1250 vibration
 

My neighbor recently bought a 1250. He replaced the rear engine mounts with neoprene bushings bought at Napa auto. The engine runs great at idle but when the throttle is increased to max there is a bad vibration that seems to be coming from the rear part of the tractor. He said the vibration was there before replacement but it was not quite as bad as now. The drive shaft was removed to install a new fan, but shaft appears to be straight and true when running. One blade broke off the fan during installation, Any suggestions? Also one other question it is really easy to move the tractor with the engine off... just push or pull and the rear wheels roll, Is that normal for a hydro?

YES

I would look at the Flex Disc(s) and the Coupler Bushing(s) at both ends of the drive shaft.

You can move the tractor a short distance, slowly, but towing or moving a long distance can damage the hydro, engine or no engine.

Vibration, i.e., tractor shaking could be the other iso mounts, or the driveshaft. If you remove the tunnel cover and run the engine, you might be able to see what is shaking.

Thanks for the replies... Running on high throttle with the tunnel cover off the shaft looks smooth, don't see any wobble. Maybe will try running with drive shaft removed. I'm not sure if he replaced the other mounts. I do believe he had the rag joints apart.... I will check them again

He said something about the ballance gears being removed from the engine to prevent future damage from failure? Im not sure what these gears do?

The "theory" of the Kohler Balance Gears was to "smooth the vibrations out". As these gears wear, they also can cause vibration and can ultimately lead to an internal crankcase implosion. Thus, most people take them out. It it cheaper to put up with a little vibration, verses pay for a massive overhaul.

the balance gears were more for at idle low engine speed vibrations. there's little to no difference WOT. you could have the new relief valves with out the button. then they roll pretty easy right away. like the others have suggested I'd be looking at the driveshaft rag joints and couplers. they see allot of wear and damage from running with bad mounts when everything is out of alignment.

Hi, Burgy Here..
It's my unit, I pulled the urethane bushings out this morning. puting the old ones back in using the best ones in the rear and bottom.

The vibration is all but gone, will get new mounts when it starts acting up again.

The next issue is the fuel tank/plastic/ PO must have cracked it and tried to fix with not so good stuff. Guess I will have to find another one.

Thanks

Broken blade?
 

Did you say ONE blade, broke off the fan? Could be part of the problem.

Welcome Neighbor... Glad you found us, you will find a lot of good useful info and a great bunch of guys on here.

There are no balance gears in a 12 HP AQS Kohler which is what should be in your 1250.

Try turning the ISO mounts upside down so the good ones are on the bottom.
There IS an upper and a lower in an NOS set w/2 thick washers that sandwich between them when assembled.

When the bottom mounts go to pot and the engine settles onto the X member this throws the driveline out of alignment and causes the rag joints to run crooked, hence the vibration

While you are in there, make sure your pan to cradle bolts are tight and this would be an excellent time to do the cradle mod and add the cross brace

IH Cub Cadet Quiet Line AQS engine models did not have balance gears, which was the major down fall of the previous engine models.

You should have used a rubber mount close to the same duro as the factory mounts. Of course, factory replacement are the best choice. I have aftermarket-modified, and have no trouble since. The real bugger is the new flex couplings I installed on my 1450. They seem to need to have a certain amount of break-in time. The old flex coupling I removed produced little vibration compared to the new.

Hood hinge- remove and repair/tighten up in a vice. Install new hood bumpers too. I can go on and on,.............

Thanks for the all the help, I will monitor the mounts and change them this winter.

The gas tank will be replaced this week, so the DW can get mowing!

Does anyone have any first hand experience with replacing the front spring (that holds the two side panels on) on a Quietline? Does that help with any rattle with the side panels? I think I still have stock spring on it - and the spring looks slightly extended when not connected (the rings have space between each other instead of rightly hugging one another). Wondering if new spring wouldn't help rattle.

Go to the hwd store and get a screen door spring and cut a piece of fuel line just big enough to go over it.
Make the line about 3/4 as long as the stretched spring between the side covers.
Get a couple of "S" hooks for the spring ends (broken rubber tarp straps work ok as long as they are small ones)
Oh the hose keeps the spring from vibrating and making additional noise.