Rotate Crankshaft Before R&Ring Vacuum Pump?
 

For some reason my searches are not locating any any threads on how to replace a vacuum pump on a MB diesel. Lots of them saying to do it though.

It doesn't look very hard but I was mostly wondering if you first need to rotate the crankshaft to a specific position to relieve compression on the vacuum pump spring to facilitate easier removal and installation.

Thanks.

I turned mine to "OT" and had no problem with spring tension it was on my 603 but from what i have read the 602 is the same. Don

I've never really noticed if the crankshaft pulley is marked. I look for the "0T"...zero degrees TDC I guess?

Thanks for the tip btw.

I dont think you can know where to rotate the engine to release the tension on the VP before you pull it. Shouldn't be a problem, just be very careful with a bottom allen, its easy to strip out. On reinstalling the V/P line up the valleys "up and down" on the little "roller coaster track" of the timing device, that will mean the V/P will not be under pressure.

I don't know at what t timing mark the crank needs to be to relieve the pressure off the vacuum pump, but it's not TDC. I don't know why they didn't design it that way, but at TDC, the roller bearing of the vacuum pump is against one of the cams of the timing gear.

There is no reason that I know of that the pump needs to be put on at TDC. I would rotate the crank until the vacuum pump can be inserted without pressing against the timing gear.

That's how I've done it before.

There is NO mark too indicate where the pressure is relieved, just remove the pump, it doesn't matter when you are taking it off. Have the "valleys" vertical when you put it back, there wont be any pressure in that position.

X2 Some pressure during removal may actually help break the pump loose. Start with the bottom screw and loosen all before you remove any.

I appreciate all the tips...thanks!

On the 602 I can see the cam lobes on #1 when I remove the oil fill cap.

If I knew where to position the lobes to place the timing gear in the correct position for zero vacuum pump compression I could do it that way.

What I am trying to say is "there is no need to know" even if you could tell by looking into the oil fill.

Wouldn't it reduce the risk of stripping the bottom Allen?

No, I don't think so, Like CR said, might help. You cant tell where the roller is anyway before removing the VP.

Answer
 

Vacuum Pump Rebuild Thread
http://www.peachparts.com/shopforum/diesel-discussion/229331-vacuum-pump-rebuild-thread.html#post1927867

I was under the impression the 602 pumps could not be rebuilt?

The Pierburg R&R instruction say to pour 50 ml of fresh motor oil into the new pumps suction port when the engine is running. I guess either port will be OK, right?

This is to fill the space behind the gasket dam for initial lubrication, correct?

Also, any sealant needed for that metal gasket? Nothing is mentioned in the instructions about this however.

Thx!

I was also under the impression that the 60x pumps could not be rebuilt. There is no rebuild kit available.

Maybe I should look at this rebuild thread...

There are 7 rebuild threads in the above link. Which one is for the 60x???