problem with craftsman 7.0 B+S after oil flush

[ziggy]

hey all. have a craftsman 7.0 horsepower briggs and stratton rotay lawn mower/mulcher. This year, i used some seafoam, maybe like 4ozs. ith the 20 ozs. of oil in the mower, as a mild flush. Lots of black goop came out. It uses SAE 30 oil, which last year i put valvoline in, this year i used fresh pennzoil SAE 30 after the flush. I also changed the spark plug, champion which i bought at local hardware store, 12YRC i think is the spark plug number.
so!! after doing so, a few weeks went by, and noticed the mower was really hard to start. I did gap the spark plug to handbook specs, .30 gap. i noticed thier was clear oil all over the copper tip of the plug as well. the old plug was all carboned up with chunky black carbon.
It will eventually start after pulling the chord like 9 or 10 times, but seems to misfire too...black to white smoke coming out of the carbeurator exhaust. what gives with it????
My craftsman handbook says under troubleshooting, for hard to pull chord, sprak plug, mower level too low, or crankshaft needs to be replaced.
is it possilbe, the seafoam messed up the crankshaft?

 

[SuperDave456]

My thought is that when you flushed you loosened up more junk than you bargained for.

I would warm it up and then change the oil again. My bet is that there are chunks of stuff on the bottom that are being suspended by the "clean" oil.

My 1 year old Toro has seemingly clean oil until you change it when it has been warmed up due to the same reasons.

 

[ziggy]

I see. well the other thing i noticed, was the mower blade seemed to be coming loose after starting up, then it would shut off. the bolt that holds the blade to tohe adapter, kept coming loose no matter how tight i tightened it!
so perhaps another flush is in order? or could thier be a damaged crankshaft at this point? are they easy to replace?

 

[motorcity]

Put some Loctite on the blade bolt. I always put it on when I change blades. I used my impact to tighten them up, but don't overtighten with it. You may also want to put some Marvel Mystry Oil in the gas. It will help clean out some of the carbon on the piston top and clean the valves.

 

[boraticus]

Just curious but how old is this engine? What prompted you to flush it in the first place?

I've owned numerous small and large engines for decades. Never flushed one - ever. Sometimes fixing what don't need to be fixed will get you into a fix.

Change the oil as required. That's all you need to do unless you submerge the engine in water. Then a series of flushes will be required. Otherwise, don't bother.

Now, regarding your problems. Starting issues have nothing to do with a crank case flush unless a fair amount of oil entered the combustion chamber. If so, you may need to put a few drops of fuel into the spark plug hole and fire it up. If it continues to run well, that means the carb is likely OK. If it's still difficult to start, you might have a flooding problem which is indicated by black smoke. White/bluish smoke is oil. Make sure your air filter is clean and if the carb has a choke, make sure it's operating correctly. If the choke sticks in the on position, the engine may stall soon after starting and you may see some black smoke.

Regarding the screw that holds the blade on. Chances are you have stretched it. I'd suggest you get a new one and use blue Loctite. Tighten according to torque specifications.

 

[Steve S]

Originally Posted By: boraticus

Just curious but how old is this engine? What prompted you to flush it in the first place?

I've owned numerous small and large engines for decades. Never flushed one - ever. Sometimes fixing what don't need to be fixed will get you into a fix.

Change the oil as required. That's all you need to do unless you submerge the engine in water. Then a series of flushes will be required. Otherwise, don't bother.

Now, regarding your problems. Starting issues have nothing to do with a crank case flush unless a fair amount of oil entered the combustion chamber. If so, you may need to put a few drops of fuel into the spark plug hole and fire it up. If it continues to run well, that means the carb is likely OK. If it's still difficult to start, you might have a flooding problem which is indicated by black smoke. White/bluish smoke is oil. Make sure your air filter is clean and if the carb has a choke, make sure it's operating correctly. If the choke sticks in the on position, the engine may stall soon after starting and you may see some black smoke.

Regarding the screw that holds the blade on. Chances are you have stretched it. I'd suggest you get a new one and use blue Loctite. Tighten according to torque specifications.

 

[ziggy]

WOW thanks for the replys all!!
how much Marvel mystery oil should i add? i forget how much gas the engine takes too fill it. Would it be wise to replace the carb?

 

[SrDriver]

Use a lock washer on the bolt holding the blade on. I had the same problem and that fixed it.

Found one in one of the "junk boxes" I had laying around.

Run mower until engine has warmed up. Drain the oil and refill with 20 oz of 30 weight oil.

 

[ziggy]

ok cool will do. I didnt reply the reason why i di a flush. Past few years, (it was my sisters fiances mower) i was doing his oil changes for him, and the oil always came out thick gooey n dark. SO! this year i decided maybe a little seafoam to clean things up* thats when this hard to pull the starting rope started*