IP timing backlash
 

I'm installing a new injection pump on a 606. I'm using the little tool that threads into the side of the pump and engages the pump shaft to prevent it from rotating and then installing it with the engine 15deg ADTC. I notice when I tighten the timing sprocket onto the front of the pump, a left hand threaded bolt is used. The engine, however, turns the opposite direction, so that there is maximum backlash between the timing chain and the pump sprocket after the bolt tightened. If I wiggle the pump sprocked bolt clockwise after it has been tightened (the direction that the engine will turn the sprocket, it has several (about 3-5) degrees of backlash, and as a result the IP timing changes the same amount. My question, is: should I simply not worry about the backlash or should I then rotate the pump again to compensate? Additionally, is the backlash a sign of something else being haywire (ie. stretched chain)?

Much thanks for any help.

Galen Bowen
1983 Toyota Landcruiser FJ-60 w/ Mercedes 606 motor/Chevy NV4500 tranny

The tool you are using isn't for pump timing but pump location, so the the pump timing can be adjusted correctly! YOU need an "A-B" lamp tool to properly adjust the timing & on the OM606 engines that should be 13.5-14deg ATDC.

When the engine is running, the slack in the chain is taken up by the oil pressure against the tensioner. I have found that I can set timing by using the earlier method of 24 BTDC spill/drip, out the #1 element.

Try increasing the tension on the chain while you install the pump.
I also made my own tool to lock the pump at 15 ATDC.

After timing checks on many of these motors, my eye ball and spill timing seem to do the job in checking all is correct.

Others may disagree.....