D4 Cat

I missed a chance at one a few years ago and its been chafing me ever since. Found a real nice one recently and just got it home.

It even came with the operators and service manual and the alemite grease can.

The previous owner thought it might be stuck - but said they put oil in each cylinder when they found that a storm had blown the can off the exhaust.

Whats the best way to try and turn the main engine over to see? Or should I just scope the cylinders first??

I grew up on a farm, but dont know that much about crawlers. What percentage of life do these tracks appear to have left??















Thanks for any advice,
Howard

Ugh. A Cat engine in unknown internal condition. That can be tricky. If you can scope it out, I surely would, because if it doesnt turn over it could be anything from some minor rust holding it up, all the way up to major internal damage. The problem is, its such a heavy hunk that the easiest way to spin it (assuming the pony engine cant/wont) is to tow it with another big machine you can try feathering you clutch to slowly get it to turn, but once you fully dump that clutch, its too late to run a diagnostic on what is keeping it from turning over in the first place. If it were mine, and a few weeks soaking it in ATF/acetone didnt free it up, I'd pull the head just to have a through look-see.



Those tracks look pretty good, if maybe a little loose. How much adjustment is left in the tensioners?. The sprocket teeth arent worn to a point, and that top carrier roller is not worn down, or grooved. Thats all good news. From what I can see, the track bushings look round, but thats one area that you really got to feel them to get a good idea how worn they are. They should be fairly round still, not worn to a flat-sided point, and definitely not worn through! Grab a track plate where the track has some slack and try and wiggle it, side-to-side to see how much play there are in your track pins and bushings. I would GUESS you have 60-70+ track life left, but thats a pretty individually subjective rating system. The only undercarriage rating I'd put any stock in is brand new stuff being ''100%''.

Get some new ''button-head'' fittings and oil your bottom rollers- if they are like most D4/D2 Cats, they havent had any oil in them for decades. If they have as little wear as that carrier does, you are in great shape because these bad boys spend their hard life down in the dirt carrying the weight of the machine.


What is the serial number on this machine?

it appears to be an electric start pony engine--engage the starter pinion and pinion clutch and see if the starter will turn over the diesel engine--apply the compression release to make it easier

Thanks. I wondered about that. The battery looks to be a 6 volt.

Should I get a new 6 volt battery - or can I boost it with a 12 without hurting anything?

Thanks for the info!

When you say track bushings, do you mean the lower rollers? Or something else?

The serial is 6U-8371.

yes, rails and sprocket look very good. pads look excellent. i would wonder how much oil po dumped in cylinders and if you should not be concerned turning engine over with a lot of oil in a cylinder ; maybe remove the injectors first.

bushings are the track parts that come in contact with the sprocket. They are replaceable wear parts meant to save the pins, which are inside the bushings & one pin must be removed to 'break' the track.

Howard try just turning it with the fan and belt by pushing in on the belt. With the decompression lever it should turn by hand easily. I can turn our D-4 over by hand without the lever. I go out and turn it occasionally so it stays loose. I need to pull it out and start it so it can oil everything up inside again. Probably this summer. Might have to take a fan guard off to get to it.

Throw the decompression lever so the valves are open and then any oil in the cylinders won't matter. Then see if it will turn. Make sure it's in neutral and the main clutch is disengaged.

I suggest you get an operators manual, I think thats a 7U model, and read up. Make sure you check the pony oil before you try to start it. In fact, just change the oil, it only holds about a quart. You shut the ponies off by closing the fuel valve, not with the kill switch.

The previous owner saying it might be stuck, the only reason he would have put oil in the cylinders is that it was otherwise why would he put the oil in?, if it's been soaking for a while maybe it will break free now, if it's it fitted with lights and a generator to charge the battery it would be best to keep it 6V, otherwise a 12V battery and 6V starter will last a long time as the starter will only have to work a few seconds at a time to start the pony, the tracks are getting worn but there is a lot of work left in them, from what I can see of the bush its good, the sprocket is starting to wear, the rails are getting thin, the rollers I cannot see, all in you will get a fair bit of work out of it
AJ

Your Cat was built in early 1953. You can use 12V on the pony starter, but make sure it is isolated from your generator. After 60+ years of wiring ''improvements'' you never know what is connected to what. Dont overheat the starter. If everything is in running order the pony should start fairly quickly.
The best thing about the Cat pony engine starting system is that the starter rope can be used 6 volt or 12 volt, left hand or right hand.

BTW, unlike those off-kilter aftermarket headlights, your rear facing light is the original, heavy-duty shielded type used by Caterpillar (and IHC on their ''T'' & ''TD'' dozers) those are getting hard to find these days. Dont use it as a step!

Get a set of manuals if you dont have them- they are a treasure trove of info on these machines. Ebay, jensales or your local Cat dealer has them.

GOOD LUCK!

Pull decompression!!! then oil not a problem

(reply to post at 13:02:22 03/12/22)

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Has the engine oil itself been drained and check first? remember I worked on a locked up D8 back in the day and the last gallons were pure fuel which was the cause of the engine failure $$$

I use 12v battery's on my 6v starters on my Cats--just don't keep spinning it for a long time

Look on ebay for manuals that will cover your serial number

top idler is showing some wear. Not bad and can be welded back up with hard surface rod. don't go to hard as it will pound off as it is used. Could also weld up the rails if you want though will serve for many years depending on how much you are going to use it. The tracks could use a little tension added to them not bad just a wee bit loose. Run them first then look at them if it has been setting they will loosen up some. I'm not just sure when they went to replaceable filters on them but ours has brass screens you wash out for oil and fuel filters on it. No filter on the little engine. Just drain and fill. Air cleaner will need new oil if it is not a paper filter. To adjust the tracks you have to remove the dirt ccovers on the roller frame from infront of the sprocket loosen the 2 bolts holding the clamp then turn the big nut. It is about 2-12 inches or so unless it has the shaft then it is smaller like about 2 inch. Push the front idler forward to tighten. Later models you used grease for that in a piston.

The important measurement is link pitch. Internal wear in bushings and external wear on pins. External wear in bushings is only an indicator. Accurate measurement across 5 pins can give a good assessment of percentage wear left.

I would also be concerned about stuck valves even if the rest of the engine is free. It should not take much to pull the hood and valve covers to see if they are all free. If a valve is stuck closed, can using the decompression damage anything (similar to turning over an engine with stuck valves and bending push rods)? Can those injector pumps stick too?

Nice machine!!!

the injector pumps can stick--usually stick in an up position and then don't pump fuel
Most of the time you can free them up by spraying loose juice and then gently prying them down

Thanks for all the great info, everyone!

In measuring the link to link distance for 5 links on tight sections on both sides, it was 34 1/4 inches.

Each link bushing was between 2.10 inches and 2.15 inches in diameter.

I couldn't turn it by hand with the fan, so it is stuck at least somewhat. I'm going to scope it and see for sure what is going on.

I also cracked the pan plug and the first drop out was honey-colored oil, so if it had water in it, it sure wasn't much. I drained a bit out just to look - and it did smell a little funny, but looked great. I assume the smell came from the ATF/acetone/oil mix he said he put in the cylinders.

The main track tensioner springs have 2.8 inches of thread left for adjustment tension.

A relative handling an estate sale he told me a storm blew the exhaust can off 4-5 years ago and when he realized it was stuck, so he put ATF/acetone/oil in each cylinder, but they'd never tried to fire it up after that.

(quoted from post at 23:09:47 03/14/22)
Thanks for all the great info, everyone!

In measuring the link to link distance for 5 links on tight sections on both sides, it was 34 1/4 inches.

Each link bushing was between 2.10 inches and 2.15 inches in diameter.

I couldn't turn it by hand with the fan, so it is stuck at least somewhat. I'm going to scope it and see for sure what is going on.

I also cracked the pan plug and the first drop out was honey-colored oil, so if it had water in it, it sure wasn't much. I drained a bit out just to look - and it did smell a little funny, but looked great. I assume the smell came from the ATF/acetone/oil mix he said he put in the cylinders.

The main track tensioner springs have 2.8 inches of thread left for adjustment tension.

A relative handling an estate sale he told me a storm blew the exhaust can off 4-5 years ago and when he realized it was stuck, so he put ATF/acetone/oil in each cylinder, but they'd never tried to fire it up after that.

Click to expand...

It will take a bit more research, but I am seeing the measurement being shown as about 27 inches. From that, I don't think you got your track measurement just right across the pins. Also, to make that measurement correctly the crawler needs to be running. A large pin is laid into a sprocket cup and the crawler is reversed bring the pin up into the track chain to stretch it tight, even compressing the track spring some. Even if the track looks tight as it sets, it isn't without doing this step.

this is what i have on the track link hight

(quoted from post at 03:58:19 03/15/22)

It will take a bit more research, but I am seeing the measurement being shown as about 27 inches. From that, I don't think you got your track measurement just right across the pins. Also, to make that measurement correctly the crawler needs to be running. A large pin is laid into a sprocket cup and the crawler is reversed bring the pin up into the track chain to stretch it tight, even compressing the track spring some. Even if the track looks tight as it sets, it isn't without doing this step.

Click to expand...

Ok - thanks... I measured edge-to-same-pin-edge across 5 track links, not 4.

Across any 4 links it is 27 1/2. But I'll need to get it out to the farm to properly stretch it like you suggest.

Ok - thanks for the info!! Looks like closing in on about 50% wear just based on rail height alone.

I won't worry about it for a while, but if I ever wanted to build those up by welding, what would be a good rod to use? Or would a person not even want to mess with stick welding??

Most guys don't build them up with weld--they source another set of rails

I would run it for a while after I got it running to limber up the pins and rollers then worry about track and undercarriage wear at this point. If you look at the top roller on the outer edges you can see where it has a slight lip on it. that would not normally have that so that is the amount of wear there. I think dad said he used a 388 rod and it was to hard it pounded off with use when he welded the rails up. We just put the beads down and let the tractor wear them off. Never ground the beads smooth. I was just a kid then and did as told.

Your pictures bring back memories. I have a D4-7U sitting under a tarp up here in Delaware that I was going to put back in the field but the years just slipped away and I had to let it sit and go to a JD 450C which didn't need that darn pony motor.

Yours looks pretty decent and if you can get that engine to spin , you'll have a nice unit. Good luck.