Injection pump

[Jackie j]

I'm replacing the injection pump on a 924g serial number dda2420 and the timing instructions don't make sense to me. According to the instructions given to me from the dealer I have to set the number 1 to tdc by aligning all the timing marks on the gear train and then put the timing tool into the number 2 injector bore and rotate the engine to 4 degrees after tdc on number 2. The problem I'm having is that when I rotate the engine to get number 2 in the correct spot the timing pin to lock the pump doesn't line up. I have never had one timed like this so I'm not sure if I'm missing something or if something is just off. At this point I think it may be me that's off.....anyone have any advice or experience with this?

 

[lantraxco]

I don't know from nuttin', but it seems to me that the timing tool would be installed in #1, else what's the point of lining up the timing marks in the first place? Never seen an engine didn't time on #1, but hey, I'm willing to learn if one of the CAT gurus pops up....

 

[Jackie j]

That's what I'm thinking too, I have changed quite a few injection pumps and never heard of timing on number two. It actually says number 2 or number 5 if that injector is easier to remove.

 

[thepumpguysc]

You have a DELPHI inj. pump.. the drive on the pump is locked @ # 1 cylinder.. use #1 cyl. on the engine..

 

[thepumpguysc]

Sorry I just assumed it was a Delphi.. if its keyed, don't worry about it..
get me some # off the name plate or snap a pic of the pump drive..

 

[Jackie j]

That sounds like a good plan to me. I wonder who at cat made the instructions for this haha

 

[Jackie j]

I don't know if it is keyed or not, the hub is already installed on the new pump. I will take a picture and try to post in a few minutes

 

[Jackie j]

Pump says it's a Bosch but you would know better than me

 

[kshansen]

Well if this helps explain it: For what ever reason they appear to be using a tool that positions #2/#5 at a point that in effect IS setting #1 at 4º hope that makes sense

 

[Jackie j]

Maybe I just misread it then, it looked to me like it said that it was putting number 2 at 4 degrees. That's what had me confused, I couldn't understand why go thru all the trouble of setting number 1 at tdc just to move it all again. Thanks for the replies, you guys are awesome

 

[thepumpguysc]

Yeah, thats a Bosch.. the drive is not keyed, the hole in the housing lines up w/ the slot & insert a timing pin or drill bit.. Your gear should have a hole in it also to acomodate the pin.. its all set at 12:00

 

[thepumpguysc]

On a side note>> THATS WHY its so important to time your engine BEFORE pulling a pump..
Had you set the engine on #1 & pinned it at 12:00.. you'd be golden..
we all learn from our mistakes.. WELL... some of us do.. LOL
We'll know better next time.. RIGHT?

 

[Jackie j]

I did pin the old pump at 12:00 with the gears timed so I'm just gonna pin the new one and install after I set the cylinder at 4 degrees. The pump was replaced a few years ago if memory serves me right, maybe timing was slightly off before and that's why the pin doesn't drop in at 4 degrees. You are correct though, always time before removing the pump, that is a lesson I learned the hard way on my first pump lol

 

[kshansen]

Well if this helps explain it: For what ever reason they appear to be using a tool that positions #2/#5 at a point that in effect IS setting #1 at 4º hope that makes sense

Well I think I can answer my question about why they are using #2/#5 cylinder to determine the timing. Took a bit of a distraction of clearing my mind by going out and doing some trim mowing in the yard!

Using the position of the piston on those cylinders is actually more accurate than trying to do it on #1. The reason would be that when #1 is getting close to the 4º position the movement of the piston is much less for each degree the crank moves than that of the #2/#5 piston. If we were talking about setting a timing dimension of 15 to 20 degrees it would be less critical. One has to remember that even when running at a steady speed a piston has to accelerate then decelerate and reverse directions every 180º turn of the crank.

Hope that makes a little sense the way I worded it.

And if you want to get even more confused take a look at this page some interesting things in there that one might not have thought about before!
http://www.epi-eng.com/piston_engine_technology/piston_motion_basics.htm

 

[thepumpguysc]

Hansen, are you high?? lol

 

[Mark250]

here is some photo of the timing tool

 

[Jackie j]

I understand what you are saying about the movement of the piston, it just threw me off when they said number two. I usually don't think about these things while mowing though lol.... I have the tool, got it from the cat dealer, they sure are proud if that little thing

 

[kshansen]

Hansen, are you high?? lol

Why just because I answer the questions I was asking. I often talk to myself and even then it can be tough to get anyone to pay attention!

 

[thepumpguysc]

I too have the pins but when I cant put my hands on them or someone "forgot" to put them back..
I just use the back end of a drill bit for the pump..

 

[Jackie j]

You know the more I think about this I know why it didnt line up correctly, whoever did this before didn't have the timing probe so they must have just set it directly at tdc and called it good. Explains why it always was a little smoky anyways. I was also mowing when I thought about that hahaha