CAV pump after re-seal problems

Q-14

New User
Ford 5000 w/turbo, ran great, fixed throttle shaft leak years ago, pump head to body leak fixed by changing O-ring.

Removed the pump, pulled the pump head out and replaced the big o-ring, re-installed the pump head, no issues, pulled the drive hub off and replaced the front seal, installed the pump back on the tractor.

Bled the pump and lines, engine fired right up but went to full throttle, only way to reduce RPM is to pull the shut off.

Figured I had something hosed up on the governor linkage I pulled the cap back off and checked it, everything OK, started it again, same issue, did that three times, even took a brand new Mefin pump I've had on the shelf for this tractor for years, took the top off to check it to make sure I had everything back as it should be, no joy.

When it starts it pops right off and if I pull the shut off out part way I can control the rpm but the throttle does not respond at all unless the shut off is all the way on, then it goes wide open.

The only thing I can think of is something in the pump head having a problem, it fit back in easily when I put it back in, really has me puzzled.

I've even taken it outside and let it run for five minutes with the shut off part way pulled, runs fine until the shut off is opened, any Ideas would be appreciated, I really don't want to have to replace the CAV with the new Mefin pump if I don't have to, the tractor came from the dealer with an M&W turbo and I have no idea if the CAV pump had to be turned up to accommodate the turbo.

Thanks
 
It's NOT the hydraulic head, but a governor problem. Something is not assembled right causing loss of governor/spring balance control. Spring gives fuel for engine speed increase, flyweights balance and overcome the spring to shut the fuel back off. Best have the pump taken back down, there's a shaft to hub O ring that should have been changed too. Then the governor curve calibration could be checked and adjusted on the test stand to verify correct speeds and response..
 
(reply to post at 19:40:56 10/25/17)
None of the governor shaft pieces were touched, the pump head was removed, the O-ring was replaced and the head reinstalled, it worked when disassembled, the governor linkage is identical to a new pump in every visible way, none of the measurements were changed.

The next step looks like replacing the pump head with the new pumps head as all of the governor linkage is set and operates as the new piece, pretty strange.
 
If you can shut it down with the shut off lever that tells you the metering valve isnt stuck. I would place money on you have a problem with the linkage, or flyweight to finger position. Pull the cover and look down. You will see whats up. Al
 
(reply to post at 20:27:50 10/25/17)

Wish it was that easy, it looks like there is only one way the plate can fit down over the governor hub, I thought that as well initially, that's why I took the new pump top apart to compare the two, the only difference I saw was the Mefin pump had a slightly shorter spring but was connected to one longer link hole so the difference was a wash.

It really does sound like a governor issue but it's not showing itself, not sure what the next diagnostic is next.
 
(reply to post at 20:27:50 10/25/17)

Wish it was that easy, it looks like there is only one way the plate can fit down over the governor hub, I thought that as well initially, that's why I took the new pump top apart to compare the two, the only difference I saw was the Mefin pump had a slightly shorter spring but was connected to one longer link hole so the difference was a wash.

It really does sound like a governor issue but it's not showing itself, not sure what the next diagnostic is next.
 
(reply to post at 20:27:50 10/25/17)
Had a thought about a thin flat spring that was in the drive hub along with the double flatted washer when the hub was removed.

I put the bolt through the flatted washer and then the spring over the end of the bolt when I re-installed the drive hub, everything seemed ok but I am a bit curious as to why they would put a spring in that location as it all gets drawn together when the bolt gets tightened.

Still looking for it on the drawings I've seen, guess I need to take the tops off of both the new and old pump and compare the movement of each of the governor flyweight hubs to see if there is a difference.

If the weight assembly was bound up and not moving for some reason that would certainly explain what's happening, still curious about that spring.
 
If that's how you put the hub screw back in, it's wrong. With the hub in place install the flat washer first, then the lock type spring washer on top, then the allen bolt with a drop of thread locker on the threads, torque to 32 FT/LB. The way you have it now the weight retainer is NOT tight against the shaft shoulder, and slipping on the shaft. With the hub tight it clamps the retainer solid, if the two washers are in wrong like you have it, bolt will be tight, but the smaller lock washer will not hold the retainer tight. That's why the flat washer goes in first, then the lock washer..
 
(reply to post at 11:59:45 10/26/17)

Right on the money, Ford manual had nothing on it so went to the parts books, changed it around, but not until cleaning up a couple of gallons of fuel on the floor and a crankcase full as well.

Had a new seal in the front of the pump not sure why it was leaking but I will be putting a new one in before slapping it all back together.

Still wondering why they would put a spring under a bolt head that will be tightened and not bottomed out, spring is unavailable now but the one I have will work, my new pump had it in correctly but the spring came out in pieces, I think before it goes back on the shelf it will get a flat washer in place of the spring.

Thanks for the help, should have looked at my parts book before putting it back together the first time.
 
(reply to post at 12:46:12 10/26/17)

Problem started when I popped the drive hub off it fell into the pan, the bolt and the spring/lock washer fell out all at once and figured the "spring" couldn't possibly go under the head of the bolt.

Should have gone to the parts books straight away.

Thanks
Much Gras...
 
(reply to post at 14:15:33 10/26/17)

Not sure why the oil pan filling with fuel caused it to leak on the floor from the area of the rear main, really don't want to have to split it to replace the seal.
 
After the hub screw, lock and flat washers are in place and torqued correctly, watch the oil level after you run the engine awhile. If oil goes up again the pump will need torn down to replace the shaft groove O ring, that seals inside the drive hub bore. Fuel into the oil is not always the drive hub front seal..
 
(quoted from post at 16:18:26 10/26/17) After the hub screw, lock and flat washers are in place and torqued correctly, watch the oil level after you run the engine awhile. If oil goes up again the pump will need torn down to replace the shaft groove O ring, that seals inside the drive hub bore. Fuel into the oil is not always the drive hub front seal..

Not sure where this O ring is, sounds like I'll have to pull the guts out of the pump to get at it.
I've got the pump on the bench now so probably aught to gut it and find the O ring you're talking about, I'm guessing it's in the gasket kit I've had on the shelf for years.

Is it on the shaft the weight assembly is on? time to get the parts book out, don't want to go through that mess again.

Thanks again for the heads up.
 
(reply to post at 19:03:09 10/26/17)

Looks like it might be the #45 on the Ford parts drawing, between the shaft and the weight assembly heading toward the drive hub, sound right?
 
Yes, weight cage assembly in place on the shaft then the shaft to hub sealing ring is placed in the groove. Cush drive shafts use the heavy thick O ring, non-cush assembly like yours uses the thinner O ring. Lube the hub inside O ring bevel area sparingly, install the hub in the housing. Place the hub face down on the bench, install the shaft assembly lining up the wide spline. Push the shaft down, you should feel the O ring pop into the hub. Hold the shaft in place while turning over the pump and install the flat washer, lock washer, and screw.
 
(reply to post at 20:44:10 10/26/17)

Thanks for the help, much easier once you've taken it all apart, obviously when the spring/lock washer was in the wrong place there was no way the hub seal O ring was going to seal, hence the crankcase full of fuel.

Still going to replace the front seal in the morning and then slap it all back together.

One funny part, there is a round ring around the shaft close to the top of the governor shaft, the one on this pump was a lot larger than what should have been there, really fit the shaft loosely, a lot.

Cut about 1/8" off of one end of it, gave it a squeeze and it now fits properly, the pump doesn't look like it's been apart before but somebody could certainly replaced the original with something too big.

Thanks again for your experienced assistance, old guys helping old guys is magic.

GB
 

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