My Tractor Forum banner

1 - 12 of 12 Posts

·
Registered
Joined
·
108 Posts
Discussion Starter #1
Briggs and Stratton 12.5 HP IC Veritical. Serial is 289707 0154 01. Engine won't crank unless spark plug is taken out. It is not an Overhead Valve. I guess it still works on the same prinicipal as a OHV engine. Would you take off the carb to get to the cover to see what the clearance is? I don't for the life of me know what to do next. Thanks.
 

·
Registered
Joined
·
241 Posts
Forgive me if I am off base here but shouldn't the starter have enough torque to rotate the engine through the compression stroke when both valves are closed?



The description you gave sounds like hydro lock, which doesn't seem too likely.
Weak battery?

can you see one or both of the valves through the spark plug hole to get an idea if they are opening and closing as they should without regard for clearance?
 

·
Certified Technician
Joined
·
8,420 Posts
Yeah remove the carb, remove the little valve spring cover. rotate the engine by hand until one valve is up, check the lash at the opposite one, and vice versa...

Get back with the results, as I recall you should be near .007" or so.
 

·
Certified Technician
Joined
·
8,420 Posts
I can tell you it was far more common for valve lash to be too small o r disappear on flatheads than to go too wide.

A stuck brush in the starter could also create issues. When the plug is out, does the engine turn over strong? When its in, does it turn sharply to compression, then stop, then go around again?
 

·
Registered
Joined
·
108 Posts
Discussion Starter #5
Battery was load tested at my local auto store and tested good. I am not able to see the valves through the plug hole. Bypassing the starter solenoid does not improve the problem. There are 10.8 volts going to starter when key is turned.
 

·
Certified Technician
Joined
·
8,420 Posts
with the key off and using your hands on the chaff screen on the top of the flywheel, can you physically turn the engine over when it comes to the point it stops spinning with the starter?
 

·
Registered
Joined
·
108 Posts
Discussion Starter #7
Thanks Red, I will do that. Briggs website says intake 5-7 and exhaust 9-11.
 

·
Registered
Joined
·
108 Posts
Discussion Starter #8
Well, didn't need to touch the valves.....noticed a little puddle under the engine. It wasn't gas. I wasn't oil. It kind of floated on top of the cement. It was H2O. I drained the gas out of the tank, and loosened up the float bowl on the carb. I got it going. Funny, I actually ran the thing for about 5 minutes before it stalled on me. The water probably needed time to work its way from tank to carb. Cheap stinkin gas these days. Thanks everyone.
 

·
Registered
Joined
·
241 Posts
Wow, I guess I should have had more confidence in my first instinct (hydrolock). I am a boater and it is much more common to see hydro lock in the marine environment.

Glad it was something so simple.
 

·
Certified Technician
Joined
·
8,420 Posts
strange, you would need a sumbstantial amount of water IN the cylinder to hydrolock it, like...probably 8-10cc's at least. And water generally will not draft easily up the carburetor into the engine (although on full choke, droplets can make it in.

Hope it stays fixed.
 

·
Registered
Joined
·
241 Posts
strange, you would need a sumbstantial amount of water IN the cylinder to hydrolock it, like...probably 8-10cc's at least. And water generally will not draft easily up the carburetor into the engine (although on full choke, droplets can make it in.

Hope it stays fixed.
I was thinking the same thing. I've never heard of hydro locking a motor from phase separation, but I don't know the history on that motor. How exactly did the water get on the floor in the first place? Is the carb leaking?
 

·
Registered
Joined
·
108 Posts
Discussion Starter #12
It looked like it dribbled out of the muffler. I'm still perplexed at to what the actual problems were. I'm using a different battery right now just to crank it to get it started. I'm not convinced that the battery on it is in good enough shape but will tackle that once I get everything back together....now I tackle the oil leak and see where that is coming from.
 
1 - 12 of 12 Posts
Top