Help me diagnose a 4T65E problem

Series I L27 (1992-1994 SE,SLE, SSE) & Series II L36 (1995-1999 SE, SSE, SLE) and common problems for the Series I and II L67 (all supercharged models 92-99) Including Olds 88's, Olds LSS's, Olds 98 91-96, Buick Lesabres and Park Avenue 91-96. Please use General Chat for non-mechanical issues, and Performance and Brainstorming for improvements.
Post Reply
User avatar
agrazela
Retired Gearhead
Retired Gearhead
Posts: 1808
Joined: Thu May 22, 2008 11:28 am
Year and Trim: 04 Lesabre, Stock
98 Lesabre, Retired
Location: San Diego, CA

Help me diagnose a 4T65E problem

Post by agrazela »

Having an issue with my home-rebuilt 1998 4T65E from about 4 years ago:
viewtopic.php?f=8&t=1483

Has no movement in any gear. Well, it'll go maybe 3 mph in any forward gear or in reverse (regardless how much throttle you give it), but that's it.

This just all of a sudden happened a few days ago while I was driving. Made no unusual clunk or noise when it happened, makes no unusual noises now. No CEL, but I don't have a tuner anymore (just a cheapy O'Reilly code reader) so it may have codes I can't see.

I think if it was a hard part (input shaft, diffy, drive/driven or chain) it wouldn't go at all (and I'd have heard something). I think if it was the torque converter, I'd have more go than I do have.

Drained fluid and dropped pan to see if the filter or seal had an issue; fluid looked fine, just a little clutch mud on the magnet, a few tiny flecks of metal in the filter. Filter fit into seal seemed a bit loose, so replaced seal and filter (now a nice tight fit). Did not fix problem.

Hooked up a 0-100psi gage I found in the garage to the pressure port; got:
P; 70psi
R; 70psi
N; 70psi
D; 55psi
3; 55psi
2; 55psi
1; >100psi

And none of these readings changed when goosing the throttle.

All the readings (except maybe 1st) are low in pressure. The book says they should be:
P, R, N; min 79-101, max 223-271
D, 3, 2; min 74-86, max 167-203
1; min 146-187, max 146-187

I don't think it's a stripped pump shaft, or I'd have probably no pressure and more shavings in the pan. I don't think it's the input piston seal, or I don't think I'd have so much pressure in first. Most signs point to a stuck open PCS (pressure control solenoid), but then wouldn't first gear be OK (it doesn't use the PCS as far as I know)?

Any other ideas? Next steps diagnostically?
sonoma_zr2
Retired Gearhead
Retired Gearhead
Posts: 3643
Joined: Tue May 20, 2008 9:39 am
Year and Trim: 1999 SSEi
1997 SSEi-Resting-353K
Location: Montevideo, MN

Re: Help me diagnose a 4T65E problem

Post by sonoma_zr2 »

This is from the Triple Edge Performance site:

No movement in any range:

This problem can have numorous causes and on higher powered cars typically a broken input shaft or drive chain set is suspect. Below is a short list of potential broken or failing parts to cause it.

-Broken input shaft
-Broken drive chain or sprockets
-Extremely low fluid level
-Broken ouput shaft
-Clogged filter from excessive debris in fluid
-Broken oil pump shaft
-Stripped torque converter splines
-Broken Input clutch drum shaft
-Broken axle or CV joint
-Badly damaged geartrain or differential

Could it be your torque converter?
Post Reply