There is not much information to figure this out. Check the oil level with the dipstick. make sure the mower is level. Screw the dip stick all the way down before checking.

If the engine has the proper quantity of oil, try turning the engine manually by rotating the grass screen on the top of the engine. If this rotates freely, check the fuse.

Here is the thought. If the fuse blows, power to the afterfire solenoid will be loss and fuel flow through the carburetor will stop and the engine quits. Additionally, there will be no electrical power to energize the starter.

Well there are a number of thing that could cause this. A magnet coming loose inside the flywheel can lock the engine up and I guess you might get some smoke. Did you run it out of oil? OR more likely, did you check the oil before starting, was it over full as perhaps from the carb leaking gasoline thru cylinder contaminating oil?

Anyway, you won't really know until you tear it down and you aren't going to be out anything by doing this. you MIGHT get lucky. IF the engine is really locked internally, there probably is crankshaft damage. Sometimes these can be cleaned up.

Tulsa Small Engine will have several interchange engines. A used engine is going to cost $75 or more shipping, look for one locally. Check local small engine repair people. Small shops, large ones don't want to fool with them.

Walt Conner

"If the fuse blows, power to the afterfire solenoid will be loss and fuel flow through the carburetor will stop and the engine quits."

That sure is not going to lock the engine up BUT it could be something as simple as the belt jumped partially off and jammed between pulley and guide, check that all is free in that area.

Walt Conner

All,
Thanks for the good information and suggestions, I will give you what I have so far. After the engine stopped, and there was smoke, the first thing that I did check was the oil level, which appears to be good, and checking the feel of the viscosity, this too seemed okay to me. The oil did have a used look to it, mostly dark, but the cause of this may be that I have not changed the oil and filter since either the spring of 09 or 08, cannot remember and did not record this action. So my guesstimate is that the oil may have as much as 100 hours on it, SAE 30, but I have run mower engines before with this amount of hours with no problems, to include this engine as well. The grass screen does not move by design, it is screwed down via Bristol screws, I need to find the correct size Bristol to remove the screen. Once removed, I can use a wrench to try and turn the crank shaft bolt, but I wanted to get under the tractor to remove the crank from the drive mechanism to see if the crank will move freely. I have not done this because here in the Piedmont area of Va, we are suffering from over 2 feet of snow and it is colder than a witches, well, you know, (wont go there). That garage cement floor is so cold, water is freezing to it within minutes. This may be an April repair job.

If I try to start the engine now, the only thing that happens is a loud click, and the battery amp meter goes down to 0. Not sure what fuse you may be talking about, but I will check behind the electrical panel to see what I can find.

As for a replacement engine, the only one that I can find is from the Sears repair/parts site, (www3.sears.com). I believe that this may be a new engine, cost is $795.00, or there abouts, and you have to call customer support for this, evidently this engine has to be ordered, so I have no time frame of getting one. I have checked locally in Warrenton at a local small engine dealer/service store, and they do not have any of these and cannot quote a repair until they start to tear the tractor/engine apart. Looks like I will have to do most of the preliminary troubleshooting of this engine, when it gets a little warmer.

I will check for the fuse when I get home tonight, I will also check the Tulsa small engine website for this engine, and if they have one. Not sure when I will get brave enough to start working under this tractor, will let you know.

I think you are mistaken about the screen (unless Sears has added another or different cover). According to the Briggs IPL for that engine, the grass screen is identified as a "Rotating Screen". If the engine is locked up, of course the grass screen will not turn, but the screen usually attaches to the flywheel and rotates along with it. The rotation is important as it keeps debris thrown off. Otherwise it would not be long before the screen was clogged til no air could enter. You may want to remove the valve cover and check for a problem in the valves & springs. I'm puzzled by your remark about the "amp meter" dropping to 0. Is this actually an Ammeter or is it a Volt meter? If it is an Ammeter, I would expect the needle to display a reading in the discharge side of the gauge when turning the key to start. If it is a Volt meter and the engine is locked up, I would expect the needle to drop to near zero as the current draw would be great enough to "flatten the battery", especially if the battery is cold and already less than fully charged.
You can post the Sears model # so the actual tractor can be viewed. The number should begin with 917. (like 917.??????)

Some 31 series B&S did have a second "appearance" shroud that had a stationary screen mounted to it. The "under" shroud was metal, not the one illustrated in IPL. There was no "rotating" screen on these.

Walt Conner

"The oil did have a used look to it, mostly dark, but the cause of this may be that I have not changed the oil and filter since either the spring of 09 or 08,"

I think your B&S Owner's Manual will say to change the oil after a specified time REGUARDLESS of the number of hours.

I know it is too cold to work on it right now but you need a game plan. I would - - -

Remove the spark plug and see if engine will turn.

Check that there are no belts binding under the engine.

Remove the valve cover, as Mownie said, and check there. I don't think you will find anything there but do the "cheap" things first. Valve could have stuck when engine stopped and since you can't get to anything to back the engine up, it may be blocking rotation.

Remove the "Appearance" screen and shroud, remove the flywheel and check there.

Somewhere along the way BY this time, check that the starter gear and flywheel ring gear are not jammed.

IF you find nothing at any of these places, then only thing left that I know of is to remove the engine and go inside.

Walt Conner

Some foot notes,

When you remove the spark plug, pull it well around away from the spark plug hole and be aware, take precautions, that gasoline/gasoline fumes, may be expelled. No open flame heat sources, trouble light that might be hit, or spark from spark plug, etc, could set gasoline off. Did that once, not fun.

Of course after removing the appearance shroud, you will also have to remove the actual cooling shroud before flywheel.

I think your screen will be held on by #2 Torx head screws.

Good luck,

Walt Conner

Yes mownie, you are right, the grass screen is screwed to the flywheel, guess I never notice rotation of the screen because I drive with the hood down. Anyway, the grass screen would not rotate, so I had to remove the Bristol screws, and use a wrench to turn the crankshaft bolt. I could not turn it clockwise, it seemed to be tightly stuck, and I did not want to force it. I was able to turn it counter clockwise, for about one revolution, and then the same tightly stuck problem was encountered. However, the first time that I was able to free the crankshaft by turning it counter clockwise, it seemed tight but would move, and there seemed to be a sort of slight clanking noise, like when you deposit change in a vending machine, you hear it fall through the tracks into the coin box. When I could not turn the crankshaft counter clockwise anymore, I turned it clockwise but did not here the noise anymore, and the crankshaft would now turn much more freely now. I am not sure if the piston is moving, my thought is that maybe the piston rod collar may have broken, and now part of it is in the sump pan.

As for the ammeter, I was not correct about that either, not paying too much attention to detail here. The tractor has a little analog type meter, Amp meter, that must provide an indication of the current in the battery. The 0 mark is actually in the middle, and when you turn the engine, the needle move all the way left, I guess indicating that all current is being applied to the starter. I believe that this is a normal indication. FYI the tractor model number is 917.272751

As for the other issues, well, you gotta give me a break Walt. I know that I should be more proactive on changing the oil and filter, but maintaining a lawn tractor is not my only weekend job when I am home. I am sure you know how it is when you work all week long and are just overwhelmed on the weekends with trying to finish the basement for final inspection sometime this year, maintaining 5 vehicles, a lawn tractor, lawn mower, tiller, 3 chainsaws (one of which was bought 7 years ago and is still in its box), 2 leaf blowers, refinishing 3 bathrooms, yada,yada,yada. What am I talking about, what weekend??? I dont have any. As you can see, when it comes to putting the time into maintaining even a vehicle, most of the time I dont have the time, so I try to convince myself that whatever the mechanical device, that it should be okay for one more run, or one more week, so on and so on.

Anyway, I will dig a little more into troubleshooting this problem, I will take the spark plug out and I will try to see if the piston head is moving when I turn the crankshaft. If it is then this may indicate that the arm collar is in tack and not necessarily the problem. And if I am not sure what is happening with the piston, then I guess I could remove the head and check as well. However, the plan that I am working on now is to find a small engine shop in Warrenton or Culpeper that believes they can work on and fix this engine, without costing me an arm and leg. If this is the case, then I am hoping to get this engine off the frame and into a shop by this weekend. I have also checked on-line for this engine, and found that 31H777-0202 is being stocked as 31P777-0202. Tulsa Engine Warehouse has this item for $662.80 with free shipping. Rineyville Small Engines has this item for $597, but I do not have the shipping price, need to call them, M and D Mower has this item for $629 plus $20 for shipping. And I do believe that these prices are for a new engine as well.

I will most likely be taking this engine off the frame and getting it repaired if the price is right, but the diagnosis and repair will be sometime next week, hopefully. So I will let you all know what the deal is when I know more.

Thanks for all the help.

Howard

hms349, all that "clinking" ain't pocket change! Them is dollar bills, and fives and tens...etc. I hate to say it, but you have probably just given a textbook example of why it is most important to to do "Preventative Maintenance" like your life depends on it. I know you are pushed for time with your busy (and full) schedule, but break this failure down into increments of time and ask yourself "How many times could I have performed the oil change ritual and purchased the oil and filters in the amount of time, and for the amount of money............that this failure is going to cost me?" And I'm not singling you out for this "transgression" (there are lots of others out there). Everybody following this forum needs to think about why it is better to change the oil "too often" than "too late". Anyhow, keep us posted on what failed (when you get inside it) and what your solution is. Be sure you take lots of pictures before and during the work so you will have a graphic trail to refer to when reassembling. Good luck.

Hmmm, no comment from Walt, guess he is mad at me. Anyway, I did take time this past weekend to remove the cover, muffler pipe assembly and air intake hose from the engine in order to remove the cylinder head. Once the head was removed, I noticed that the piston was about three quaters toward the front of the cylinder. I then turned the crank to see if the piston would move, but this time, I was only able to turn the crank about one quarter turn, seems for some reason I have lost most of the travel in the crank area. The piston did not move. I was able to push the piston back into the cylinder a little more than half way, the piston moved freely without any binding when I did this. I then turned the crank again several times back and forth, but did not see any movement in the piston. Sort of sums up the fact that the piston is no longer connected to the crank. Not sure if it is just the crank collar or a broken piston rod at this point, but on Monday I did speak with a gentleman from a mower repair shop who was familiar with this type of engine, he said he actually had one in the shop for repair, about 7 years old that apparently has a broken rod. He indicated to me that this model engine (31H777-0202) seemed to have this problem after a few years of usage, and that the newer model (31P777-0202) should have better parts to last longer. When I asked for an estimate of the cost of repair, which I assume would require a total breakdown and rebuild of the engine, he was not able to give me an exact figure, but indicated that there would not be much difference in the repair cost and the cost of a new engine.

I have not done any more research to verify if this model engine does have this type of breakdown history, but if this is the case with this model B&S engine, then regular maintenance of this engine may not have made any difference in this outcome. At this point I need to put more of my time going in the direction that will get this tractor back on-line, so the plan will be to acquire a new engine for the best price. Guess I will shelve the old engine until I can either find someone who is willing to buy it from me, or use it for parts, or rebuild it myself. If I do a rebuild of this engine myself, I guess the suggestion of taking pictures will be beneficial for future hobbyist.

Thanks for all of the input guys, I will stay in touch.

Howard

hms349 - No, we aren't preaching here, and we aren't saying
" Told ya so " and sticking our collective tongue out at ya, either. We are maybe a little more experienced and offering free and good advice. Yes, even some critical observations. The ultimate goal for any of us here is to help each member here to answer questions and to try to help out. If you can get an engine that cheaply, I'd jump on it. One that size for that price isn't a bad price. Go get it, and thank your lucky stars you can at least put it on yourself. It would cost nearly the cost of the engine for labor to install it. Good luck!

I have this same engine.

The connecting rod blew in it.

I am trying to figure out whether or not to buy a short block or simply a new engine.

Are short blocks universal for the 31h777?

Someone else suggested I just get a new vertical shaft engine. They stated it didn't need to be the same horsepower.

Any help is appreciated.

Sybil

"Are short blocks universal for the 31h777? "

Yes but by the time you buy a short block from B&S you probably can buy a complete engine from some place like Tulsa Small Engines.

When the "stretched" engines such as these throw a rod they always have crankshaft damage. Sometimes this can be cleaned up if just deposits on it, not scored. Often they take out the camshaft and crack the camshaft bearing tower in the block. Sometimes take off a chunk at the bottom of the cylinder bore. Did you check the block behind the starter for cracks?

I small percentage of these I can salvage, you'll never know what you have until you tear it down and examine it.

Walt Conner

Have the same engine with similar problem..... looks like the key may have sheared, but when I got ready to pull flywheel, i noticed a crack on the back of block on the side where the steering wheel is.... Prior to that, I was able to turn the flywheel with wrench and it did loosen up but engine will now only crank and won;t start. (confirmed I do have spark). Also sounds like something is loose or banging around in there. Think I might just go for replacement engine now. Thoughts? Anything I may be missing?

Thanks,

I have the following Craftsmen LT1000 with these numbers: 917.270671 lawn mower model #. Markings on Briggs and Stratton: Model 31H777, TYPE 0297E1 , CODE 040126ZD. The mower smokes a bit upon starting but runs great, sometimes it smokes a little bit during mowing but generally all good, i keep oil in it. It DOES take oil but it's also got some age on it. but the mower is in really good shape. However, i was cutting yesterday and it was running great but i needed to go open the back gate because i forgot to open it before starting the front yard. Got 3/4 of the front done, shut the engine down. Got back on 2 minutes later and it sounded like a shoot-out at the OK Corral. Neighbors probably though i had weapons. it was turning fast like compression was limited or something and then POP every once in a while. Waited till it cooled off, same thing, when i hear one loud pop i just stop and try later. But no-go. So I heard that maybe this could be a sheared key? I have a flywheel puller on the way (briggs & stratton) and a new key just in case. Does that sound like a possibility? I can turn the grass screen on the top of the engine and i hear the different strokes, for example, i can see that the carb is making a noise through the big opening sucking/blowing during intake stroke, and i can hear the exhaust stroke, turns just fine with hands (kind of hard to turn) and with ratchet (turns much easier). I'm sure i need new piston rings due to the smoke, but she runs great and mows my yard like a champ (correction, did). If I can get through the rest of this season with a minor repair , perhaps i could rebuild the B&S motor with these parts (below) after my last cut of the season:

Engine Gasket Set 796187

$75.57

Piston Rings Set 594437

$41.80

Any Ideas are kindly appreciated!!!!

Well, it could be a sheared flywheel key. You won't need a puller to check as it is a straight key. If the key is sheared, watch that the flywheel isn't cracked. The new key number 796335 and the torque is 110 ft pounds. But, it is also possible that you have a rocker issue under the valve cover. IE a loose stud, a migrated guide in the head possibly etc. Oil consumption is more that likely a failed head gasket. I know the thing is 16 years old, but most likely the rings are fine enough.

Thanks a ton @tomplum !!, i will be pulling the head no matter what due to reported issues and your advice. When you say a straight key, where should i look for it and what does straight key mean? i have this plastic fan blade thing over the flywheel that I'm going to unbolt once a set of Torx i just ordered comes in. I'm sure that needs to come off to see the straight key you speak of? Here is the key I ordered the other day Stens 445-064 Flywheel Key, Replaces Briggs & Stratton 222698S, hope it works but if it doesn't it was only $1.68 and I'll look for the 796335 you speak of. I take it that the CODE starting with "04" is short for 2004, correct? If I don't do a full rebuild and try the head-gasket only & maybe key, does the engine have to be taken off of the mower to do the head? I assume so. Forgot to mention that the spark plug was fouling with TONS of black gunk. I was having to replace the spark plug after a few cuts repeatedly. Again, thanks for your guidance on this and sorry for so many questions !!

update: it was a blown head-gasket and displaced valve seat. all back together and starts right up , had to center-punch the displaced valve seat down after pounding the back in place with a hammer on the top of the valve, I also dimpled the other valve seat even though it did not displace with a few center-punch dimples. but engine surges now. i will pull valve cover back off and lash valves again using a different method (i used screwdriver method to find TDC but i'm not sure what stroke i was on), this time I will use moving the engine to one valve open and one closed and doing opposite valve lash then rinse repeat. setting bottom one to .004 and top one to .005 or .006 , somewhere in that range but Im not sure that would have caused the surging of the engine. Carburetor maybe? update2: got the valve clearances correct and it's bolted up back together and running! But the surging is bad. When blades engaged and and normal running speed, no surging.. bad surging at low-idle so I'm going to take carb off (ugh!) and clean out the low-idle jet and all jets and all parts of the carb with Carb cleaner (i don't have a liquid vibration machine - sorry, don't know the proper name for it).
Thanks TomPlum!