AUTOPSY of a Caterpillar Pony Motor. | What Went Wrong?

I have a feeling those mysterious gear teeth are from a previous catastrophic failure that wasn't cleared out before being replaced, or were left to make a speedy recovery in the field then forgotten about, before being parked.

Those teeth (my guess) are from a starter Bendix gear that was smashed from all that slop in the main bearings. Very interesting watching to dismantle something I'll probably never even see. Thank you Matt

BEFORE Diesel Creek I had NO idea what a pony moter was, and never even operated any piece of the sorts of equipment Matt is doing.(I'm a computer guy) NOW I own a tractor, bought a farm, and are fixing all sorts of duhdah's for whatever i need to get by, inspired by Matt and others like him. GREAT content !!

Hey Matt - I worked for a large Caterpillar company in Denver, CO in the early 70’s. (I am 81, now). I worked on a lot of D8 Cats. We changed out the pony motor as an assembly and never got the chance to tear one apart. Very interesting.

a small gear like that, my guess is that it came from a broken starter that since have been replaced.

I will never, ever need to know any of what Matt tried to teach me today, but strange as that is I could not stop watching this. The flywheel slop was epic. These episodes are why you have 3/4 of a million subscribers.

In all my years of rebuilding engines of all sizes, I've never came across one with that much wear that still ran. AMAZING! Thats why those old Cats just keep on going.

Regarding the grey/silver sludge, I didn't see that anyone suggested it is actually LEAD from leaded gasoline. We used to call it grey paint. I was an apprentice car mechanic in the 60s when leaded gas was the norm. The grey paint would get so thick in the oil pan it would plug up the oil pickup. When removing an oil pan with that in it, it felt as heavy as if half a crankshaft was there. With the age of that pony engine, it likely ran most of its life with leaded gas.

I believe the teeth were from a failed starter bendix that never was retrieved when they had the initial starter problem Matt. The size and number is similar to the teeth count on the bendix.

Matt, at around the 10 minute mark you explain why you save old junk like this, but there's a neat side-effect of what you and those of use who care about old stuff do: there's a "gap" generation around old equipment where the old codgers who worked with it every day start to retire and pass on and the new kids in the field have new, high-tech fancy stuff and don't need things like pony motors &c., so off they go to collectors or the scrapper. With luck it's to a collector, and with greater luck still it's to a collector that will use it and instruct others in its use--like you're doing right now in this video. When these things pass out of every day use and into the "antique" world, there's a risk that they themselves as well as the understanding of their use is going to disappear forever. Think about steam engines, and how a whole generation of teachers were mostly lost before the nerds picked it back up again. All it takes is a generation of folks going "I don't know WTF that does" to lose that real-world, practical knowledge of the thing. Great example is live steam, which in the UK is SO MUCH more robust than here in North America. Why? The Brits took forever to switch from coal, we didn't. And that switch just so happened to coincide with folks starting to wake up and realize that it's worth saving the old stuff, even if it's not "useful" in a conventional sense anymore. Like a CAT pony motor. :) Thanks for giving a hoot about the old iron, Matt--preservation and conservation is a gift to future generations. There's always "a million of them" out there... until there isn't. Good, old machines deserve to be saved and ought to be put to work. They might be the only things that actually last in our age of emissions equipment and computer-controlled common-rail injection. Cheers, and I hope you and your pod have a happy Easter weekend. 🐇🐇🐇

After rebuilding starters and alternators for the last 40 years that appears to be the remnants of an opinion that came apart from a previously installed starter

What I love about this channel is how you always steam clean or pressure wash an item before you start to video. That removes the blackened grease/oil sludge from the working surface and allows much better video content.

My take away from watching this is pure amazement with the engineers who designed and manufactured that whole assembly pre computers. I can't imagine the cost to make all the tooling to cast all those different pieces in an economical way. Mind blowing to me.

Fascinating teardown! The crankshaft bearings on these ponies are commonly ruined by a leaky carburetor valve: if the fuel shutoff isn't used and a tank of gas drains into the oil, the oil becomes useless. Just a short runtime with ruined oil will trash the crankshaft bearings.

From an expert ‘ole cat skinner’ who has gone to the dozer home in the sky: after you start the Diesel engine, disengage the pony, but don’t kill it. Turn off the gas and let it run dry. That warms up the pony, drains the carb, and your pony cast iron warms evenly to fight dampness. I pulled down my D7-3t pony and found a shop that could weld up and grind the crankshaft back to spec. We had to bore the cylinders off center to get them round again. My 3T was dry clutch so the previous owner managed to beat on the bendix with the canvas-and-sheet metal links that break in the dry clutch. I found bendix parts from a 2U in a junk yard. Be thankful for your oil clutch and be assured it could be worse.

I agree with the mystery teeth coming from a previous starter catastrophic failure. I have never been in a position where my (and possibly my family's) next meal depended on me getting a piece of equipment operating so I could finish a job and get paid. The pressures of life and the mindset of someone who doesn't perform recommended oil changes and would also leave gear teeth inside a gear case is something I cannot relate to in any way. Matt has clearly established that neither the motor or the gear case received recommended maintenance and that the carnage occurred because of the wear on the engine main bearings which was due to oil that was filled with abrasive particles. Maintenance is not done for various reasons. I know/have known people that can always find money for beer and smokes but can never find money for oil changes. If every machine owner put maintenance high on the list of important things Matt wouldn't have a channel. Without so many mistreated machines we wouldn't have such entertaining videos illustrating the effects of that mistreatment.

I'm so glad you posted a video today, because the 10th. of this month I was on my death bed, but I barely pulled through and it seems that each day now is a Blessing, but I'm still very weak and very limited mobility from this awful Flu I caught from my Grandson that he got at the Daycare. I hope I get to see more of your videos .

Wouldn't be hard to braze up that gear case. Worth saving. Doesn't have to be difficult. Prep the weld seem. It doesn't have to be huge. A 3/16 v is enough. Drill holes at each end of the crack. Build a nice big wood fire and get it all hot in some coals. Keep it in the coals while you heat up the joint and braze it up. Finnish by building up the fire a bit to bring it all up to an even heat. Cover it all with the coals and ashes when it dies down so it cools slow. Leave it till the next day. It sounds like a lot, but really isn't. Most of the effort is building a bonfire and watching it burn.

who else does this each time a new video comes out I sit here scanning his work shop for new toys and etc .🙂

I am an IT guy from Germany. So I could not be further removed from this topic, but yet still I love watching these videos. Keep up the good work of reviving old steel that others have left to die. Also very nice to see your channel frow over the years, almost at the 1 million mark now, great :D