Kickback from Tecumseh Engine

15 years ago

Hi,

First of all, I'd like to say thanks to the members for all that I've learned by reading this forum. But I have a problem that I need help with.

I'm working on a friend's Scotts mower (Tecumseh engine OVRM120-22032D) which is kicking back while attempting to start it. I've replaced the flywheel key, which was slightly bent, but that didn't fix it, so perhaps the crankshaft is twisted. The blade adopter key shows no signs of damage and the blade is tight on the shaft. The mower did start up once and seemed to run okay for a short period until I deliberately killed it.

A couple of questions.

- Can anything else cause the kickback besides flywheel misregistration, a twisted crankshaft or a loose mower blade?

- Does anyone know how many degrees before TDC the spark plug should fire on this engine?

- Does anyone know where the flywheel magnet is positioned relative to the sensor coil assembly at the moment of ignition, ie, is it centrally aligned with the coil assembly?

- Are flywheel keys available that retard the spark by a certain number of degrees?

I would appreciate any help. Thanks.

Jim

Sort by:Oldest

Comments (5)

bill_kapaun
15 years ago
Not sure about that specific engine, but "some" engines have an offset key.

Kickback pretty much has to be flywheel/ignition timing.
I've seen it on a severely worn engine, where the flywheel actually had noticeable side play.
rustyj14
15 years ago
I've got a Tec engine here that had a nudged flywheel key, so i replaced it with a new key. Went to start it, and got the "sheared key kick-back message".
Turned it up on its side--and there i found that whatever they had hit with the blade, had sheared off the alignment pins, and turned the blade a 1/4 turn. I replaced the adapter and installed the blade. But, no start, and still conveys the sheared key message.
I'm stumped! I used the same type key as i took out of it-so--whut?
Related Discussions
Tecumseh engine with no spark.
Q
Comments (2)
I forget whether the coil is below the flywheel or outside the flywheel on yours. Likely the wisest thing to do would be do remove the kill wire from whatever switch it is attached to. Still no spark- isolate the coil from the breakers, then hook an ohmmeter to the point stud and a ground. (Re-tighten the stud nut.) While slowly turning the engine, it should ground when the points close and open when the points open.
...See More
Tecumseh engine problem...Any advice?
Q
Comments (8)
Problem(s) solved! Much thanks to Saxman1 and Baymee! The photos (especially) were very helpful. I can honestly say I would've missed the smaller hole without the blown up photos. Even after it was cleaned it was still damned hard to see with 47 year-old eyes. There was a bit of a film that cleaned right out of the bowl and I'll assume it was in the finer parts of the carb as well. After getting it running a little better, I did turn in the one screw a bit to adjust the 'hi' speed rpm's (I did this by 'ear'). I do believe there is a gauge for such but I've always had good ears for the right rpm. I'd say it was running about 2400-2500. I now have it just a shade below what sounds right (3000ish). After a short discussion with its now happy owner, he mentions to me that it had not been running well since he got it back from the service he uses this March. I suspect his repair shop was somewhat at fault. I can see no advantage to it running at that rpm. A nice guy, my neighbor but perhaps a little too trusting of their work. I think I would've burned the phone line up fairly quickly if I had gotten equipment back not running correctly. Of course I'd not have left without hearing it running. Final question for discussion: Could having it set up to run at a lesser rpm have contributed to the problem? The plug was replaced in March but seemed awful dirty for 4 1/2 months (I dropped in a new one). The oil was also low so I cautioned him to keep an eye on it in case it is burning oil (I also changed it for him). Thanks again Guys. Great forum We have here, isn't it?
...See More
Another baffling Tecumseh engine problem on a snowblower
Q
Comments (8)
The compression was 100#. I was going to give up on Thursday, take a loss, and give it back. The large-gap spark tester would produce sometimes a spark every revolution, and then would skip some, and then every rev. I decided to go over the ignition with a fine tooth comb. Removed the head and installed a dial gauge. The points should open at .89MM btdc. Used some flexstone on the points and gapped at .020 Brought the piston around and the points opened about .070 btdc, close enough. I adjusted them to .89 btdc. With the coil tester, I checked the coil (under the flywheel) and condensor. Put everything back together and it started. Maybe the water (3" ice storm) made corrosion on the points ?? I didn't find the problem. It sparks more consistently now.
...See More
Tecumseh engine leaking gas in storage
Q
Comments (5)
Well, there is no primer bulb so I guess that leaves the inlet needle. I am waiting for a call back to sell this chipper, so the timing is really not good. I guess it would be bad to just put a shutoff on the fuel line (especially if I sell it), but I hate to go mucking with the carb when it seems to be running fine now. If I open it up and check the float, how will I know it is bad? Will I be able to shake it and hear/feel fuel in it? Should I just go ahead and order one with the rebuild kit? Obviously this isn't the sort of thing I usually get into, but I think I should be able to handle it if I have to do it. You may recall I bought the Mighty Mac chipper near you from Dave. I wasn't going to buy this chipper, but I was buying a bunch of stuff from a guy who was moving to Florida and he made me a deal I couldn't refuse. This one came with a tow kit for the tractor and I was thinking that it might be easier to deal with that than mounting the Mighty Mac on the tractor (which is not easy if you don't have someone around to help you). I finally decided that I really didn't want another engine to maintain and the might mac has more power anyway, so I posted an ad for the Tomahawk. Of course now it seems I was right about maintaining another engine. I don't know though, I may have to reconsider the mighty mac if I get personally 'invested' in this chipper. Greg
...See More
cuejal
Original Author
15 years ago
Thanks Bill.

To Bill and Rusty:

This probably doesn't apply to your machine Rusty, but I found the problem with my friend's Tecumseh. In addition to having a partially bent/unseated flywheel key, which I had replaced prior to posting here, I checked the valve lash. It turned out to be about 4X what the manual called for, on both valves! Apparently the compression release mechanism wasn't able to do its thing, at least not to the full extent, because of the excessive play in the exhaust valve train (which the CPR acts on in this case).

After adjusting that to spec, and replacing the recoil starter, which finally broke for good during prior testing, it starts nice and easy now.

Jim
kersplat
14 years ago
There is Two major flywheel keye used in Tecumseh engines, a grey aluminum one and a gold aluminum one. each one times the flywheel magnets differently and if you use the wrong one it will kick like a mule.
1saxman
14 years ago
'Apparently the compression release mechanism wasn't able to do its thing, at least not to the full extent, because of the excessive play in the exhaust valve train (which the CPR acts on in this case).'

I was going to say the compression release was not working but I did not know why. This is probably it.

Kickback from Tecumseh Engine

Comments (5)

bill_kapaun

rustyj14

Related Discussions

cuejal
Original Author

kersplat

1saxman

COMPANY

BUSINESS SERVICES

GET HELP

CONNECT WITH US

Kickback from Tecumseh Engine

Comments (5)

bill_kapaun

rustyj14

Related Discussions

cuejalOriginal Author

kersplat

1saxman

COMPANY

BUSINESS SERVICES

GET HELP

CONNECT WITH US

cuejal
Original Author