I have a late 70’s early 80’s international td15c. Dozer sat for a long time before I got ahold of it. Have everything pretty much running and operating as it should other than moisture keeps getting into the transmission. Been flushed twice now with filter replacement/cleanse and oil still gets milky after little use. Clutch pressure gauge also shows in danger area but operates and shifts very well. What could this be?
I'm not too familiar with IH tractors but will ask are you losing any water from the cooling system that you can't account for? I ask because I know some of the older tractors cool the oil in the transmissions with an oil/water cooler. if your does it is possible it would be transferring there. I'm sure there will be much smarter people coming along soon that will help you work through this, sorry I couldn't offer more. Good luck with your problem.
Three different possibilities as I see it: 1. water is getting into the transmission through rain or condensation. The fluid stays clean while working, but after a rainstorm it gets milky, or after a wet season it gets milky. 2. water is getting in while working through a coolant leak like Mcrafty said. 3. the fluid that's left in the trans has enough water that the new fluid is milky after five minutes of running after the oil change. You have to figure out which it is to know how to fix it. An oil sample SOS from Cat will detect glycol from antifreeze in the oil.
TD 15 s have oil to air trans cooler, its a separate swing out radiator in front of the main radiator so cannot get water in from that. Its been a long time now since I have been around one but if my memory serves me right there is some rubber boots on the foot brake linkages down under the seat, there could be a way for water to get in the backend thru them.
So probably a combination of #1 and #3. You can dry oil out instead of replacing it. I'd do that, because it takes a lot of attempts to get it reasonably dry, so dry the same oil over and over until mostly dry, even if you're going to change it again when done.
Does the tractor have a winch on the back of it? That was the most common entry point for water when I worked for a IH dealer. I don't remember any swing out coolers on a C model dozer. In those days I only remember the shell and tube coolers using engine coolant.
So i don’t think it’s the cooler on the front as it looks like it trans oil only. The boots on the brake bolts are cracked so that could be the issue. Every time I replace fluid I clean and replace filters as needed. Clutch pressure gauge always reads to the right in the danger zone but seems to drive and shift fine. I hate to keep draining and replacing fluid due to costs and the boots are no longer available.