Lawnmower very difficult Turn Over and will not start

16 years ago

Tec Engine very difficult Turn Over and will not start

I have a Lawnmower with 6.25-hp Tec engine it hit a rock broke the blade hub (the blade did not bend) it also broke the fly-wheel key. I replaced the blade hub and the flywheel key and tried to start the mower. It seems to puff out of the exhaust and carburetor. Three observations when pulling the cord I notice that the engine is difficult to turn-over there seems to be a hissing sound and it seems to be puffing out of the carb and exhaust vs. from the exhaust only. There is a spark and when I remove the spark plug the engine does not seem to spin free (just 1 complete turn vs. a few turns) I also removed the head and the piston and the valves all are working normally. Any ideas

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Comments (13)

1saxman
16 years ago
I'd guess the crankshaft is bent and binding.
rolm
Original Author
16 years ago
The crank shaft is not bent when looking under the mower.
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roadbike
16 years ago
Sounds like a valve timing problem. Everything connected to the blade tried to keep spinning while the blade was making little rocks out of the big one. Check out the timing gears.

Must have been one heck of a rock....
rolm
Original Author
16 years ago
I am curious so I will pop the bottom off and see if any gears or springs are broken. As I said compressed air seem to be coming out of the carb vs. air been sucked in.
rolm
Original Author
16 years ago
Ok I pop-off the bottom end of the engine all seems ok. The big question is how do I insure that the valve timing is ok when I re-assemble. Just a reminter this is a 5.5-Hp Tec engine
baymee
16 years ago
Both valves will be closed with a tiny space at the rocker, just immediately before TDC on the compression stroke.
rolm
Original Author
16 years ago
"Both valves will be closed with a tiny space at the rocker, just immediately before TDC on the compression stroke"

Sorry I am missing something, Looking from the buttom of the engine, the piston is a TDC and both valves are closed and is that it, I noticed a dimple on the camshaft gear should I line that up with a mark on the crangshaft ?
rolm
Original Author
16 years ago
Success Success It was the valve timing as mentioned by Roadbike wow I have seen everything (I think) a rock broke the blade hub and the flywheel key and the cam and crank gears spun misaligning the valve timing with-out breaking any teeth on the nylon cam gear. I saw a small dot on one of the crank teeth and matched it up with the cam dot on one of its teeth and that was it. Thanks to you guys you saved another nice running engine.
1saxman
16 years ago
Score 1 for roadbike for the tip and 1 for Rolm for digging in and fixing it. Way to go, guys!
rolm
Original Author
16 years ago
One more item I need help with, The primer bulb is not priming, The primer bulb is the hour glass type, no breaks or craks on the primer bulp the carb. is spotless, Anything I can try ( mower starts great once I squirt gas in the carb.
baymee
16 years ago
Did you check all the way back where the clamp ring is?
rolm
Original Author
16 years ago
The clamp ring on the primer bulb was ok I did replace the primer bulb and the ring with a new set, no change, as I said the carb was very clean and all the passages looked clean and were no blocked on the carb.
roadbike
16 years ago
Glad I could help with the valve timing problem. Your well written description helped to narrow it down to the piston pushing air out the wrong valve.