Endloader Stalls

Hello:

I have an Allis Chalmers 840 Endloader that is giving me problems. I had it running like usual and it stalled, and would not start. The last time that happened was 12 years ago, I replaced my inline fuel filter and it was fine. I replaced the inline this time and got it going but it stalled after a few minutes. I bled the system and got it going again for a few minutes, but then it stalled. I did that again and it stalled again. It has been sitting for around 10 days, and lately we have had some warmer weather. I just went out there to see it it would go and it wouldn't. It runs for a second or two, I suppose long enough to use up the ether. I bet if I went through the bleeding process it would run for a few minutes again and stall.

Does this sound like a filter problem? When I get it running it seems like I can keep it going if I have my foot on the gas, but it stalls at idle.

Any help is appreciated.

Thanks.

That has a Rosamaster injection pump on it??? Your troubles sound exactly like what happens when the dampening ring in the injection pump fails. It plugs up the return fitting at the top of the injection pump first. This fitting has a small glass check ball in it. It regulates the return fuel pressure in the injection pump. Remove this fitting and see if you find little small pieces of black looking stuff/dirt. This is the remains of the rubber dampening ring. You can run the engine with the fitting removed to see if your engine runs with it out.

When the dampening ring falls apart it plugs the return fuel system first. This makes the return pressure increase to the point it is equal to the transfer pump pressure on the other side of the injector pump head. When this happens the high pressure pistons inside the injection pump head can not work. They depend on the lower return pressure to allow the slightly higher inboard pressure return the piston to take in a new charge of diesel fuel. The reason yours will run above an idle right now is the vane pump on the inlet side is pumping higher pressure than the return system restriction at higher engine speeds.

In a short time the internal passages will plug up and the pump will completely quit pumping. You can remove the check ball in the return fitting but that is a sort term "fix" that usually only lasts a short while. Also running it very long this way can cause major damage inside the injection pump. I would recommend removing the injection pump and having it repaired. I do this repair myself as the seal kit to do it does not cost much. You have to completely take the injection pump apart to totally clean it out. This takes some knowledge. It is not real hard but can be daunting to someone not experienced in doing one.

If I recall 840 came with the 248 Perkins four cylinder engine, CAV DPA injection pump. Perkins uses a constant bleed fitting on top of one of the filter bases, it removes any trapped air from the base so no air gets to the pump inlet. When the orifice gets plugged then the air gets to the pump and causes shutdown. There could be either a straight fitting or a banjo type fitting that the line goes from the base to the tank return, usually across the top injector leakoff line. Worth a look to see if it's plugged.

Thank you to both of you. And thank you again Dieseltech for your advice last summer. Don't know if you remember but you diagnosed my broken head gasket on my David Brown 990. I got that fixed just in time to cut hay thanks to you. I really appreciate that.

The loader does have a CAV pump on it, and a Perkins engine. I will take a look at what you mentioned tomorrow and see if that is the problem.

JD Seller, it is interesting that you mentioned the Roosa Master pump and that problem. That is exactly what happened to my pump on my Oliver 1755. Found those little pieces and thought it would be an inexpensive fix. $450 later I was back in the field.


Thanks again.

Just thought of another thing to check, if NAPA or WIX fuel filters are used the flow through the filter is different than original CAV filters. All filters seal at the top lip by the base groove O ring, but just inside the lip on NAPA/WIX filters is the filter inlet groove. Don't make the common mistake of putting one of the extra O rings in there or flow will be restricted, or shut off completely. I've lost count how many service calls have been made to find that..

There are wix filters on the loader, and they have been there since I purchased the machine, which is almost exactly 13 years ago. The previous owner is a dirt contractor and went right through the machine before he gave it to me, replacing the fuel filters among other things. I don't use the machine that much, would be surprised if I have 300-400 hours on it.

Funny you mention the extra O ring, I replaced the fuel filters on my David Brown before you mentioned the head gasket, and initially I put them in wrong. I didn't use the extra ring but did something stupid, could not get fuel past the filter when I bled it. I figured it out.

Anyway, I guess it is about time to replace the fuel filters on this machine anyway, and I will be going out there shortly to check that line you mentioned.

Thanks again for your help.

Glad Dieseltech steered you right. I have owned AC 745 loaders and they had the AC 2300 series motors and Roosamaster pumps.

Thanks for your input. I have probably read hundreds of your posts by the way, so I appreciate it. I don't know how you know so much about so many pieces of equipment, but it sure is valuable to guys like me when you pass on your knowledge. Thanks again.