Guys,
I'm new here but not new to lawn tractors. This Troy Bilt (Seems to be a MTD/Yard Machine mower) was sporadically hard to crank so I figured the engine must have a compression release during crank that wasn't getting activated because of loose valve lash...I've seen that before on other mowers.
So, I looked up the valve lash specs online and found them .005/.007"
Then, I took the valve cover off, and I see no way to set lash. There are no lock nuts, only the nut that the rocker pivots on. I've owned this mower since it was brand new, nobody has ever been in the valve cover except me.
I then looked at the service manual and I see that there are supposed to be torx lock nuts in the center of the rocker pivots. Again, mine are missing.
How could this mower have run for 5 years like this? You can literally spin the pivot nuts by hand. The lash was at about .020" or so and the mower still ran. I heard nothing.
The pushrods appear to be straight. The rockers appear to be OK.
If I snug down the pivot nuts, intake is at .003 and exhaust is at .004, so perhaps this was where it was when it was sent out...and it runs like that, but obviously isn't correct. It cranks a hell of a lot easier; apparently it does have a compression release that lifts the valves during low speed cranking.
I've ordered the locks and some other gaskets and such and will put it back together per the engine service manual, but I just wanted to report this finding and sanity check with the group. Those locks ARE supposed to be there, right? For both of them to be missing makes me thing someone missed a step.
Byron
I'm new here but not new to lawn tractors. This Troy Bilt (Seems to be a MTD/Yard Machine mower) was sporadically hard to crank so I figured the engine must have a compression release during crank that wasn't getting activated because of loose valve lash...I've seen that before on other mowers.
So, I looked up the valve lash specs online and found them .005/.007"
Then, I took the valve cover off, and I see no way to set lash. There are no lock nuts, only the nut that the rocker pivots on. I've owned this mower since it was brand new, nobody has ever been in the valve cover except me.
I then looked at the service manual and I see that there are supposed to be torx lock nuts in the center of the rocker pivots. Again, mine are missing.
How could this mower have run for 5 years like this? You can literally spin the pivot nuts by hand. The lash was at about .020" or so and the mower still ran. I heard nothing.
The pushrods appear to be straight. The rockers appear to be OK.
If I snug down the pivot nuts, intake is at .003 and exhaust is at .004, so perhaps this was where it was when it was sent out...and it runs like that, but obviously isn't correct. It cranks a hell of a lot easier; apparently it does have a compression release that lifts the valves during low speed cranking.
I've ordered the locks and some other gaskets and such and will put it back together per the engine service manual, but I just wanted to report this finding and sanity check with the group. Those locks ARE supposed to be there, right? For both of them to be missing makes me thing someone missed a step.
Byron