My mower is spitting gas back out of the little vent holes in the gas cap. It also seems to have more vibration than usual. (I did just also install a new blade.) Motor is a B&S 3.75 HP Sprint. It is about 8yrs old. Ideas? Joe?
Sounds like the blade is not balanced...... they sell those little blade balancers at alot of hardware type stores. I bought a blade that did that once.....had to grind a little "meat" off of one end Mike
Check with the blade and see if it clears up. How hard is it vibrating? Maybe the vibrations are strong enough to slosh the gas around to do that. Did you notice any vibrations or problems before the new blade? How long has it sat without being run before you started it? How long has it been since it had a new plug and oil? How did you install the new blade? Joe? Sorry if some of my questions sound like the obvious, or dumb questions, its hard to tell without actually seeing it for myself, im just trying to go through the whole list..
Used it once previously this year, a couple of weeks ago. No problems then. Only does the vibration thing while cutting, not just sitting. If I put my foot on the deck it goes away. Changed the oil this morning with the blade. The blade is a universal one from Home Depot, and uses a little squared-off washer adapter thingy in the center to attach to different mowers. May try to just get a better blade that is specific to my mower. Went ahead and finished the yard and the spraying gas problem went away after five minutes or so, so maybe it's always done that and I was just paying more attention than usual. Joe Naab(?), the guy with the 67 Riv with the Nailhead, is a small engine mechanic, IIRC.
How about this: The vibration will cause the fuel to come out the vent hole in the cap. The tank is full (I assume) and the vibration causes "white caps" in the fluid and it splashes out. After 5 minutes the level is low enough in the tank that the "white caps" don't hit the vent. - Bill - Bill
Sounds to me like you have a bent crankshaft.....possibly from the blade hitting a sewer pipe or a tree stump.....maybe a large rock? Here's what to do- Disconnect the spark plug wire, then stand the mower up on end so you can see the blade bolt. Have another person pull the rope slowly, and watch the blade bolt.........if it spins off center then the shaft is bent. It doesn't take much to cause the shakes. :bglasses:
Thanks, Joe!!!! I bet you are right, because, now that I think of it, I do think I remember hearing the blade just scrape the deck when it first started. I bet it bent the deck out of the way after a revolution or two... I'll check that. If it is bent, should I just spring for a new mower? (given it's age...)
give me a mdl type and trim and i can get you a price of that crank. you may also/or have a cracked mower deck had one that would shake like crazy and it was because the deck fatigued and had a crack in it and only holding the engine on by basicly 2 bolts. -nate
It's prolly cheaper to just get a new mower, unless you have $650 Toro or something like that. You could possibly get the shaft straightened at a small engine shop, but they would have to be willing to do it. That poses a liability issue, as the crank has become weakened and if you hit something again, it could snap off :shock: (seen that happen) Replacing it with a new crank is the best remedy, but usually a new crank will set you back at least $75 and a lot of work installing it. I'd be OK with straightening it if it was only slightly bent. :bglasses:
