Block Heater on my D4-6U

The fitting is 3/4" pipe on the water pump....
There is a smaller plug on the side of the block between the injection pump and the starting motor clutch that is used...
One of my CAT 112 graders still has this type of block heater on it...which is also piped into the heater hose to the cab heater...
I took it off the other one...Don't need it here...

You can probably use either plate. The forward one is used on the industrial engines for temp shutdowns, etc. The rear plate was used for heat to the filter tower which was abandoned in later models. Having this high connection and the low pipe plug connection is ideal for thermosiphon heating.

Thanks for the feedback gentlemen. I had assumed I would want to heat the coolant in the head as well as the block, which is why I was looking at the thermostat housing. I have ordered a few pieces to put this together. Will take some pics when finished. Thanks again - Bob

On my D4400 I put a drain valve in the plug between the injection pump and starter motor.
Took a bit of work but once in there,I can drain the block and make no mess.
Im still a bit carefull about leaving antifreeze in it overnight.
Drains pretty quich there so it should circulate very good from their too.
Chris

Keep in mind that the block drain draws from a pocket in the block that is frequently known to collect crud that could interfear with water circulation for a block heater.....also common to remove plug and get no flow.

So it would be a good idea to remove it now and then to keep things clean?

It cleared off and warmed up today...so I went out and took a look at my two CAT 112's graders and the electric circulating heater on one of them...That block drain...between the injection pump and the starting clutch...looks like 1/4" pipe...There is a pipe fitted into the hole and then other fittings added to adapt to the heater hose going to the electric circulating heater... The rest of heater connections you already know about...at the water pump and down below...When I took the heater off the one 112...I had a good flow of coolant coming out of that block drain...Incidentally, I fitted a nylon hose barb fitting into the radiator drain...with some plastic hose attached to the hose barb...and drained the coolant from the radiator and block into a barrel...so the coolant could be re-used...You've not asked for photos...so I reckon you don't need any...
Good Luck...Keep Warm...Respy, Carl

Not all are the same...the early models appear to have 1/4" pipe block drains and the "U" models have a plug that is 1/2"-20 tpi. I have replaced mine on the D4's and D6 with a short 1/2" fine thread flanged head bolt. Requires a slight thread relief in the hole so the flange will seat tight. Could also add a brass washer if you like.

The machine thread would make heater connections a little more complicated if you want to use that connection.

What about enlarging the block drain to 3/4 NPT? I'm using -10 AN and hard tube. Makes sense to me to go to the block rather than the radiator pipe. But 1/4" NPT seems prety small.