i have a 1998 C5, about 3 days ago the gears started to slip. It wouldnt go into reverse, about 2 days ago it ran perfectly fine, now yesterday its slipping, wont go into reverse stays in 1st to about 4k RPM's then finally shifts, i replaced my gear oil yesterday, and im gonna do the trans fluid today but i thought i should get extra opinions. any idea of what this could be?

 

Wait for a moderator to move this to the C5 Tech section so they can help you.

 

all set !

 

welcome though

 

Shift linkage failing?

 

If you find a lot of black grit in the tranny fluid when you drain it for replacement, you might want to just put it back in and think about a rebuild. If the clutches are damaged i.e. shedding their friction material (the black grit), putting fresh fluid in could wash the rest of the material off and result in no movement at all (have seen that happen multiple times when I owned several transmission shops).

If the fluid is relatively clean you may just have a valve or valves sticking in the valve body. In that case, try putting in a bottle of LubeGard (the red bottle, not black) with the fresh fluid. Really good stuff, at the shops we often used that to free up sticking valves. I run it in both my Chevy trucks just as a preventive, as it also helps minimize heat effects.

 

I am assuming the car has an auto A4 transmission. If so, the first thing would be to check fluid level and probably change fluid and filter:

Changing the fluid and filter on a C5 A4 is fairly easy, but there are specific procedures to insure that the fluid level is correct after the change:

After replacing the filter and bolting the pan back up, fill with new fluid to the drain/ check level plug hole. Then start the engine and leave it running with the transmission in PARK.

Immediately add fluid through the drain/ check level plug hole until fluid flows out of the plug hole. It may take as much as another couple of quarts.

With your foot holding the brakes, cycle the transmission through all the gears, then back to PARK.

Go back underneath and make sure that fluid is still dribbling out of the fill/ check level plug hole. You might have to add some.

With the engine still running and the transmission in PARK, monitor transmission temperature on the DIC. When transmission temperature rises to 122 F, put the plug in the fill/ Check level hole. Keep a pan under the hole, fluid will dribble out as the transmission temperature rises.

Do NOT shut the engine down until the plug is in the fill/ check level hole. If you do, HOT fluid will gush out and the transmission will be low on fluid.

I recommend full synthetic fluid.

Keep in mind that the above procedure drains about half the fluid in the A4. The other half is in the torque converter and other works.

You will need a small hand pump to pump the fluid into the fill/ check level hole.

 

Moving this to C5 Tech.

 

Some have had success using a new, or CLEAN, pump insecticide sprayer. I've used a homemade, 4" PVC tube, hooked to an air compressor with quick disconnects. Just a basic air over oil setup. Cheap, and worked great for me. Hope this helps someone.....