DC Radiator Drain Pipe Size

I had the old "51 DC running this past weekend and found that she was overheating. i want to back flush the system and maybe rod out some of the radiator tubes without removing the radiator/core. I need to know what size the pipe thread is for the drain. It looks like someone put a bolt in there as a plug, and i hope that the threads are not all buggered up!

My plan is to drain the coolant out, back flush the system with a hose-pipe adapter then rod out as many tubes as i can. then run with straight water for a couple hours, then drain/flush again. Hopefully this will be enough to keep her cool as all she does is pull a fire wood wagon around a few times a year.

so what is the pipe size so i can get a nipple and cap? Also, any other tips will be greatly appreciated to try and keep her cool! Thank you!

After back flushing run a little washing soda in her and back flush again. Most of the ones i've seen had a lot of sludge in the block that flushing really doesn't get out.

DC COOLANT ERATIC. go to the archives case forum and work your way back. Start with this topic,and you will find many more topics. let me know how u do! Chuck

(reply to post at 16:36:09 04/23/12)

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1/4 NPT

After you get her flushed and running again, take a magnet out of an old radio speaker and wire it inside the radiator above the core. You'll be suprised how many rust flakes it will catch. (My $0.02 worth. jal-SD)

The drain pipe is either 3/8" or 1/2", both regular pipe thread. Good luck gettingthe old pipe out . clint

Household drain cleaner called the works. let it run 45 minutes and backflush while running usually works for us on the old DC's!!

Unless the bottom tank has been modified it is still 1/4 NPT. A 4 or 5" long nipple and a cap.
mEl

I plan on washing the system with washing soda after the initial flush. Also, could i put a small ball valve on the end of the pipe nipple so that I do not have to unscrew the pipe each time i need to drain? Has anyone done this? The magnet idea sounds good ans is simple enough too. Lastly, anyone have a definite answer on the pipe size? I am assuming that a 6" nipple will be long enough.

I would go check but I am at my normal residence now which is ~3hrs from the tractor

My DC had a 1/4' pipoe nipple in it.

as Larry said 1/4 pipe

I have several DCs, an L, and a C. Restoring cooling systems that overheat on these tractors is a big headache. I have four done and two to go.

If backflushing means adding water thru the drain which is a 1/4 pipe nipple, 99% of the added water routes thru the lower radiator hose into the engine then into the top tank and overflows out the top opening. To truly backflush the radiator, one method is to disconnect the lower radiator hose from the engine and plumb a water supply to the radiator's lower hose. The problem with this medhod of backflush is garden hose water flows backwards ONLY THRU THE OPEN CORES. Most plugged cores will remain plugged.

Whatever cleaner you try, the cleaner cannot reach the plug in the individual cores because of no curculation thru the individual cores that are plugged.

I remove the bottom tank and remove the plugs from the bottom using an asortment of home made tool to remove the plugs. The plugs vary from half inch deep to 3 or more inches deep. A wire rod usually will succeed in removing only a small percent of the plugs. Continuing to jam the rod against the plug tend to do no good.

Typically the plug is either an extremely thick rust paste or fine particles of rust grit tightly packed in the core. Rigging a hose to oval on one end and pressing 100 psi air pressure to the end of the plugged core is generally fruitless for either the paste or the packed grit.

The radiator that I unplugged this past winter had 42 of the 125? cores plugged. The tractor would overheat at half load when the temp was over about 85 degrees. With my homemade tools, I probably averaged about one hour to unplug an individual core ie 42 hours of work to unplug the rediator. I ended up with one seap and Bars leak fixed that.

make sure you wire the valve closed,I would hate to see you loose coolant from a valve that might vibrate open. my 2$ worth

I put a valve on the pipe on the bottom of my 38CC radiator. I then put a nipple and cap on the bottom of the valve. Like Chuck said, anything could happen to open it, vibrations or mischievous hands. Good luck, Allan.

Now that you guys have me fully afraid that flushing and washing out will do nothing for the overheating problem, what are the steps to remove the entire assembly from the tractor. I believe that I need to remove the flanged pipe 90 connecting the head to top tank, then remvove hose at bottom, then its just the two large bolts that go into the lower tanks and lift off..is that correct?

After I get the whole assembly off, what am i looking at for just removing the lower tank and rodding? What are the chances for broken screws (16 i believe) connecting the core to tank? any other tips or things I shuold be watching out for? Thanks again for all the help so far!

All the bolts that hold the bottom tank have nuts so no problem if you twist off a bolt. At the top, some of the bolts screw into the casting.

To get the radiator off the tractor, there is a sheet metal fan shroud across the bottom held on by four 1/4 screws that must be removed. They screw into the casting and easy removed from the sides. A hoist is helpful since the assembly is quite heavy.

Squeeze the radiator hose. If it feels flexible, I loosen it at the upper end only and bend it sharply as needed to detach it and to get it past the fan blade. I leave the fan attached. I have to rotate the fan a few degrees to maneuver the hose beyond the fan. If the hose is old and stiff, I cut it off and replace it.

The six inch long drain tube can be left in place but does complicate the process a little because the top of the radiator has to be leaned forward at the top.

When the radiator is removed, that is a good time to replace a marginal generator belt because the fan blade has to be removed to replace the generator belt. Also a good time to free up the rusted fan belt tigtener mechanism.

The core is probably stuck to the tanks so use a thin blade and gently pry the bottom tank from the core.

You mentioned a bolt being used for a drain plug. If the 1/4 pipe threads are damaged, there is material to enlarge the drain hole to 3/8 pipe. I find it a good idea to make the drain nipple long enough so that vise grips can be used to hold the nipple from unscrewing when draining the radiator or use a shut off valve rather than a pipe cap.

Excessively forcing a rod thru a core may cause a hole in the core. I very slightly round the end of the rod. If you have a problem with some of the cores and I expect you will, let me know and I will elaborate on how I proceed. Good luck.

Ron,
Thank you very much for all your help, and everyone elses. My plan is to first drain the radiator by removing the bolt that is there. Then see if the threads will take a 1/4" nipple. If that goes well i will first flush the system, then rod ot as many tubes as i can through the fill openeing, then flush again. Then run the washing soda solution for an hour or two and see if she gets hot. If she doesn't, i will flush one last time and refill with coolant, place a magnet in the top tank, and hope to be good for a while.

If the threads are too messed up, or if rodding through the opening doesnt work, i will remove....crossing my fingers that the first plan will work.

I plan on using a dipstick and rounded wire to "rod" out the tube. The dipstick already has a round end, and i will file/grind the end of the wire....at least this is the plan. The tractor is about 3hrs away and i wont be there for about a month still, but planning ahead never hurt anyone