Keep Losing Alternator belt tension

dag019 · Monday at 15:29

Feel free to say this is a foolish idea, I am spitballing here before comiting to anything.

I have a discovery 200tdi with a 100amp alternator, unlike the defender 200tdi, the alternator sits on a sperate belt, the setup works very well but I need to tension the belt every 3 months ish. I have tried all sorts of different nuts and locking washers and it doesn't make a difference th belt slackens off. I know belts stretch with age but I am unconvinced it should just keep stretching and instead think the alternator itself is moving back down the slide. I am thinking of fitting a turnbuckle along the slider with some longer bolts though both the turnbuckle and the mounting points.

Do the learned people on there think that this will work and make any difference to the issue.

Found this on ebay (LINK):

This would fit between the two bolts here in green:

boguing · Monday at 15:51

I'm sure it would work, but obviously wonder why you have the problem. Are you perhaps over-tightening? Or faulty belts?

lynall · Monday at 17:19

Discovery 200tdi are well known for that top smaller belt wearing the sides of the belt away and going slack.
I would have been impressed if mine lasted 3 mths between belt adjustments.

Anaconda · Monday at 17:22

My son's Disco 200tdi does exactly the same thing, less annoying for us as it doesn't do anywhere near the mileage you do.
Let's us know how you get on if you fit a turnbuckle.

dag019 · Monday at 17:52

lynall said:
Discovery 200tdi are well known for that top smaller belt wearing the sides of the belt away and going slack.
I would have been impressed if mine lasted 3 mths between belt adjustments.

I know and I am on my second new alternator pulley for that reason, but am beginning to get fed up with it.

Anaconda said:
My son's Disco 200tdi does exactly the same thing, less annoying for us as it doesn't do anywhere near the mileage you do.
Let's us know how you get on if you fit a turnbuckle.

I know it is not just me and is quite common. I was looking at the second AC position alternator mounts and if that would solve the issue but a turn buckle is a cheaper starting point!

Hicap phill · Monday at 18:11

Nothing wrong with this idea.

Does the joiner have LH/RH thread?

Put some more flat spots so you can tightening with a spanner.
(There must be something that joins threaded rod for cable tray systems,may not be long enough though… Off for a search)
On the bolt on your lower bar does it have a serated edge/head? This would grip the flat bar. S2-3 used to have serations on the bar

lynall · Monday at 18:19

dag019 said:
I know and I am on my second new alternator pulley for that reason, but am beginning to get fed up with it.

I know it is not just me and is quite common. I was looking at the second AC position alternator mounts and if that would solve the issue but a turn buckle is a cheaper starting point!

My father in law swore blind that the smooth v belts were better and longer lasting than the toothed style, so maybe worth getting one and trying?
Have to say even with my 200tdi defender, the pas steering belt and alt belt tension was also a regular feature when used as my daily.

Hicap phill · Monday at 18:27

lynall said:
My father in law swore blind that the smooth v belts were better and longer lasting than the toothed style, so maybe worth getting one and trying?
Have to say even with my 200tdi defender, the pas steering belt and alt belt tension was also a regular feature when used as my daily.

Only ever used smooth ones. Even in the series. They seem to bit in the pulley more.

dag019 · Monday at 21:45

lynall said:
My father in law swore blind that the smooth v belts were better and longer lasting than the toothed style, so maybe worth getting one and trying?
Have to say even with my 200tdi defender, the pas steering belt and alt belt tension was also a regular feature when used as my daily.

Hicap phill said:
Only ever used smooth ones. Even in the series. They seem to bit in the pulley more.

I have never considered a smooth belt. Will go and have a look what I can find.

Hicap phill said:
On the bolt on your lower bar does it have a serated edge/head? This would grip the flat bar. S2-3 used to have serations on the bar

I have tried serrated bolts and washers but made no difference hence looking at other options.

I will take some measurements and buy one of the turnbuckles along with a smooth belt and see if that improves things.

Brown · Tuesday at 05:09

Yes, why not, if you can get it to fit. I've always thought that some sort of threaded adjuster would be better than trying to lever the components apart at the same time as trying to tighten a bolt. Some engines - especially in the US - seem to have these as standard.

Hicap phill · Tuesday at 07:38

@dag019
Spotted this. Unsure if the site they purchased it from still live
It gives you the idea of what can be done
https://www.the-t-bar.com/forum/22-cjj-s-guides/93532-how-to-fit-a-modified-alternator-adjuster

lynall · Tuesday at 07:41

Hicap phill said:
@dag019
Spotted this. Unsure if the site they purchased it from still live

https://www.the-t-bar.com/forum/22-cjj-s-guides/93532-how-to-fit-a-modified-alternator-adjuster

Very nifty.

kermit_rr · Tuesday at 07:50

Make sure you aren't overtightening the belt, is easy to do, they don't need to be as tight as modern multi groove belts that are on spring tensioners.
Also make sure you aren't under tightening otherwise it will slip. It won't make noise/you won't notice it if it's only a minor slip but it will wear out quicker

GRATCH · Tuesday at 08:05

Make sure both pulleys don't have surface rust where the belt contacts. This will act like sandpaper.

kermit_rr · Tuesday at 08:11

As will a slightly bent bracket, wrong spacer etc to push alignment out

tottot · Tuesday at 08:23

A basic tension test for a V belt.
At its longest length between pulleys grab between finger and thumb. Twist belt and if you can turn it 90 degrees that is about right. Cant turn it too tight, more than 90 too loose.

dag019 · Tuesday at 09:25

Brown said:
Yes, why not, if you can get it to fit. I've always thought that some sort of threaded adjuster would be better than trying to lever the components apart at the same time as trying to tighten a bolt. Some engines - especially in the US - seem to have these as standard.

This is my problem with doing it. To do it successfully you need two people, one with the lever and wone tightening the bolts! if I do it on my own it last less than a month before needing to be done again.

Hicap phill said:
@dag019
Spotted this. Unsure if the site they purchased it from still live
It gives you the idea of what can be done
https://www.the-t-bar.com/forum/22-cjj-s-guides/93532-how-to-fit-a-modified-alternator-adjuster

That is exactly the sort of think I am looking to do! website seems to still be live but not sure if company is still active, will give them a call.

GRATCH said:
Make sure both pulleys don't have surface rust where the belt contacts. This will act like sandpaper.

kermit_rr said:
As will a slightly bent bracket, wrong spacer etc to push alignment out

all of the pulleys got cleaned up when I put the engine in, and the alignment was checked then, but I will recheck as the alternator is designed originally for the serpentine belt so the pulley was swapped onto it.

dag019 · Tuesday at 09:27

Hicap phill said:
Only ever used smooth ones. Even in the series. They seem to bit in the pulley more.

before I go diving into the depths of the internet where do you source you smooth belts form? I assume all I need is width and length to find the correct one once I have found a supplier

Hicap phill · Tuesday at 12:15

dag019 said:
before I go diving into the depths of the internet where do you source you smooth belts form? I assume all I need is width and length to find the correct one once I have found a supplier

Not changed mine in years…will search my spares for make & size.

Rangieman123 · Tuesday at 13:19

The 3.9 V8 Range Rovers had a nut and bolt device to tension the alternator belt. You might be able to adapt one for your vehicle.

Keep Losing Alternator belt tension

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