Murray Riding Mower Engine wont turn unless spark plug removed

[tbone]

That looks like a likely suspect, especially if you've never adjusted the valves before. From the illustration I see rockers and valve lash adjustability, so I'd go right to that next since they're probably overdue for adjustment anyway. Best case scenario is you do routine maintenance and fix a big problem in one fell swoop.

Well good news and bad news. Good news is adjusting the valves did the trick. Bad news is I made about 3 laps around the yard and bam, abrupt engine shut off. Removed the valve cover and I now have a broken rocker arm and bent connecting rod on the intake. So the question is what to do next:

1) Order replacement valve kit and try and fix it.
2) Take it to a repair shop and let them fix it.
3) Buy a replacement engine and install.
4) Buy another riding lawnmower.

So I think it comes down to cost benefit. Let me know what you guys think.

 

[jeff]

Try jackssmallengine.com for a replacement engine. Otherthan that, take to a shop for repair. You may find that labor and parts to repair may exceed the replacement engine cost.

 

[Jetblast]

Holy cow, sorry to hear that. If the rest of the mower is in real good shape I'd probably call a local shop and run the scenario past them for a wild price guesstimate, then repair or replace the engine based upon the feedback you get. If there's a lot of rust on the mower and things are feeling pretty loose and sloppy, a replacement mower might be the better bet in the long run.

 

[tbone]

Holy cow, sorry to hear that. If the rest of the mower is in real good shape I'd probably call a local shop and run the scenario past them for a wild price guesstimate, then repair or replace the engine based upon the feedback you get. If there's a lot of rust on the mower and things are feeling pretty loose and sloppy, a replacement mower might be the better bet in the long run.

Took a gamble and bought new push rods and a rocker arm. After several tries at getting the valves adjusted, I finally got it to work. Now I read several posts and looked at several videos explaining getting the engine to top dead center and then an additional quarter inch turn. Nothing very clear at all. In short the top valve is the intake, the bottom the exhaust. You adjust the valves on the compression stroke. What is not clear is this at the start of the compression stroke or the end? What I did is turn the engine until the intake opened and closes. At this point I think you are at top dead center. Had a long extension in the spark plug hole and it was at the top. Did'nt move the engine another quarter inch as that starts the exhaust valve to open. I found that you have to kind of play with this until both valves are closed and there is no pressure on the valves with the rocker arms. Adjusted both to .004 and works like a champ now. So $20 bucks hopefully saved me some money for a little while longer.

 

[jeff]

Good deal, saved a ton!!!

 

[RobertBrown]

Took a gamble and bought new push rods and a rocker arm. After several tries at getting the valves adjusted, I finally got it to work. Now I read several posts and looked at several videos explaining getting the engine to top dead center and then an additional quarter inch turn. Nothing very clear at all. In short the top valve is the intake, the bottom the exhaust. You adjust the valves on the compression stroke. What is not clear is this at the start of the compression stroke or the end? What I did is turn the engine until the intake opened and closes. At this point I think you are at top dead center. Had a long extension in the spark plug hole and it was at the top. Did'nt move the engine another quarter inch as that starts the exhaust valve to open. I found that you have to kind of play with this until both valves are closed and there is no pressure on the valves with the rocker arms. Adjusted both to .004 and works like a champ now. So $20 bucks hopefully saved me some money for a little while longer.

Great post/great thread tbone!
That's the kind of post that makes this website valuable and worth while. A few pictures would have been excellent, but a great post none the less.
Thanks
RB