Serpentine belt tensioner

[MikeT]

Contacted my M-B dealer for a quote on some work for the car and they indicated that my hyper noisy serpentine belt tensioner is no longer available for the 450 cdi. That's rather surprising, as parts were reputed to be available for M-B and smart for a.....LONG time....

 

Anyway, does anyone have experience with a decent aftermarket tensioner, and if so, what is the brand and where did you get it?

 

TIA

[Mjolinor]

10 years is sort of normal, agreed by most manufacturers. It is 17 years since your car stopped production and the diesel 450 was a rare beast.

 

I would have thought the 451 would fit. Do you have a picture of it? I have a spare 451 engine in my shed I shall go and take a picture later if you don#t find proof.

 

 

[MikeT]

There are tons of various brands available online, so getting one will not be a problem; however I'm just surprised that Mercedes apparently has no stock. It used to be said that you could get 40 year old Mercedes parts no problem. Maybe that was the old days.

[Nigel]

3 hours ago, MikeT said:

It used to be said that you could get 40 year old Mercedes parts no problem. Maybe that was the old days.

And if the part was out of stock they would air freight it next day from Germany.

[Willys]

IMHO, MB wants nothing to do with us any longer and have priced their parts accordingly....and why would they if you think about it......we are a dying breed......plus the number of Smarts still running on the road is reducing by the bucketful year after year...?

 IF we want to keep our cars for a very long time then it's up to us to buy the parts that are wear items and make sure that when we do need them we don't have to scrap our cars because we can either afford the parts or can't find them...

 

[stickman007]

I’ve always tried to stick with the brand Febi. Their quality is fairly consistent.

[MikeT]

Idler pulley arrived from my German friend today. Supplier is OEM and maybe the part number on the box will help others when they need one.

[Willys]

The next big question will be.....how much tension does one put on their belt?  How do you gauge the tension? Do you measure the distance of flexation? OR is it a capable twist amount once tight?
Too much tension applied to your system will simply prematurely destroy your bearings.

What are the recommendations....?

[MikeT]

The bearings are shrieking now so it may well be too tight.....mind you, 179K km....

 

I'll use common sense and have the dealer tension it using the tool at the upcoming suspension change.

[Mjolinor]

As a rule of thumb the middle of the longest run should be able to be pushed sideways about half an inch. I usually do it by rotating it in the middle of the longest run. If you can rotate it about 1/4 of a turn then it is good enough.

 

It is way better slack than tight. If ti is slack it will wear out the belt and squeal, if it is tight it will bugger up your bearings.

 

Edited May 23, 2024 by Mjolinor

[Willys]

4 hours ago, Mjolinor said:

As a rule of thumb the middle of the longest run should be able to be pushed sideways about half an inch. I usually do it by rotating it in the middle of the longest run. If you can rotate it about 1/4 of a turn then it is good enough.

 

It is way better slack than tight. If ti is slack it will wear out the belt and squeal, if it is tight it will bugger up your bearings.

 

This is the method I generally use, twist the belt to see if it's at "E" flat like a guitar string and loosen it to a slight twist as suggested above. IF I can twist the belt to a sideways position I'm good to go. 
V belts are a bit different imho, you simply push the belt in the longest stretch and get just more than the width of the belt in deflexion....seems to work for me. 
I also agree anything that pings when you flick it is way too tight and will eat your bearings in hurry.

But to each their own....it's an easy task once you are happy with what you are hunting for. Tension wise.