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Followup To If the intake is set to .002 and the exhaust to .004, would I lose power?
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Followup To
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I got a lawn tractor from my neighbor with a 12 HP, OHV Tecumseh engine. He said the engine only has about 500 hours on it. Sears installed it for him. It would not start. I changed the gap on the coil (solid state ignition) and got it to start. I put the mower deck on and the tractor has enough power to run up slight grades in 6th gear and does not even show signs of being loaded. The engine dies when I try to engage the mower. I eliminated the brakes on the pulleys on the belt drive (used to stop the blades) but it still wants to stall the engine. If I engage the mower for a brief period and then release, the blades are turning and they coast for 10 - 15 seconds before stopping, but if I leave it engaged, the engine will stall. I have even removed the belts and spin the pulleys separately by hand and they coast for at least 10 seconds.
As it is stalling I have pulled the linkage on the governor all the way back (throttle plate full open) and it still wants to stall.
I got “on line” advice from someone who said to reset the coil gap to .010. I did this. It still stalls. Is this the correct gap?
I changed the oil and gas, but it still stalls when the mower is engaged.
What should the compression be on this engine? My “on line” source said there was no value, but to turn the engine backward by hand and if it springs back, it is OK. Is there a “spec” value for the compression?
I set the intake valve to .002” and the exhaust to .004”.
I thought about the fuel filter being plugged, but when I open the throttle “full open” by hand, the engine does not starve, even though it sounds like it is going to rev apart.
How do I perform a leak down test?
What else could cause it to lose power?
The engine is a Tecumseh. The Model number, as it appears in the Sears Owners Manual, is 143.386012.
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Does it loose power or completely stall? Have you check the blade engagement safety switch and seat switch?
Let me know.
Eric
It slows down and if I leave the mower engaged it will eventually stall. The seat and blade switches have been removed from the circuit years ago.
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I believe those valves should be set to .004 inch...I'll check for sure tomorrow.
If the intake is set to .002 and the exhaust to .004, would I lose power?
Eric
AnswerA leak down test is performed using a special tool. You connect the tool to an air compressor and then screw the tool into the spark plug hole. The tool checks the piston, rings and valves for leakage.
You could loose power with the vavle set to .002. I had a similar problem with a Tecumseh engine years ago. It turned out to be a leaky headgasket. When the mower got hot the head/cylinder parts expanded and the headgasket would leak...took me a long time to find the problem. Replaced the head gasket and the mower ran great.
You can try tightening the head bolts, 200 inch pounds of torque, and see it that helps.
Let me know what happens.
Eric
