John Deere engine ran backwards damage warning

[73440]

I forgot to lower the rpms when shutting off the JD D140 mower to clear a clog Sunday night and once again the engine ran backwards .
Would not restart as it normally would so I had to push it to the shed so the horses wouldn't chew on the tractor again. Sat night the horse pulled the mower blade on off switch out of the dash and from the wiring harness. Its not like they don't get enough to eat, haha.
Pulled the rocker covers today and found one bent intake pushrod and one missing exhaust pushrod .
Could the pushrod have completely gone down the oil drain hole ?
Engine was making some noise but didn't seem like piston eating a pushrod noise.

[Brads70]

Am I not seeing the pushrod still on the rocker arm?   I had a customer with this just yesterday. Threw a rod, piston came up and smacked the valve bending the pushrod. Can you push down on both valves to see if everything moves as it should?  Likely damages go beyond what you can see I'm sorry to say but once in a blue moon you get lucky and replace the pushrod and away it goes. Another  thing that I've seen ( usually in single cylinders ) is the rocker arm bolt backs out and causes the cup/lashcap ontop of the valve to fall off allowing the pushrod to fall out. Or if the engine has overheated the valve seats sometimes fall out jamming the valve open.

[73440]

Correct the exhaust push rod is missing which of the only place it seems that it could go is down the drain hole.
I pushed on all four of the valves they all move.
I'll drain the oil take a look, like you say I doubt I can get by with just putting the push rod in .
Maybe I'll just put the 27 horsepower Briggs & Stratton in this is the 22 horsepower , I kind of need that extra horsepower as I tend to let the grass grow high.

Yeah I didn't tighten the rocker adjuster enough on my Norton years ago and the adjuster bolt backed off and like you say the push rod came up and broke the rocker arm and I was left with just the single cylinder Norton 850 Twin .

I just can't believe that the entire push rod is missing.
before I shut it down yesterday it was actually running, now it had the exhaust coming out the intake which I knew was not good, haha.

[73440]

Found the pushrod , laying flat along the bottom. Oil was dirty, but did not see metal.
Photo is the oil drain plug with pushrod beyond.

[jimynick]

I was going to say that it likely got driven off the cam lobe, bent and fell into the crankcase, and there you were. I'd check the cam and lifter before trying to just start it, but that's just my 

[73440]

I will probably pull the head off that is closest to the pushrod and try the magnet or claw to retrieve.
Tried the magnet  through the oil drain where it fell through originally , no luck.
It seems like a simple turn in the oil drain back would keep a pushrod from going into the crankcase.
And from what I've read online this happens frequently 187 hours on this one .

If I end up having to pull the engine I think I may go with the 27 hp they'll be five more over the 22 I have now and maybe that'll stop some of the grass clogging also.  Try to check the torque difference in those two .

[Brads70]

Found the pushrod , laying flat along the bottom. Oil was dirty, but did not see metal.
Photo is the oil drain plug with pushrod beyond.

I had a customer today with the exact same issue as yours, same engine. He's going to scrap it.  I've had at least 2 of these this summer. unusual as these engine last a long time for the most part if they are maintained.

[73440]

Ouch, I feel for them, cant believe Briggs and Stratton designed something like that.
Bought pushrods and gaskets today.
Plan to try once more to pull the pushrod out the drain hole, if no luck , pull the head for maybe easier access to the inside, third is pull the engine and split cases.

Or just put new pushrods in and run it till it grenades and put the 27HP in it.

[73440]

Found the pushrod , laying flat along the bottom. Oil was dirty, but did not see metal.
Photo is the oil drain plug with pushrod beyond.

I had a customer today with the exact same issue as yours, same engine. He's going to scrap it.  I've had at least 2 of these this summer. unusual as these engine last a long time for the most part if they are maintained.

@Brads70 , did their problem start with not lowering rpm when shutting down and engine running backwards also ?
I think mine would have been ok of I had known the fact the pushrod could fall into the engine, I would have removed the rocker cover and inspected before starting and running the engine for a minute like I did.

[Brads70]

Found the pushrod , laying flat along the bottom. Oil was dirty, but did not see metal.
Photo is the oil drain plug with pushrod beyond.

I had a customer today with the exact same issue as yours, same engine. He's going to scrap it.  I've had at least 2 of these this summer. unusual as these engine last a long time for the most part if they are maintained.

@Brads70 , did their problem start with not lowering rpm when shutting down and engine running backwards also ?
I think mine would have been ok of I had known the fact the pushrod could fall into the engine, I would have removed the rocker cover and inspected before starting and running the engine for a minute like I did.

I'm not sure if they lowered the rpm when shutting it down. I'm not sure on the running backwards thing? Never heard of that one before you mentioned it. It's always so far been the drivers side head, and exhaust valve. What I think happened is it stuck the exhaust valve or the exhaust valve seat has fallen out, then the piston hitting the valve, and bending the pushrod. As in all the ones I've had this summer I couldn't move the exhaust valves afterwards which leads me to believe they are bent. I never bothered to tear them down to see,just my theory . Might be a camshaft issue as well?  Hard to know without tearing it down. 
If I were you , for the low cost of a head gasket I would pull the head and see before you installed a new pushrod and tried to start it again. 

[Cuda Cody]

You guys got me worried a bit.  I'm looking to buy a new mower and not sure who makes a good one anymore?  I want to get another stand up mower to replace the older one I have now.

What's the better / best brands in mowers?

[Brads70]

You guys got me worried a bit.  I'm looking to buy a new mower and not sure who makes a good one anymore?  I want to get another stand up mower to replace the older one I have now.

What's the better / best brands in mowers?

I find in my neck of the woods,90% of the pushmowers, lawn tractors and snowblowers  are made by one of 3 manufactures. They paint them different colours and decals, maybe a different hood but other than that....  ( just like appliances) I tell people when looking for new equipment, 1st,before you buy make sure there is a dealer where you live  for parts availability down the road.  Around here the exceptions to the 90% thing is Toro, Ariens, and John Deer , the rest are made by either MTD, American Yard Products (AYP) or Murray which was taken over by Briggs. Of those 3 AYP is my favorite. For lawn tractors I avoid JD as the decks bend so easy when you hit something you shouldn't . Everyone else you replace the mandrel assembly and go 90% of the time, with JD
the main deck bends and the blades never run straight again, you will have to replace the entire deck $$$  Common re-branded names for AYP are poulan pro, some Sears( craftsman) and husqvarna.
I then say to shop for features, like engine type etc...  I sure what some of the manufacturers do with engines  is tender them out and who ever has the best deal that years gets the business. Like on pushmowers and snowblowers one year it might get a Honda engine, next year offshore,  , next year Briggs, Kohler
If you want the best quality look at commercial equipment not residential box store offerings. But expect to pay much more.

[73440]

I bought the head gaskets and pushrods so pulling one or both heads is the right thing to do.
Have also heard the valve guides loosen and slide out of the head which then does not allow full valve movement which then causes bent pushrods.
This mower is a JD D140 with Briggs and Stratton 22HP V twin with 187 hours in 3 years of mowing , mowing up to 10 acres , 3 ' high grass on 8 acres , did it well , could use 5 more HP, if this engine is toast ,, will put the 27 HP in.
Only trouble had was frequently it would run backwards when throttle was not lowered rpm when shutting down. Other than that its been a tough mower.
The valve guides loosening in the heads resulting in bent valves is the majority of the problems I read online, people will peen the guide to the head to prevent.
I still cant believe they have left a path for a pushrod to fall completely into the crankcase.
Thanks all for the help and pushing me to not start it with the pushrod in the crankcase, just need to do it right.

[73440]

Was thinking, what about gluing a magnet that is large enough not to go down the oil drain hole to hopefully capture the steel exhaust pushrod if this happens again ?
My 7 yo nephew , who I gave 303Mopar 1967 440 to him when he was 4 yo, will be visiting at Thanksgiving , may wait and have him help on this small engine project.

[Brads70]

Was thinking, what about gluing a magnet that is large enough not to go down the oil drain hole to hopefully capture the steel exhaust pushrod if this happens again ?
My 7 yo nephew , who I gave 303Mopar 1967 440 to him when he was 4 yo, will be visiting at Thanksgiving , may wait and have him help on this small engine project.

I'd pull the head off now. Might be not fixable  or at least you'll know what parts you will need?