Hello all I have D4 6U serial #10508

Plungers are stuck only one barely moves when electric starter is engaged. Would like to get suggestions of how to unstick and not damage anything

looks like they are all stuck in the up position, that might make it harder to withdraw once unbolted. I would try to lightly encourage them to move down with out twisting them (one is bound to be on the cam lobe). If you can unbolt them and slip them off the yoke, you could soak them in hot penetrating oil and then gently try to free them.

I would remove the injector lines and try spraying a good penetrant in the outlet. There’s a discharge valve in there but maybe it leaks a little and your penetrant can soak into the piston.

Gentle tapping might get some back down but as mentioned earlier there’s always going to be one or two on the camshaft lobe, so gently is the rule. I personally would use a torch and heat the barrel of any that were uncooperative with the previous measures. The tolerances are so small that even a slight thermal expansion should help.

"ccjersey" wrote:

I would remove the injector lines and try spraying a good penetrant in the outlet. There’s a discharge valve in there but maybe it leaks a little and your penetrant can soak into the piston.

Gentle tapping might get some back down but as mentioned earlier there’s always going to be one or two on the camshaft lobe, so gently is the rule. I personally would use a torch and heat the barrel of any that were uncooperative with the previous measures. The tolerances are so small that even a slight thermal expansion should help.

Yes, that might work, one could start with an electric heat gun. I have one that I've even propped up to blow hot air into a engine jug water jacket. The pumps didn't all get stuck overnight, so it may take time and patience if you want to save them. If I was really under the gun for a job, throwing money at it with new parts and a more aggressive disassembly might be in order. Please let us know what did or didn't work for you.

Stephen said to unbolt them off the yoke. Is that to remove them, does not seem like theire is room enough to get them out unless you disassembled the whole fuel distrubution housing taking the fuel pumps off from above? Or do you mean to unbolt off the yokes so you twist them in place.

Heating the barrels seems reasonable ( just to make sure we are talking about the egg shaped sockets that the steel plungers reside in). That would be heating and tapping the barrel gently for a few minutes over a couple of days?

Are there springs at the base of the pumps that push the plungers back down to the cam?

I am hesitant to remove pumps sounds complicated.


Here is the Cat undressed. I have a blade for it also. Have not really needed for years but would like to get it going again. l got a few years back a nice 4 wheel drive JD which replaced this old mule. Could use it this spring for some vine removal. Plus I can't go to work because of the virus outbreak, so will work on my old Cat.

Patrick

The lifters are returned to the cam with a spring that is hidden in the lower part of the housing by the injection cam Each pump is secured to the housing with 4 bolts on top. Not sure about your situation, but if you remove the top bolts, you might have enough travel against the spring to lift the pump off the dowels and move the plunger element sideways off the yoke. Yes, it would be possible to loosen the lock nut and unscrew the yokes out of the lifters to remove the pumps, if they won't come apart any easier way. Access is limited right there and hard to get much wrench swing. You might need to modify a wrench. If you have to do that to remove the pumps, you will need to reset the injection timing with a depth mic on the yoke. I don't know what tools you have access to or your relative expertise or
if you are looking for adventure , so think about your options and work out what path makes sense in your situation. If your pumps weren't stuck it would be very simple to remove and refit the pumps. The stuck part is to be overcome by trial. If you don't have a service book, we can supply a few pics of that area.

Ok, here is a pump with the plunger withdrawn, and the yoke(from a larger engine) so you can see how the yoke will slip off the plunger, and how the plunger will hopefully come out (eventually). You can see the two dowel holes on the base of the pump, you would have to lift the pump high enough to clear the dowel, or free the plunger in place, or unscrew the yoke to remove the pump intact and work at it in your hand / bench

"STEPHEN" wrote:

Ok, here is a pump with the plunger withdrawn, and the yoke(from a larger engine) so you can see how the yoke will slip off the plunger, and how the plunger will hopefully come out (eventually). You can see the two dowel holes on the base of the pump, you would have to lift the pump high enough to clear the dowel, or free the plunger in place, or unscrew the yoke to remove the pump intact and work at it in your hand / bench

Thanks! I had the same problem and this solved it!

Ok I made progress today.

I removed the injector pumps using the heat, PB blaster and tapping with a hammer on the pump barrels. It took some time and patience.

Reassembled, turned starter, compression level set to off on valve cover, all of the lifters are lifting and going back down.

Pump rack connected to throttle moving back and forth nicely.

nice to be moving forward.

With reattaching the fuel lines to the top of pump barrels #2 line the collar on top of the knurl that attachs to the top of barrel broke and is missing so need to get #2 fuel line. If anyone has a field modification fix please share.

Thanks for the help and pictures These truly are amazing machines

Patrick

Sorry if I'm doing this incorrectly, didn't know if I should start a new thread or reply to this one? Finally back on the sight since 2016. You know how it is work, hunting, kid in college playing baseball for 5 years etc. but now I'm DOZING! The D6 9U I was asking questions about years ago is finally mine, pony motor removed and I am planing to machine fly wheel housing for electric start, still have print of where to drill 3.5" hole except for horizontal center line. So that's one problem but more importantly we pull started it last week end and it's running on three cylinders wide open RPM. Number 1,5 and 6 pump plungers were rust stuck and rack would not move from wide open. I removed seized pumps, very carefully freed up plungers, going to reinstall pumps, time the plunger gears to the rail but need to know how to set the lift of the plunger that's attached to the lifter below the 4F5019 pump so the timing of each plunger is correct. I know fairly close to where they are to be set but would like to be exact. There was some talk on line about a dial indicator setting. I know if I want to do it correctly I needed to ask here! Any body have explanation or picture of service manual? Please let me know if I'm using sight incorrectly!