Hopefully some of this information will help others. I was able to find some very helpful info in this forum.
I was having issues of losing power over the past couple of years with my LT1018. (has a Briggs 18.5hp 31Q777 motor) This mower is about 11 years old with approximately 400 hrs on the motor. It was to the point of barely being able to go up a small incline while mowing. I have performed all the routine maintenance over the years including replacing belts, pulleys and other parts that just wore out. Of course I replaced the spark plug and air filter which showed no improvement in performance. I read in this forum that I should check the valve clearance as the rocker arms may need adjustment. That was easy enough, only having to remove 4 bolts on the valve cover to gain access to the rockers. The clearance measured close to the tolerance but I did notice while turning the flywheel by hand that the intake valve (bottom valve) was barely moving compared to the exhaust (top) valve. I pulled the push rod out for inspection and found no problem with it. Must be the camshaft lobe...
Removing the motor from the lawn mower was no problem except you do need an impact wrench for the removal of the electric PTO bolt. (Of course I had to drain the oil, remove the throttle cable, choke cable, gas line and unplug electrical wires as well as the exhaust pipe.) Then (thanks to reading in the forum) I removed the 4 engine mounting bolts from underneath allowing me to move the engine back far enough to remove the drive belt from the pulley. The engine then came out. Removing the drive pulley was another issue. After 11 years of use, it was stuck on the shaft. I soaked it with with penetrating oil and placed a puller on the pulley and motor shaft (using a bearing splitter behind the pulley) Still would not move. Using another trick found in this forum, I used an air hammer against the puller bolt a couple of times to jar the pulley free. I saw a slight movement of the pulley on the shaft and was then able to remove the pulley with the puller. (later after cleaning the shaft and inside sleeve of the pulley, it would slide on and off the shaft easily.) Once the motor was out, I carefully removed the sump (the 10 bolts were very tight due to the thread lock but the impact wrench made that easy). Then I slid the slinger/governor off the cam shaft and was able to pull the cam out. The intake lobe was almost completely gone. I also removed the tappets. No wear indicated on them, just the cam lobe. I ordered a new cam which came with new tappets and also ordered a new sump gasket. The inside of the motor looked clean so I assume the metal particles cam out with the oil during my normal oil and filter changes. The parts came in a couple of days and by then I had the old gasket removed and the engine cleaned up. Installed the new cam and tappets (Oiled them well with fresh oil), (make sure timing marks are lined up!) and carefully replaced the slinger/governor in the correct position. Also had to make sure the oil pump was lined up with the slot on the end of the camshaft before putting the bottom of the motor (sump) back on (with the new gasket in place of course). Put the motor back on the mower (in reverse order of removal), filled with oil, checked everything twice to make sure I did not forget something, and started it up. Checked for leaks and listened for funny noises. I let it run for several minutes at a lower rpm before going to full throttle. Ran great! Cut the grass the following day and I a can't remember the last time is ran so well. Plenty of power now!
Sorry such a long story but hopefully this will help someone else with the same symptoms.... Please comment on anything I may have left out or any questions you may have. Total cost of parts was about $80. (compared to a new motor being $600-700 range, not too bad!)
Thanks again to others in this forum!
#2
reynoldston
The only thing I would add to this is I like to give everything a coating of LUBRIPLATE No. 105 as I assemble.
