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I've been fighting some pinion seal leaks on the front pinion seal of the middle axle on my M923A2 truck, and am at the point where I'd like to make sure I'm not missing something obvious.
My truck was a ~2011 rebuild at Kansas. When I got it, there was a very slow leak at the front pinion seal of the middle axle. I tolerated it for a few years because it never leaked enough to form drips, but the front of the axle housing was always damp. There was orange RTV around the gasket surface, so it had obviously been open at some point earlier in its life, but I am the first owner of this truck after the rebuild and surplus sale. I've removed the axle vents and have them running through DOT air hose to a filter near the washer reservoir, so this is not due to clogged vents.
This Spring I decided to buy a socket and a seal and replace the seal per TM9-2320-272-24-3, task 4-102 (page 4-575). I read that the TM isn't correct, that you don't need a puller to get the flange off, and that the tin housing just pulls off by hand. This was *very* valuable information from the forum, for which I am extremely grateful, and matched the condition of my truck exactly.
The first time I replaced it, I used a new seal I got from Ebay and I made a new gasket off the old one using Karropak sheet. I sealed the outside of the seal to the housing using Permatex "Right Stuff", as well as a light coat on both sides of the gasket. I used a light film of grease on the seal lip and on the pinion flange surface. After the trip to Haspin (~100 miles), it was leaking worse than before. The entire under side of the truck in that area was coated in oil. I thought maybe I had messed something up with my homemade gasket, so I ordered another seal and ordered NOS gaskets from Red Barn Customs. Luke at Red Barn said that he recommended using grease on both sides of the gasket rather than RTV, and to use a lighter lubricant than grease on the seal lip because that could make it overheat. Prior to removal I tried the pressure test from the TM, task 4-106, but it didn't show any leaks despite obviously leaking oil.
On replacement #2, when I disassembled it, I found that the outer dust lip of the seal was torn, probably from when I pushed the pinion flange in place. So I reassembled the flange into the tin cover on the work bench this time, making sure it didn't fold that dust lip over, and used Lubriplate 105 as an assembly lube. I put those pieces in together and used grease on both sides of the gasket surface per Luke's recommendation, and I tightened the bolts in a criss cross pattern in 3 steps to the final torque of 100 ft.lb. After a 45 mile drive last night, it still appears to be leaking, from the seal surface, not the gasket surface. Is there anything else to check, other than the tin housing just being junk? The bearings seem tight once the cover bolts were tight, tightening the shim pack. The axle doesn't seem to run any hotter than the other 2, and it has never had any debris in it when I've drained it.
Any thoughts on things to check that I may have missed? Has anyone else had one leak that was this persistent? Should I start looking for a new center section that is known to not leak?
My truck was a ~2011 rebuild at Kansas. When I got it, there was a very slow leak at the front pinion seal of the middle axle. I tolerated it for a few years because it never leaked enough to form drips, but the front of the axle housing was always damp. There was orange RTV around the gasket surface, so it had obviously been open at some point earlier in its life, but I am the first owner of this truck after the rebuild and surplus sale. I've removed the axle vents and have them running through DOT air hose to a filter near the washer reservoir, so this is not due to clogged vents.
This Spring I decided to buy a socket and a seal and replace the seal per TM9-2320-272-24-3, task 4-102 (page 4-575). I read that the TM isn't correct, that you don't need a puller to get the flange off, and that the tin housing just pulls off by hand. This was *very* valuable information from the forum, for which I am extremely grateful, and matched the condition of my truck exactly.
The first time I replaced it, I used a new seal I got from Ebay and I made a new gasket off the old one using Karropak sheet. I sealed the outside of the seal to the housing using Permatex "Right Stuff", as well as a light coat on both sides of the gasket. I used a light film of grease on the seal lip and on the pinion flange surface. After the trip to Haspin (~100 miles), it was leaking worse than before. The entire under side of the truck in that area was coated in oil. I thought maybe I had messed something up with my homemade gasket, so I ordered another seal and ordered NOS gaskets from Red Barn Customs. Luke at Red Barn said that he recommended using grease on both sides of the gasket rather than RTV, and to use a lighter lubricant than grease on the seal lip because that could make it overheat. Prior to removal I tried the pressure test from the TM, task 4-106, but it didn't show any leaks despite obviously leaking oil.
On replacement #2, when I disassembled it, I found that the outer dust lip of the seal was torn, probably from when I pushed the pinion flange in place. So I reassembled the flange into the tin cover on the work bench this time, making sure it didn't fold that dust lip over, and used Lubriplate 105 as an assembly lube. I put those pieces in together and used grease on both sides of the gasket surface per Luke's recommendation, and I tightened the bolts in a criss cross pattern in 3 steps to the final torque of 100 ft.lb. After a 45 mile drive last night, it still appears to be leaking, from the seal surface, not the gasket surface. Is there anything else to check, other than the tin housing just being junk? The bearings seem tight once the cover bolts were tight, tightening the shim pack. The axle doesn't seem to run any hotter than the other 2, and it has never had any debris in it when I've drained it.
Any thoughts on things to check that I may have missed? Has anyone else had one leak that was this persistent? Should I start looking for a new center section that is known to not leak?
