I’ve been noticing a chatter coming from either my transmission or transfer case at speed and under load, and it’s getting louder. Looking through the service manuals is, as usual, pretty useless. There’s no decent picture of the T-19 I have, and no direct reference to where the drain plugs are or how to service them.

Update: Realizing I had neither the time nor the pump to change my own gear oil, I stopped by the Jiffy Lube and paid the guys there to do it for me. Transfer, Transmission, and front diff are all full and clean—of Gl-5. So that will have to come out sometime this spring, after I’ve bought a pail of 50 wgt. The rear diff was full of chocolate milk so that got replaced, and he lubed all the points on the front and rear driveshafts. On the short ride home, I still heard chattering, so it’s looking more like a driveshaft problem than a simple lubrication issue. Oh, well.

Checking the Binder Planet, I found three posts with great information:

4 Quarts Valvoline 50 wgt racing oil is correct. See FAQs for details.

The fill and drain plug are on the passenger side of the transmission/
drain is directly below the fill plug.

—You pull the lower plug to drain, should be a 5/8″ square plug. The upper plug is the filler hole and you fill it until it starts to trickle out… to the bottom threads of the filer plug. They make an 8-point socket, or you can use an 11/16″ 12-point socket. Difference is the 8-point will be less likely to strip the plug. Crescent wrench is not acceptable… lol. Clean each plug while looking for metal chunks attached to the magnet on the end. Clean the threads, apply some RTV or thread sealer (no teflon tape) and snug them down to… IIRC, 35 lb-ft. Don’t quote me on that though, I am guilty of tightening them to 1/2 grunt… looking up pipe plugs it says a 3/4″ thread is 33-37 lb-ft and a 1″ thread is 70-85 lb-ft.

—I myself prefer to pull the top plate and just dump the gear oil in until it is to the bottom of the filler plug.

—One thing you must know is that the gear oil is not a standard gear oil you’re going to find on the shelf at Wal-Mart or whatever and most counter-monkeys will tell you “just regular gear oil” or “GL-4 or GL-5”. Truth of the matter is the gear oil you need to run is a non-ep. GL-1. 90 weight mineral gear oil, no EP additives. Many are running 50w motor oil.

—Reason it needs to be GL-1 is that the EP additives in GL-4 & GL-5 will destroy yellow metals. That means the synchros, any bushings/spacers, brass or copper will disintegrate. Mobile has a synthetic Trans fluid that is supposed to be superb, but I stick with Gold Band Industrial Mineral Gear Oil, which is the brand we used in all out heavy equipment, international as well as CAT, from gear oil to hydraulic and I run it in both the transmission and transfer case.

This link has two very good photos showing the drain plug on a Dana 20 transfer case.

I take the nozzle cap off a quart of gear lube, cut the tip off, and push it into an appropriate length of 5/16″ or 3/8″ fuel hose. Long enough so you can screw the qt bottle onto it right side up and hold it above the level of the fill plug while you squeeze it. Turn it upside down, squeeze, right side up, let some air back in, and repeat. Repeat until the bottle is empty, then screw on the next one. When the oil starts running out into the pan, stop and put the plug in. With the tunnel cover off, your best bet is to run the hose down into the fill plugs from the big hole there. Protect the interior from spills as necessary, this isn’t the cleanest method, but it works.

The transfer case takes just short of 2 quarts, and the transmission just under 4. If you start with 6 quarts you’ll end up with about 1/2 quart left over. At least that’s what I ended up with on the 800 a couple weeks ago.

The trans, transfer case, and both axles have square headed plugs to check the gear oil level. The trans and transfer case have 2, the lower is a drain so use the upper. They shouldn’t be too dirty but as long as they’re full, you’re in the ballpark. There’s no filter in a manual trans. Also, greasing the u-joints, steering, and up on the bell housing there’s grease fittings for the clutch linkage and transfer case shifter.

Of course, with all the free time I have, crawling under the truck and servicing it myself is going to happen about as soon as hell freezes over. The Jiffy Lube out on 40 does transfer case and transmission servicing, which sounds better in the short term.

Date posted: January 28, 2012 | Filed under Repairs | 1 Comment »

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