7.3 6.9 IDI Injection pump play or loose?

[Macrobb]

how long you have some running this way?..im thinking about stowing this one away for rainy day in case it well...rains..when you say changes timing, is it considerably and i wonder what are the repercussions of running it that way? seems creepy

I'm honestly not sure. I'd prefer to fix it before using them, that's for sure. Shouldn't be a big deal if it's just a thrust washer - I've pulled these pumps apart and it's not hard. You don't really have calibration to worry about except in certain places, and just measuring length of screw / counting turns is 'good enough' when you are talking about a beater pump that's beyond it's warranty period in any case.

I honestly didn't notice/realize the whole in-out play until a few months ago - When I bought big red(93 in avatar), it ran fine(advanced a bit when I got it; retarded it on the way home and she ran good). A few months after that, when I started to leak coolant from the head gasket, I figured "Eh, needs more power anyway. What's the harm?" and swapped on my RD2-110 IP, put the original IP aside as a 'known good'.

Cut to a couple months ago, when I'd just built a motor for my '88(block from big red - that got a running 7.3 IDIT instead of just a head gasket swap), and decided I needed my RD2-110 for the '88. So I pull it off Big Red, and need an IP. I pull out the 'known good' IP, install it... and notice it has a bunch of in/out play... I got it running, but then got concerned and decided /not/ to use it. So I search through my IP pile and find several IPs... all doing the exact same thing. I found one that didn't do it(actually the one that came with the running 7.3 IDIT) and used that instead.

So, I'm not currently running(that I know of) a loose IP, at least in my DD. I'll have to check my other vehicles, and /have/ to learn how to fix it, because my 3-4 year old RD2-110... is doing the same thing! That's too expensive to give up on, when it has less than 30K on it(and still works fine, though I wondered why I'd get a puff of white/blue smoke on deceleration).
Once I tear into one and figure out what part needs replacement, I'll probably buy a half-dozen; got a stack of pumps that otherwise would be perfect.
Worst case, I might have to do something silly like make a custom IP-gear-cover front place that contains a thrust bushing of some sort and just push in on the shaft that way. Hey, if it works...

 

[Jbone36]

I'm honestly not sure. I'd prefer to fix it before using them, that's for sure. Shouldn't be a big deal if it's just a thrust washer - I've pulled these pumps apart and it's not hard. You don't really have calibration to worry about except in certain places, and just measuring length of screw / counting turns is 'good enough' when you are talking about a beater pump that's beyond it's warranty period in any case.

I honestly didn't notice/realize the whole in-out play until a few months ago - When I bought big red(93 in avatar), it ran fine(advanced a bit when I got it; retarded it on the way home and she ran good). A few months after that, when I started to leak coolant from the head gasket, I figured "Eh, needs more power anyway. What's the harm?" and swapped on my RD2-110 IP, put the original IP aside as a 'known good'.

Cut to a couple months ago, when I'd just built a motor for my '88(block from big red - that got a running 7.3 IDIT instead of just a head gasket swap), and decided I needed my RD2-110 for the '88. So I pull it off Big Red, and need an IP. I pull out the 'known good' IP, install it... and notice it has a bunch of in/out play... I got it running, but then got concerned and decided /not/ to use it. So I search through my IP pile and find several IPs... all doing the exact same thing. I found one that didn't do it(actually the one that came with the running 7.3 IDIT) and used that instead.

So, I'm not currently running(that I know of) a loose IP, at least in my DD. I'll have to check my other vehicles, and /have/ to learn how to fix it, because my 3-4 year old RD2-110... is doing the same thing! That's too expensive to give up on, when it has less than 30K on it(and still works fine, though I wondered why I'd get a puff of white/blue smoke on deceleration).
Once I tear into one and figure out what part needs replacement, I'll probably buy a half-dozen; got a stack of pumps that otherwise would be perfect.
Worst case, I might have to do something silly like make a custom IP-gear-cover front place that contains a thrust bushing of some sort and just push in on the shaft that way. Hey, if it works...

Sounds like you've been in the ford business even longer than i have been in the toyota. I have alot to learn on these but I can already see why these motors get alot of attention as reliable.

I think ill probably hold on to the other pump in case I have a failure. Which begs the question, what is usually the failure point on the IP? The one i put back in looks to be the original from the 6.9 . I only say this because the one off the 7.3 had a nice chrome stanadyne plate where as the 6.9 if i recall was more stamped and dul old looking. I dunno like I said I have alot to learn. FUN FACT I bought the ambulance without an engine. Shortly after had it shipped from arizona to California and bought an engine from a dude that listed it on craigslist as a 7.3. well knowing didly squat about 7.3 or even diesels for that matter I bought it from him and decided to try to find a year date and found out based on head bolt size it was a 6.9 ...but what should have really tipped me off should have been the bright yellow sticker on the the valve cover that said 6.9 so after that I conceded to lack of knowledge and binge searched this forum for 2 months soaking up everything I could and then realized I should have been tinkering with these motors long ago due to the shear simplicity and reliability to power ratio.

This is only my second diesel and the first I never really worked on "cummins 4bt" in box truck. now thanks to or the fault of this board I know enough about these motors to be dangerous but hopefully keep it running for many trips out in the middle of no where

 

[Thewespaul]

Couple things, first when these pumps get worn to the point of having that much play, there’s bound to be metal particulate throughout the pump from the bearing failure, which can easily contaminate your injectors.
Secondly, just like in an engine that looses a main bearing, the pump’s driveshaft is likely damaged from the bearing faliure, and will need machining or replacing. Not a simple bearing swap.
Lastly, to remove the shaft from the pump the housing will need to be completely stripped down, which is not possible to do without special tooling to perform properly, and once you have it torn down you cannot simply reassemble back with the same adjustments and have a properly running pump. More than likely, you will have a runaway or the pump will never fire. There’s a reason why pump rebuilds cost what they do. These pumps have been around for nearly a century now, if it was possible to repair a bearing failure without a full rebuild, it would be common practice to do so by now because of the cost savings.

 

[Macrobb]

I think ill probably hold on to the other pump in case I have a failure. Which begs the question, what is usually the failure point on the IP?

Typically, when a pump is totally unusable, it's because the head/rotor clearance got high enough that it won't start when hot(requires complete replacement of head/rotor, the expensive internal parts). This is a true 'failure'.
A more typical "failure" is when the timing gets stuck fully retarded. Not entirely sure why this happens, but over time, the pump will become more and more retarded, or simply 'jump' much more retarded - resulting in blue or even white smoke, crummy performance.
When I have a pump that otherwise works fine, but is doing this, I just pry up the IP gear cover and skip the IP gear a tooth ahead. This gives about 7 degrees of advance, generally enough to get it back into the normal "adjustment range" by rotating the pump. It's a cheap fix that seems to work fine, though sometimes you need to adjust the light load cam from there if it's too advanced down low.

One other failure that I've heard about but not seen myself is the head/rotor actually siezing together. This would be due to a lack of lubrication in the tight tolerances, or some sort of metal getting in the wrong spot. When this happens, the "tang" breaks off internally and the pump drive spins freely. This IP core is basically spare parts and not practically rebuildable.

You also have seals leaking/weeping diesel, which isn't a 'failure' per se, but becomes one of those things you want to replace. Again, something that ordinarally would need replacement, but it's possible to swap seals without too much hassle, especially if it's one that's easy to get to.

Couple things, first when these pumps get worn to the point of having that much play, there’s bound to be metal particulate throughout the pump from the bearing failure, which can easily contaminate your injectors.

Any failed bearing material would be in the housing, not in the pressure side of the pump. It would get returned to the tank and filtered through the fuel filter before getting to the injectors.
Pretty much the only thing that would send material to the injectors would be the inlet vane pump on the input of the IP.

Secondly, just like in an engine that looses a main bearing, the pump’s driveshaft is likely damaged from the bearing faliure, and will need machining or replacing. Not a simple bearing swap.

We shall see. Fortunately, it's a thrust bearing, not a side bearing, so there should be no wear on it - I'd expect the only real issue would be destroyed seals if it slid too far out. Remember, the shaft comes out that way, so there's no bosses or other diameters to catch on things and wear.

Lastly, to remove the shaft from the pump the housing will need to be completely stripped down, which is not possible to do without special tooling to perform properly

No, you don't need any special tooling. Just need a vice, hand tools and allen wrenches. The only 'special tool' that you are supposed to need, a tool for removing the inlet cone on the back, well, a open end wrench worked just fine. At least on the pumps I took apart, it wasn't on there that tightly. You could even leave the brass adapter from the inlet hardline still attached to the IP, for added strength there.

, and once you have it torn down you cannot simply reassemble back with the same adjustments and have a properly running pump. More than likely, you will have a runaway or the pump will never fire.

I've done it several times. Never had any issues. In my case, it was simply a matter of tearing it down far enough to replace the shaft seals(which is /past/ the thrust washer portion), which I did. Seriously - you don't *have* to take apart every single screw and plunger buried deep in the head or housing - just need to get the main parts out, which limits what you need to put back.
There's also settings like the guide stud in the back which will work "ok" at pretty much any position you physically can put it in; it will just affect drivability - so you can adjust and drive and get it good enough again.

There’s a reason why pump rebuilds cost what they do. These pumps have been around for nearly a century now, if it was possible to repair a bearing failure without a full rebuild, it would be common practice to do so by now because of the cost savings.

Would it? Most people don't even want to mess with the pump at all, let alone tear into and rebuild one. Instructions are out there, and, well, I followed(most) of it and succeeded... but that was just a re-seal job.
The real problem is that to affect performance and actually make one new, you tend to need new parts or at least a flow bench to modify some of the settings. Otherwise, you just have a fixed, but still worn IP.

 

[Thewespaul]

Rob, if there’s metal in the pump, it’s circulated everywhere. You’re thinking of the fluid flow as if the pump is constantly under pressure, but as soon as the pump stops spinning the pressures reach equilibrium, allowing fuel to flow to whatever the path of least resistance, often times this is backwards of its designed path since pressure steps up going forward through the fuel route.
Yes, you need special tooling to properly tear down a pump.
If you got a pump running after tearing it down, that’s amazing, but I wouldn’t recommend anyone else doing it, they may not get as lucky.

I started my diesel career with heavy equipment field repairs, if there was a way around the textbook to get something working without a full teardown, it was done. I learned in that field what you can get by with, and what you cannot. With fuel systems, especially mechanical, you are risking an engine at the cost of a pump. If you don’t get lucky and everything isn’t exactly as it should be, your engine runs away and you will down and engine and a pump.

 

[Agnem]

A couple of comments here. There is a certain amount of generous in and out play that is built into these pumps. The drive shaft floats internally, and in fact on some models of the DB series the drive shaft is not even internally retained. On a John Deere 4020 for example (which actually has 12 possible pump models used on it) when you take the pump off, the shaft stays with the tractor. On our IDI DB2's, the in and out play is controlled mostly by a snap ring riding against a wave washer. If the wave washer breaks, you will have a lot of in and out, and possibly some governor control issues. If the snap ring breaks, the shaft will come out. As long as you don't have side to side or up and down play, its not a bearing. You will have metal getting around in the pump though (large chunks), and its not inconceivable that you could have a runaway. On the early GM implementation of this pump on a 6.2 or 6.5, there is no internal snap ring. Just a clip or an O-ring. Like the farm tractors, you can pull the shaft out with a good jerk. These applications rely on a spring on the gear case cover to keep the shaft pushed into the pump while it operates.