TH400 Mystery and Misery . . . Nothing in any gear

[flippinbanker]

820D34D5-2719-4D5A-9CA3-D50A72354224

• flippinbanker
• Jan 10, 2019

0810E833-FBF6-4632-B236-8CDC3650A1BE

• flippinbanker
• Jan 10, 2019

FB962379-8025-42ED-AF4E-E3B40A28C21F

• flippinbanker
• Jan 10, 2019

About a year ago I bought a 1974 Camaro Z28 with about 45,000 miles and looks, runs, and up until a few days ago drove like a new car. I have driven the car about 1000 miles since I bought it and no mechanical problems of any kind, no leaks, no unusual noises or other issues. Last week I get into the car to take for a drive and shift into reverse and no movement. Shifted to all other gears and nothing. I thought possibly a shift cable issue but no problem with shifter movement and I observed the movement and it is moving the gears properly at the transmission. I checked the transmission fluid while warm and running and fluid was nice and red. Up to this time I had no shifting or engagement issues. I checked the trans fluid again while it was cold and the fluid was about a half inch above full line. I started the car and warmed it up to normal operating temp and checked the fluid while running and the fluid level was still the same (above the full line about 1/2 inch). I had checked the transmission fluid warm level a few weeks before this issue developed and it was right on the full line. I dropped the pan and the fluid was bright red with only a very small amount of black sludge at the bottom and no metal particles at all on the magnet. Filter and tube also in good position and condition. I shared these symptoms to a mechanic friend and he says it is probably torque converter or transmission pump. Before I pull the transmission and go to work, am I missing something easier?

 

[Twisted_Metal]

Does moving the shift arm leave the transmission in "Park"?
(I'm trying to eliminate disconnected linkage somewhere internal.)

It would be nice to know if there was fluid pressure but you've already drained it and removed the pan.

 

[flippinbanker]

Does moving the shift arm leave the transmission in "Park"?
(I'm trying to eliminate disconnected linkage somewhere internal.)

It would be nice to know if there was fluid pressure but you've already drained it and removed the pan. [/QUOTE
Twisted Metal, yes the shift lever moves everything as it should. I’m thinking about putting the pan back on and re-filling and testing the pressure. The test plug is on the driver’s side, correct? Thanks.

 

[flippinbanker]

Twisted Metal, yes the shift lever moves everything as it should. I’m thinking about putting the pan back on and re-filling and testing the pressure. The test plug is on the driver’s side, correct? Thanks.

 

[Twisted_Metal]

Right there in the red circle.
1/8” NTP plug.

Good luck!

 

[camaro71/holland]

Don't think changing oil will do much good here....

With rear wheels of the ground, does the driveshaft turn in gear and stop in Park?

Would say there is something wrong on the mechanical side of the shift cable & valve. With pan off, check if the rooster comb is moving the shift valve - could be stuck.

 

[Grady Farrer]

Fluid level doesn't change...pump is likely broken.
You can fill it with fluid again... pull a cooler line and start the car for a second and see if it pumps any fluid out. If not...the pump is broken.

 

[flippinbanker]

View attachment 70555 Right there in the red circle.
1/8” NTP plug.

Good luck!

Thank you! Replacing filter, fluid on Saturday and run some pressure tests.

 

[flippinbanker]

Mystery solved for the moment. Replaced the filter and added 5 quarts of fluid and it showed at the operating range on dipstick. Started her up and let it warm. Anxiously awaited pulling the dipstick hoping that the fluid level declined and it did! Added another quart and still showing low. Added more until right on the full line. (Total of 7 quarts). Got in car and again anxiously awaited shifting in gear. Beautiful lunge forward then reverse and all gears working again. Weather too bad to take for test drive but hopeful! Thanks all for the guidance.

 

[Twisted_Metal]

Sounds like you may have had a stuck valve in the body.
It may happen again.

I had a TH350 which did that.
It would only do it once every few weeks and only when it was a cold start. (Never twice in the same day.)
I would hold the brake (Firmly!) and give the accelerator a couple of blips and it would pop in gear.

I eventually pulled that trans for a 2004R swap.