[wlb50]

Yesterday, I realized that it had been awhile since I replaced my serpentine belt on my 1996 SL500. It had no cracks, which is the traditional way to check for the belt condition but curiosity led me to go through my 1.5" stack of invoices (you do keep your invoices for your records, don't you?) - anyway it was October 2013, 10 months after I bought the car, that I changed the belt.

About 100,000 miles ago.

And I learned that mostly the only thing that shows visible wear on the belt these days is the grooves that catch the drive pullies - the "valleys" will widen over time. Gates Rubber makes an inexpensive (i.e., free) plastic tool that can tell you if they are worn, but it seems that, while they are free, they are geared towards the shop professionals. IOW, they tell you to contact your Gates Representative.

I can remember back in the 60s you'd service your car every 10,000 miles, which generally included plugs, points, condenser, distributor cap, rotor, belts, hoses, and repacking the wheel bearings.

How times have changed. Even my upper and lower radiator hoses have a good 70,000-80,000 miles on them.

As for mileage, I read anywhere from 60,000 miles to 100,000 miles and the belt should be changed.

While it is off, you should check the pully bearings to make sure they turn freely and silently.

Guess I'll have something to do this week.

Oh, as far as the fact that you may not see any cracks - they are making them out of a much better material - they used to be made of neoprene, which would show the cracks after awhile.

I used a Continental brand, bought at the dealer, and even now makes no noise, slipping, etc. But at 100K miles think I should change it. I could make one of those boring YouTube videos showing people how my idling M119 at 223,000 miles just purrs but there's enough of those videos up there

Anyway if that belt breaks on the road at the least it will stop you cold, at the worst do some damage to the harmonic balancer I'm told.

Change them on schedule.

 

[wlb50]

Does anybody want any documented instructions here for the M119 and replacing this belt? I’ve just taken off the plastic shrouds and realize now I really need a piece of cardboard to cover that radiator in case the wrench slips. After all, it’s been 97,000 miles.

So everything stops. I realize when working on the cars if you don’t do things methodically you can really regret it and denting or punching the radiator from a slipped wrench removing the fan clutch is on the list

but I’ll make a little three or four step documentation if anybody wants it. Let me know in the next 12 hours

 

[Sparking1]

Does anybody want any documented instructions here for the M119 and replacing this belt? I’ve just taken off the plastic shrouds and realize now I really need a piece of cardboard to cover that radiator in case the wrench slips. After all, it’s been 97,000 miles.

So everything stops. I realize when working on the cars if you don’t do things methodically you can really regret it and denting or punching the radiator from a slipped wrench removing the fan clutch is on the list

but I’ll make a little three or four step documentation if anybody wants it. Let me know in the next 12 hours

I've got a serpentine belt tool that makes the task so much easier; leverage and long reach make the difference. Enjoy!

 

[260e crusier]

I change my serpentine belts out at 100K or when I acquire a used car. I treat my new belt with Aerospace 303 before installing, usually the night before.

 

[wlb50]

I've got a serpentine belt tool that makes the task so much easier; leverage and long reach make the difference. Enjoy!

If it’s the tool I’m thinking of I got that at eBay and it’s used to hold the back end of the fan clutch while you use the 8 mm hex bit? You have to have that thing.

And if I remember correctly a breaker bar gives you a little more room to fit that bit in The front of the fan clutch. IIRC The factory manual shows you using a little hex key but usually those things are so tight you really need some leverage.

and I made sure I got some cardboard to tape in the back of that radiator in case the breaker bar slips.

just that and a little prybar to push the belt tensioner in to get the belt off the pulley and that’s it.
Then have fun threading the new one


You want to hand turn all of the pullies slowly to see if any bearings are on the way out. That’s the time to do it.

I know soon after I got the car I replaced the idler pulley bearing.

That was eight years ago

I was surprised as I’ve got both belts at the dealer and the new belt was the same price as the one eight years ago.

and I always put the old one in the trunk just in case…

looking at my records it’s been 97,000 miles since I last put the new belt on. I remember doing it because I had to put a new power steering pump on at the same time.

figured it was about due

 

[wlb50]

I change my serpentine belts out at 100K or when I acquire a used car. I treat my new belt with Aerospace 303 before installing, usually the night before.

What’s the Aerospace 303 supposed to do? When I was reading up on these belts it was interesting to learn they’re making them out of a new material over the last 15 or 20 years. You cannot just look for cracks thinking that is a sign of wear because the new material rarely shows cracks.

and if the thing breaks it of course stops you cold and can even damage the harmonic balancer.

i’d be willing to bet this is one of those neglected maintenance items.

in years past you just automatically replace the belts and hoses once a year or 10,000 miles. They’re making them a lot better now

 

[wlb50]

By the way I was amazed to learn with these fan clutches for the M119 are $700 although I haven’t priced them for discounts because I’ve never needed one.

On my M103 W124 years ago it was about 100 $150.

I will say the one for the M119 looks a lot more complex and there’s a lot more to it…

 

[260e crusier]

What’s the Aerospace 303 supposed to do?

Make it look purty

It's a protectant for rubber/vinyl/plastic.............. probably not need as you noted that belts made today hardly ever crack.

 

[wlb50]

New one is on the left. Old one has 97,000 miles on it. Maybe you can’t see it but the “valleys“ between the grooves do look a bit wider with the older one.

 

[Lumpy2]

I just had my belt replaced today. Previous owner replaced the belt 9 years ago and about 30k miles ago and it had similar cracks and a little fraying at one edge. I just turned over 53k miles the other day so the car has done a lot of sitting by previous owner.

 

[kdawgdurst]

Does anybody want any documented instructions here for the M119 and replacing this belt? I’ve just taken off the plastic shrouds and realize now I really need a piece of cardboard to cover that radiator in case the wrench slips. After all, it’s been 97,000 miles.

So everything stops. I realize when working on the cars if you don’t do things methodically you can really regret it and denting or punching the radiator from a slipped wrench removing the fan clutch is on the list

but I’ll make a little three or four step documentation if anybody wants it. Let me know in the next 12 hours

wlb50,
I know this is an older thread, and hope you will reply. I have a 97 sl500 and need to replace the serpentine belt, and was hoping you could provide any information on videos. Thanks so much for your help.
Kdawg

 

[C Cortez]

wlb50,
I know this is an older thread, and hope you will reply. I have a 97 sl500 and need to replace the serpentine belt, and was hoping you could provide any information on videos. Thanks so much for your help.
Kdawg

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