603 belt tensioner and camshaft removal tips needed
 

Hello,

First of all, section 5 Engine Timing, Valves and section 13 Belt drive are completely omitted from the factory paper service manual. :mad: :mad:
For the price of that thing I am very dissapointed in MB.

Anyways, I need to remove the cyl. head on an 86 300SDL and am doing the preliminary work today. Removal of camshaft, any particular warnings besides mark all the parts and put them back to their respective cylinders?

Also, I need bonehead level instructions for removing the belt tensioner. First, how do you slip the belt off, do you just pry the belt off?

Thanks in advance.

The camshaft needs a specific procedure when it is removed, otherwise you will snap it.

Don't remove the camshaft without the FSM for this.

I wish I had one myself. I'm going to need it soon.

Thanks Brian, that's what I thought I remembered from somewhere. Isn't it nice that they left out the whole section on those items?

I know you know about belt tensioners. Any tips? ;)

On the top of the tensioner is a hole in the plastic piece. Stick a big screwdriver in there and rotate the tensioner so that you compress the spring. The belt will slip right off. Release the spring carefully.

When you go back on with a new belt, do the same thing. Rotate the plastic piece, compress the spring, and pop the belt over the idler.

Now is a good time to make sure the idler is in good shape. It should roll smoothly without any rattle. If you can feel any roughness in the bearing, replace it. It tends to let go and do all kinds of damage.

BTW, take a good look at the belt routing and make a diagram of it, if you don't already have one. It's easy to make an error. Don't ask me how I know. :rolleyes:

If you are removing the Tensioner Assembly be sure to clean all the threads of the locating bolt and those in the block for the main bolt. Use Loctite on these threads when you reassemble and torque to factory specs. Like Brian, don't ask why I know this :eek: :D

Check the tensioner Shock-absorber as chances are it will need replacement as they don't seem to have a long service life.

I used a 2ft 3/8" ext in the hole on mine couldn’t move it; I thought I was going to break the plastic piece.
I don't have too loosen the bolt that goes thru the spring eye?

Also on the piece with the hole in it, mine had a pin in it down below the hole and a bracket that came across the face of it from the bolt that was holding the shock. It appears that I have to take the bolt out of the shock holder to remove this bracket? And then release the tension? Rotate up & down correct.

I need to replace my idler pulley; it is making a chirping noise

that bolt DOES need to come out before you can release tension on the spring! Its what holds the whole thing together to make it work.

If you're planning on removing the fan... There's a special MB tool for this, I've never tried to do it without the MB tools, but I assume one could use vice grips or similar to hold the pulley and a REAL short 8mm allen to break the fan nut loose.

You remove the nut on the end of the bolt that goes through the spring eye. Then insert dowel into the hole immediately to left of the spring eye and twist towards the passenger fender. That will lift tension off the bolt that goes through the spring eye and you can push out the bolt. Now let the dowel come back to the right and the assembly will have slack on it. You can now push against the idler pulley towards the passenger fender to create even more slack but the belt should come off at this point anyway. The bracket that connects to the tensioner shock does not come into play until you decide to remove that tensioner shock.

It should take very little force to rotate that lever. The amount you were using is too much.
Also I used a strap wrench to hold the pulley when removing the fan clutch and idler bolt. Maybe hit that fan clutch bolt with some penetrant and then sleep on it. Also, be sure to store the fan clutch in an upright (its normal orientation) position. But then, I am taking the head off, so you might not need to remove the fan clutch.
Thanks to BillyBob for the pdf.

Does anyone have the cam removal sequence?

Yes Yes, Now I see, MASTER

What do you mean by that? I'm only trying to help.

That means I thank you very much for the great right up, that has shown the light to me on how to do this, You are the MASTER

It can be done without special tools or removing the rad, I have the scraped knuckles to prove it :D I used a 8mm L-Shaped Allen Key that would just clear between the rad and Fan bolt. When the bolt was loose enough I was able to undo it the rest of the way and remove it by hand. Clearance is tight and you must loosen the Fan Shroud and hang it over the fan to gain access.
I can't see how you could remove the Tensioner assembly without taking off the Fan first. OK if you were just replacing the Belt though.

A proceedure for cam shaft removal/installation is outlined in the service library listed below. http://skinnerbox.steaky.org/service/library.html

I just checked and it is there, you just have to look for it......BB