51 DC rebuild?

Hey guys. Most of you might know of my saga with the old '51 DC. in the weeds for 20 years.........stuck motor.........quick fix to get running for Grandpa before he died..........NOW

Now I have water in oil and bubbles in the radiator. I pulled the head this last week to replace the head gasket and do head work. So I got some questions for all of you DC guys out there.

If this was your tractor and you were going to use it for field work what would you do to it?

I am already going to have the head overhauled with new springs and grind the valves. But I am seriously thinkning of dropping the oil pan and then pulling the pistons, put new bearings in it and new rings. I would LOVE to be able to afford the 4 1/16" pistons and sleeves but maybe another time. (would you have to change the head for that?)

Pull the pan VS working through the hand holds? What do you do?

If you guys were in my shoes what would you do to this tractor this winter?

Clutch?
Rings?
Bearings?
Oil pump? (has good 30 pounds pressure)

Anything else?

Thank you guys for your inputs.......

Get an I&T manual from TSC or Farm and Fleet. You need to
clean all the rust and crud out of the water jacket, probably need
new O-rings to seal the sleeves to block. The bearings are
poured babbit so some plastigauge to measure clearance and
shim as required.But 30 lbs. is pretty good oil pressure already,
Case manual says relief is at 30-35 for engine in good shape.
Rings? maybe if it was stuck they may be broken or collapsed.
Have never had to replace a DC clutch and they were main farm
tractors here until late 1960s, lots of adjustment!

You might want to check the archives on this, but I think DC Tom advised to always line bore the main bearings in a DC block after replacement of bearings to avoid a broken crankshaft. Maybe a check of bearing clearance is a better way to go.

I would pull the pan and just clean,
inspect while the head is off. You have
real good oil pressure now. If I didn't
find any ring material in the pan, and if
the hone on the cylinders is good, and if
the cylinders don't appear scored, and if
the compression checks good (after head
is back on I would be apt to put the head
and gasket on it and run it for several
hours to see exactly what I had to deal
with.

If you are getting bubbles (foam) in the radiator, it could be a bad water pump. They will not leak but will "suck" air in around the seals and new seals will solve that problem. (My $0.02 worth. jal-SD)

Pulled the inspection covers and found this. This is a pic from right side looking at front main bearing.



This is looking up toward #1 piston



This is the front two head studs. There are 2 more that look like this.



The Water pump is new this year. Could it be bad? What do I look for on it if it is causing the problem? What about the white foamy oil at front of motor? Thank you.

Wayne

The foamy stuff is a mix of condensation and oil caused by not getting the engine up to operating temperature. Dad had a late DC back in the day, and it would have that problem in the winter. The cure was a head bolt heater. This gave it a better chance to warm up. When a 730ck took over the main work load the DC got new tires and was permanent feed wagon tractor. It was better in mud than any other tractor we had regardless of age or beauty or horsepower.

pull the sleeves and hone them (then properly clean them), clean out the block, replace the sleeve o rings and put in new piston rings and it will be ok for what you want it to do, you already have 4" pistons, you don't need to pull the pan to do this, main bearings don't give much problems, unless you want to spend a bunch to buy reman bearings and having them bores, which requires a complete engine dissasembly

Have you considered the possibility that you have 2 unrelated problems?

I had a very similar problem with coolant in the oil of my DO. Pulled the head and discovered a crack in the block between the side of the #2 sleeve and the channel for the push rods. I removed the piston and sleeve (without removing oil pan) and then used a dremmel (with lots of brake cleaner) to clean the crack before sealing it with RTV. This has been holding for a year now (knock on wood).

When I reassembled the tractor, I installed a rebuilt head that I had been saving for a few years. Unfortunately there had been a mouse living it at some point, which caused a large amount of cotton to be introduced into my cooling system. This ended up plugging the radiator, which caused the coolant to foam and the tractor to overheat. Lots of flushing and a new radiator core fixed this problem.

Good luck.

Thanks guys. I think I know what route I am going to go now. I have never pulled pistons and sleeves before but am confident that I can do it just fine. I will have to make a sleeve puller but that will be not problem. Does anyone have a pic of their sleeve pullers? I found one on fleabay and was going to copy it.


Dboll I do have a couple more questions. First is how can you tell I have 4" pistons already? Ihave not measured them yet as I just figured they were the original ones.

Second is my book says that the rods and caps are numbered. Mine are. It also says that the numbers are to face away from the cam shaft. Mine are facing the cam shaft from what I can see from the handhold that I opened up on the left side of the motor. I have not opened up the left side to see if they are numbered on both sides. I assume that they have been in this configuration for the last 40 years or so as Grandpa said he had this motor put in in the late 60's. by the serial number the motor is a 1948.

On a good note the sleeve walls are in great shape. I can barely catch my fingernail on 1 and 2 and cant catch it on 3 or 4. That is a good sign I guess. I dont think this tractor was used hard after it got it's new motor.

I am excited to do this work but a little nervous too as I have never been this deep into a motor before. But it looks more like pay attention to detail and take your time and it should turn out just fine. And keep everything clean, clean clean.

Pulled the pistons..........#4 rod cap...........this is what I found...........now what? Who does rod babbiting and should I just send of all rods to be redone?

On another note two of the pistons had rings that grooves lined up. On #2 the two middle rings lined up and on #3 the oil and next one up lined up............that couldn't be any good.

Well, update........I made a sleeve puller and pulled the sleeves tonight. That was a good decision as #4 was totally packed shut and no way water was getting there........#3 was half packed.

The sleeves were pretty corroded........how do I know if they are too thin? Has anyone ever had that problem?

The clean up begins now and in search of a good machine shop to rebuild the head......