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Old 04-15-2008, 04:43 PM
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sixto sixto is offline
smoke gets in your eyes
 
Join Date: Jun 2000
Location: Eastern TN
Posts: 20,841
The belt has been replaced so I'll assume you can do that.

With the belt off, try to determine if the skewness is caused by a wobbly idler pulley or tensioner arm. Even if the tensioner arm doesn't wobble, check that it pivots smoothly. As the bearing wears, there will be detents or a clickiness to the pivot motion. That's reason enough to replace it.

I've replaced the tensioner arm in an SDL without removing the fan but there was a lot of luck involved. Remove the fan unless you enjoy puzzles.

If you have any reason to pull the radiator, do so, but it's not necessary. If the radiator stays in place, cover it with something like thick cardboard for protection... the radiator's and yours!

If you're really lucky, the water pump will have a big rib at the top which extends almost to the pulley flange. That will allow you to use a 3mm pin or stiff wire to hold the pulley while you loosen the bolt that goes through the clutch. That bolt takes an 8mm hex tip. There's a special tool stubby 8mm bit available but I use a hex key and slip over the long end a deep 10mm socket on a breaker bar. If your water pump has a small top rib, you probably won't get a pin to hold the pulley. You'll need a special tool to grip the pulley so it doesn't turn. Here's a pic pilfered from gsxr's collection - http://www.w124performance.com/images/tools/OM60x_serp_belt_tools.jpg

With the fan out, pop the plastic cap off the tensioner pulley then use a 6mm hex bit to remove the pulley.

Move the tensioner arm so you have access to the tensioner shock lower bolt. Use a 13mm wrench or socket to remove the bolt.

Pop the plastic cap off the tensioner arm pivot. Use a 12mm hex bit to remove the tensioner arm. It might be tight. Heck, it should be tight. Spec is something like 70Nm (injector tight) plus some sort of sealant since the hole in the timing chain cover goes through to the timing chain; i.e., the oily innards. There should be a thick washer between the arm and the timing chain cover. Many get tossed with the old arm and new arms don't come with the washer. I suspect 603s prone to belt derailment are missing this washer.

Installation is the reverse of removal but confirm tightening torques and sealant specs since I have a bad memory. It might be easier to get the shock on the tensioner arm before the arm goes on the engine.

Check the shock for continuous resistance through its stroke in both directions. Check also the Heim ends. Loose Heim ends can cause a scary knocking sound like a bad main or rod bearing.

I don't think there's a top and bottom end to the spring.

Sixto
87 300D
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