Engine/Transmission (1994 - 1998) Injection Timing

[BTanzini]

I would like to know how or why the injection pump timing slips when once it is set and held in place by tightning the nut down on the shaft supporting the gear. Can some one explain ?

 

[K5IP]

Probably three reasons folks have problems here.

1. The gear can move on the shaft as it is being torqued, (a special needle bearing washer can be used to prevent this)

2. Some folks do not get the pump shaft really clean (it can take a can of brake cleaner sprayed on the shaft to really get it dry.

3. The pump does take a lot of horsepower to turn and the original torque spec on the gear nut was too low.

 

[Fordiesel69]

Wear on the timing gears, multiplied by incorrect nut torque. Not sure if it actually "slips" but wears down to being less advanced. This is according to the mechanic I talked to.

 

[BigPapa]

Wear on the timing gears, multiplied by incorrect nut torque. Not sure if it actually "slips" but wears down to being less advanced. This is according to the mechanic I talked to.

Brother, I don't know who you're talking to but you'd be better off talking to my 7 year old son. At least if he doesn't know something that's what he'll tell you, "I don't know". And I certainly wouldn't repeat something like that if I didn't KNOW it was correct.


If you have that much wear on your drive gears you've got some MAJOR lubrication problems.

Scott

 

[Fordiesel69]

Brother, I don't know who you're talking to but you'd be better off talking to my 7 year old son. At least if he doesn't know something that's what he'll tell you, "I don't know".



If you have that much wear on your drive gears you've got some MAJOR lubrication problems.



Scott

Which is why I am still skeptical of having any "local" mechanics do my timing. I don't know how they can work for a cummins dealer. I would tend to think they at least know enough, and it sounded somewhat true. Come to think of it, on my ford I could only feel just a few thousands of backlash, which would probably not affect the overall timing too much.

 

[BTanzini]

Thanks for your reply's . The timing was advanced to 14. 5 degrees while I was in Las Vegas in the late 90's, I believe the TSB on the nut toruqe was out at that time so hopefully it has not slipped. I under stand that if timing slipped it would be harder to start, since I adjusted the valve lash it starts like new except on cold days which I think it's because of the fuel being supplied today.

 

[JoeBioDiesel]

It can slip because the pump shaft is connected to the gear by a "fricition fit". It is not splined or keyed to the shaft. While it can't slip quickly unless installed incorrectly, it can slip trace amounts. As other have said, there is a pretty large load on that connection, so trace slippage is not impossible.

Joe

 

[PToombs]

Something else no one mentioned. If the nut is loosened or removed for any reason, replace the lock washer!

It's so easy to reuse the washer, but they are a 1 time use washer.

 

[dseabaugh]

Joe BioDiesel. You hit the nail on the head in your explaination. the amount of pressure from the torque on the nut just holds the gear against the shaft. If the pressure is too light ( not enough torque) or expansion and contraction over time, rapid accelleration ( Like anyone would ever do that) or oil between the 2 parts can let it slip. Like he said it can just be little by little over time. It's a crappy deal in a way but it also allows your timing to be infinitely adjustable. Thank God that's all we have to worry about. We could have a Furd with Electronic pump and injectors that leave us setting dead on the highway .

 

[Vaughn MacKenzie]

Yep it's basically a friction fit. And that timing gear is exerting as much as 40 horsepower twisting your little P7100's shaft! And the guys running more fuel and higher RPM the horsepower drag is higher than that. . . goes up exponentially with RPM.