"The Lawn Mower Repair Man's Front Page"
Sometimes a problem can be very elusive and totally frustrating. Once in a while the cause turns out to be a simple modification that was made to correct another problem or, a Tim Taylor "Rewire" job.
The following is a message from "Joe", who has become a good cyber pal over the past year as we've discussed his MTD lawn tractor and he has shared some enjoyable moments and info about his homeland of Ireland. He's been kind enough to allow me to use his letter regarding the cause of a running problem created by a need to make a modification which created an additional problem.
I felt it was a perfect example for a "Tip Of the Moment" of how easy it is to induce a unexplained running problem when deviating from what the manufacturer has, hopefully, already worked out in their R&D process. Not so much for the purpose of scaring someone from trying to fix an unusual problem by making a modification, but to point out that if a new problem arises that didn't exist prior, not to overlook the modification as a possible cause.
HI Bob ,
My sincere apologies for not replying sooner, How are things?
I eventually discovered what the problem was with the MTD, ie ( Stalling after 30mins use ) Some time ago I bought a new muffler , the guy I bought it from kindly offered to fit it , no big deal , but ..ok, if he wanted to do it..go ahead.
The muffler in question is a big mushroom shaped thing that sticks out at a right angle to the block. Well...he over-tightened it , stripped some of the threads in the block and for ages afterwards I'd do about 200 yds and the muffler would fall off.
One day I was just about sick of this and decided to take a rather drastic step.
I made up a flange to fit to the muffler port , drilled and tapped two screw holes in the side of the block , used some flexable muffler pipe and mounted the muffler under the front of the engine ..pointing down. Worked like a dream (Very quiet ) and doesn't shake loose.
However , if I stop for too long in one place it scorches a neat little 6 inch circle in the lawn ( Possible way of dealing with persistant weeds ? ) but all is ok.
Then this stalling started, It drove me nuts Bob, I dismantled half the engine changed the plug , nothing made any difference . And then one day because my grass badly needed a cut I didnt bother to put the engine cover back on , as I was planning to have another look at the carb . Abracadabra !...... no stalling. I figure that with re-routing the muffler , the new route meant that the heat now exited under the mower , with the cover on , it built up after a while..Air cooled engine..Hot air..!
Solution .. for the moment ..leave the cover off. Later on I will either lag the pipe in some way, or figure on a way to get more cold air in.
This probably sounds very dumb to you, but the thing that threw me was that all the hardware checked out ok...so I guess you might call it a software problem.. heheh !
Bye for now
Thanks Joe for sharing your experience with us. I'd like to make one additional point here. The flange which bolts to the block should have about a 1 inch sleeve extending into the exhaust port. All B&S flange type exhaust mounts use this as it prevents a lot of heat from being transmitted back into the block by directing it out the exhaust. The old screw in muffler accomplished this automatically. It helps prevent overheating of the exhaust valve.