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ST112 Frozen engine


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#1 KA1J OFFLINE  

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Posted October 10, 2016 - 07:30 PM

Things just got curiosier. I've been talking about my new ST110 and some issues with the steering http://gardentractor...steering-wheel/  This supposedly has been garaged from the beginning though there are some small rust blisters on the paint. For all intents, its in physically nice shape body-wise.

 

I just picked up a parts tractor today which was left outside for quite a few years, its a ST112 Model 3112G Serial 0100332. The steering on this is ideal so I can transfer the steering parts over and all will be tight. The brake seems to be more solid of a feel than the one on the ST110 as does the shift seem to be. At least the shift appearsa to lock into the selector indents properly & on the ST110 I have to fudge a little to be sure its in gear. Both the brake and the shift might just be a matter of adjustment.

 

The main difference is the body on the ST110 needs some touch-up paint and it is much looser in brake, gear and steering. The ST112 needs a fair amount of prep and paint but the overall mechanisms seem to act as they should. However, the engine on the 112 is frozen. It has supposedly sat for years without being turned over. The oil is at the tip of the dipstick, not full as it should be.

 

I'm thinking if the 12 HP ST112 can be made to run, there is more HP and I won't have to bother swapping parts. If the engine is toast, then its only going to be good for parts. I'm not clear on how to remove the shroud and to get to the valves. If there's a bent valve, its over but perhaps the valve is just stuck? I removed the spark plug and it looks good, no carbon and there's no sign the engine filled with gas from a leaky carb valve. 

 

Any suggestions on how to remove the shroud so I can get a good look at the engine and better, how to best access the valve cover? I'm sure the carb needs overhauled, I can do that easily, I have done that plenty on old Yamahas but I have to admit, I've never had to unstick an engine that does not budge. I'm not wil;ling to force it to see if it breaks free, I'd rather go about this conservatively.

 

Suggestions?

 

Thanks,

 

Gary



#2 secondtry OFFLINE  

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Posted October 10, 2016 - 08:23 PM

   If the oil is over full it may be full of water. Irregardless if it sat in the weather for years the first thing I would do is drain the oil an see what I find. At the top of this page you will find the manuals tab. Check there for your engine manual. Some people on this forum read all the post and try to help any one they can. The more information you can provide in your post as far as the engine make, model and size the more effective and knowledgeable the responses will be. I'm sure the Bolens guys know what engine is in the ST112 but I have no clue. It sounds like you have two valuable projects. Enjoy the process. Don


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#3 KA1J OFFLINE  

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Posted October 11, 2016 - 07:45 AM

The engine is a B & S and this version of Bolens (ST112 Eliminator) uses a single cylinder 12 HP model 281707-0127 and when I try to turn the engine by hand, there is zero rotation. Removing the plug did not free up rotation.

 

The case is not full of fluid, there was only the least drop of oil on the dipstick. The cylinder does not contain fluid and the spark plug is dry and shows no carboning, the ceramic is not discolored and does not appear to have been in a lean environment. The air filter is in place so it does not appear any water or oil overfilling has happened.

 

The engine is seized and I don't know why. Since the oil is so low, its possible the last owner ran it dry and the piston seized. Perhaps it threw a rod but I see no sign of oil splatter. I'm assuming this has push rods so perhaps one of those is bent and has jammed the cam. Maybe... Well, I just don't know but it 's frozen solid as a rock. Seems like I'll have to remove the side panels, grill & hood to have access to the engine. But even with that, I don't know how to adjust the valves on this engine. I checked on youtube and see info on a 12.5 HP, probably much the same but I have no idea how to adjust valves when its not something with a valve cover to give access to adjusting like I used to do on auto engines like my V-dub, back in the day.

 

I'll enjoy working on this but finding the technical info on exactly how to repair & tune up might be more of a challenge. 


Edited by KA1J, October 11, 2016 - 07:46 AM.


#4 boyscout862 OFFLINE  

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Posted October 11, 2016 - 07:53 AM

Is this the one that was advertised as an ST120? Before pulling the engine out, pull the spark plug out and spray PB Blaster into the combustion chamber. Replace the spark plug and give it some time. Check that it isn't a stuck belt or PTO that is keeping the engine from turning. Also check that the electric starter isn't jammed against the flywheel. Some picks will help us. Download the B&S Repairman's Manual from our Manuals Section. If the engine ends up being shot, there are plenty of B&S donor engines around. Many parts tractors only suffer from a safety switch gone bad. Good Luck, Rick

Edited by boyscout862, October 11, 2016 - 07:55 AM.


#5 KA1J OFFLINE  

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Posted October 11, 2016 - 08:18 AM

Hey there,

 

Yes, this is the one you pointed out. I really only went to see about the steering parts but when I found they are working pretty much 100% as new, I was sold on getting it. But then I came to realize there are things on this one that are even better than the original ST110 and seeing as I plan to touch up the paint on the 110, maybe I'd be better off keeping this ST120? Either way, this new one has excellent steering, a nice seat, brakes, transmission linkage is good and more. What's nice is there's much to be swapped to make for a really fine tractor from the two of them & I'm glad to have it. Now I have a choice as to what to do.

 

I'll check & see if any belts are binding but I don't know how to check for the PTO causing this problem. I'll spray with PB as you suggested. 

 

Is this the manual you're thinking of?  http://gardentractor...ylinder-l-head/

 

And thanks!


Edited by KA1J, October 11, 2016 - 08:32 AM.

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#6 Bruce Dorsi OFFLINE  

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Posted October 11, 2016 - 08:24 AM

 

...there was only the least drop of oil on the dipstick.

 

The engine is seized and I don't know why. Since the oil is so low, its possible the last owner ran it dry and the piston seized.

 

I'll enjoy working on this but finding the technical info on exactly how to repair & tune up might be more of a challenge. 

 

 

Usually, when an engine seizes up from not enough oil, the connecting rod seizes to the crankshaft journal.  .....As heat is built-up due to insufficient lubrication, material from the connecting rod is deposited onto the crankshaft journal.  ...When this happens, one of two things occurs.  ....Either the engine seizes and stops running, or the connecting rod breaks, which can puncture the block and/or cause damage to other internal parts.

 

If you are lucky, the crankshaft can usually be saved, and just a new connecting rod needed.

 

The piston can seize in the cylinder, but that is not as common.  ...If the piston does seize in the cylinder, the bore is usually trashed, so the block is unusable.

 

A Repair Manual covering your engine model is located here:  http://gardentractor...singles-270962/


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#7 KA1J OFFLINE  

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Posted October 11, 2016 - 08:43 AM

Bruce, Thanks. The first big clue is the low oil. I have zero history other than it supposedly was running, the owner was too old to use it and it sat for years, someone bought it to flip and I bought it being sold for scrap/parts. The battery is long since toast and there's extensive surface rust on the engine. Once I figure out how to remove the hood & metal surrounding the engine, I'll do as Rick suggested and post some pics.

 

I've restored several old Yamahas but none were stuck like this so its a new problem to resolve.


Edited by KA1J, October 11, 2016 - 08:44 AM.


#8 Bud W OFFLINE  

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Posted October 11, 2016 - 09:48 AM

A couple of years ago I bought a Bolens 770 with a vertical shaft briggs at a consignment sale that was tight (no oil visible in the crankcase). When I got it home, I pulled the spark plug and PB blasted the cylinder and let it set for a couple of days. I got a breaker bar with a cheater bar and socket that fit the flywheel nut and at first it wouldn't budge. then I got a little movement and finally got it loose. I put oil and gas in it and it fired right up and runs good! 


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#9 KA1J OFFLINE  

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Posted October 11, 2016 - 02:29 PM

I've taken it apart shroud wise and it is going to be a sad day for the rodents that made it a nest and bathroom because their palace is no longer there. I'm guessing the "frozen" engine might have to do with the thick layer of crud under the starter gear. I can't get to it, I've tried urging the gear to move now that I vacuumed everything I could. I used a block of wood and tapped it with a rubber mallet, didn't hit it hard but one of the teeth still broke and there is zero motion. 

 

I tried to get the three screws out from the round screen on top of the engine so I could get a huge pipe wrench onto the shaft but I can't get them to come off. I used Kroil which is about the best penetrating oil out there but they are not budging. I don't want to damage them or break/cut them off but I do think this engine is toast.

 

Seems like my best bet will be to use it for parts, remove what I can and take the body for recycling. The ST110 really is in beautiful condition and buying a good engine for the ST120 is not going to give me much more power and it will cost too much to make it cost effective.  I just tried the starter and it's working perfectly so I'm just about breaking even already.

 

ST120-1.jpg

 

 

It just doesn't seem worthwhile to get the engine going, too much rodent damage.

 

 

The ST110 below is really in great operating condition. I'll move the steering over to it and see what I can do about the brake, it feels much more "solid" on the 120, maybe its just an adjustment? Either way, I now have a lot of parts for the ST110. Moving the seat over to it right away.

 

ST120-2.jpg


Edited by KA1J, October 11, 2016 - 02:32 PM.

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#10 KA1J OFFLINE  

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Posted October 14, 2016 - 09:18 PM

Is this the one that was advertised as an ST120? Before pulling the engine out, pull the spark plug out and spray PB Blaster into the combustion chamber. Replace the spark plug and give it some time. Check that it isn't a stuck belt or PTO that is keeping the engine from turning. Also check that the electric starter isn't jammed against the flywheel. Some picks will help us. Download the B&S Repairman's Manual from our Manuals Section. If the engine ends up being shot, there are plenty of B&S donor engines around. Many parts tractors only suffer from a safety switch gone bad. Good Luck, Rick

 

I've had a bit of time to put into the project and have made some headway. I am not familiar with the way the PTO works, I think it is like an electronic clutch which engages as locked to the shaft and turns as a pulley. You mentioned perhaps it is a stuck PTO that is causing the engine not to turn. 

 

I removed the mower bed from both the ST120 & ST110. The 110 is working properly and when the motor is running, the bottom pulley does not move until the PTO is engaged. When the engine is shut off, the bottom pulley spins freely. On the 120, the pulley does not move and nothing I have done has moved it in the least. I have not put a wrench to it to try to force it as that's probably a good way to further damage something. With this, your comment about a stuck PTO may be exactly what the problem is.

 

I'm trying to figure out what to do to remove the PTO and then, how to test it.

 

Is the PTO something that can be easily rebuilt or is it a throw-away if its failed?

 

Thanks!

 

Gary


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#11 boyscout862 OFFLINE  

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Posted October 14, 2016 - 11:26 PM

Sometimes the PTOs are repairable. You should save it anyway. BTW 12 hp B&S engines are cheap and common. Good Luck, Rick

#12 KA1J OFFLINE  

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Posted October 15, 2016 - 12:27 AM

Thanks, Rick!

 

I'm glad you told me about the 120; the seat is much better, the tires are better, the starter works perfectly, the steering is way better. It says "tilling transmission" on the 120 so maybe that's a better transmission & if so I'll transfer that over next spring. All in all, this was a great find for me.

 

Couple questions, I was looking at the manual trying to find out about how to deal with the brakes and i finally found what I need to know on Youtube. Hopefully I won't need new brake pucks, if I do, I'll ask which #'s to look for. Maybe I can just use the ones from the ST120, those brakes seem just fine.

 

Cheers!






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