Ford 4610SU jumped timing?

[showme1946]

The equipment: 1981 Ford 4610SU with 3 cyl. diesel, more than 7,000 hours; I've owned it since February; all fluids new, new filters, new radiator and thermostat; everything else old (including owner).

Attachments: Koyker K2 loader that was on tractor when new; JD 7' rotary cutter.

The question: The tractor has been running like a top. Yesterday I was mowing ("brush hogging") in a pasture, and I hit an old stump. There was a lot of noise and shuddering as the cutter chewed up the stump, but then the tractor engine suddenly quit. It will not start. It turns over fine, the starter is fine, fuel tank is full, fuel comes out when I loosen the bleed screw in the fuel pump, the battery is fine.

The service manager at my local New Holland dealer wondered if maybe the driveline shock that occurred when I hit the stump caused the (old, worn) engine to jump timing.

I have learned that the cam timing and fuel pump timing are controlled by a gear train of helical gears on the front of the engine. I suppose, after 36 years and >7,000 hours those gears could be so worn that they would jump a tooth or two given a sufficient shock.

I'm interested in what the sages of tractor-by-net, who have saved my bacon more than once, think of this situation. Why would hitting a stump with a brush hog cause a diesel tractor engine to quit and then not restart? Is jumped timing a good possibility?

thanks in advance for your help.

George.

 

[rustydollar]

Maybe a broken crankshaft.

 

[thepumpguysc]

Yes they will shear the keyway and the gear teeth.. white smoke when cranking & no start..

 

[showme1946]

Would it still crank over normally on the starter if this had happened? Doesn't seem to me like it could, it would at least make some strange noises.

Thanks your reply.

GR

 

[showme1946]

No smoke at all; definitely no start. It cranks over normally on the starter, no untoward noises. But I understand what you're saying about the sheared key, and given the age of the tractor I think it's a real possibility.

My previous experience with other machines where the cam timing got off were very bad because those were interference engines and valves were bent; there were also a lot of bad noises. Nothing I've read (operator's manual, service manual, online postings) even mentions the idea of valve/piston interference. Of course it could be that the gear that sheared its key is the gear driving the fuel pump, not the gear driving the camshaft.

If I can't find some obvious and easily fixable reason for the no start today, the tractor will have to go to the shop.

GR

 

[showme1946]

Thanks to everyone who responded. I have an update. Today the tractor started, and I was able to get back to work. Later in the afternoon, the tractor quit on me again, this time after I hit a rut and jostled everything pretty good. As with the previous occurrence, it would not restart. My conclusion is, nothing is wrong with the tractor except that it is old and close to being worn out. I am expecting that, after it sits for a while, it will restart and once again run for a while until, for one reason another, it doesn't.

The bottom line is, I think, that if I wanted a really reliable tractor, I should have spent the money necessary to get one.

George Rickerson

 

[showcattle]

That series of tractor is about as bulletproof as they come. My guess is the fuel system needs cleaned out. Tank and filter.

 

[showme1946]

I agree with you on both counts. Clearly the tractor is basically solid, otherwise after 36 years and 7,000 hours it wouldn't function at all. And I believe the problem with it quitting under certain circumstances is a fuel system issue. After its been running a while and there is the right kind of jolt, something interrupts the flow of fuel causing the engine to stop running. That same something prevents it from being willing to restart until it has sat and cooled off.

Thanks for the insight.

 

[Happy Gilmore]

Keep us posted.

 

[Jerry/MT]

Thanks to everyone who responded. I have an update. Today the tractor started, and I was able to get back to work. Later in the afternoon, the tractor quit on me again, this time after I hit a rut and jostled everything pretty good. As with the previous occurrence, it would not restart. My conclusion is, nothing is wrong with the tractor except that it is old and close to being worn out. I am expecting that, after it sits for a while, it will restart and once again run for a while until, for one reason another, it doesn't.

The bottom line is, I think, that if I wanted a really reliable tractor, I should have spent the money necessary to get one.

an appropriate additive.

George Rickerson

Is this a diesel tractor? If it is, check for fuel delivery at the filter. There should be a drain fitting on the filter. Diesels mostly stop running when their fuel supply is interrupted. That's how they are shut down.

Clogged tank strainers, clogged pinched fuel lines, clogged filter head, clogged fuel filters, improperly installed O-rings in the filters, etc. No white smoke when you try to start is an indicator of a lack of fuel delivery. Fuel tanks can collect water via condensation when they are not kept full. hat's the beginning of problems .Bacteria can live in the fuel/eater interface and "eat" the fuel resulting in a snotty looking sludge which can clog the tank strainer, fuel lines, and filters. Consider keeping your tank as full as possible to minimize condensation and treating your fuel with an appropriate additive.

The fact that it quit when you jostled it in a rut makes me think you have some nasty stuff in your fuel tank that temporarily clogged the outlet and stopped the engine. Your tractor has an independent pto and has a clutch between the pto shaft and the drive shaft to the pto. That clutch probably absorbed some of the shock loading and slipped to protect the rest of the drive line. That's why you were able to later restart it. Enough fuel leaked through the clog to allow it to restart later.

So check the fuel delivery system to the pump and I'm sure you'll find the problem.

 

[showme1946]

Wow, that analysis is right on. Thanks very much. I'll get to work on your suggestions.

George Rickerson

 

[showme1946]

Today I drained the fuel tank and removed the fuel shutoff valve. It was packed almost solid with gunk. I cleaned it up and put it back on the tractor. But when I reattached the line to the fuel filter, I cross-threaded the nut. So I removed the valve again and took it to the local New Holland dealer to see if they had one.

Not only did they have one, but it has been upgraded. The petcock on the old one is plastic, it is metal on the new one. But even better, the new valve protrudes up into the fuel tank and has a filter that fits on top, so it should be less susceptible to the sludge monster. So the crossthreading mistake was a blessing in disguise. I'll put the new valve on tomorrow (being extra careful not to crossthread the fuel fitting).

I am eager to see how this tractor performs with a proper fuel supply.

George Rickerson

 

[Happy Gilmore]

Im glad everything worked out. Nice

 

[showme1946]

I installed the new fuel shutoff valve this morning, hooked everything up, filled the tank (checking for leaks during the process), bled the fuel filter and the fuel pump, and bingo the tractor started right up. It ran great all day, I finished mowing the south pasture with no hiccups.

Thanks again to everyone who weighed in, especially Jerry/MT.

George Rickerson

 

[Jerry/MT]

I installed the new fuel shutoff valve this morning, hooked everything up, filled the tank (checking for leaks during the process), bled the fuel filter and the fuel pump, and bingo the tractor started right up. It ran great all day, I finished mowing the south pasture with no hiccups.

Thanks again to everyone who weighed in, especially Jerry/MT.

George Rickerson

Glad you got it running!