A different sort of Rainwater problem (IH utility)

Guys, I have a puzzling (to me, that is) issue with rain water in a Brother and Sister pair of IH utilities.
Sadly, I don't have a shed so both of these tractors live al fresco. One (300U with T/A on gas) in Southwest Missouri where it rains fairly often, and one in West Texas(350U with T/A on LPG) where they get far less rain. The 300U was changed long ago to vertical exhaust, while the 350U retains the original downward utility type exhaust.
My 300U gets copious amount of rainwater into the transmission, while the 350U gets massive amounts of water in the engine. I kidded my neighbor that I was about ready to split the tractors and join the 350 drive to the 300 engine!!!! I have replaced lots of gaskets and looked until my eyeballs glaze over, but I can't seem to solve this. I have ruled out most of the obvious (No coolant loss, replaced rocker covers, etc.) so I have to throw myself at the mercy of the crowd here. Any ideas?

I have had the same problem on more then one tractor. It has been rain seeping in by way of the exhaust pipes where they are not water tight at the manifold. I too live in Missouri so understand the rain thing.

The Transmission is getting its liquid from condensation (and some rain down the shifter). The Texas climate has large temp differences every day causing "breathing" into and out of the trans. When in the trans, the moisture condenses on the cool metal and stays.
I agree with old. The Missouri tractor likely gets moisture at the joint where the manifold attaches to the exhaust pipe. This perpetually rusty joint is often leaking water from the muffler (a collection device) to that joint. Two solutions for the engine issue: remove the pipe, tap the manifold to get clean threads, put in a new 2" npt black iron exhaust pipe using molybdenum disulfide anti seize compound. Or invent a umbrella for under the muffler that directs rain off of the hood and doesn't touch the hood.
A CV joint boot with a small axle end hose clamped to the base of the shifter can keep some of the rain out of the Texas tractor (and Missouri as well). Working the tractors often will heat the oils enough to drive moisture out. When these were the main use tractors the issue never became obvious. A they are used today, the heat is usually minimal and the H2O builds up. Jim

Sounds like a good thing to check, especially since I know I have an exhaust leak on the 350u. The only thing is, on the 350u the rainwater goes directly to the crankcase, it has never been in the cylinders. And it is a LOT. I am now in the habit of loosening the drain plug on the oil pan, and draining out as much as a gallon of water. The first time it happened I pulled the pan and pressured up the cooling system, and waited, and waited, and waited. Only then did I realize it wasn't coolant. It does give me a great reason to put on the new exhaust manifold, though!

Check the dip stick and make sure the pipe fits tight and that the stick it self has a good cup over the stick so rain water does not seep in there.

I like the cv boot on the shifter idea, I will definitely give that one a try. I also have an old boot from a large master cylinder that might fit well. The condensate in Missouri is exceptional for sure,when I moved from west Texas to Missouri, I took along all of my Military surplus jerry cans and metal gas cans. My place is right beside a creek in a bottom, and within a year or so, several of the cans had holes from rust. SOGGY BOTTOMS! Probably made my brain moldy as well.

Water down the exhaust will run into the crankcase through/past the piston rings without rusting it up much if any. When cold the ring gap can be 10 to 15 thousandths. Jim

Okee dokee, I will check that out. I was so relieved that it wasn't a cooling system related failure that I avoided even considering that one. Like most folks, I often fail to take into account the element of time- Drip drip drip can really add up in a few weeks.

Do you have a rain flapper on the 300U exhaust, or at least an old bean can?

The 350 has the under slung exhaust, which always stymied me that it would be getting water in the engine. It never occurred to me that it could get between the head and the manifold as previously suggested, but now that I think about it, it very well could be happening. I haven't seen any water come out of the exhaust, but I wouldn't, unless I was riding the tractor backwards and looking at the three point. I don't have a borescope, but maybe I could borrow one the next time it rains in Texas (which could be many years from now at the rate it is falling)and see if the water is going through the manifold, into a cylinder, past the rings, and into the pan. When I got the 350, it was supposedly recently rebuilt, and the first time it milked up the engine oil, I was certain that the guy had sold me a crack. Wrong!
I appreciate the thoughtful ideas and replies, when I figure it out I will post the answer to my puzzle.

Rustmonger, I know all about rain and water problems. I live in Lincoln City Oregon and my house is about a 1/4 mile from the beach!! I built a temp machine shed for my 300 utility other wise it would rust away!!! Even inside it gets condensation in the tran and in the oil, not bad but enough to bug me! So good luck with your issue! Stoner!