I am in the middle of changing my pump, and I was wondering if I need to get the engine to TDC and why? I am having much trouble finding a way to get to the crank nut, and I haven't even been able to figure out what size the nut is.

I'm at a standstill. Please help!

Mark

 

Well since nobody else has responded I will give it a crack. I am assuming that the early pumps are similar to the 24V units. The pump has a key in the shaft to index it to the valve train. This key must be in the 12 o'clock position or it will fall into the front cover and cause havoc. The bell housing has a plastic plug on the passenger side that allows access to the flywheel. A special tool available from cummins fits in the hole and engages the flywheel. The tool has a square drive for a half inch ratchet that allows you to turn the engine to TDC. On a 24V you remove the breather on the front cover by twisting it CCW, this lets you see the pump gear and you simply barr the engine over until the keyway is at 12 o'clock. The details may be different on the 12V engine but I hope I was of some help.

 

There is no key on the 12 valve pump as you wouldn't be able to set the timing. Moving the gear on the pump shaft is how the timing is moved.
You must have the engine at TDC and the locater pin on the pump depressed when installing the new pump or it will take hours to get it timed right, you could even have it 180° out and think you were in the ball park.

 

To turn the engine over to the timing pin , I use a long rachet with a 7\8 on the alternator and rotate the engine in reverse and the belt will not slip and the engine will turn over . like Infidel said there is no key on the pump shaft. so it is critical that the pump is in time and locked .

 

Well, there is a windriff key on the pump shaft, right? that is what I used to line it up with. Is the locator pin the thing that you have to put the crescent key in before you start the truck?

I have already screwed the pooch on this one. I'm afraid it's going to be a bear to get it timed now!

 

I think to pin must be already sheared. I can't get it to lock. I pulled the valve cover on the front cyl. that rotated the engine to "close to" TDC and put the line on the balancer directly under the crank sensor, but I still can't get the pin to drop in. I am going to pull the key from the pump and see if I am close or 180 out.
Any thoughts?

 

Whoops, gave you advice for a 2nd gen, sorry the 1st is different, can't help you.