12.5HP Briggs and Stratton lawntractor motor. See details...?

Question

Ive tinkered with lawntractors and engines for a while now, all different sized motors . One in particular, ive noticed has some issues. Its a 12.5HP Briggs and Stratton engine, the two ive owned have self destructed ( by previous owner) - lack of maintenece? Bad assembly/materials? These two were on mid 90's Murray widebody tractors with 40" decks. It just seems odd that this motor failed , when i have more engines alot older then these still running and being Briggs and Stratton engines as well, with no issues.
Anyone else have this motor on thier tractor and had any issues with it? I have the model numbers if needed.
Kidd

I have a couple tractors with 12HP motors and 42" decks and never had any motor issues - it just seems its this 12.5HP motor type with issues - one block actually had a hole in it, the other has no sign of it , but the rod shattered ( piston doesnt move- I still have it- sometime ill open er up an look). I have a couple tractors/motors 20 some odd years old were seriously abused before i got them, still running great. Go figure.

Ive owned alot of lawntractors thru the years, I maintain them but use them to thier potential, personally ive never had an engine let go on me, and thats a pretty good track record since most the motors i have today are 15-20 some odd years old, and been tweeking them for around 12 years now. Im just curious why this single motor has this destruction record ( by previous owners) - it could be from neglect or overevving - ill never know.

Answer 1

Some of those briggs engines are made as cheap as possible. Also a 12 hp engine with a 42" deck is underpowered. This will cause early engine failure. The briggs industrial engines are built better and last longer. It also helps to have a full pressure oil system with a filter. Maintenance is also a big part of the issue. Most people just don't take good care of their lawnmowers. How many do you think change the oil every 25 hrs or even know how many hours are on the engine. I had a 12 hp briggs on a noma tractor that my wife abused for years. Finally a valve seat came out and I shimmed it back in with a strip I cut from a bush light beer can. It is still running today. But, I changed the oil a lot. Bottom line, they are basically good engines. There will always be problems because there are millions of them out there in the hands of people that don't take care of them.

Answer 2

Briggs And Stratton 12.5 Hp Engine

Answer 3

12.5 Briggs And Stratton Engine

Answer 4

These mowers are made to run on flats ground. You need to use some STP in the mower to stop the excess wear when the oil does not reach the oil slinger because of tilted ground.
Also running the mower on high for a long time burns the valves and need to be re seated. Never run them past 3/4 full throttle.
The transmissions are a pian too if you have an steep stops in your yard don't shift gears on the hill the transmission will break and is a pain to repair.

Answer 5

I have a 2000 model yard machines with a 17.5 hp single cylinder. that piece of junk has already locked up on me. It wasn't from lack of maintenance either. I, like you, tinker with mowers for a hobby. If you want a good, stout and reliable engine, get one of those super old Murry garden tractors. I have 3 of them, two 1980's and one 1981. they have 18hp Briggs on them. They are easy to rebuild and the mowers use all of the standard blades and hubs that some of the newer ones use. you can abuse the motors all you want and you cant hardly break them.
Everything now a days is made to sell, not to last.

Answer 6

It sounds like a fuel problem. Check the gas tank for water and dirt. water will look like "blobs" on the bottom of the tank. If it is clean the problem is most likely the carburetor. I assume that the carburetor sits on the gas tank on your engine. If that is the case there is a diaphragm between the carburetor and the fuel tank. They go bad and some were bad new. A new one costs about $5.00 and will have the required gasket with it. It will require that you remove the fuel tank with the carburetor on it and than remove the carburetor from the fuel tank.. It is not a hard job, just make sure you note the location of the springs and rods that connect to the carburetor. A digital picture may help in putting it back together correctly. If the fuel tank is dirty you will have to remove it to get it cleaned out, if that is the case remove the carburetor too and check the pickup tube that goes into the fuel tank and replace the diaphram. Good luck..

Answer 7

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get a can of sea foam and pump a bunch in and let it sit for a bit, do not waste you time with the fuel "stabalizers" they cause more problems than the old gas does, sea foam is the best that I have seen short of laquer thinner for cleaning things out.... The old gas with the fuel stabilizer likes to grow black moldy stuff in the bowel of the carborator, if you are good with engines you can find this out, flush it out good and give it some sea foam and you should be good.....