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Discussion Starter #1
Hi guys, i have a quick question regarding the belt tensioner replacement on my 1991 500sl.
First of all, the tensioner squeals like a pig, so i am planing to replace it. I have seen online that i could either buy the tensioner pulley or the entire tensioner assembly. Which would you recommend i get? The pulley it's self is of course the cheaper rout but will it include the bearing or do i have to buy the entire assembly?

Thanks
 

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I would buy just the PULLEY!!!! The only time that I would replace the entire thing is when the spring is so weak that the belt slips. Just get the PULLEY!!!! You'll be fine!!!!
 

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Discussion Starter #4 (Edited)
Thanks drags, i appreciate your input. I will just purchase the pulley.

I was looking on Autohausaz.com. Pulley = $23.90 and tensioner assembly = $131.95. I will probably get the belt too while i am at it: $31.13
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Thanks drags, i appreciate your input. I will just purchase the pulley.

I was looking on Autohausaz.com. Pulley = $23.90 and tensioner assembly = $131.95. I will probably get the belt too while i am at it: $31.13
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You have a '91 with the original tensioner...those things wear out you know...

If it were me and there was only a $100 difference, I would replace the whole thing. The labor is going to be about the same to just replace the pulley, and then you know you don't have to revisit it later and pay twice to have the same work done over again.
 

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Again, Just replace the PULLEY, If the BELT is worn or cracked replace it also. Replacing the whole tentioner would be recommended if the spring inside it was weak or broken!!!! ANYONE can change the pulley in 5min. or less, The whole thing will take longer, And just think: saving the $100 bucks will ALMOST pay for a couple of tanks of GAS!!!!!!!!!!!!
 

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Again, Just replace the PULLEY, If the BELT is worn or cracked replace it also. Replacing the whole tentioner would be recommended if the spring inside it was weak or broken!!!! ANYONE can change the pulley in 5min. or less, The whole thing will take longer, And just think: saving the $100 bucks will ALMOST pay for a couple of tanks of GAS!!!!!!!!!!!!
I second that.
If it is not broken why fix.
Don't look for trouble.
When you know.
That trouble is looking for you. ;)
Regards.
aam.

PS. Gas, is going up again. :(
drags, I like the way you put it. (ALMOST).................
 

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Discussion Starter #8
Thanks guys, parts are on order! New plugs and intake snorkels (original ones are dried and cracked up) are on the way too.
 

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Well, I guess I am too late to help, but I will put in my two cents anyway. BIG mistake to just buy the pulley on an original 1991 SL!!!:eek: You took the advice from someone with a 2000 SL, NINE YEARS NEWER. Second, there is no "spring" inside the tensioner. It is molded rubber! Yes, the pulley is probably squealing like a pig, but trust me (please note the year of my car!), the entire tensioner is next, if not already toast. The reason the tensioner goes bad is the rubber finally gets hard, cracks and separates from the internal walls of the assembly. Your rubber might be getting there after 18 years, do ya think?

Replace the entire assembly and be done with it for the life of your baby!:cool:
 

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Well, I guess I am too late to help, but I will put in my two cents anyway. BIG mistake to just buy the pulley on an original 1991 SL!!!:eek: You took the advice from someone with a 2000 SL, NINE YEARS NEWER. Second, there is no "spring" inside the tensioner. It is molded rubber! Yes, the pulley is probably squealing like a pig, but trust me (please note the year of my car!), the entire tensioner is next, if not already toast. The reason the tensioner goes bad is the rubber finally gets hard, cracks and separates from the internal walls of the assembly. Your rubber might be getting there after 18 years, do ya think?

Replace the entire assembly and be done with it for the life of your baby!:cool:
Ya, I know... I dunno why he doesn't wanna do it, it's only $100 more, and like I said before, those things wear out. Why not just knock it out while you're in there anyway?

This is how people get worn down with maintaining an older car, because they never want to do anything proactively, instead only fixing things when they break. When you start down that path, you find yourself running on the car's schedule instead of the car running on your schedule.

I mean it's common sense, really. If you have to do an oil-pan gasket, then replace the sending unit while you're in there. If you have to replace a pulley, then replace the belts and the tensioner while you're at it. If you need one O2 sensor, replace all of them. If you're replacing one bushing, then replace the rest of them at the same time.

When you get to this type of stuff that will eventually fail anyway, just get it out of the way now so you won't have to make a special trip to the shop to deal with it later. It seems more expensive at first, but in the long run you actually save a lot of money since you don't have to pay to duplicate labor on a task that could have been done while they were already doing something else that's related to it. If you handle it this way, you will avoid unscheduled shop visits as well as many headaches.
 

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While I do respect some of the other opinions, I STILL would just replace the pulley, Using chris's statement, While your changing that pan gasket, You may as well do the timing chain,Rod and Main bearings, and so on!!!!!!!! After all!!!! They will wear out sooner or later,To some of us who live on a budget, AND, are able to repair our own, A simple job like a pulley, takes only a few min. I am NOT trying to start a flaming war, just making a point! And yes, My car is newer,But trust Me, New STUFF breaks ALL THE TIME!!!!!!
 

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While I do respect some of the other opinions, I STILL would just replace the pulley, Using chris's statement, While your changing that pan gasket, You may as well do the timing chain,Rod and Main bearings, and so on!!!!!!!! After all!!!! They will wear out sooner or later,To some of us who live on a budget, AND, are able to repair our own, A simple job like a pulley, takes only a few min. I am NOT trying to start a flaming war, just making a point! And yes, My car is newer,But trust Me, New STUFF breaks ALL THE TIME!!!!!!
Well you do have a point. There IS a limit to which you should go with it, and I certainly wouldn't advocate replacing a timing chain just for the hell of it (unless you are at 170k+ miles...they do get loose after awhile), or anything like that.

I was referring more to the small stuff, like in this case the belt, pulley, and tensioner. Each of those wears out, and if I knew I had to replace 2 of the 3 already, I would just go for replacing all 3 if the cost isn't astronomical, which it's not in this case. It WILL eventually fail, and this way you've already got it out of the way.
 

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Discussion Starter #13
This is great input, it is always good to hear from people who have experience with the vehicle in question. I can order the tensioner assembly without the pulley if things don't work out. YES i do all my work my self in my shop, so don't worry about me, besides i'm always looking for an excuse to work on my babies!! I am NOT reluctant to do the whole thing, thats why i asked you guys about it. There are many cars in which the tensioner assembly's last for a very long time. My car has 57000Km on it so i would assume that the spring and such should be ok, mind you it is 17 years old so maybe i will just order it anyways and throw it in, then i guess i won't have to worry about it.
Cheers!
 

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Hi guys, i have a quick question regarding the belt tensioner replacement on my 1991 500sl.
First of all, the tensioner squeals like a pig, so i am planing to replace it. I have seen online that i could either buy the tensioner pulley or the entire tensioner assembly. Which would you recommend i get? The pulley it's self is of course the cheaper rout but will it include the bearing or do i have to buy the entire assembly?

Thanks
This morning I turn on the key and started my 92 500 SL. A loud squeal was heard. At first I assumed it was the belt or belt tensioner. Driving it without pressing the pedal (coasting) was fine but as soon as I give the car some gas the loud squeal began. Anyway I return home and tried to find out exactly where the squeal was coming from. It turns out that when the ac compressor is on, and when I press the accelerator the squeal is heard. If I turn the AC off and give the car some gas, no squeal is heard. It makes me to believe the AC clutch is beginning to seize. I spray some lucubrate behind the AC clutch, not sure if that's what its called, and when the AC is on the squeal goes away. My question to anyone, I believe the bearing in the compressor is beginning to go south, can the front AC clutch be replaced ONLY, as if I recall in older domestic cars it can be done while the unit is intact and without draining the AC system. Any info would be appreciated.
Thanks,
carltwo
 

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Hi Carl, yes the clutch can be replaced only it is costly.
But I would say walk don't run.
If your belt is glazed or old, same thing goes for the tensioner.
See when the A/C is on you have a lot more resistance.

CK it very well before you spend your good $$$ my friend.
If you decide to replace the compressor.

Chris, has a few I think new ones, that is if they fit your car.
Or Bob, may have some good used ones.

Personally I don't replace the clutch, I replace the whole unit.
I am using rebuilds with out any problems, so far.

Regards.
aam.
 

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Hi Carl, yes the clutch can be replaced only it is costly.
But I would say walk don't run.
If your belt is glazed or old, same thing goes for the tensioner.
See when the A/C is on you have a lot more resistance.

CK it very well before you spend your good $$$ my friend.
If you decide to replace the compressor.

Chris, has a few I think new ones, that is if they fit your car.
Or Bob, may have some good used ones.

Personally I don't replace the clutch, I replace the whole unit.
I am using rebuilds with out any problems, so far.

Regards.
aam.
Hello aam,
So far I've been driving the car all afternoon with many stops and starts and no squeaking so far as now it's in my opinion definitely the AC front clutch as since this morning when I sprayed some lubricant directly behind the clutch, the squealing noise has gone. The S belt was replaced 15,000 miles ago with no signs of cracks.
Also almost 3 years ago when I had purchased the car, a AC (new) compressor had already been just replaced. The only thing on my car is everytime I start the car the Air automatically turns on and I believe that can cause the AC to a shorter life span. any comments..
Carl
 

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OK so it is the clutch, your belt etc are good.
My A/C in only on when I want it to be.

On the EC compressor is off, fan and temperature on.
So I don't know why yours is on, maybe other members with 92 can comment.

A compressor should last a very long time, as long and is properly maintained.

Regards.
aam.
 

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OK so it is the clutch, your belt etc are good.
My A/C in only on when I want it to be.

On the EC compressor is off, fan and temperature on.
So I don't know why yours is on, maybe other members with 92 can comment.

A compressor should last a very long time, as long and is properly maintained.

Regards.
aam.
aam,
The AC comes on automatically when I start my car as I believe its culprit is a faulty climate control unit as several of the fan speeds do not function, no center air and cosmetically shows lots of wear. That's my next fix. But how is an ac compressor maintained? any lube openings?
 

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There are no lube openings it is the refrigerant pressures and the adding the right amount of the correct oil, as the compressor seals and others always leak a small amount.

Regards.
aam.
 

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I priced out the compressor clutch and compressor separately once on an MB, they were within $100 of each other. It's not gonna save you any money if it's just the clutch, unfortunately. :crybaby2:
 
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