley comes polished.

There are also many spray products that assist with belt grip. Not the best answer, but definitely a help.

[snowrx]

I use a big Hook spanner to rotate the alternator around the pivot bolt, so I can reach under the alternator with box wrench or deep socket to tighten the tension bolt. Usually I slip a pipe over the handle of the wrench to make it easier to move the alternator, which does not like to move, perhaps because I have not also loosened the bolt that attaches the slotted adjuster to the block.

[jonwat]

14 hours ago, ab2cv said:

Yes mine is so loose that it's screeching under normal load.

Once they've started screeching like that they become polished & won't grip properly so I'd recommend you replace the belt while you're at it. 

[DaKa]

Agree with last comment, change the belt while you are at it, as once loosened it is straight forward to slip off/on.

I also agree a second person above the engine is ideal to help push on the alternator to add tension to the belt while underside the nuts are tightened leaving the pivot nut top to be tightened last.

[ab2cv]

Thank you for all the replies. I’m going to get a new belt ordered in that case, and also look into hook / c-spanner to help tension the alternator. 
I will likely need to look into a ramp solution in order to get under the car too but that sounds like a different thread/search. 
Am I right in thinking that the alternator pulley should spin freely? I wasn’t convinced that it was, which is now making me think seized alternator is the real source of the issue, which has then knackered the belt to the point it appears slack. 

[jonwat]

43 minutes ago, ab2cv said:

Am I right in thinking that the alternator pulley should spin freely?

Yes, sounds like it needs replacing 

[ab2cv]

OK so I'm no longer convinced that the alternator is goosed. I think the reason I can't turn it is because, well, the belt is still engaged, albeit, loosely.

Either way, I want to try and master tightening the existing belt, even if it just turns out to be for practice.

However, the alternator which does not like to move, definitely does not like to move (not even after several swear words)...so I think I am off to shop for a C Spanner / Hook spanner if I can find one that looks big enough.

[Escape]

Just to add my 2 cents, I've just removed the alternator from an SE, all from the top, about 10 minutes of work including fighting the mounting bolt that was stuck. I know getting it back in will be a bit harder, but should be possible from the top as well. I do remember working from underneath last time, not that it was that much easier.

If your alternator is reluctant to move, try loosening both the nuts on the mounting bolt and the adjuster not a bit more. The more wiggle room you have, the easier it should move and the better you can tension it.

Good luck, I'll be having a go tomorrow.

Filip

[jonwat]

14 hours ago, ab2cv said:

OK so I'm no longer convinced that the alternator is goosed.

When the engine is running does the red ignition light go off, what's the battery voltage & can you see the alternator spinning? 

[ab2cv]

6 hours ago, jonwat said:

When the engine is running does the red ignition light go off, what's the battery voltage & can you see the alternator spinning? 

Time to start the engine and find out - I've been paranoid about doing this in case the belt fails or comes off, but should be fine if engine is just idling....

17 hours ago, Escape said:

If your alternator is reluctant to move, try loosening both the nuts on the mounting bolt and the adjuster not a bit more. The more wiggle room you have, the easier it should move and the better you can tension it.

Thanks, yeah I tried loosening everything off quite a bit and found that the alternator would now 'jiggle' side-to-side easily, which I felt was hindering it from being able to cleanly pivot in the direction that I wanted it to, so I tightened them back up again, just to the point the alternator wasn't wobbling

[Escape]

Hope your test gives a good result!

I put in the rebuilt alternator today, about 15 minutes to fit and tighten the belt. I used a medium prybar to lever the alternator to tighten everything. It did involve what I call the reverse Lotus position: head in the engine bay, feet somewhere sideways and my bum high up in the air. 🙂 I hope nobody took pictures...

[Chillidoggy]

I check mine precisely as Filip has suggested above. It isn’t any more complicated than that.*

 

 

 

*Just as long as you don’t accidentally knock the exciter wire off the back of alternator and have to be rescued on the M25 by a Watford Exotics jump-start the following day when it crapped out on the way to Brands Hatch Lotus Festival.

[Escape]

I remember that story, I was there at Brands as well. And funnily enough, I did notice after tightening that the exciter wire was lose! I was sure I had connected it earlier though... I did of course ran the engine and checked: a nice 14.2V and 30A going into the battery, much better than the 11.5V I got with the old one.

[stevefh]

Hi, block of wood, square at one end and approximately 2.5cm by 5cm.One side 20cm opposite side 22cm to make a wedge (for my S4.)

Pull the alternator up on its pivot bolt, jam the square end against the chassis near the aluminium coolant pipe and force the sloping end against the casing,holding it in position and providing the correct movement for the belt and freeing your hands to torque up, all from kneeling in boot ,leaning over top of engine.

Edited August 31, 2021 by stevefh
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[CarBuff]

[ab2cv]

Forgot to update this to say that a medium sized pry bar did the trick and was able to generate the required leverage to tighten up the belt and then nip up all the nuts and bolts. Thank you to everyone for contributing and generating discussion.

[MrDangerUS]

With rear wheels up in the air and belly pan removed, crawl under the car and insert a ~ 2'x1" hard wood stick from the bottom toward the alternator. Find a good spot so the upper end of the stick won't slip off the alternator housing. Try to keep stick as vertical as possible. Push up on the stick with a floor jack or small bottle jack until you get desirable belt tension. Tighten the alt. nuts/bolts. Now you can release the jack.