B&S 31C707 0230 E1 030517ZE flywheel

[jwales]

Something new with this old machine. Owner called me and said he thinks he "blew the crank on the mower". I asked him what happened and why he thought that. He tried starting it for first time this season and battery was dead. put in a new battery. Started fine ran for a short period then boom and puff of white smoke out the muffler. Could not get it to start again. Asked if there was grinding noise when turning ouver he says no. Does not sound like a broke crank to me.
Any thoughts?? Flywheel key? Valve adjustment loosened up??
Thanks.

[bgsengine]

Sounds like he dropped a valve lifter pushrod... or valve seized in valve guide or both

[38racing]

Head gasket?

[jwales]

I can handle a head gasket. It is an OHV so I will open that up and take a look at the valves. BGS, is the engine shot if it is a valve problem as you describe? I have pulled the valves before and replaced the guide and adjusted before.
Thanks

[bgsengine]

I can handle a head gasket. It is an OHV so I will open that up and take a look at the valves. BGS, is the engine shot if it is a valve problem as you describe? I have pulled the valves before and replaced the guide and adjusted before.
Thanks

If you can do a head gasket, then you can handle the valve issue pretty much - Walt Connor (forum member) has a procedure to "save" those heads with the shifted valve guides , or you can just go with a head set (they run about $90 - $120 or so) Other than that you may want to plan on new push rods (if you want to take a guess at parts before taking valve cover off) if it is the valves, the problem will be immediately obvious when you pop the valve cover off (which you have to do anyway to replace head gasket, right, right?)

[KE4AVB]

the problem will be immediately obvious when you pop the valve cover off (which you have to do anyway to replace head gasket, right, right?)

What BGS your Voodoo stick not working? I wave mind over engines and they magically fix themselves.

Jwales, As for the problem you will not know until you get your hands on it. It could be something simple or could be a broken rod as customers usually don't the difference between a normal turning engine and one that's free wheeling. Most only knows it will not run.

[jwales]

Well I have gotten around to pulling the head... The head gasket does not look bad. the previous time there was a definite stress in a corner between the valve galley and push rod galley. Nothing real obvious here. The valves look ok, with a little more carbon on the intake than the exhaust. The push rods are true (straight)per rolling on granite countertop. One appears aluminum and one steel. As I think about it I am guessing one is for intake and one exhaust and are probably not interchangeable. Everything looks pretty clean and no visible damage. I wonder if maybe the flywheel key is sheared??? Would this produce the results (described earlier in this post)?

This mower appears to have been taken care of on the outside and so far nothing on the inside would indicate different. The owner likes it and hates to throw anything away if it can be repaired (within reason).
Thanks

[Fulltilt]

Well I have gotten around to pulling the head... The head gasket does not look bad. the previous time there was a definite stress in a corner between the valve galley and push rod galley. Nothing real obvious here. The valves look ok, with a little more carbon on the intake than the exhaust. The push rods are true (straight)per rolling on granite countertop. One appears aluminum and one steel. As I think about it I am guessing one is for intake and one exhaust and are probably not interchangeable. Everything looks pretty clean and no visible damage. I wonder if maybe the flywheel key is sheared??? Would this produce the results (described earlier in this post)?

This mower appears to have been taken care of on the outside and so far nothing on the inside would indicate different. The owner likes it and hates to throw anything away if it can be repaired (within reason).
Thanks

They aren't interchangeable. Do you not have a service manual? I'm sure one is available in the manual section here, no?