JD 350 crawler injector pump replacement

motomojo

Member
Hello need some help with putting a new injector pump on my 68 JD 350 crawler.
I had a mech put it on back in Feb and he was not familiar with it and got something wrong as it started filling my crank with fuel.

I have new seals umbrella and shaft and the special tools to put them in what i am not sure of is the pilot bushing/tube.
Does that come installed in a rebuilt pump or something that still needs to be added?
Obviously if it was installed without it i'm sure it would cause this problem so i'm hoping someone can give me some good advice and any tips on reinstalling this pump.
I guess there are OEM and aftermarket bushings, which would be best and where can i get them.

Thanks
Joe
 
A rebuilt pump will have a new bronze bushing in it (Stanadyne calls it a pilot tube). There are two umbrella seals facing opposite directions. The one facing the pump flips over very easy, even when using the proper tool. Just have to be careful. I had to go out and redo many that other mechanics screwed up when installing a pump.

I put motor-oil on the seals and on the bushing. Use a compressor on the seals and then gently slide the pump on as your rotate it back and forth. Let it slip over the shaft and never, ever, push it.
 
Are you sure it isn't the fuel lift pump leaking fuel into the crankcase?

On the other hand, the guy installing the IP could simply have pulled the shaft out far enough to mangle a seal, and simply installing new seals correctly/carefully should fix it, unless the pilot tube/bushing us badly grooved/worn/damaged.

The bushing is pressed/epoxied into the pump body.
Pilot tube installation
 
Thank you so it did come with a new bushing.
I'm ordering a new one just in case he damaged the one in it and have a very good mech helping now.
I'm figuring since the old mech didn't have the tool to put in the umbrella seals he got one in wrong and hence the problem.

Seems fairly simple to do but i guess not...you don't live anywhere near Kingman AZ do you Ha!

We are going to do this next week will let ya know how it goes.

Thanks
Joe
 
A rebuilt pump will have a new pilot tube as JDEM mentioned, so the rear shaft seal may be all you need if it's been folded over. If the seal is NOT damaged, then I'd question on how the new tube was installed. Correct way to seal the tube is with the two part epoxy mix the bonds the tube OD to the housing per Stanadyne instructions. I've seen other sealing methods used that did not work, allowing fuel to leak between the tube OD and the housing bore with fuel ending up in the crankcase. Had a MM pump in this past summer like that, new tube, but not installed correctly leaking fuel into the oil.
 
Thank you i do not believe the old mech did any epoxy at all at least i don't remember him applying any so that may be the whole issue.
What brand 2 part epoxy do you recommend or does it matter.

Thanks
Joe
 
Did the installing mechanic also repair the pump? No epoxy is ever needed in the field if the housing had the tube installed correctly. To save time most shops use an oven to "bake" the newly installed tube so it will dry faster. Then the pump can be bench tested. Armstrong is the supplier I use. With the pump off, look closely at the rear seal, if it's folded over that's will be your leak. Replace it, lube the seal and tube well and re-install the pump. One way to make sure the seal is not folded is to slide the pump back and forth a bit once it's over both seals, if it moves easy, all is well. If it takes heavy pressure to slide the pump, rear seal is damaged. Pumps I repair use a modified tube taper so the seal enters easily with no tool needed, as most guys don't have the seal pliers on hand. Even without the tool, if lubed well I've just used my fingers only for years when installing pumps.
 
No i bought a rebuilt pump. Mech was from a local mobile Mech co. in Kingman and he was not real sure of how to do it never had worked on an old JD tractor.
So tube should have been epoxied at the factory so i may not need to replace it if it is still in good right?
Just lube the new seals and like you say slide it back and forth a couple times to make sure it's in right.

The guy doing it is an engineer and really good at delicate stuff like this so should go much better this time around.

Thanks for the info
Joe
 
Very common to damage one seal when installing. Hard enough to do even with the correct tool.
a178982.jpg
 
Success got the pump off sure enough an umbrella seal that rolled back on install.
With he proper tool it went on very smooth moved it back and forth a couple times and it was nice and easy going on.
Tractor fired right up and is running fine.

There is a leak on the #1 and 3 return line and i remember seeing a piece of a small oring laying on the engine so i'm sure there is an oring that has failed. is that a special oring or one i can buy at an auto parts store.

Thank you all for the info it was very helpful.

Cheers
Joe
 

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