1979 B7100 bad engine vibration 650 hrs

[masscity]

In the spring I noticed an engine vibration that you could feel in the foot plate. I'm not a mechanic. I checked the engine mounts. Checked clutch in/out for change at all rpm's. No change. Vibration got worse in August.

Talked to the dealer on the phone. He said to open up injectors one at a time, which I did even though I had full power. Disconnected the Dynamo belt to see if Dynamo was the problem. No change. Brought it to the dealer.

They adjusted the valves. Pulled the engine and oil pan. They said it was tight below and looked like brand new. With the engine out, they checked the clutch and said no problem and very little wear. They're waiting for a compression tester and head gasket now. He'll take the head off and gauge the pistons for possible bent rod and check compression.

Any ideas would be appreciated. Thanks.

 

[Volfandt]

I've seen where a cooling fan with broken/bent blades make an engine vibrate like crazy but it seems you discounted that when you disconnected the fan belt (dynamo).
I've also seen a nicked and/or loose harmonic balance do the same. A heavily damaged pressure plate/ ring gear can do it also.
Does it do it only when moving or all the time?
If only when moving I'd then suspect a bent/damaged driveshaft. But from how you described it I would guess it does it sitting still also.
Seems like your machanic has just about ruled out all the easy fixes.
Good Luck

 

[masscity]

When I posted this yesterday, I was tired. It has the vibration when not moving, clutch in or out and when moving at all rpm's. Of course it is worse at higher rpm's.

He checked the harmonic balancer. The dealer also said he checked for a missing piston skirt, because he saw that on another Kubota and that caused bad vibration. Mine were ok.

The reason I asked for help is that the mechanic there didn't sound to confident that he was going to find the problem.

 

[amitysanimal]

Just a heads up, I have a parts engine, let me know if you need anything. I was going to suggest checking to be sure the pressure plate hadn't come loose, but appears the mechanic has checked that. I'm curious to know what it is. I have a 1977 B7100 with over 7500 on the tractor and about 2600 on the engine thats in it. I just love this little tractor, it sure is a working little machine.

amitysanimal

 

[masscity]

Just a heads up, I have a parts engine, let me know if you need anything. I was going to suggest checking to be sure the pressure plate hadn't come loose, but appears the mechanic has checked that. I'm curious to know what it is. I have a 1977 B7100 with over 7500 on the tractor and about 2600 on the engine thats in it. I just love this little tractor, it sure is a working little machine.

amitysanimal

Thanks for the offer on the parts amitysanimal. Still waiting to hear from the dealer.

If this dealer can't fix it, I might bring it to another, because I don't think I could stand operating it with that bad vibration.