Hi,
I have a 1993 White/MTD riding mower with a Tecumseh OHV130 engine. The muffler studs
were stripped so I re-tapped to the next size larger. While the head was off I cleaned the valves
and lapped them in. Reassembled head and set valve lash to 0.004". Mower started right up
and I cut the front grass. Tried to restart again and no luck. Spark was good, but plug was dry.
Pulled valve cover off and found intake pushrod displaced from tappet. Thought I didn't tighten
the locknut enough so I put the rod back and set the lash again and tightened locknut to spec
with cylinder at TDC. Started it up, it ran for about 30 seconds and stopped. No restart again.
Pull the valve cover to find intake pushrod displaced and stuck next to tappet. Bent pushrod getting
it out. Replaced with new pushrod, rocker and stud. Started again ran little longer than stall in driveway.
Found the new pushrod stuck again. I have now pulled the engine out getting ready to checkout the
cam and tappets. Before I open the bottom of engine is there anything else that can cause the pushrod
to not stay in place? The intake valve does not seem to be sticky but the guide does have a little
play, maybe 5 mil? It is old. Can't find new guides.
Any thoughts would be appreciated!
Thank You!
Larry
Check to see if the valve guide in the head has walked up in the head, not allowing the rocker arm to open the valve properly. This will cause the push rod to bend. Cause of this problem is engine overheating, allowing the guide to move.
#3
cpurvis
Probably the valve guide.
When you set the valve lash, don't use TDC. Rotate the engine in the correct direction until the exhaust valve starts to open. Set the intake lash. Continue to turn the crank until the intake valve has just finished closing. Set the exhaust lash.
