Tecumseh OH160.


Old 12-11-08, 07:03 AM
Thread Starter
Join Date: Aug 2008
Location: Wisconsin, USA
Posts: 10
Angry Tecumseh OH160.

:wall. I'm at wits end with this problem. I rebuilt the engine putting new valves, new rings and a new piston in. The starter spins the engine like a top without the sparkplug installed or with the sparkplug installed and a spark tester between the sparkplug and the sparkplug wire. If I put the wire right on the sparkplug and try to start it, the compression at TDC is too much for the starter to overcome. I pulled the camshaft and looked at the compression release mechanism and don't see anything broken, but the books don't say much about it other than if it's broken the camshaft has to be replaced. The compression release mechanism isn't connected to anything, except the camshaft. Can you tell me if there's supposed to be a little rod or something connecting it to something else? The valve gaps are set to spec and the timing marks are lined up between the crankshaft and camshaft. When I try to turn the engine over by hand with the sparkplug in, it's very hard to turn when it's around TDC and you get a slight hissing sound. I don't want to reinstall it in the tractor again without somehow getting it limbered up so the starter can spin it fast enough for it to start. Any advice you can offer with regard to the compression release mechanism and how to know what to look for on that in addition to the minimal info mentioned in the book would be greatly appreciated!
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Old 12-11-08, 02:59 PM
Join Date: Jun 2006
Location: St. Louis
Posts: 2,333
The compression wouldn't change by installing a spark tester, the ignition timing might change slightly so it might be possible the ignition module or the flywheel key alignment is off and the engine is trying to kick back. Have a good one. Geo
Old 12-11-08, 03:33 PM
Thread Starter
Join Date: Aug 2008
Location: Wisconsin, USA
Posts: 10
Question Tecumseh OH160

I have the timing marks lined up between the crankshaft and camshaft. Is the flywheel key alignment something different than that?

Also, the engine tried to **** to the left when I tried to start it and wouldn't budge from TDC with the sparkplug connected to the ignition wire. The engine spun fine and the spark tester showed spark when that was connected in line. It also went like a bat out of hell with no sparkplug installed.
Old 12-11-08, 06:19 PM
Join Date: Jun 2006
Location: St. Louis
Posts: 2,333
The crankshaft, camshaft is valve timing, the flywheel key and ignition module is ignition timing. If you have ever had a lawn mower that tried to jerk the rope out of your hand when you tried to start it, it was because the flywheel key was partially sheared which changed the ignition timing causing it to fire at the wrong time, which can make it seem as though it had massive amounts of compression. Have a good one. Geo
Old 12-12-08, 01:31 PM
30yearTech's Avatar
Join Date: Oct 2006
Location: Central Texas
Posts: 1,176
What did you set your valve lash at?

If you have too much clearance on the valve the compression release operates, it will not work to release any compression. Valve clearances are very important.
Old 12-13-08, 12:41 AM
cheese's Avatar
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Join Date: Jul 2001
Location: USA
Posts: 16,575
I agree with the above. Double check the valve clearances and the flywheel key. One or the other is likely to blame.

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