603 Belt Tensioner office emergency - PeachParts Mercedes-Benz Forum

locry · #1 08-05-2009, 09:23 PM

ok... so i pulled into the office garage early morning and noticed a weird RPM related squeal... found that the tensioner was cocked to one side... good thing the belt didn't derail on me mid trip...

anyway, i will attempt to replace the tensioner after office hours... it's an 87 300TD... from what i've read so far this is the gameplan:

loosen shroud to access the FAN
somehow stop the fan from rotating...jam the belt at the power steering pulley?
(replacing the belt anyway)
remove fan with an 8mm or 10mm allen?
remove belt...
remove PULLEY from tensioner before removing tensioner...
remove tensioner using what? 12mm hex?

i have to be absolutely sure about the sizes because i will have to buy these... my tools are at home...

thanks

ah-kay · #2 08-05-2009, 09:30 PM

I changed out my serpentine belt last night and I only need

1) 13mm wrench to remove the the tensioner bolt
2) 12mm wrench to remove the damper screw.
3) One long screw driver to leverage the tensioner black plastic thingie. Insert in into the hole to torque the tensioner to position.

That should be all it takes. You should not need to remove the shroud or clutch fan. I suspect the hook on your tensioner is cocked sideway.

locry · #3 08-06-2009, 12:02 AM

ey thanks for the reply...

so the tensioner can be removed with everything still in place?

ah-kay · #4 08-06-2009, 12:31 AM

It depends on whether you are removing the tensioner itself or the tensioner spring. I have not removed the tensioner ( the round flat pulley ) myself. I would expect it seldom goes wrong.

You can remove the tensioner spring without removing the fan clutch. Then you can exaimine what needed to be fixed.

locry · #5 08-06-2009, 02:10 AM

i'm replacing the entire tensioner.

Billybob · #6 08-06-2009, 02:20 AM

Quote:

Originally Posted by locry

ok... so i pulled into the office garage early morning and noticed a weird RPM related squeal... found that the tensioner was cocked to one side... good thing the belt didn't derail on me mid trip...

anyway, i will attempt to replace the tensioner after office hours... it's an 87 300TD... from what i've read so far this is the gameplan:

loosen shroud to access the FAN
somehow stop the fan from rotating...jam the belt at the power steering pulley?
(replacing the belt anyway)
remove fan with an 8mm or 10mm allen?
remove belt...
remove PULLEY from tensioner before removing tensioner...
remove tensioner using what? 12mm hex?

i have to be absolutely sure about the sizes because i will have to buy these... my tools are at home...

thanks

Pull the pin holding the outer and inner shrouds in place, rotate the inner shroud, remove two metal clips holding outer shroud to radiator, remove outer shroud, remove inner shroud, loosen and remove the fan bolt and fan, loosen tensioner pulley bolt, loosen and remove tensioner pivot block nut slide bolt to the rear while using lug wrench handle to relieve tension, remove tensioner pully bolt and tensioner pulley, loosen and remove shock top bolt, rotate tensioner clockwise, remove shock bottom bolt and shock, loosen tensioner center bolt while removing tensioner. Check the belt Auto Zone has it 2145 mm 6 Poly V

You can use the serpentine belt and a pair of vice grips to make a strap type wrench to hold the fan pulley, take the belt off first then pad the jaws if you will be reusing the belt.

Fan bolt is 8 mm Allen
Tensioner pulley is 6 mm Allen
Tensioner is 12 mm Allen

The lug wrench handle fits the tensioner pivot block hole

13 mm tensioner pivot block bolt and shock top bolt

11 mm shock lower bolt

3/8" drive 4-10 mm Allen set from Auto Zone
1/2" drive 12/14/17 mm Allen

If you have a Harbor freight close by get this tool:

Pulley Spinning Tool ITEM 66385-0VGA $7.99 on Sale now!
Ideal for holding or spinning the crankshaft and camshaft on motors using deep forged pulleys.
Applicable for Mercedes Benz, VW, Audi, BMW, Ford, Opel, Peugeout, Renault, Volvo and Japanese cars
Long handle for extra leverage
Overall dimensions: 13-1/16" L x 1-1/2" W x 1-1/2" T; Handle length: 4-5/8"; Jaw opening: Min. 1/4", Max. 7/8"; Pry bar dimensions: 13-1/16" L x 1-5/8" W x 15/16" T
Weight: 0.87 lbs.

locry · #7 08-06-2009, 04:09 AM

ey thanks for the comprehensive guide bro!

appreciate it...

update: got an indie to work on it as i'm still in the office (working)... he encountered a problem with his allen wrench... it seems the 12mm isn't that snug...so he's looking for a mchine shop to grind down a bigger allen... doesn't want to round off the bolt.

when i checked up on him, he's managed to remove the radiator... he probably couldn't get to the fan...

i'm just waiting for him to grind down the allen.

thanks again... will keep you posted

locry · #8 08-06-2009, 05:58 AM

done! whew...

i've been running without the shock thing for the longest time... i think that's what caused the early bearing failure, as was ponted out earlier... can't fix the shock problem yet coz there's a stuck piece of bolt where the shock mounts to... deym!

airbus · #9 10-17-2009, 05:56 PM

Quote:

Originally Posted by ah-kay

I changed out my serpentine belt last night and I only need

1) 13mm wrench to remove the the tensioner bolt
2) 12mm wrench to remove the damper screw.
3) One long screw driver to leverage the tensioner black plastic thingie. Insert in into the hole to torque the tensioner to position.

That should be all it takes. You should not need to remove the shroud or clutch fan. I suspect the hook on your tensioner is cocked sideway.

Thanks a lot, that really is all you need to know. Took me ten minutes, I'm surprised it's actually that easy!

oilslick · #10 10-17-2009, 06:56 PM

I changed the entire tensioner assembly without removing anything but the assembly itself. I didn't remove the fan, fan clutch, and especially not the radiator. I replaced the tesnioner assembly on my brother's '93 300D 2.5 the same way. It took about an hour on each vehicle.

Long story short...........................................................I'm glad I don't own an '87 300TD. Whew!

fullcircle · #11 10-17-2009, 07:56 PM

I bought my '87 300TD needing a belt tensioner and didn't drive it until I'd fixed (at least) this problem. I'm new to the 603 so this might help fellow first-timers. I had done a lot of searching and reading on the forum regarding this repair and, thinking I might save some time, attempted to do it without removing the fan. After dropping the allen wrench 19 or 23 times between the shroud and the radiator while removing the main tensioner bolt, it turned out the lower tensioner arm interfered with the fan pulley, so I had to pull the fan anyway. After removing the fan (which was actually OK, albeit tight quarters), I wished I had done it from the start. It would have saved me a lot of time. Additionally, as a first timer, it gave me so much more room to see and, therefore, do much better work, which, in turn, made me feel much better about the repair. I also replaced the original style vacuum pump while I was there just for peace of mind. With the tensioner out of the way, this was straight forward and relatively easy. Long story short, if I were to advise a person doing this job for the first time, here are some things I would suggest:

-Search the forum and read the different approaches

-remove the fan, fan pulley, and serpentine belt. This will also help with the first-time belt installation when your done because of the ability to see and move.

-I removed the tensioner pulley with the assembly in my vice. The bolt was very tight and this afforded me better positioning than removal while mounted to the engine.

-Don't forget the spacer (looks like a big washer) that was between the tensioner and the timing chain cover on the old assembly when you're installing the new tensioner.

-If your doing the vacuum pump, rotate the engine on the crank pulley bolt so the pump is not under pressure from the cam circle (or whatever it is called). If I remember correctly, the high sides of the cam circle were at the 12:00 and 6:00 positions, but don't hold me to that.

-I also rotated the engine from the crank bolt to draw the 10cc of clean oil into the vacuum pump. The instructions said to do this with the engine running, but I wasn't sure I could get my wrenches on the fittings with the fan and belt installed. I don't know if my method is acceptable, but it seemed to work for me ok. In retrospect, I imagine the engine could run for this short period without the fan or belt.

Just some observations.

locry · #12 03-27-2011, 09:55 PM

update...
Since that time that I had an indie replace the belt tensioner I have replaced it again less than a year ago. And now I noticed that it's slightly cocked again.
Whyy am I chewing up belt tensioners? Is it because I have been running without the damper? If so... what in particular is affected? is it because of the absence of damping that's causing the bearing to fail? or the missing "counter" force exerted by the damper's position, it being on the other side of the belt pulley?

bustedbenz · #13 03-27-2011, 10:39 PM

Quote:

Originally Posted by locry

update...
Since that time that I had an indie replace the belt tensioner I have replaced it again less than a year ago. And now I noticed that it's slightly cocked again.
Whyy am I chewing up belt tensioners? Is it because I have been running without the damper? If so... what in particular is affected? is it because of the absence of damping that's causing the bearing to fail? or the missing "counter" force exerted by the damper's position, it being on the other side of the belt pulley?

I would think that yes, running without the damper would cause premature wear on the tensioner.

vstech · #14 03-27-2011, 10:42 PM

I suppose the dampner prevents the CHATTER that's forced on the parts. loosens everything else.... and that timing cover is pretty fragile, so I'd want EVERYTHING in place to protect it!

locry · #15 03-28-2011, 02:25 AM

will try to extract the bolt that's stuck in there... aaarrrgh