Sorry guys but, I'm looking for advice on a New Process 203 transfer case, I have one in a late 70's Dodge and was looking as to how you service the 203? I find no drain holes in it, just the fill port. After you get it drained what is the recomended oil to refiill it with? I have heard it takes 10w40 or the likes, not gear oil.
Thank You in advance for you thoughts and knowledge!
Kim

 

You have to use a suction pump to clean it out, unless of course it's out of the truck, then you can tip it.
Most people run motor oil in them, you are correct. You might consider synthetic motor oil though to keep the chain as cool as possible. When the chain get's hot it stretches, then skips.
If the NP203 was a gear drive instead of chain I would use one on my Dodge! It's a great transfer case, as long as you don't care about gas mileage!!!!

 

203 is full time right?

 

YES, 203 is full-time and chain-drive.

I have seen them get to slapping and wear a hole through the case.

 

THere is a chain guide that is supposed to keep that from happening. I have never had one wear through, but I don't drive them long with a loose chain!

 

Part-time conversions used to be pretty cheap.

 

OK, what's the best way to check for too much chain play? Jack up the front axle and turn the front output? What is considered a loose spec.?

As far as changinf the oil, could you pull the PTO cover off and also pull the rear lower bearing cover off and drain it that way?

 

If you stand on it and hear a popping sound, it's too loose. Otherwise don't worry about it until it starts slipping.
I would take the dude to your local rapid oil change place and pay them to suck it out. I don't know if you can get all the oil out through the PTO cover...

 

To drain the oil, simply remove one of the rear bolts to the bottom right of the fill plug. There will be a circle of bolts at the back of the case. Remove the lowest bolt. It will drain slow, I remove the fill plug to let it flow a little easier. Once it's mostly drained out, if you have compressed air, you can shoot air into the fill hole to get more oil out. Then vice versa, shoot air into the small bolt hole, and oil will come out the fill plug. Don't be looking directly at it when you start shooting air as it will shoot you in the face with 30 year old motor oil lol. Factory fill is 10w30 motor oil. I've used 15w40 motor oil, because I usually have it around, with no issues.

 

Thank You all for the help!