John Deere 155C riding mower

[FergusonTO35]

Dad just bought a John Deere 155c riding mower with 25hp Briggs twin and 48" deck. He mowed with it yesterday and it seems to work really well for it's age. I warned him that the 155 is a box store model and not the same thing as the 277 he used to have, but he really likes it and the price seemed fair.

So, any known trouble spots on these machines? What sort of oil is best for the hydro transaxle?

 

[ElevatorGuy]

I’ve never heard of that model until now but a quick search reveals it has the dreaded k46 trans.

 

[FergusonTO35]

Yeah, I told him to not get too excited about it!

 

[FergusonTO35]

The thing cuts well enough, however the alternator is weak. Barely keeps the battery past 12 volts when running. So, is this just a matter of selecting the correct alternator and regulator and replacing it? The engine is a Briggs 25hp twin, model 445777 type 0264 E1.

 

[Pincher]

The alternator is part of the flywheel with a stator mounted to the engine behind it. I am not familiar with the new models but typically the stator will have only two wires going to the regulator. With regulator unplugged the two wires from the stator should produce 20 to 40 volts AC with engine running. Check continuity to ground on the same wires while unplugged to eliminate a short. If tests ok, the likely culprit would be the regulator.

 

[FergusonTO35]

Thanks, will do!

 

[FergusonTO35]

So, I checked it out last night with the engine running. Getting only 2.5 volts coming out of the regulator into the battery. It has a harness with two wires coming out of the engine to the regulator. Are both of those supposed to be positive?

 

[Pincher]

set you volt meter to AC voltage when checking the two wires coming out of the engine to the regulator. black tester lead on one wire and red on the other. With engine running should develop over 20 volts AC (alternating current) across the two wires.

 

[FergusonTO35]

Thanks!

 

[FergusonTO35]

Ok, so we have 6.8 volts AC coming out. I 'spose it needs an alternator. With key off engine off, I do have continuity between either of the two wires and ground. Is that normal?

 

[stretch5881]

The manufacturer has 10w30 conventional oil in the transaxle to keep costs down. They suggest draining it and putting in 10w60 full synthetic. You can find this info on the trans manufacturer's website. There are videos on youtube on how to do this. Mine has the k46 with 1100 hours on it, with 10w60 oil, and no problems. 10w60 can be hard to find, so, 10w50 would be fine.

 

[stretch5881]

1 thing not mentioned while checking voltage, the engine should be running at over 3000 rpm for the test.

 

[Pincher]

The stator with the two wire you are testing should not have continuity to ground. Looks like you may have found the problem.

 

[FergusonTO35]

Thanks, gonna take it apart tonight.

 

[FergusonTO35]

Ok, turned out the stator was cracked and had a huge burned spot in it. Replaced with a new Briggs part and she is charging great. Unfortunately, looks like my riding mower now needs one too!

 

[stretch5881]

Ok, turned out the stator was cracked and had a huge burned spot in it. Replaced with a new Briggs part and she is charging great. Unfortunately, looks like my riding mower now needs one too!

Not so unfortunate. You got to use what you learned. While you have the blower housing off, it gives you a chance to clean out any mouse nests. Pay special attention to clean the cylinder fins. A lot of engines have valve guide problems because the fins are blocked.
Good job on your Dad's tractor.

 

[FergusonTO35]

Thanks! Surprisingly there was very little debris on the fins of Dad's machine.

 

[FergusonTO35]

And, it's dead. The 155 just quit on my dad while mowing. I finished up with my trusty 32 year old Murray and told him I'll look at it. I don't think he is going to like the diagnosis. It has been really hard to start the last few times I tried it, had to squirt carb cleaner into the intake to help it out. Also, when engaging the blades I hear what sounds like the beginning of a rod knock. I'm guessing at bare minimum rings, bearings, and valve grind.

 

[FergusonTO35]

Turns out it quit because the ignition switch came unplugged. Dad must have the magic touch because it then fired right up and actually ran pretty good yesterday. Ida know, mebbe it just doesn't like me 'cause I'm a Ferguson guy.

 

[stretch5881]

And, it's dead. The 155 just quit on my dad while mowing. I finished up with my trusty 32 year old Murray and told him I'll look at it. I don't think he is going to like the diagnosis. It has been really hard to start the last few times I tried it, had to squirt carb cleaner into the intake to help it out. Also, when engaging the blades I hear what sounds like the beginning of a rod knock. I'm guessing at bare minimum rings, bearings, and valve grind.

You get too exited. Small engines are noisy. They are thin walled with no water jacket to insulate the noises. When they work, you never notice all the noises. They do not get a rod knock. They just have *s-wordty balance that cause the noise. Most do not have rod bearings, and before you would guess at rings and valve grind, you would check the health of the engine with a cylinder pressure tester. Modern small engines have totally different problems and troubleshooting procedures than the old engines we are used to.
It's great that he found the problem.