I'm restoring a 1937 Chevy 1.5 ton Firetruck. Yesterday I found a big puddle of fluid under one on the rear dual wheels. My first thought was brake fluid, but it looks, smells and feels like gear oil to me. When I pulled the drum off, it looks like the gear oil is running out of the axle into the drum. I have never worked on one of these before. I'm assuming there is some sort of oil seal here that I need to replace? Should I go ahead and replace the wheel bearings while I'm here? Anyone have any idea on part numbers? The reproduction sites I visited primarily listed only bearings and seals for the smaller trucks. Thanks for any help and suggestions!
Hy acfd, welcome, wash the seal with solvent, there might be a part number on it. The bearing components should have numbers on them as well, your bearings may be New Departure barrel bearings, if they are not damaged there is no need to replace them. Barrel bearings have not been available for decades, but standard tapered replacements should be available. If you have a good bearing supplier in your area you could take your cleaned up components to them to have them inspect them, the seal can be measured and a replacement found by matching dimensions, hope that helps.
I believe you have a Torque Tube drive shaft, if so the transmission oil could migrate down into the rear causing it to flood the wheel seals making it leak. Park the truck on level ground, remove the rear axle oil fill plug and see if any runs out indicating it's over filled. If you get oil coming out then go and check the transmission to see if it's low on oil...oil should be about level with the side plug...if you can't touch oil with your pinky finger it's low.
There should also be a axle vent on top of the housing, make sure it's clean and working...if the rear can't vent it will build pressure when it warms up pushing oil out the seals.
If you parked the truck with the leaking side down hill, then the seal is bad.
