Cat Pony Engines - Replacements?

Anonymous-0 · May 7, 2012

Has anyone ever replaced the old 2 cylinder pony engines with a newer horizontal shaft gas engine? I know there is an electric starter motor pony replacement being made by a company, but I really don't want to update to 24 volts along with some other reasons. Seems to me with a little setup and basic engineering you could stick a small Honda, Briggs, or Kohler engine in there and have a much easier to start pony motor. Yes, you would lose the heat transfer to warm the coolant, but you could still figure out a way to pipe the gas engine exhaust around diesel air intake. And for that matter, if you wanted to get creative you could make a simple heat exchanger to warm the coolant also from the gasoline exhaust. I believe anything can be done, just curious if anyone out there has tried it.

Thanks, Nate

NCWayne · May 7, 2012

I'd have to check my books to be sure but I believe one problem your going to run into is that the poney engines don't turn anywhere near as fast as the other small engines your talking about. Then there is the matter of the poney having a true flywheel and clutch setup on it that the other engines won't have. Without that there is no way to stope the start pinion and engage it into the flywheel ring. Without being able to do that your talking a major expense to put in new flywheel rings on a regular basis.

That said, I do agree that pretty much anything is possible. Unfortunately in instances such as this one, I don't believe the cost and time spent trying to 'reinvent the mousetrap' is worth it.....especially given the work necessary to pull the engine to replace a broken/damaged ring gear if something doesn't go exactly right.

dpendzic · May 8, 2012

a while back on the ACMOC or ACME sites there was a posting of a guy who rigged up a small engine to spin the pony motor--he used a belt to drive the pony flywheel--similar to the pony electric start belt. can't remember if he used it to start the pony or just spun the pony to spin the diesel.

BCnT · May 8, 2012

i dont think hooking a modern small engine up is gonna be the real problem...finding one with enough torque is gonna be the question...IIRC the pony's had a pretty hefty flywheel setup...you need that weight spinning.

Fritz Maurer · May 8, 2012

All that work because it "starts hard"? A tune-up is out of the question?

Anonymous-0 · May 8, 2012

To answer some of the questions and clarify a few things, I'm considering this for a D2/D4 style pony motor. The one I have appears to have a cracked block or something. It's getting combustion into the water jacket and then pushes water out the radiator. These old engines are expensive to rebuild and from what I've gathered can be rather temperamental. My book lists a D2 pony as 10 HP @ 3000 rpm. That's 17.5 lb-ft of torque, not out of range with what you could find on a modern gasoline engine.

To answer NCWaynes question, you must be referring to the pony engines on larger Cats. The D2/D4 pony engines have a gear directly attached to the crankshaft that spin the idler gear which spins the pinion shaft. That is where the clutch and throwout mechanism is located that engages the diesel flywheel. So by mounting another engine with a gear on it to drive the idler you accomplish the same principal as the original design.

Bret4207 · May 15, 2012

If you got to either of the antique Cat sites there is info on converting to direct electric start. I'd think that'd be far, far easier than cobbing another engine to the diesel. Fot that matter you'd even be better off belting another 10 or 15 hp engine to the pony flywheel and going through the pony gearing system.

Myself, ponies aren't that hard to find in running condition for a reasonable price. I'd find one and exchange engines. I promise that will be more likely to succeed than cobbing another engine onto the diesel.

Cat Pony Engines - Replacements?

Anonymous-0

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NCWayne

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dpendzic

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BCnT

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Fritz Maurer

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Anonymous-0

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Bret4207

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