7710 Ford Minimac injector pump

fordman81 · Mar 3, 2018

I just changed the oil in my injector pump and got a little oil and the rest diesel. How can I stop it from leaking fuel into the oil? Or should I just not worry about it and change the oil more often?

Also the drain and check plug threads are almost striped completely out. I don't know if anyone else has tried to fix the threads on these before. Which way should I try and fix them drill and tap a bigger size, heli coil or use a threaded insert?

RickB · Mar 3, 2018

Change the pump oil every time you drain the crankcase. Addressing the internal fuel leakage will be a four figure repair anywhere I know of.
I?m not sure a helicoil would be leak free. I?d go oversize. 14mm or 9/16?nf.

Dieseltech · Mar 3, 2018

The supply pump on the side might be your fuel into the cambox leak, replacing it may help. Some inline pumps are more prone to leaking fuel into the cambox also, that's why some engine builders don't engine oil them so there's no chance of ever getting fuel into the engine oil. If the housing is not badly damaged a heli-coil insert will fix the damaged threads. DON'T ever use a longer bolt, I've seen that done before and it's not pretty when the governor weight cage catches and blows out part of the housing. My opinion, but the best oil drain and level setup is 1/8 inch pipe radiator style drain valves, stops the thread wear and possible damage to the aluminum housing turning in/out hardware. That's what American Bosch used on there inline pumps and governors years ago, never saw any damage on those like what happens on CAV/Simms housings.

Bern · Mar 3, 2018

I've heli-coiled several of those pumps over the years. Done correctly, it will be better than new when done. As for the fuel leak, it's
likely leakage past the plungers and barrels, and as Rick said, would not be cheap to repair. If it still starts and runs good, just change
the oil in it every time you change the engine oil, and don't look back. There's far worse fluids you could run in there besides diesel fuel.

showcrop · Mar 4, 2018

How much smoke does it make when under a load? If it is much it is likely that it has been turned up which will increase the amount of fuel pushed past the plungers. My 9000 will dilute the oil pretty well in an hour.

fordman81 · Mar 4, 2018

(quoted from post at 19:17:00 03/03/18) The supply pump on the side might be your fuel into the cambox leak, replacing it may help. Some inline pumps are more prone to leaking fuel into the cambox also, that's why some engine builders don't engine oil them so there's no chance of ever getting fuel into the engine oil. If the housing is not badly damaged a heli-coil insert will fix the damaged threads. DON'T ever use a longer bolt, I've seen that done before and it's not pretty when the governor weight cage catches and blows out part of the housing. My opinion, but the best oil drain and level setup is 1/8 inch pipe radiator style drain valves, stops the thread wear and possible damage to the aluminum housing turning in/out hardware. That's what American Bosch used on there inline pumps and governors years ago, never saw any damage on those like what happens on CAV/Simms housings.

I thought the lift pump might cause the fuel to leak in but it is not running bad. If the lift pump was leaking wouldn't it run bad?

fordman81 · Mar 4, 2018

(quoted from post at 19:26:58 03/03/18) I've heli-coiled several of those pumps over the years. Done correctly, it will be better than new when done. As for the fuel leak, it's
likely leakage past the plungers and barrels, and as Rick said, would not be cheap to repair. If it still starts and runs good, just change
the oil in it every time you change the engine oil, and don't look back. There's far worse fluids you could run in there besides diesel fuel.

I can only find course thread heli-coils and the original bolt looks fine thread does that matter? Do you use thread sealer or silicone on the outer part of the heli-coil?

Dieseltech · Mar 4, 2018

If the feed pump diaphragm is just starting to fail engine will still run fine, just put more fluid out the overflow tube. On place I get fine thread Heli-coils is NAPA. Should be available through other sources too.

RickB · Mar 4, 2018

If it runs ok with the top tank empty your lift pump is good.

RickB · Mar 4, 2018

The original bolt is all but certain to be metric.

Bern · Mar 4, 2018

Bolt is 5/16 fine thread. Should be easy enough to find a heli-coil kit from NAPA or similar location. That said, you could sub a
coarse thread bolt in its place if a course thread kit is easier to find. You won?t need to worry about thread leakage if the bolt has
a sealing washer on it.

fordman81 · Mar 4, 2018

(quoted from post at 17:59:46 03/04/18) The original bolt is all but certain to be metric.

New Holland online says the bolts are 5/16-24 x.45". I just figured they used fine thread to help it not leak and to give it more threads in the aluminum.

fordman81 · Mar 4, 2018

(quoted from post at 17:58:14 03/04/18) If it runs ok with the top tank empty your lift pump is good.

Yea it runs fine with the top tank empty.

7710 Ford Minimac injector pump

fordman81

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