The Stovebolt Site Forums The Shop Area Engine Shop Pinion seal leaking

How do I go about sealing the leak (small but still there) in the pinion seal on my 53 3/4 ton 3600. Where do I get a new seal if thats the case or is there a different way to go? :confused:

Remove the drive shaft from the yoke. Remove the cotter key & the pinion nut. Tap the yoke off with a hammer or you may neen a puller. Remove the 5 bolts holding the fange on & remove the flange. You can than remove the seal from the flange. Any good parts store can get the seal. They may take a number off the old one. They may be able to supply the gasket for the flange or a G.M. dealer can. You can use RTV on it. Put it back in reverse order. Tighten the pinion nut securly & tighten more to line up the cotter pin holes. Fill the housing up with grease.

Adding a bit to the instructions. Works best if you mark the nut and trunnion with a punch before you loosen the nut. That way you can return to the same position without having to check the preload. Also be warned, the pinion nut will be a bear to remove. It takes a 1-5/8" 12 point socket, iirc. I borrow a 3/4" drive impact when I do mine, and still had to use a torch on the nut the first time. I also put a big pipe wrench on the trunnion with enough cheater to go against the frame. It also helps to have the rear wheels sitting loaded, say on some ramps.

When you buy the seal, also get a redi-sleeve. It's an expensive piece. Fits on the trunnion and covers up the worn surface for the seal. Well worth the $$$s. You might have to get these parts from one of the vendors, it all depends on your local parts store.

When you put the trunnion back on, use some anti-sieze on the splines and the pinion nut. It doesn't take much, but will make it a lot easier the next time.

One other thing. Check the air breather. It's on top of the differential housing, driver's side near the spring. If it's plugged, when the lube gets hot and expands, it will blow out a seal. It's simply a 1/4" pipe fitting with a loose sheet metal cap and unscrews out of the housing.