Monitoring Transfer case fluid

I'm generally not fond of a vehicle fluid I cannot monitor. I want to remove the drain and fill plugs and replace them with hose fittings and run a clear piece of tube between the two so I can monitor the level of fluid.

I'm sure this has been done before, it is not some brilliant or new idea, but I can't find anything on it. Just curious if anybody has done it and what they used for hose fittings and what size. Hopefully save some time running back and forth to the hardware store buying stuff. :laugh3:

Just source it out yourself at McMasterCarr.com. That's how I added it to my NP205 and NP241 (didn't use the factory plugs though).

I'm guessing the factory plugs are NPT 3/8" or 1/2", though I've never checked.

If that's the case, just grab 2 NPT to Swivel push to connect fittings (i.e. 51495K157) from mcmaster the right size and some clear nylon or polyethelene tubing cut to length between them.

Install and you're good to go.

Anybody know the size needed for the factory drain and fill plugs?

IIRC the fill plugs are M22 x 1.5 ... They are metric, did a bunch of emailing with NVG techs a few years back ... been that since the NP208's intro in '80.

I wonder how they seal straight threads...?

I don't believe they are straight threads, I am real sure they are not

I might be thinking of the hex head plugs that use a gasket. Didn't even think of the hex socket plugs. Sorry for the confusion, the earlier 231 in my YJ was a gasket plug.

The plugs are big enough that you could probably drill and tap them for 1/8" pipe fittings

Hans

I would just drill and tap the case next to the plugs, that way you dont have to disconnect your setup everytime you want to flush your t-case

This^

souske said:

I would just drill and tap the case next to the plugs, that way you dont have to disconnect your setup everytime you want to flush your t-case

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x3, same way it's done on an atlas.

Yeah that came to mind. Too bad it didn't come to mind until I finshed my SYE install. :dunce:

MoparManiac said:

I wonder how they seal straight threads...?

Click to expand...

There's no pressure, so it's easy. There are straight pipe threads that hold pressure, you know.

Generally speaking, pretty much any thread may be sealed with a little effort. Common methods:
- Fibre washer
- Rubber washer
- Fitting machined to accept O-ring (seals light to moderate pressure, the AW4 cooler line fittings are sealed to the case this way.)
- Applied sealant on assembly (RTV, PTFE paste)
- Slight interference fit between threads (very uncommon, similar to the interference between tapered threads.)

But, since the drain/fill plugs are just a "splash seal" (no working fluid pressure, and there's a vent for when the case heats up,) simply applying RTV is enough.

I rather like your idea, but I'd probably look for a way to do it without having to tap the plugs (since maintenance is something I'd like to keep as easy as possible.)

I just pull the full plug from time to time and make sure they are still full and the fluid is not burned.