Craftsman/Briggs starter

12 years ago

I've been having for a few years trouble with my Sears Craftsman LT1000 Briggs 31C7070230E1 engine starting after it has been used a while, like when the engine is hot and gets the starter hot. I've recharged the battery with an external charger beforehand, that doesn't seem to help. When I turn the key when the engine is hot, I can get silence for a few seconds, then slow spinning, but most times it won't spin the engine long or fast enough to re-start. I've cleaned/steel wool all the connections. I used my DC voltmeter and the lawn tractor's generator is charging (13.2 volts across the battery when it's running).

When I try to start the engine when it's hot, the starter draws a lot of voltage, dragging the voltage (measured at the starter itself or over the battery) down to 8 volts. Because a brand-new battery has operated the same, and a 4-amp charger overnight didn't help, could the problem just be a weak starter motor itself? The part number I have for the starter is #693551. When running, the engine runs smooth and strong, just has trouble spinning to get it re-started after using a while Thanks for the input.

Comments (8)

Greg Goyeneche
12 years ago
First thing I would do is check valve clearances. If too wide, engine will be very hard to crank, as this defeats compression release.

Valves are set just past TDC (Top Dead Center) on compression stroke, an additional 1/4" past TDC. Both intake and exhaust should be .004 - .006 as measured by a feeler gauge. Loosen nut on rocker, adjust screw to get a "soft" drag at .005 and then retighten nut, holding screw. Recheck clearances to make sure nothing has moved. Rotate engine several times by hand and recheck one last time at TDC + 1/4", and if you're in spec, put it back together.

Could also be a bad solenoid, but I'd start with valve clearances.
walt2002
12 years ago
Valve clearance is .003" - .005" for Intake which is the important one for compression release. .005" - .007" for the exhaust.

If you continue to heat up the starter like that, you will ruin it if it isn't already.

I have detailed instrucitons for adjusting the valves plus some other helpful info IF you would like it at address below, put in proper format and remind me.

Walt Conner
wconner5 at frontier dot com
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cusser
Original Author
12 years ago
I can re-check the valve clearances; I checked them about two years ago when the mower would stall out after about 30 minutes due to a choke stuck closed (I added a 10 cent spring to fix that) and they were OK then. Do they wear/change over time?

I didn't realize that this could be causing hard cranking/resistance.
walt2002
12 years ago
IF you check your owner's manual for the engine, I think B&S will recommend valves be rechecked every two years. And yes, valves being out of adjustment is the most common cause of difficulty in cranking for B&S OHV engine.

Walt Conner
bill_kapaun
12 years ago
In the OM trouble shooting chart, "HARD TO START" has "engine valves out of adjustment" listed.
cusser
Original Author
12 years ago
Thanks for the input, I'll check my valves before I try to use the tractor.

Bill - to me "hard to start" can be either hard to crank/spin the engine, or the engine doesn't fire. I was reading the OM more as the second instance, but maybe I mis-interpretted that.
cusser
Original Author
12 years ago
Thanks, Walt and Bill, checked my valve clearance first (using a 1/4 inch drive long extension as I forgot my plastic straws) and both intake and exhaust were over 0.015 inches. So I re-set, and then re-checked, set to 0.004 at intake and 0.006 at exhaust. And it definitely does crank way better now, thanks a bunch. I even did the visual check where one watches the intake valve do a "jump-step" as indicator that the compression release is working. I had no idea that valve clearances where involved with cranking difficulty.
rustyj14
12 years ago
Yes, when i first got involved with fixing lawn mowers/tractors, the valve adjustment thing wasn't in my realm of thinking, but it didn't take long to figure out the cause of the "balking" when trying to start an OHV lawn tractor engine, or other apps! Yes, i was sent much helpful info, by Mownie, Bill Kapaun, and others.
Back when i was ignorant of valve problems, i even went so far as to change the whole engine! I wondered later, why a guy offered such a low price for the engine i took out! :^( Live and learn!
Rusty Jones