[Rocket99]

The problem: After engine and head exchange ... OM617 (low miles sedan 617.951 engine into 1984 wagon using the rebuilt wagon head with SLS pump mounting....

With the head off I dropped the timing chain into crankcase, fished it back out after some jimmying the crank back and forth, after installing the head the the valve timing was off by four teeth, 36 degrees rotation at cam 72 degrees rotation at crank .. this equals four sprocket teeth .... I jumped cam sprocket (moving cam sprocket counterclockwise relative to marks) by four teeth which brought cam timing back to perfect relative to the crank. Simple enough. Then doing that same operation with IP pump timing should bring IP timing back to perfect. Logical? That is what I did. It is possible to lift the timing chain off the IP timing device, and rotate by four teeth, let the chain back down to the IP timer being meticulous about marking sprocket teeth and chain to reference where things were and where you want them to end up. Now the drip timing procedure suggests start of delivery is off the scale, maybe 100 degrees BTDC ... as though I didn't correct the IP device as the crank to cam synchronization by 72 degrees (72 plus 25 = 100) .... but I did. This engine was purchased used and I'm unable to verify timing prior to this.

It starts and runs, requires heavy accelerator foot until its warm, has low power with abnormal amount of a loud "knock", (too much combustion BTDC, ie its self defeating...?)

Is this logic regarding bringing IP timing back to correct without removing IP??

Thanks in advance....

John Freeman
[email protected]

 

[300Dman]

I am kind of lost trying to figure all the degrees and teeth jumps out.

If this happened to me I would just go back to the basics.

As far as the Camshaft Timing goes when the Timing Mark behind the Camshaft Drive Gear and the Timing Mark on the Camshaft Bearing Tower are perfectly aligned down on the Crank Shaft Damper degree marks you should be pointing to Zero (Top Dead Center).

To make Sure that the Fuel Injection Pump is timed correctly I would remove it (and change the Gasket also) and follow the procedure for sticking it back in. That will get you into the Ball Park for the Drip Timing.

When Drip Timing you need to keep as constant of a pressure as you can with the Hand Primer while you are counting the drips. If you cannot do that get someone else to do the Pumping for you while you concentrate on rotating the Fuel Injection Pump and counting the drips.

When Drip Timing you need to keep as constant of a pressure as you can with the Hand Primer while you are counting the drips.

If you cannot do that get someone else to do the Pumping for you while you concentrate on rotating the Fuel Injection Pump and counting the drips.

 

[Rocket99]

Thanks for the comment.... re: hand primer... I gather if you pump it a few times there is residual pressure for a period so continuous pumping isn't necessary.

 

[300Dman]

Thanks for the comment.... re: hand primer... I gather if you pump it a few times there is residual pressure for a period so continuous pumping isn't necessary.

It is like this; a higher pressure makes it drip faster. As the pressure drops it drips slower and slower until it stops dripping.

If you cannot maintain a reasonably constant pressure the amount of drips can vary so much it is hard to tell what is going on.

I think the idea that the residual pressure is going to be a constant pressure is wishful thinking.

When I did mine I counted the drips while I was still pumping on the Hand Primer. As long as I am pumping at a regular rate the Pressure Relief/Overflow Valve will keep the pressure as close to constant as you can get.

When you stop pumping the pressure starts to drop and the amount of drips per second also drops.

At the Fuel Injection Shop I used to work in we had a Gravity Feed Setup. A little extra work to install but there was no doubt the pressure was constant compared to pumping.

I have also used an Electric Fuel Pump in place of the Hand Primer or Gravity Feed.

 

[Rocket99]

I fiddled with drip timing (with your good council) until I got the hang of it and determined within maybe two degrees when start of delivery was, from that knew how many sprocket teeth to "jump" the timing device to get it back in the range it could be "nailed" via the usual ip adjustment routine

remove the IP? Not if I can help it.

I can see, as you say, you have to pump 'n pump at any given crank position, then advance the crank just a degree or so then pump 'n pump .... you can get it down to within close tolerance maybe a degree+ of error. Your feedback was helpful with this.