Caterpillar D4 7J

rustred · Nov 14, 2023

I found a 1939 model cat. Someone was fiddling with the
starter engaging lever. I cant budge the pony engine or
the big engine. The owner said he saw the other guys
turning the pup engine over before fiddling with it. So
how do you get that starter pinion retracted with the
engine not running to kick it out ??he said it sat for about
5 years and in decent shape. Dont want to buy it if the
engines are stuck.

Fixingfarmer · Nov 15, 2023

With pony OFF rotate big engine often is enough or bouncing that lower lever a bit. I didnt get to mess with as many of the ponies a ton were converted there was one local d8 a gravel company kept on the other side of a river I think because they didnt want to move it or bring anything else over that everyone hated working on but it did start good once everything was working you could crank for 10 minutes at 40 below she would start no matter what.

rustred · Nov 15, 2023

So the only way is to remove the pup engine? Cant be first time someone engaged this lever. Thats a bunch of work.

TomA in CA · Nov 15, 2023

Not sure when they started putting access hole in bell housing. If there pinion can be tripped with a punch or screwdriver to release.

rustred · Nov 15, 2023

Yes there is about a 2 inch round hole kinda on the left side. All new to me as to what to do.

Olfolks · Nov 15, 2023

The pony should have a clutch to disengage it from the pinion, if the clutch is released the pony should turn over by hand or crank.
Take out the plug on the bellhousing use a bar/screwdriver to release the pinion if like the d7 of that era the pinion moves toward the back of the tractor to release

Fixingfarmer · Nov 15, 2023

Yeah that 2 inch round hole at least on later stuff fits a engine turning tool on a half inch ratchet. Or just grab a chain wrench and go off the dampener pulley if you can reach it. I dont have the socket it came with the service truck so it went with it when I left. Ill see if I can find a picture

Fixingfarmer · Nov 15, 2023

Yeah dont pull pony I meant power switch off dont want it to start its probably magnito ignition so if it rolls it might fire the likely hood of you getting it spinning fast enough with your ratchet or pry bar is incredibly low but surprises hurt.

rustred · Nov 15, 2023

Ok more info. This cat has bend sitting for around 5 years or more. Owner had it included in farm deal. He dont want it. I want to buy it. I cannot budge either engine. Clutch is seized also. He told me he saw them turn the engines. Then they were fooling around with them levers. I want to see both engines turn with my own eyes. I dont want to buy scrap iron. Plus it 2k. Thats a lot for scrap iron. Its a 1939 model the first year for this model.

Fixingfarmer · Nov 16, 2023

Well there is demand among certain people for an early d4 with pto and blade. I think hes asking a little much in its current state regardless how it locked up. Its not painted the right colors to get people to go crazy. Running and functioning if not all restored worth about 4 to 6. Its the kind of thing id love to have finish clearing my grove. Drive the little auger. and inconvenient enough to move no one else wants to steal it...but is also old enough some parts are gonna be difficult but not impossible to find. Hows the undercarriage? Did it have coolant in it did it turn a bit for someone till they got to the right spot? So this is going to be early enough engine prefixes dont mean much for serial number its all gonna be under d4 is 7j the prefix? I have 40a and 5t parts books and those appear to be the earliest although the library from the dealer I got them from was incomplete I think it might be more of a 50s machine from a bit of online forum research. Whats it look like?

rustred · Nov 16, 2023

its the 30th one built in 1939. these 7J models were from 39-42 serial number is 7J30. the 5T model as u show is newer. yes its full of coolant. it looks pretty decent for that age. he said the former owner used it, just that it has now sat for a few years. undercarriage is pretty good yet. sprockets look really good.. probably run over there and see if it has an hr. meter . far as i know the models go 4G,7J,2T, AND 5T.

Fixingfarmer · Nov 16, 2023

Yeah I wish I had the rest of the dozer books I got a ton of excavator and scrapers the 5t said it was from 1956 but was a reprint...It defiantly sounds like one that would be cool to save the undercarriage being in good shape is big. So back to the attempt to turn it did you end up with a turning tool? Part number was 9s 9082 but its 90 bucks a lot of money to spend to try to turn with being unsure if the tool will fit. I still wonder if it doesnt have a blade on it that gets in the way if your better off going at the front dampener in some way or another. Later model stuff was all held on with multiple bolts makes it easy (relatively) to pull off and stick longer bolts in without the pulley there and spin with a good size bar if the chain wrench doesnt do it with pulley attached

rustred · Nov 16, 2023

Been thinking here, if the main clutch is stuck to the flywheel. As the clutch lever is stuck in engage position. A person still should be able to turn each engine if the pinion is engaged in the flywheel. Try to get there Tommorrow to do more investigating. You need the main engine running to kick the pinion out of the flywheel. Or need to get in there to Release it with a punch. Or need to pull the whole unit out and release it. Cause if the big engine would turn it would also turn the pup is the way I see it. ? But see what I find out.

rustred · Nov 16, 2023

Yes, gonna try that.

Fixingfarmer · Nov 17, 2023

I was kinda thinking if you rotate the big one that would be enough to possibly push the pinion back since it happens when big engine speeds up. Rotating it even slow is faster than pony which is stopped but it could be stuck in there too and need popped out

rustred · Nov 17, 2023

yes , gonna try that.

Cash4Toys · Nov 18, 2023

Here is a picture of how the pinion is locked into starting position. The locks are like govorner weights, and at 3550rpm pony clutch speed they open. This pic is from a 5U manual, but it's probably same design. On a 5U you can access the pinion shaft through a small hole and using a punch open the weights, thus freeing the starter drive. If, in your case, the starter clutch is released, you should be able to rotate the pony and the diesel.

Check Break · Nov 18, 2023

(quoted from post at 20:52:13 11/16/23) Been thinking here, if the main clutch is stuck to the flywheel. As the clutch lever is stuck in engage position. A person still should be able to turn each engine if the pinion is engaged in the flywheel. Try to get there Tommorrow to do more investigating. You need the main engine running to kick the pinion out of the flywheel. Or need to get in there to Release it with a punch. Or need to pull the whole unit out and release it. Cause if the big engine would turn it would also turn the pup is the way I see it. ? But see what I find out.

Sounds like someone engaged the pinion on the starting engine. You will have to release the dogs. I'm familiar with how to do that on a 7U but don't know what's different on the earlier tractors. Go over to ACMOC and post your question. You'll have more answers than you need re how to release the pinion.

For immediate satisfaction re determining the engines are not stuck, you should be able to open the compression release and turn the main with the pony starter rope.

rustred · Nov 19, 2023

i have the pinion released, i can turn the pup engine. but i can only turn the diesel engine like a 1/4 inch back and forth. and the engine
clutch is stuck in the disengage position. dont know how that can affect the engine turning over ? going back today to drag it out before
freeze up and will try putting it in gear to see if it turns over.

Check Break · Nov 19, 2023

(quoted from post at 08:49:08 11/19/23) i have the pinion released, i can turn the pup engine. but i can only turn the diesel engine like a 1/4 inch back and forth. and the engine
clutch is stuck in the disengage position. dont know how that can affect the engine turning over ? going back today to drag it out before
freeze up and will try putting it in gear to see if it turns over.

Sounds like the main is stuck.

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