B9200 bent pushrods

[bigcountry8530]

Ok like the title says. My friend has a B9200HST and all the pushrods bent. What would cause this? I know they hit the pistons but why did they. What should I be looking for with this engine and tractor?


Thank you
bigcountry8530

 

[D2Cat]

"B9200HST and all the pushrods bent".

For ALL the pushrods to be bend seems unusual. But I'd say the first guess is hydro-locked. Massive amounts of water into the combustion chamber, usually caused by a head gasket giving up after engine overheats.

So I guess you need to discover what other troubles the owner has had that lead to this.

 

[RCW]

Before I saw D2Cat's reply, I thought same thing. Betting on his diagnosis, and recommendations.
Good luck!


Sent from my iPhone using Tapatalk

 

[JerryMT]

Ok like the title says. My friend has a B9200HST and all the pushrods bent. What would cause this? I know they hit the pistons but why did they. What should I be looking for with this engine and tractor?


Thank you
bigcountry8530

If the pistons hit the pushrods that's a really big problem!

Most likely the valves were stuck and the push rods were bent by the lifters pushing up on the push rods.

Alternately, if this is an "interference engine" the valve timing was lost and the piston(s) hit open valves(s) causing them to bend the push rods as well as the valves.

In the former case, clean the valves and guides up with brake cleaner to unstick them. Replace or straighten the push rods.

In the latter case, open the timing cover to find out why the valve timing was lost. Pull the head and examine the pistons and the valves for damage. You might also want to pull the pan and make sure none of the rods are damaged.

 

[bigcountry8530]

The head is off and there is a valve outline on the top of the piston but no shiny spots or gouges. The tractor was smoking white ish gray. Head gasket is fine. The tractor was smoking when he bought it. It quit running after some hard use.

 

[bigcountry8530]

He thought the smoke was an injector issue so those are brand new. I think it was a compression issue. I think the pushrods were bent some when he bought it. And the he finished them off.

 

[North Idaho Wolfman]

I think this is the only Kubota engine I've heard of that has done that.

The only way I know to bend the push rods is to either set the timing wrong, have it skip time, which is very hard to do with a Kubota as it's a gear drive timing system, or possibly it ran backwards at some point???

 

[100 td]

The only way I know to bend the push rods is to either ........ or possibly it ran backwards at some point???

Haven't thought about damage from running backwards before excepting from the point of lubrication. If it does, can you explain to me how/why? Is it because of the different shape of the lobe on the close (now being the open) and vice versa - rate of open/rise now possibly being faster on a steeper lobe or similar?
Since the valves have hit the pistons, is this a possibility when running backwards due to rate of open and possible over shoot?

 

[Yooper]

I've seen bent pushrods from too much ether. But all of them? Who knows what somebody did when it's not yours.

 

[North Idaho Wolfman]

Haven't thought about damage from running backwards before excepting from the point of lubrication. If it does, can you explain to me how/why? Is it because of the different shape of the lobe on the close (now being the open) and vice versa - rate of open/rise now possibly being faster on a steeper lobe or similar?
Since the valves have hit the pistons, is this a possibility when running backwards due to rate of open and possible over shoot?

Yep, it might be possible to "float" the valves because of the cam shape.

 

[bigcountry8530]

Thanks I think the head is going to the machine shop. And the front cover is coming off to check timing. Does anyone have the timing procedures?

 

[North Idaho Wolfman]

It's fairly strait forward and simple.
But don't be fooled when you open it up and they look to be off, the marks all only align every 138 crank revolutions.

Interesting note:
Some Kubota B9200s experienced timing gear problems that were replaced by Kubota during the first ten years of service.

This is what the d750 gear timing looks like and I'm pretty sure the v1200 looks the same.

 

[JeffL]

Sounds like a classic run away. Engine rpm ran unregulated until valves floated and contacted piston. This is an expensive repair but preferred to rod bolt failure and piston exiting the block. Jeff

 

[Billdog350]

Wolfman mentioned the timing gear issue before I could mention it...if that had failed, I could see that possibly being the root cause. Any update on the condition of the timing gear?

Assuming timing gears and cam are good, I'd say JeffL is right on the money...

 

[bigcountry8530]

The owner is not sure what he wants to do yet. He has mentioned selling the why it is. I will update when he figures out what he wants to do.