Injection pump timing

cooped1 · Sep 18, 2022

I pulled my injection pump off of my 4400 John Deere to rebuild it and found that the geared shaft that drives the pump was broken in half. Half of it is still in the pump. How do you time the pump once you have replaced the shaft. Also where can i find a new shaft without breaking the bank?

Dieseltech · Sep 18, 2022

If the shaft is broken, then the injection pump hydraulic head
is probably seized too which is why the shaft broke in the first
place. Old pump head needs pressed apart to find the cause
BEFORE replacing the pump and shaft so the damage does
not happen again

wore out · Sep 18, 2022

(quoted from post at 06:08:54 09/18/22) I pulled my injection pump off of my 4400 John Deere to rebuild it and found that the geared shaft that drives the pump was broken in half. Half of it is still in the pump. How do you time the pump once you have replaced the shaft. Also where can i find a new shaft without breaking the bank?

As to timing, there's a little cover on the engine mounting flange held on with a reversible bolt/timing pin.

You remove the bolt and cover, and insert the pin into the hole that is now uncovered and SLOWLY bar the engine over while putting light pressure on the timing pin. It will eventually drop into a hole in the front face of the flywheel. That will be either #1 or #6 tdc.

You want #1 tdc as evidenced by the rocker arms on #1 being loose.

Line up the marks viewed inside the timing window on the injection pump and tighten down the mounting bolts.

You have bigger troubles, though.

The broken injection pump driveshaft indicates the ''head and rotor'' in the pump have seized, likely from water/rust or other debris in the fuel. (There's a narrowed-down area on the pump shaft designed to break when this happens to prevent the timing gear train from being torn up.)

Will take quite a few $$$ for a new head and rotor plus the rest of the pump repair.

Driveshaft is part # R36538, GOOGLE will find you some use ones.

cooped1 · Sep 18, 2022

Ok, I was afraid of that. Thank you.

cooped1 · Sep 18, 2022

Ok, I was going to rebuild the pump anyway, so that is a planned expense. When i replace the injection pump drive shaft, would it be best to have it installed in the pump first with the timing marks lined up and the engine at TDC on cylinder #1? If not I'm not sure how to get the shaft in the right rotation other than just guessing by looking into the end of the pump and trying to line it up. Thank you for the part #! I hope i can find one from a salvage machine. I am going to contact the local JD dealer tomorrow to get a price. Thanks again.

Dieseltech · Sep 19, 2022

The pump has a drive shaft key slot to correctly locate the shaft. The shaft pump end has a dot that must align with the hydraulic head drive slot dot inside the
pump. I wouldn't put on another pump until the old head seizure cause is found first, or you might wreck another pump/shaft assembly.

cooped1 · Sep 19, 2022

(quoted from post at 10:58:04 09/19/22) The pump has a drive shaft key slot to correctly locate the shaft. The shaft pump end has a dot that must align with the hydraulic head drive slot dot inside the
pump. I wouldn't put on another pump until the old head seizure cause is found first, or you might wreck another pump/shaft assembly.

Ok, that's my next step is to get the pump apart to try and find the cause of it locking up. I'm guessing it's got something to do with the combine sitting for 20 years. I was getting pieces of the flex ring out of the timing window. Thank you.

Injection pump timing

cooped1

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Dieseltech

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wore out

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