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Apr 26th, 2026 | | AD Chevy Trucks  Over 6,000 pictures Brad Allen has an awesome collection of Chevrolet factory pictures that he has set up from film strips. Check them out!
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| | | | Joined: Aug 2012 Posts: 50 Wrench Fetcher | | Wrench Fetcher Joined: Aug 2012 Posts: 50 | Follow up on a rear end oil leak on a 3/4 ton truck
I had oil from the rear differential appear around the rear wheel lugs,shop manual said put locktite around the bolts which stopped the leak for a few days then the differential began leaking around the pinion seal (and making a pretty big puddle) which I replaced,this stopped the leak for a few days then the new pinion seal started leaking again......another truck owner said to check the rear axle vent tube which I did not find in the shop manual. This vent tube is on top of the rear axle about 6 inches from the differential on the drivers side.once this was removed and cleaned the rear end leak finally stopped, I guess the oil in the diff heats up and expands and then exits out the weakest point. Cleaning the vent tube first would probably have fixed it from the start. Are these axle vent tubes on all AD trucks? Thanks | | | | | Joined: Aug 2012 Posts: 50 Wrench Fetcher | | Wrench Fetcher Joined: Aug 2012 Posts: 50 | Wow!! I just made "wrench fetcher"!! | | | | | Joined: Dec 2011 Posts: 241 'Bolter | | 'Bolter Joined: Dec 2011 Posts: 241 | Do you have a picture of this vent tube? Just curious where it is. It will give me something else to check on my 52 if it has one.
Mark | | | | | Joined: Jul 2013 Posts: 388 'Bolter | | 'Bolter Joined: Jul 2013 Posts: 388 | My 54' and 55' rear ends both have them. If they're missing you can get a new one that presses in. | | | | | Joined: Aug 2012 Posts: 50 Wrench Fetcher | | Wrench Fetcher Joined: Aug 2012 Posts: 50 | I don't have a picture but the vent tube is a 3/8 inch bolt with a central vent covered with a metal moveable covering lid that rotates and allows pressure relief,mine was easily removed and was plugged with grease and dirt,a few minutes cleaning with solvent and blowing it out opened the vent passage and stopped the back leak out the pinion seal.,,mine on the 3/4 ton was 6 inches away from the differential on top of the axle on the drivers side....I never knew it was there. | | | | | Joined: Nov 2009 Posts: 639 'Bolter | | 'Bolter Joined: Nov 2009 Posts: 639 | A plugged vent tube will cause the leakes you discribed. I picked up a spare '52 rear axle to rebuild it in preperation for my open rear/T5 conversion. When I pulled the brake drums off, the brakes were soaked in gear oil. I checked the vent tube and it was plugged solid | | | | | Joined: Aug 2005 Posts: 278 'Bolter | | 'Bolter Joined: Aug 2005 Posts: 278 | Vent tubes on all differentials that I have seen. On torque tube models, you may find the vent on the torque tube instead of the differential/axle housing. | | |
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