New to me 1936 Caterpillar RD4, get it running project

m1west

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Today I removed the pony gas tank, magneto, carburetor and belt driven governor. I took the cap off of the Mag, everything looked good in there so I cleaned the rotor with scotchbrite and put it back together, took a short video ,if I can load it you can see it spark against the table. ( nice blue spark 1/2" long. So I think a new rotor, cap and wires should do the trick, then keep the old stuff for spare.
The Carburetor, I took off the air inlet ( kind of neet, it tightly seals the carburetor intake when not running and to run, you pull up on the top and turn it and it stays open while running. I put WD40 in the bowl through the fuel inlet and drained it out the bowl drain plug. the float and needle and seat are working so I'm just going to give it a good cleaning. same with the sediment trap.
The gas tank has a little rust on the inside with some varnish. I will use molasses mixed with water to de rust it. I ceeaned the paint off the outside with a wire wheel and didn't find any holes.
The governor arm was a little sticky but some WD40 on the shaft and a little working it, freed it up.
Also I removed all the bleeders and pipes one at a time going to the injectors on the main engine. All clean with clean fuel present.
I think I may just remove the radiator pipes leaving the radiator in place to clean it.
Was thinking if it would be necessary to remove the injectors from the head and inspect, then I can look in the cylinders with a bore scope too.
( advice needed on that one )

also going to pull the valve cover to check out the rockers, valves and springs. Then do a cold valve lash adjustment.
Pull the inspection covers and peek at the lifter assemblies also for the crank case.
Anything else I should be doing, let me know.
 

mla2ofus

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OK, first now unless it has a hand operated fuel priming pump, you'll need to leave injector line connections loose, by loose I mean connected at the injector and just backed off a quarter turn, at the injectors to bleed all the air out of them while cranking the main engine which IIRC someone has to hold the starter pinion engaged with the flywheel. The injectors I wouldn't bother unless they show a problem after it's started and warmed up. BTW those funny looking thing with the flats and rounded ends beside each injector line connection is a bleeder valve for bleeding air out of the pump but they won't help in your case unless you bother the fuel filters.
Regarding the pony carb I was taught by the old timers to close the gas valve to the carb and let it run until it dies. They said leaving gas in the carb would wear the float needle and seat from the vibration of the main engine. Just remember to close the intake after it dies. I've never seen one with that setup. All the old ones I was around had little oil bath filters.
Beware those spark plug wires while it's running. That 1/2" spark will really light you up!! Sometimes I think those old mags generate some extra amps along with all that high voltage.
What is the object in the 3rd pic p/n 1A2847
 
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m1west

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1- Magneto
2- carburator
3- pony fuel tank
4- pony belt driven governor
5- Fuel injector pump with a lien off showing fuel, main engine
 

sno-drifter

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Another trick is to find out where to manually turn the pony engine over so that the points are open. This stops the corrosion on them when the pony is not started for long periods. I always shut off the gas and let the engine run dry. Use only non-ethanol fuel. Also mine have a drain plug on the bottom of the carb bowl. I drain there too when sitting for long times. Looks like you are doing a great pre start job. Keep it up, and you will earn a diesel living.
 

mla2ofus

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I think some of the old ponies had a rope start option in that you wrap the rope around the rope pulley like the first lawn mower engines had. I also recall some had compression relief valves like a fuel valve on each head.
 

m1west

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I think some of the old ponies had a rope start option in that you wrap the rope around the rope pulley like the first lawn mower engines had. I also recall some had compression relief valves like a fuel valve on each head.
Yep this one is rope start, like a lawn mower.
 

m1west

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Today, I pulled the valve cover and upper radiator pipe. Inside the valve cover, I found that the back 2 hold down bolt gaskets had leaked just enough to get the rocker stand and 2 rocker arms a little rusty. It came off with WD40 and a rag, it didn't make it to the valves or valve springs and that is a good thing. I verified that all the valves and rockers are free by rolling through a complete engine cycle using the pony motor start wheel. Also all the valves rotate, I did find a couple tight valves while I was doing so and made the adjustment. When I pulled the upper radiator pipe I found it was nearly full of antifreeze, if the radiator cap wasn't missing there would be no need to clean it. That was a good find as now I don't have to worry about a freeze crack somewhere. Tomorrow I have to pull the inspection cover from the bottom of the radiator to get at the bolts for the bottom radiator pipe. Also I think how you get the belt on is by screwing the upper pull assembly in, should move the fan away from the radiator enough to get it in. After the radiator and cooling system is flushed out I will put it on. Feel like I rescued the old girl just in time, a few more years sitting outside it would require much more work.
 

mla2ofus

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I'm not positive but I think the movable part of the pulley just threads on the fan hub and moves in and out to change the pulley pitch diameter. Can't you just loosen the radiator mount bolts enough to tip it ahead and gain enough clearance for the belt. Just start at the top fan blade and rotate to thread the belt over the next blade and so on.
That large hex nut on the water pump shaft compresses some graphite impregnated packing and it is the shaft seal. Can't tell for sure but it looks like it may be about out threads. If that's the case it will soon start leaking coolant around it. There's a special wrench made for that so look for a pic of it. It might be possible to sacrifice a 12 point box end wrench by cutting just enough to slip over the shaft. It doesn't have to be super tight, just enough so it weeps a drop or 2 a minute as the coolant is the lube for the packing. Once you get the wrench made just try to tighten it a little bit. If it will you may be OK. If you can't tighten it all then it's new packing time and I'll recommend removing the water pump which might force you to remove the radiator anyway. I hope I'm not discouraging you, just trying to make sure you only have to do this once. One caution if you have to change the packing. The packing is one piece with a split in it to slip over the shaft. Of course you have to dig out the old which can be a real biotch!! I hope you can find a video of this being done. Probably better than all my typing!! Once installed run the nut down 'til it's just past finger tight fill with coolant, start the main engine and watch how much leaks past the packing and gently tighten the nut until it leaks a little bit.
 
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m1west

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I'm not positive but I think the movable part of the pulley just threads on the fan hub and moves in and out to change the pulley pitch diameter. Can't you just loosen the radiator mount bolts enough to tip it ahead and gain enough clearance for the belt. Just start at the top fan blade and rotate to thread the belt over the next blade and so on.
That large hex nut on the water pump shaft compresses some graphite impregnated packing and it is the shaft seal. Can't tell for sure but it looks like it may be about out threads. If that's the case it will soon start leaking coolant around it. There's a special wrench made for that so look for a pic of it. It might be possible to sacrifice a 12 point box end wrench by cutting just enough to slip over the shaft. It doesn't have to be super tight, just enough so it weeps a drop or 2 a minute as the coolant is the lube for the packing. Once you get the wrench made just try to tighten it a little bit. If it will you may be OK. If you can't tighten it all then it's new packing time and I'll recommend removing the water pump which might force you to remove the radiator anyway. I hope I'm not discouraging you, just trying to make sure you only have to do this once. One caution if you have to change the packing. The packing is one piece with a split in it to slip over the shaft. Of course you have to dig out the old which can be a real biotch!! I hope you can find a video of this being done. Probably better than all my typing!! Once installed run the nut down 'til it's just past finger tight fill with coolant, start the main engine and watch how much leaks past the packing and gently tighten the nut until it leaks a little bit.
This is good stuff, likely not going to know by reading the manual. Keep it coming
 

mla2ofus

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M1, I'm just passing along what I was taught by old timers and the school of hard knocks. https://www.acmoc.org/s check out this site 'cause they collect and restore old Cat eqpt. of all sorts. Maybe join them and you might get more informative info than I'm able to give. The pic of the water pump jogged my memory on the water pump packing nut so keep the pics coming. Those pics help pull old memories out of the cobwebs in my brain. I haven't been around any cats for 20 yrs and it's been 40 yrs since I worked on the old cats.
 

mla2ofus

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When you get around to it pull up the floor plates and post a pic of the clutch/flywheel. I may have comment to make on that. Which reminds me: if you plan to get off the cat and leave it running make a habit of putting it in neutral and engage the clutch. This will save wear on the pilot brg. When ready to put it back in gear do so only from idle to reduce grinding gears. The kindest thing Cat ever did for stick trannies was the decelerator pedal which with a push of your right foot would bring the engine down to idle and upon release of it would bring the engine back to preset speed. Again a little tidbit from the old timers!!
 
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m1west

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Today got the cover and lower radiator pipe off.
while under there I chipped all the crap from around the oil pan inspection cover.
noticed the old gal has had its radiator housing and oil pan repaired with gorilla welding in the passed. You would think this thing would have come with a skid plate to prevent such things. It will have one before it gores to the mountain, there are rocks everywhere.
In the end the radiator is going to be supported from overhead and loosened or removed to give clearance to remove the water pump assembly, as its on studs and there is no room.
While playing with the adjustable fan pulley I noticed the fan has play on the shaft. I watched a video and there are an inner and outer bearing that will need to be replaced, so might as well remove it and service the whole pump. Its hard to remove so now is the time.
today o filled the pony gas tank with acetone to remove the varnish and noticed a pin holier the weld on top the tank. its not a rust hole, must have been there since the beginning. tomorrow I will dump the acetone and add molasses and water to de rust then repair the pin hole.
 

m1west

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M1, I'm just passing along what I was taught by old timers and the school of hard knocks. https://www.acmoc.org/s check out this site 'cause they collect and restore old Cat eqpt. of all sorts. Maybe join them and you might get more informative info than I'm able to give. The pic of the water pump jogged my memory on the water pump packing nut so keep the pics coming. Those pics help pull old memories out of the cobwebs in my brain. I haven't been around any cats for 20 yrs and it's been 40 yrs since I worked on the old cats.
I have been on there web site as a lurker, there is a lot of info there also. I watched a video on the injectors and thats something you don't want to go bad, there are no replacements except for used you may or may not find. A guy had a test stand made up to test when they crack ( 1500#) and to see the spray pattern. It looked like he used a brake cylinder with a resivour and gauge to make the pressure required. In the video he stated that as far as he knows there are no services to get them rebuilt at this time.
 

m1west

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The turning brake handles move but are stiff, what is the procedure to remedy that.
 

mla2ofus

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IIRC they are just naturally hard to pull. I doubt they have hydraulic boosters like the later cats have. Oil all the linkages on them and that should help some. As for the injectors I advise to just leave them alone and make sure those injector lines and all connections are operating room clean. A microscopic speck can create injector problems. just remember the fuel going thru them has already been thru the fuel filters.
The clutch should have some definite resistance as it toggles in. If not adjust as needed. Try to avoid slipping the clutch. Slipping it at idle Is OK but not for over a few seconds. DO NOT slip it at full throttle, it's designed to be either in or out. You'll be surprised at what you can do with the clutch fully engaged in first gear at idle.
the 5th pic jogged my memory about the track rollers. They should have a pipe plug or a large "button head" grease fitting on the outer end and it wouldn't hurt to pump a little grease in them. Once you have it running and ready to work have someone move it in 1st ge3ar at idle and observe all the rollers to insure they are turning. If you have a laser thermometer and you've given it a good workout you can use it to compare temps on all the rollers. A cat mechanic told me yrs ago if you run a cat long distances on even hard dirt roads you're leaving a trail of dollar bills.
 
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