Help with excessive belt ware

[DWW]

Can anyone help with a phot/drawing of front of engine showing the routing of the belt round the various pulleys, alternator and the idler/tensioner pully. Thanks



Is this correct?

The reason for this is that I keep having an issue with excessive belt ware, every few hundreds of miles the belt shreds itself.

[abowie]

The idler pulley is supposed to be on the left side of the engine viewed from the front, and goes inside, not outside.

[DWW]

Are you sure, this is an S1 3.8, there is no place to fit it on the left, that is the way it always was. The only thing that bothers me is that the new alternator pully is not 100% in line, slightly offset, with the water pump and crank pulleys.

[mtnjag]

It is as abowie states. I have a 62 S1 3.8.

Your car would have come with a Generator not an alternator.
The alternator is a retrofit and evidently whoever fitted it did not align the pulleys.
You need to shim either the mounts, the alternator, or the pulley on the alternator shaft, or a combo of those in order to bring the pulleys into alignment.
Not a big deal but get the idler where it belongs. Tight fit and close to the bottom hose but it fits.
There was a change in the idler at some point, make sure you have the correct one for your car.
Check out "images" on line or perhaps you shop manual and they will show location.

[abowie]

Pretty sure. Both my 3.8s are set up like that and in over a dozen S1 E Type restorations it's the only way I've seen them.

The bracket mounts to the two 3/8" bolts that go through the timing cover on the LHS. The tensioner goes on the inside. See picture below. This is a S2 motor but it was all I could find quickly.

WRT shredding the belts, if your pulleys aren't exactly aligned (better than 1mm) the belt will wear excessively. You will need to fix this.

If you are using a W belt (not sure when they changed to these from V belts) there have been bad ones in recent years that only last a few 100 miles. You could try a different vendor.

You don't actually need the tensioner. I have removed it on one of my 3.8s and it was never fitted on my MK2. If you use a 1030mm belt there is enough adjustment in the generator to keep the belt tight. My 3.8 has 1000s of km on it and no belt failure so far.

[DWW]

What you say makes much sense, my engine does use double v belt. The car was converted to alternator (Neg earth) and now uses a 1050 belt. I am not sure what the offset is, will check it tomorrow, the alternator is fixed with no way to adjust it and the belt fits snugly, I don't think the tensioner is doing anything anyway in its position. If I find the alternator pulley to have a too great offset I will have to find a way to move it either in or out as necessary.

It is quite possible that the belts I was supplied may have been sub standard as this is the second one from the same supplier that suffered the same damage.

Thanks for your help so far

BTW I looked all over the internet including Youtube to catch a glimpse of a 3.8 engine front view to try and confirm the position of the tensioner to no avail

[AussieEtype]

If your car had a serpentine belt your diagram you be correct but it has V belts and tensioners always go on the V not the back of the belt - V belts are not designed for tension on the flat side, only the V side.

That is the reason you have been shedding your belts.

Garry

[chrisfell]

I had a belt shred recently. On inspection I surmised it was because that particular belt was too big for the pulleys. The previous (and subsequent) belt sat fully in the pulleys. I’m guessing but I think the larger belt, some of which sat proud of the pulleys, suffered from differential heat stress, causing the rubber to crack and the steel belting to fray. Or it just may have been a substandard manufacture. Such things happen.

My 4.2 engine has a 1050 belt which is tensioned by the alternator mount - no tensioner pulley.

[mtnjag]

Danny, see post 5 for a correct image by abowie. Look no further, that’s correct.

V groove belts should not be down in the groove too far. They usually sit slightly proud. You do not want it bottoming out in your pulleys. It will wear the pulley, especially if they are aluminum.

[DWW]

The only aluminum pulley is the alternator one. I measured the offset of the alt. Pulley in relation to the othe two and it is within tolerance. I have ordered a new belt from SNGB should be with me soon. Will give it a try this time with a differently sourced one and follow its progress. As I previously said the tensioner in its present position hardly plays a part and could probably be deleted. Thanks to everyone for the help and participation.

I did some further check looking at my front of engine photos during the restoration when it was being put into the car, there is no tensioner to be seen on either side. This must have been added when my dynamo was replaced by the alternator and it is a smooth roller rather than double v grooved and as mentioned is hardly in contact with the belt.

[mtnjag]

Well I think it was dropped early on for some reason as the early cars had the tensioner. The bearings were a bit of a problem I believe.
Mine's a V groove. A smooth one is definitely an add on from some other car application no doubt, and it's on the wrong side of course.
My WP pulley is alum. Looks like steel but is alum.
Hey, If you don't need it one less thing to go south on you.

[DWW]

exactly