Need to replace my water pump on an 86 420 SEL.
How do I hold that crank without the factory tool?

I've never done this job on a 420 but I remember the 450 has a notch in the crank pulley that you position to expose the water pump bolts so you don't have to pull the crank pulley.

Sixto
95 S420
87 300SDL

I was curious about this and did some digging(SEARCH). Mostly ran into comments from pro techs that more or less said you want the special tool.

I've had to do this on numerous Asian cars and said fooey to the special tool.
I fabricated by own.

Bottom line is simply this.

You're going to have to study the face of the crank pulley and look for anything that can be used for anchoring a counter..ie..an oval shaped pulley with eye-holes on each end. I've encountered that situation and built a tool accordingly. Just one example.

Last but not least, there's the ole "bump the starter" trick. You disable the ignition to prevent the car from starting, connect a long breaker bar with appropriate size socket to crank pulley bolt, then position breaker bar so that when the ign. siwtch is quickly tapped, the engine turns a hair and the wedged breaker bar acting as a counter causing the bolt to come loose.

The problem I have with this is:

a. potential damage if something gets air-borne
b. how are you going to tighten it up when you reinstall the bolt. You sure don't want to "bump the starter" on reinstallation.

Build yourself a tool. If Mecedes did it, so can you.

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Mike Murrell
1991 300-SEL - Model 126
M103 - SOHC
"Fräulein"

I would, especially if i could locate some drawings for the factory tool. I have a small picture and number for the tool from the manual.

If your talking about the 116/117 V8 Engine? You only have to remove the 6 either alan key bolts or 13mm headed bolts to remove the Pully and viburation damper and gain access to water pump bolts. Stu

I can't remember 100% but I think I just jammed the ring gear with a good screwdriver when I rebuilt the motor in th 380sel. Try hard not to damage the teeth though.
On the M103 there is a special tool you bolt to the trans that engages and jams the ring gear. Does such a tool exist for the M116?

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Andrew
300e 294,000mi
380sel 185,998mi
380se 309,980mi

Well....I am looking for a better way than the screwdriver (potential damage to ring gear) and less expensive than the tool ($100)
Does anyone know if the reference to a notched pully is only for later models of my car? It drives me nuits to believe the krauts (I am 1/2 of one) could make a 5 hr job (factory manual) out of a water pump replacement!