Strange tranny problem

[rasouth]

A few months ago, after rebuilding crankshaft, I was driving my '96 4.0 and I suddenly heard a loud buzzing noise. It sounded like a motorcycle racing by my window. I didn't see anything and then realized the noise was coming from my tranny. I pulled over and checked engine, belts, loss of fluid. All fine, idled fine, revved up fine. Then I put it into gear...Nothing...No reverse, no drive. Every time I switched gears it sounded as if tranny was not engaging, just slipping. After a few minutes I tried Drive and it worked but still no revese. I drove up the street about a hundred feet, made a u-turn and checked reverse. It was working. I made it home and did a filter and fluid change. I think I got the correct amount of fluid and fluid type (Merc) in it but last night the same thing happened to my son. Both instances we we doing around 50 MPH and going downhill. These happened about 2 months apart and I have put at least a few hundred miles on it after the filter change. Is the fluid level too low for going downhill or is fluid foaming up and not letting trans work properly?

 

[D.R.Ball]

How are your checking the fluid level ? In accordance with the owners manual or just checking the dipstick...? Do you have any warning lights ? O.D. and or checking lights ?

 

[rasouth]

I usually check fluids after I drive for 20-30 minutes, park on level ground, with engine running and in park. No warning lights. Occasionally I will get a PO 420 error code but that is "Catalitic efficiency below threshold..." code. Probably O2 sensors or the Cat itself. Sometimes I will put the trans through all the gears while parked just to be sure before checking levels.