Fake drain plug?

[2oldschool]

After changing the trans fluid & filter in our 90 Vette (119k miles)I decided to change the diff fluid also.I pulled the fill plug & black fluid tricked out,full but needed to be changed.I removed the 13 mm drain plug at the bottom face of the diff & nothing came out. I probed the hole with a screwdriver & hit solid metal.My camera showed a solid plate at the end of the threaded drain hole. I pumped the old fluid out thru the refill hole. Anyone ever run into this before?-----(-I checked the drain plug location twice)

 

[Hib Halverson]

Uh...that's not a drain plug. That's one of the bolts which holds the back of the rear axle to the rear axle housing.

C4 rear axles do not have drain plugs. You have wither pump all the old lube out or install a drain plug. When I owned a '95, I installed a drain plug in the back of the axle housing and it worked great.

Here are the instructions:
The center of the drain plug hole is in the cover, 1 3/8" left (drivers side) of the center cover bolt. Then 3/4" up from the lower edge of the cover. The hole will enter the case just above the lowest part of the case floor. Thread it for ¼-in. NPT and use a 1/4" NPT plug.

When you drill though the back of the cover, the oil flowing out will bring the chips with it. While the oil is draining, thread the hole with a ¼-in NPT tap and let the oil flow wash out the chips. Once the axle has drained dry, install the plug and fill with the appropriate lube.

I'd jack up the front higher than the rear to drain the lube but have the car level when you fill the axle. You want the oil level even with the bottom of the fill hole.

Good luck.

 

[2oldschool]

Fake drain plug location.

I have 3 different C4 manuals,1 Chilton,1GM & 1Haynes.All 3 show the 13 mm bolt at the bottom rear face of the diff as the drain hole for the diff & give a torque for tightening the bolt. It must have been a drain hole at one time on early C4s.Thanks.

 

[Hib Halverson]

I have 3 different C4 manuals,1 Chilton,1GM & 1Haynes.All 3 show the 13 mm bolt at the bottom rear face of the diff as the drain hole for the diff & give a torque for tightening the bolt. It must have been a drain hole at one time on early C4s.Thanks.

I cannot find that illustration in my 1990 Corvette Service Manual. What page is that on?

 

[2oldschool]

Fake drain plug location.

"Chilton General Motors Corvette 1984-96 Repair Manual #28502-Covers All U.S.& Canadian Models of Chevrolet Corvette." Section 1-Page 47,Fig 190-191 Photos with descriptions.Very good detailed manual.You should pick one up.Thanks for responding.

 

[Hib Halverson]

I line my cat box with Chilton and Haynes Corvette manuals.

I've reviewed both, several times over the years. The inaccuracies in the information, especially Corvette-specific info, makes them of use only to my cat.

When I want service information to work on my Corvettes, I use only the Factory Service Manuals. FSMs are available from CAC sponsor Zip Products.

As for C4 Dana RDUs, I've never seen one from the factory with a drain plug. Admittedly, my experience with C4s is not quite as great as that of some professional Corvette service technicians, so there may have been some early cars with D36 or D44 axles with drain plugs, but, again, I've never seen one.

 

[gmjunkie]

I line my cat box with Chilton and Haynes Corvette manuals.

I've reviewed both, several times over the years. The inaccuracies in the information, especially Corvette-specific info, makes them of use only to my cat.

When I want service information to work on my Corvettes, I use only the Factory Service Manuals. FSMs are available from CAC sponsor Zip Products.

As for C4 Dana RDUs, I've never seen one from the factory with a drain plug. Admittedly, my experience with C4s is not quite as great as that of some professional Corvette service technicians, so there may have been some early cars with D36 or D44 axles with drain plugs, but, again, I've never seen one.

on the cat box thing Hib!

on the GM Factory Service Manuals !~!

on the Drain Plug too!~!!!

My work on C4's is purdy extensive through the years,Never Ever seen a C4 with a drain plug in the differential from the factory, Unless I put it there!~!~!~!!