Jd450 how does this seal

[Georgia088]

Had to remove bell housing from jd450 loader to replace seal. I am in process of reassembly. In order to get bell housing off, a 90 degree fitting must be unscrewed from the transmission front cover because it goes through a hole in the bell housing to attach to the transmission front cover.

From that 90 it goes to the oil cooler by the transmission via hose/pipe.

My question is how does this fitting seal? It appears to be regular pipe threads. I can tighten it by hand, but the part that the hose clamps over the nipple must point in the correct direction to get hose to the oil cooler. If I try to tighten another turn, it gets tight, so tight that I must use either a 1-1/8 wrench or pipe wrench to turn. it feels like it’s going to break before I can get a full turn so that the nipple is headed in the right direction.

It is like the threads have bottomed out in the transmission front cover. But if I loosen to where the nipple is headed in the right direction it is barely hand tight. Can this possibly seal? As, this has quite a bit of pressure I would think.

It is part number 14 in the transmission oil cooler lines and filter breakdown in the schematic and there is no mention of a proper way to tighten in the service manual.

Thanks.

 

[Jim.ME]

That fitting has a hose secured with a clamp, it is not "high" pressure as such. Your Service manual should give you info on checking that system. I think you will find the oil cooler system runs at 200 lbs., or less. You do need to use an oil rated hose spec'd for the location, not heater hose.

If it is tapered pipe threads (NPT) it seals by the interference fit between the male and female threads. When a tapered fitting is forced in, it can reduce the OD of the male threads on the fitting and can increase the inside diameter of the mating female threads. If there is a step in the fitting at the end of the threads (as it appears there is in your picture) check to see that it is not bottoming out on the housing, stopping it from advancing in the threads. If it is bottoming out there, you could try cutting the step back a bit more.

There are a few options with NPT threaded fittings. You can get a new fitting and see if it tightens up at a different point. You may be able to carefully run a die on it a small amount to allow the tapered threads to go a bit deeper. Use a thread locking sealer on the threads. Use multiple wraps of pipe tape, being careful to keep the tape back at least a full thread from the end to lessen the risk of any tape getting inside the oil passage.

Loctite 51604 "tight", Loctite 545, Leak Lock (there are others) are a few sealants that will seal and lock threads. Threads need to be clean (no oil) and dry for use. There may be cure times required. Some may require heat for removal.

Edit to add: Another thought would be to get a heavy hydraulic nipple the right length and a 90-degree hose adapter to go on the outer end. New threads may tighten up in different locations.