AC 5040 Fuel Leak

steve-in-ga · Oct 17, 2017

My dads AC 5040 has developed a significant leak (dripping pretty bad) from the bottom backside of the injection pump. The leak appears to be coming from what looks
like some sort of stubby little rod with a washer on the end of it and cotter pin holding the washer on. The rod that you pull to shut off the fuel looks like it runs around the
rod that is leaking. I can use a screw driver to gently push on the rod that is leaking and it is loose and when I move it it really starts pouring fuel. I used a wrench to try
and tighten the nut that is hold the leaking rod and I cannot seem to stop the leak.

Any help is appreciated stopping this leak if only temporarily.

thanks,
Steve

JoeM(GA) · Oct 17, 2017

that rod goes around both sides of the stud and the washer under it to keep the shutoff rod tracking straight

for some reason I'm remembering that the stud is also the cold start manual advance?? You pushed it up when starting the engine in really cold conditions??

Dieseltech · Oct 17, 2017

Long/Fiat tractors with the CAV DPA pump had that stub shaft in the advance block. When the stub shaft is pushed sideways it prevents the advance from working for faster cold starts..

Dieseltech · Oct 17, 2017

I replace the seal inside that bolt assembly any time I repair a pump with that advance lock out rod. Bolt assembly has to come apart to get at the seal. Has a few small parts inside that are easy to loose too..

steve-in-ga · Oct 17, 2017

Assuming I have to pull the pump to fix the seal. It has to be fixed it is leaking badly. How hard is it to pull the pump? Do I have to line up any timing marks before pulling? I'm pretty mechanically inclined. Any helpful instructions on pulling the pump would be great. I don't have a service manual for this tractor.

Dieseltech · Oct 17, 2017

If it's like the Fiat/Long engines I've worked on, pump may go off/on with no worries about timing. Gear has a key for the tapered drive shaft, gear stays in place but the shaft needs pushed out of the gear after the shaft nut is off. One of the pump mounting flange ears has a scribe line that should align with a timing cover scribe mark. Is there room to remove the advance bolt under the pump? If so it might be the leak could be repaired without pulling the pump. If there are any other leaks it would be best in the long run to reseal the complete pump assembly though, at least that's been my experience in over forty years of pump repair..

steve-in-ga · Oct 18, 2017

Dieseltech, thanks for all your help.

I found a schematic of this pump online and it refers to the part that is leaking as the manual retard device. Apparently if you push the shutoff rod all the way forward it engages this retard device and keeps the automatic advance from working so the tractor will start better in cold weather.

If I do have clearance to remove the manual retard device should I be concerned about anything else falling out like any of the automatic advance parts? Will the seal that is leaking come out with the retard device or will it be left in the pump housing?

Dieseltech · Oct 18, 2017

Pushing the rod in any direction will lock out the advance during starting. If there's at least two inches below the assembly it can be removed, nothing will fall out. There are two O rings and one steel washer on the assembly, one O ring is in a groove and the other O ring seats against a shoulder on the bolt, and the steel washer is next to it. The steel washer and O ring MAY not come out with the bolt, both sometimes stay up inside the block and need a hook tool to pull them out. Steel ring is re used, but both O rings need replaced. Once the bolt assembly is out, it can then be taken apart to replace the leaking seal inside it. If you like send me an E mail, [email protected] with your address and I'll mail the O rings and seal to you. Call five seven four eight three five 3292 if you like, leave a message and I'll call back as I don't hear the phone when the test stand is running.

Traditional Farmer · Oct 18, 2017

I have a David Brown 990 that has a similar leak and I think it has a CAV pump on it would the repair be the same?

Dieseltech · Oct 18, 2017

Yes, David Brown had a similar fitting that was turned fully IN for cold starting, then turned fully OUT for running. Just keep in mind, if only that leak is fixed, others MAY show up later. That's why it's best to reseal the complete pump, I've seen too many times other leaks show up soon after.

steve-in-ga · Oct 18, 2017

No such luck on the 2 inch clearance. I can barely get my finger behind it. I will need to pull the pump and reseal the whole thing while I'm at it.

Where do you get your seal kits from for the CAV DPA pumps with this retard device? I see there is one for sale on this site but unsure of quality. And does it come with the o-rings and seal to fix this leak or do I need to get them separate?

Time to buy a service manual for the Ac 5040 I suppose.

Thanks again.

thepumpguysc · Oct 18, 2017

There are 2 different sized seals that were used on those manual retard devises..
BUT only 1 size comes in the kit now adays.. They, {CAV, Lucas, Delphi} wanted you to "update" your pump parts when they needed repairs, so they did away[quit supplying] the part in the kit for the older style devise..
The seals are still available by the tons, but I just wanted you to KNOW that it may not come in your kit..

Good call on the 2" clearance DT.. probably saved him alota cussin'.. & a wet arm.. lol.. {you know what I'm talkin about..}
The pump is full of fuel & if you tried to get it out & you didn't have the room, a lot of that fuel woulda ran down your arm & you'da abeen cussin up a storm because you would of had to screw it back up in..

AC 5040 Fuel Leak

steve-in-ga

Member

JoeM(GA)

Well-known Member

Dieseltech

Well-known Member

Dieseltech

Well-known Member

steve-in-ga

Member

Dieseltech

Well-known Member

steve-in-ga

Member

Dieseltech

Well-known Member

Traditional Farmer

Well-known Member

Dieseltech

Well-known Member

steve-in-ga

Member

thepumpguysc

Member

Similar threads