Was doing a little preventative to my '52 GMC 3/4 ton today and when I stuck my pinkie into the fill/level check hole on the differential it came back with the color below and a bunch of tiny bubbles. When this happens in the engine's oil pan you hope for a failed gasket and pray it is not a cracked block. Color of the lube shown below.
The rear end is a circa 1968 GM 10 bolt with a 3.55 gearset. I had it apart about 3-4 years ago to replace an axle bearing that was starting to make a little noise. I wouldn't swear that I have checked the lube level since then (maybe 15000 miles), but I don't remember driving it through deep water. It does get driven in the rain though.
My plan is to drain the lube by pulling the two lower bolts of the rear cover and let it drain for a few days (not sure this works on my differential), put the bolts back in, fill to the proper lever and monitor the system. Or should I pull the rear cover and "wash" the innards? If so, wash with what?
'57 GMC 102, Original 347 V8, HydraMatic, 3.08 rear gear, added A/C, disk front brakes, HEI, AFB carb, '98 Honda Black Currant paint. T-boned and totaled 10/12 '52 GMC 152 Stake Bed, Original 228, SM420, added A/C, HEI, disk front brakes, '67 Chev 3.55 rear gear. Gets used as a real truck.
The only time I had that happen was when I drove through about 20" of water...had no choice but the rear end did suck water into it and was a mess. I cleaned it with kerosene but that stuff isn't as easy to find today as it was 40 years ago and it is $$$. Good luck!
~ Jon 1952 1/2 ton with 1959 235 | T5 with 3.07 rear end
I'd consider Diesel fuel if you can't find Kerosene. Jon is correct, kerosene is expensive. I'd recommend draining it as you've proposed. Partially fill with Diesel or Kerosene and run it in low or second at idle for a minute, drain it and then remove the cover and inspect it. I assume you'll lift it up and put it on jack stands, so the "run it for a minute will be a no load condition. Good luck.
Ron - - Dusty53 1954 Chevy 3604 In the Gallery Forum "You can't dance with the Devil and then wonder why you're still in Hell." "They will forget what you've said, and they will forget what you have done but they will never forget the way you made them feel."
Check the axle vent hose, normally on the drivers side of the axle tube with a hose that goes up to the frame and makes an inverted trap. If that hose is missing/disconnected, you may be getting rain in it. I would pull the cover off, spray it with a full can of brake cleaner, it will evaporate fast enough where you could put the cover back on the same day.
1957 Chevrolet 5700 LCF 283 SM420 2 speed rear, 1955 IH 300U T/A, 1978 Corvette 350 auto, 1978 Yamaha DT175, 1999 Harley Davidson Softail Fat Boy
Check the axle vent hose, normally on the drivers side of the axle tube with a hose that goes up to the frame and makes an inverted trap. If that hose is missing/disconnected, you may be getting rain in it. I would pull the cover off, spray it with a full can of brake cleaner, it will evaporate fast enough where you could put the cover back on the same day.
Doesn't seem to have a hose. It does have a little vent device on the axle with what sort of looks like a hat on it. Maybe 1/2" diameter and no more than an inch tall.
'57 GMC 102, Original 347 V8, HydraMatic, 3.08 rear gear, added A/C, disk front brakes, HEI, AFB carb, '98 Honda Black Currant paint. T-boned and totaled 10/12 '52 GMC 152 Stake Bed, Original 228, SM420, added A/C, HEI, disk front brakes, '67 Chev 3.55 rear gear. Gets used as a real truck.
Yes, that's the vent. The little hat is supposed to keep rain, dust, etc out of there but based on what mine did if you submerge the rear end (even if the seals are okay) water will run right in there. Maybe it isn't supposed to, but mine did. The 12 bolt rears have a little tube onto which a rubber hose is attached. I ran mine up to the bed level.
~ Jon 1952 1/2 ton with 1959 235 | T5 with 3.07 rear end
You can buy a brass hose barb of the same thread size and run a hose up high if you intend to go in higher water than the axle housing. I plumbed my military 5 ton truck that way to prevent water from entering.
But I can't remember running through any water over a couple of inches deep. The again, there is water in the housing.
'57 GMC 102, Original 347 V8, HydraMatic, 3.08 rear gear, added A/C, disk front brakes, HEI, AFB carb, '98 Honda Black Currant paint. T-boned and totaled 10/12 '52 GMC 152 Stake Bed, Original 228, SM420, added A/C, HEI, disk front brakes, '67 Chev 3.55 rear gear. Gets used as a real truck.
Bii, When I flushed the diff on my 53 I pulled the cover and drained the old lube. Then I used a mixture of Marvel Mystery oil and ATF and sprayed the diff and left it to drain for a few days.I did that a few times until I got no carmel looking liquid draining out. Dave
The stuff I drained wasn't near as light brown with bubbles as was the stuff I had on my finger thru the level checking hole Friday. I drained it (no, it wouldn't drain through the bottom bolt holes) by taking the cover off, used some diesel in a spray bottle to wash down what I could reach, let it drain for a few hours, washed it with diesel again and let it drain overnight. This morning I put the cover back on, filled it with diesel, jacked the back wheels off the ground, started the engine, put it in high gear with the idle set high and let it run for 20 minutes or so. Shut it off, pulled the cover, drained the diesel and let it dry out for 6 hours with a fan aimed at it. Put it back with a new gasket and filled it with GL-5. It took almost a quart.
I was wrong about the vent. It is on the cast center housing about 4" above the horizontal centerline of the rear axle. Being a flatbed, there is lots of room under the bed for water to splash around from driving through puddles, but I really can't think of a time when I was in water over an inch or two deep. Certainly not deep enough to submerge the vent.
'57 GMC 102, Original 347 V8, HydraMatic, 3.08 rear gear, added A/C, disk front brakes, HEI, AFB carb, '98 Honda Black Currant paint. T-boned and totaled 10/12 '52 GMC 152 Stake Bed, Original 228, SM420, added A/C, HEI, disk front brakes, '67 Chev 3.55 rear gear. Gets used as a real truck.
1950 Chevrolet 3100 (Ol' Roy) 1939 Packard Standard Eight Coupe (The Phantom) | 1956 Cadillac Coupe de Ville (The Bismarck) | 1956 Cadillac Sixty Special Fleetwood (The Godfather) | 1966 Oldsmobile Toronado (The Purple Knif) | 1966 Ford Mustang (Little Red) | 1964 Ford Galaxie 500 coupe | 1979 Ford F-100 | 1976 Ford F-150 (Big Red) | 1995 Ford F-150 (Newt)
Do you ever launch a boat? A couple of my customers who ran the bass tournament circuit had chronic problems with water in rear ends until I did the vent tube trick for them, with a hose run up into a frame rail. Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt! There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway Love your enemies and drive 'em nuts!
No boats in the 10+ years I've had the truck. And I drained and replaced the lube 3+ years ago.
If I were to do the vent hose trick, what should I do at the top end?
Put the same vent at the end of the hose? Make an upside down U at the end? Something else?
'57 GMC 102, Original 347 V8, HydraMatic, 3.08 rear gear, added A/C, disk front brakes, HEI, AFB carb, '98 Honda Black Currant paint. T-boned and totaled 10/12 '52 GMC 152 Stake Bed, Original 228, SM420, added A/C, HEI, disk front brakes, '67 Chev 3.55 rear gear. Gets used as a real truck.
A porous rock diffuser like aquarium air tubes use makes a good filter for the end of the vent- - - -lets air in and out for thermal expansion while keeping dust and debris out. Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt! There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway Love your enemies and drive 'em nuts!
