How install or loosen serpentine belt without removing radiator, etc.?

Can't seem to get to the belt tensioner w/o removing loads of hardware.

 

*I've never done this. After looking at that square peg of an engine in that square hole, I paid the dealer. 30 minutes and $150 later they were done*

Then I found out there's a 17 mm bolt under the belt going to the tensioner pulley. I think you can access the bolt from underneath with the splash shield removed. I've read this can be done all from on top after the fan is removed, but I think the driver's side radiator hose would be in the way. And who want's to pull the fan? At any rate, turn that bolt counterclockwise to release the belt tension. There's a notch on the right side of the tensioner were you can wedge a pin in to hold the tensioner in the released position.

Please either post back or PM me and let me know if this is the correct way to do it, or I sent you in the wrong direction. Also, if someone 100% knows exactly how this is done please add details to this thread.

 

after an idler breaking and tearing up a belt...

marcus, as usual, posted reliable info. i have a 320, so i'm not sure about what's in the way of the tensioner.

 

Got it done.
Took me about 1 hour to figure how to do it.
After that, actual job took about 20 min.
I did it all from the top of the engine.
1. Release two clips from the top of the radiator, that retain the fan shroud. After the shroud is loose, manipulate it, wriggle it, mess with it, until you can move is away from the tensioner pulley.
2. Relieve the tensioner pulley. How? I used a 3/8 In. rachet drive, with a torx socket. It's tight. You'll probably knock some skin off of your knuckles. Fit it onto the torx stud on the tensioner pulley. Put an extension on the drive. I use a 2 foot piece of cast iron pipe from the pluimbing dept. at Home Depot (Sometimes called a 2 foot nipple.), which I slide over the handle of the drive. Get the racheting action set so that when you pull the extension handle to the passenger side, it will relive pressure on the belt. I was able to wedge the handle against the steering pump, and it held there. I was never able to find the locking hole that's supposedly keeps this tensioner in place.
3. Slide the old belt off at the small alternator pulley. It's easy to get to, and it's a small pulley. Remove the old belt.
4. Get a new belt. I got a very good V belt from Oreilly’s, Gates #KO6O942, $42.99. Dealer wanted $72.
5. To install it, you will need to remove the drive, extension handle etc. in order to get the belt threaded. I tried a few ways, and found that the only real way to do it is to fit it on from the lower pulleys first. You might need a long screwdriver or rod to move the belt onto the pulleys. I got my belt/pulley diagram from my WIS software. The last pulley should be the alternator pulley. Refit the drive and extension handle onto the tensioner again. Relieve the tension, and slip the belt onto the alternator pulley, and you are done. With the extension handle I was able to use one hand to hold the tensioner, and my other hand to manipulate the belt onto the alternator pulley.
6. Give the belt a good look over to make sure it is seated correctly. Before you start your engine, make sure to remove the drive from the tensioner, and make sure to refit the fan shroud. Give the engine a tweak, just to make sure nothing, tools, etc., was left in the way of the fan or belt.

I hope that this is clear enough to be understood.

 

This place is awesome!

1/2 of the belt on my '99 has disappeared. No weird sounds from under the hood. Did not know anything was amiss until I saw a section of the belt hanging out under the splash shield. It looks like a tiny bit is wrapped around the fan so I'll have to clear that out before I put it back on the road.

The fact that fan belt is even still on there (looks like the original!) is amazing. Thanks for taking the time to write up the process!!!

 

One more thing. The radiator can be pulled forward enough to clear the idler pulley so that the bolt can be removed, almost. Here's the "almost" part. The info I had gotten from surveying the web were about idler pulleys that had disintegrated already, ie. broken into pieces, and only the stem was still in place surrounding the bolt. My pulley had not broken up. It was still in one piece, just making a big noise because the bearing was wasted, and I wanted to replace it. Problem is that if the pulley is in one piece, then there is not enough clearance for the wiggle room needed to move the bolt all the way out of the bung. If the pulley is broken, ie, not as wide, then there is enough wiggle room to work the bolt loose. What I had to do was use a ball pein hammer and a large pair of channel locks to break up the pulley so that I could wiggle it out, and it came out with relative ease.

Another thing, after removing the clips on the top of the radiator, be very careful of the flimsy plastic prongs that stick up. When you are working, it is very easy to lean on them, or brush against them and snap them off.

That's about all of the touchy things about the job that I can recall. Best of luck. Post again if you run into any problems.

 

Just completed the job, and have a few additional pointers. I searched earlier and didn't see these mentioned, so thought it was worthy of posting to this older thread:

1.) If you have a torx security bolt on the tensioner pulley, don't loosen this bolt. For these later model tensioners, there is a 17 mm bolt at the 8pm position on the tensioner, below the pulley to the left, about 4 inches away from the center of the pulley, located on the tensioner assembly, if you turn this bolt counter-clockwise, it will rotate the tensioner pulley assembly and release the tension on the belt. Other threads talked about the older tensioners or non-W208, and with these, you can turn the pulley bolt, but not with the newer tensioners (at least the one on my 202 CLK430). This was mentioned in a different thread on a different board, so props to the original author, but it's really helpful here. The 17 mm bolt is impossible to see from the top, but if you feel around with the socket, you will find it. Took me about 2 hours to figure this out, hope if saves you a little time.

2.) If replacing the idler pulley, the bolt will definitely hit the radiator, but you can unbolt the top radiator support (4 bolts on the top), and this will allow you to pull the radiator forward a quarter inch, and this worked for me.

 

The 17mm bolt is the one with the yellow circle around it, right?

 

Marcus, what engine is that out of?

 

Marcus, that's the one! Thanks for posting that photo! It will definitely make things easier for other people that need to loosen their serpentine belt.

 

That's an old photo and I can't say precisely, but I think it was from an SLR (M113).

 

What is the pulley shown in the most lower right corner?

 

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