154 Starter/Genny

Been having an issue with my starter/genny on my 154 for years, so I decided it was time to figure it out. Turns over fine cold. When it gets hot, as in running for say 2 hours or more, if I shut it off, or bog it down by accident, it will turn over, but it acts the battery is bad. If I let it cool off, it will spin right over again. I do my best to not bog it down, and have gotten pretty good at lifting the deck and knocking off the pto at the same time. So far, I have replaced the cables with bigger ones, I think it was 0 gauge, but I cant swear to that but they are bigger than the originals. Have had 2 new batteries in it since I got it. The solenoid was replaced, and the starter/genny was gone through and reinstalled Saturday. It has a newer Prstolite distributor, btu that was installed when I got it, and I have it set dead on, but it may not be the right one for the 154, as the tag has broken off. I installed a Zenith carb due to the IH carb top being warped beyond repair, and the dealer had this one in stock. The engine was rebuilt when I got it. After running it for close to 3 hours yesterday, I shut it off after letting it idle for 15 - 20 minutes to cool off some, attempted to restart immediately after shutting it off and the starter just dragged as before. I hope I have included anything relevant to help figure this out finally, if not ask. Any ideas whats going on?

I forgot, it charges fine.

Are the valves set to specs?

They were 2 years ago, and that was the first time I checked them since it was rebuilt. Cold they were at 15 for the most part. I think one or two of them were at 16. Set those back to 15.

I'm sure you have all ready checked this out but is the belt slipping? I have two 154's and on occasion the belt will slip and result in a very sluggish turning over. All I do is turn the engine over by hand to get if off that one cylinders compression stroke. This does not sound like your problem but worth a mention.

Forgot to mention also could it be the wrong size pulley on the starter/generator, just throwing the easy suggestions out there.

I actually thought it was the belt back when I first got it. It didnt need one, but I put a new one on when I put the starter back on. I have done the fan deal to get it off of comp., and have had it work a time or 2. As far as the pulley, I cant swear its the right one, as it is what was on it when I got it, but there is no excessive adjustments I had to make for the belt to get tight, and I know the belt is right. Thanks for the suggestions.

Adapting a smaller pulley would be my suggestion. It would provide more torque and less RPM. One of the things that cause it is the mediocre combo gen/starter. and heat in the windings reduces the conductivity. Putting a second battery (motorcycle) to power the ignition only when cranking, would determine if the starter is drawing too much current to allow good spark. Jim

Is the engine over heating?
There was originally a foam seal between the radiator and nose cowling. Without that seal grass will get sucked in a plug the radiator with clippings.
When it won't turn over, make sure the ignition switch is off and try to turn the engine by hand. Maybe the engine is tight and there's nothing wrong with the starter.
I assume you are disengaging the PTO.

Worn bearings in the starter/generator can cause it to act that way. The armature could be near rubbing on the pole shoes. Thermal expansion of the armature causes it to drag until it cools off again.

Open it up and see if there is any evidence of the armature rubbing.

It was checked out last week. The guy who does all my starters and gennys said it was in very good condition, other than the brushed were about half wore down.

Not overheating at all. The system is very clean. That seal on mine is gone, but I haven't had any serious problems with grass getting in there. As I mentioned above, I have turned the fan to get it off of compression to get it to turn over. Sometimes that works, sometimes it doesn't.

I would prefer to fix it the way its suppose to be, instead of putting a band aid on it.

What about ignition timing? There are two marks, one TDC and the other at 16? BTDC. An issue with timing can be a loose crankshaft pulley. The pulley should be secured with a thick (about 1/4" thick) washer. Often a thin washer is used which gives away and allows the pulley/crankshaft keyway to be become worn. Resulting in the timing marks being off.
You mention using the fan blade to move it off compression. Any chance the timing gears not properly timed when overhauled?

I know who built the engine, and I trust he installed everything right. I will have to check that washer, but the pulley wasn't loose when I put the starter back on. I do have the distributor timed right, but I'm really starting to think the Prestolite is the problem. Possibly the advance is hanging up or something, because it does act like timing, but only when its hot. As long as I keep from bogging down, it will run all day.

My interpretation of Jim's suggestion of rigging another battery for the ignition only is to aid in the diagnosis; not as a band aid. IMHO, no offense intended.

Yes, not a permanent solution, just diagnosis. You could use a jumper from a second battery , not necessarily a MC battery but it might not be as convenient. Farmalls of many models, and other tractors and vehicles have the same issue of slow hot cranking. I think a smaller pulley is an upgrade, not a violation of originality. Jim

No, I meant absolutely no disrespect at all in my response to you Jim, none what so ever, nor was I referring to your statement of the extra battery. The pulley on the thing now is pretty small, so I dont think I would be able to put a smaller one on it without major work. Even then, I do not think this will fix the problem, at the most it will cover it up, hence the band aid reference. Again, no disrespect at all and I apologize it came out that way.

The clue here to me is that it is related to HEAT.

Starts fine cold.
Acts sluggish when hot.
Starts fine again after it has cooled down.

Now, I'm not thinking the engine is hot. I'm thinking the GENERATOR is hot.

You said it charges fine. Does it charge heavily and continue to charge the entire time you use it? It should charge heavily at the beginning, then taper off after a few minutes.

If it's pegging the ammeter the entire time the engine is running, then it is overcharging, and the generator is likely very hot after charging at full blast for a couple of hours. It won't handle this forever. Eventually you'll start noticing problems cold too.

It will peg the gauge for a few seconds then slowly drop to just off of the center line, unless the battery is a little weak, then
it just drops slower as the battery is charged up. I am going to have my shop replace the field coils, although he said they were
fine. Maybe they are breaking down under the heat and it wasnt hot when he worked on it.

No issue at all with me, I am just attempting to make the engine spin and start as it should. I really think the blending of a starter with a generator for cranking an engine is marginal. Jim