verifying TDC

[jethro]

I have to take my injection pump off to get new O-rings (slight leak from case)
Before I remove it - I want to verify TDC position. I may have moved the base that holds the timing pin (not sure)
a little inadvertently. Is there a way to verify exact TDC position short of taking the front cover off and looking at the dots on the gear teeth ?
Can I use a wood dowel down the injector hole ?
I did paint a wide white stripe on the rim of the balancer which lines up with the pickup- so I could later easily see TDC
once it is installed in the truck- something I didn't have to struggle to see. Not sure it will be accurate enough to use to reset the pin base though. Ideas ?
Want to try to get it perfect before I tighten down the lock screw on the pump.

Tim

[CumminsPower59]

No need dude, it's keyed, so no worries. you can spin the engine over without the pump on the gear a hundred times, throw the pump on and it's already "timed". I usually take an inspection mirror and a flashlight in one hand and turn the engine over with the other and get the keyway lined up about the 2 o'clock position, almost 12 o'clock on the pump. Easy as can be.

[jethro]

Thanks for that encouragement !
I don't really understand what I am doing yet as I havnt had this apart yet !
I guess I am concerned that I may have the timing off just a little if I have inadvertently moved the timing pin just a little.
I was thinking it might be good to get that re-adjusted. Sounds like from what you said it doesn't matter if I do it before I remove the pump or after I put it back on. Is that correct ?

Thanks- Tim

[CumminsPower59]

Correct. You van get TDC pretty darn close thought the way you mentioned earlier, pull the timing cover and verify that the markings are aligned where they need to be, and adjust the pin to where it needs to be. With the pump off, the gear may just be sitting in there. Honestly, I've never fiddled with the timing pin on the back of the case....yet.

[dr_funk]

If you use the timing pin, then that will get you to the correct position. Just remember to follow the correct procedure in getting to that position (you have to approach TDC from the correct direction - the engine's normal forward direction - if you miss the timing pin hole, you have to rotate it back to well before the hole and approach it again - this ensures that the gear lash has been taken up and you're dead-on TDC with the pump position).

And if you install it again using the correct procedure (taking up the gear lash), then your pump will be dead-on TDC again.

That's really all there is to it. I wouldn't rely on your marking to see TDC, because its not accurate enough. As long as you got to the timing pin position by rotating the engine forward, and you lock the pump down at that point without playing with anything, you'll be fine.

[Tacoclaw]

Pop your #1 valve cover and get lash at both valves, then rotate the crank so the balancer bolts are parallel to the ground. I marked my dampner as well and noticed that the bolts form a square that would sit flat on the ground at TDC. My pin was broken off long before I got my truck.

Your results may vary due to worn motor mounts and/or flat tires.



Also, fwiw, you wouldn't have to worry about gear lash if your pin was functional. It pins the pump gear specifically, so if you're trying to time the pump then it would be correct. You'd have to consider gear lash if you pinned the pump gear then started messing with the cam or crank stuff.

[PToombs]

The pin locks in the cam gear.