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Discussion Starter #1
Hi all, been a while.

I have a briggs that is very hard to start, technically, it won't. It will struggle to trying to turn over.

It seems like the culprit might be a bad compression release, but i'm not sure if this motor even has one. It's a 311777. For what it's worth, I turned the motor to see if the one valve will dip just a bit (compression release), but it does not do that.

I'm wondering though if something like a bad gap on the valve could be to blame. I set them a while ago but when i tested it today, they were very close (i couldn't get a .003 feeler gauge through when it calls for 003-005.

The only clue i have is that, when i turn the engine by hand, i can hear a hiss of air trying to come out of a valve, i'm not sure which one. Can anyone give me a reason as to why this would be? Is it normal? I would think not.

Anyway, thanks for any advice. I have a video where you can hear it. It's a struggle to even turn the engine by hand with a 14" wrench. https://imgur.com/a/OfJNegM
 

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Discussion Starter #2
just an update. i went and reassembled the valves just to make sure everything was seated right and adjusted the gaps more closely to spec. i removed the springs and pushed in the top rod beneath the spring in some, the motor could turn by hand much more freely. so i put everything back together thinking maybe it was a valve adjustment, still hard to turn. if i push in the valve by hand while im turning, it frees up the flywheel and makes it easier to turn. here's a link to a video showing what i mean - https://imgur.com/a/Bb8233a
 

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Have you removed the sparkplug yo see if it turns freely? I have to assume though that you did because it's pretty much the only way to find 1/4 inch past TDC to do valve adjustment. The compression release works on the intake valve. The other reason to crank with plug out is in case you have flooded gas and oil into cylinder and it's hydrolocked.
 

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The bottom one is the intake on a 31 series (and most briggs) and should be the one the compression release (ACR) "bumps" open right after it closes.
The gap for the intake is .003-.005 and the exhaust is .005-.007. Valve on this one are set at piston 1/4 inch down past TDC compression stroke.

After you adjust valves if you have no ACR bump you cna get it to start by turning it past the compression stroke or backwards away from it and then remove air filter cover and hold your hand over the intake to block all air. Then crank it. It should be enough to get past the hump and start up.
 

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Discussion Starter #5
Have you removed the sparkplug yo see if it turns freely? I have to assume though that you did because it's pretty much the only way to find 1/4 inch past TDC to do valve adjustment. The compression release works on the intake valve. The other reason to crank with plug out is in case you have flooded gas and oil into cylinder and it's hydrolocked.
Hi 38. Yes, I removed the spark plug and it was able to turn over freely by hand and via starter. I started turning the engine with by energizing the post on the starter and it spun with no issue. I watched the spark plug hole to make sure there was no liquid spitting out, there wasn't any. I also watched the valves (i kept the cover off), and they seemed to be functioning normally. once i replaced the spark plug, the starter couldn't get it 1 rotation.


After you adjust valves if you have no ACR bump you cna get it to start by turning it past the compression stroke or backwards away from it and then remove air filter cover and hold your hand over the intake to block all air. Then crank it. It should be enough to get past the hump and start up.
Hi Toby, i did see this trick somewhere but couldn't get it to turn, though you have given me more info (turning it past compression stroke / backwards), so i will give that a shot. thanks.
 

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You have to block off all the air flow going into the intake for this to work. It's amazing what a difference it makes.
 

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Discussion Starter #7
just curious, can the motor run, at least for a short time, with with the valve cover off? Would like to readjust valves if i can get it started but would like to skip the step of putting it back on / taking it off.

thanks.
 

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What size battery are you using? How many amps? Have you had the battery tested? Unless you weren't at tdc when you did the valves everything you've described sounds normal. Make sure you've got a good, full charged battery. Go to Menards and get the big one and give her ****!
 

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Discussion Starter #10
lol i won't be trying to adjust valves while it's running, i'd love to see someone try.

as for power, i've tried jumping it from another rider, jumping it from a car battery and one of those little power pack jumpers (which i managed to destroy in the process)... there's just a lot of compression, its tough to spin it using a wrench by hand. when i remove the spark plug or push in one of the valves, it turns like it should.
 

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Discussion Starter #12
unfortunately i do not. when i try to spin the engine with a wrench, i can hear the air trying to escape out of what i believe to be the valves. it's almost like it's hydrolocked, but with air since there's nothing in there. nothing can escape (well it does, slowly hissing out of a valve, it's possible it could be another close area).
 

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It's not that anyone would try to adjust them with it running, is that you do not adjust them once they're warm. All valve adjustment on Briggs & stratton's are done on a cold Engine with the Piston 1/4 inch down past top dead center. You don't need to get them warm every checked them because you're reading this would be wrong.
 

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What you're hearing is probably air escaping slowly around rings into the crankcase.

Explain how you found TDC when you adjusted the valves. Your cam (if I remember right) is solid and has no moving pieces for compression release. It's a special cam lobe and if you adjust valves at tdc instead of 1/4" past TDC, you effectively just eliminated your compression release feature.

To adjust, take out the spark plugs and rotate the engine until you see the intake valve open and then close. Once it closes, put a screwdriver down until it touches the piston. Rotate until the piston is at TDC (piston stops moving). Turn for another 1/4" so the piston begins to retract on the compression stroke. Both rockers should now be loose, and this is proper location for valve adjustment.
 

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Discussion Starter #15
thanks for that info toby, i did not know that the engine should be cold to test the gaps.

hi bacon, yes, that is how I adjusted the valves. you're saying that this motor does not have the compression release feature?
 

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This was a quote from Walt 2002 some time ago, but supplies to your engine

Your engine uses an "Easy Spin" cam grind where the Intake cam lobe is ground in such a way that the Intake valve does not close until very late into the compression stroke. This allows some compression to be expelled back thru the carb easing starting. Once the engine starts the "leaking" compression is diminished due to the "lag" of incoming air as piston speed increases according to B&S.
 

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What you're hearing is probably air escaping slowly around rings into the crankcase.

Explain how you found TDC when you adjusted the valves. Your cam (if I remember right) is solid and has no moving pieces for compression release. It's a special cam lobe and if you adjust valves at tdc instead of 1/4" past TDC, you effectively just eliminated your compression release feature.

To adjust, take out the spark plugs and rotate the engine until you see the intake valve open and then close. Once it closes, put a screwdriver down until it touches the piston. Rotate until the piston is at TDC (piston stops moving). Turn for another 1/4" so the piston begins to retract on the compression stroke. Both rockers should now be loose, and this is proper location for valve adjustment.
I turn until the piston actually moves down 1/4 inch from tdc.
 

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Discussion Starter #18
so...

have you ever had one of those moments, a moment where you really need to re-evaluate your life choices, where you need to just shut it all down and wonder what in the f was i doing or thinking at some point in time?

well, that happened to me today. i've adjusted valves before (including on this engine) and this thing had run prior to me working on it this time. the last time i worked on it, i must have maladjusted the valves causing it to lock up.

so i'm looking at it today and i'm getting it to TDC. then i realized -- i'm going the wrong **** way, i was looking for TDC with the piston down near the shaft. i don't know what i was thinking. got my mind straight and put it to actual TDC, adjusted valves (still a little stiff to turn, but it's easier and i'm seeing the decompression bump on the one valve).

double checked the valve clearances, reinstalled the cover, added some gas and a bit of starter fluid.

fired right up, let it run for about 3 min sounds great.

sorry for wasting everyone's time, i don't know where my mind was. i'm going to go cry in a corner somewhere...
 

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so...

have you ever had one of those moments, a moment where you really need to re-evaluate your life choices, where you need to just shut it all down and wonder what in the f was i doing or thinking at some point in time?

well, that happened to me today. i've adjusted valves before (including on this engine) and this thing had run prior to me working on it this time. the last time i worked on it, i must have maladjusted the valves causing it to lock up.

so i'm looking at it today and i'm getting it to TDC. then i realized -- i'm going the wrong **** way, i was looking for TDC with the piston down near the shaft. i don't know what i was thinking. got my mind straight and put it to actual TDC, adjusted valves (still a little stiff to turn, but it's easier and i'm seeing the decompression bump on the one valve).

double checked the valve clearances, reinstalled the cover, added some gas and a bit of starter fluid.

fired right up, let it run for about 3 min sounds great.

sorry for wasting everyone's time, i don't know where my mind was. i'm going to go cry in a corner somewhere...
been there, done that. Oil into the gas tank, gas into the crankcase. Last night I had to use a battery charger boost to get mower running. Wife is yelling at me to stop as I was dragging it across the lawn. Had to round up enough extension cords to get it started again.
 
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