2000 Pontiac Montana no 4th gear

Tiny
JACK0
  • MEMBER
  • 2000 PONTIAC MONTANA
  • 6 CYL
  • FWD
  • AUTOMATIC
  • 185,000 MILES
Transmission shifts 1-2 2-3 just fine
will not shift 3-4.
fluid and filter have been replaced. No change!
Fluid level is correct.
NO RPM change between 3 to 4 shift position with same road speed. Moving lever from 3-4, NOTHING noticable in vehicle operation.
All parts and pieces within transmission are in factory position. Any logical reason for defect in operation?
Any answers to this Montana problem? OR is this Junk it situation?
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Thursday, May 27th, 2010 AT 11:45 AM

3 Replies

Tiny
FACTORYJACK
  • EXPERT
Here is a list of possibilities for no fourth gear. The first question is what condition is the fluid in? Does the RPM's raise without forward vehicle movement when fourth is attempted? Also is there a check engine light.
Slipping or No Fourth Gear
Checks
Cause

DEFINITION: A large engine RPM increase is noted in fourth gear, Drive range, with little or no vehicle forward speed increase. First, second, and third gear operation are normal. Shifts into fourth gear are soft or do not occur. Fourth gear ratio is 0.705:1.

Automatic Transmission Fluid Level
Low fluid level

Transmission Main Line Pressure
Low transmission main line pressure

Oil Filter Assembly
" The oil filter assembly (100) is missing, plugged, or damaged.

" The oil filter seal assembly (101) is missing or is damaged.

Control Valve Body Assembly
" The 3-4 shift valve (362) or the 4-3 manual downshift valve (360) is stuck or binding.

" Debris is found in the passages of the control valve body (301) or of the control valve body spacer plate and gasket assembly (396)

Case Cover Assembly
Distortion or damage occurs at the manual valve (404) or at the case cover (401), causing PRN oil leak.

Driven Sprocket Support Assembly
A plugged third clutch oil passage in the driven sprocket support assembly (609)

Fourth Clutch Assembly
" The clutch plates (500-502) are worn, damaged, or misassembled.

" A missing or not seated fourth clutch spring retaining ring (601)

" A damaged spring assembly (602) or piston (603)

" Worn or damaged fourth clutch piston seals (604, 605)

Third Clutch Sprag Assembly
" The sprag (720) was misassembled or backwards on the inner race (661).

" A damaged third clutch sprag assembly (653, 661, 719-721)
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Thursday, May 27th, 2010 AT 11:48 PM
Tiny
JACK0
  • MEMBER
No engine change. Nothing differant when driving in / between 3-4 4-3. Just as if the lever movement has no effect.
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Tuesday, June 15th, 2010 AT 1:24 PM
Tiny
CARSANDAIRPLANES
  • MEMBER
The 4th gear clutch hubs in these 4T65E trans-axles tend to de-spline after a while, due to going in and out of torque converter lock-up. The only way to fix this is to remove the trans-axle and change the clutch-hub. After this problem came to light, GM started to heat-treat these clutch hubs to prevent this from happening in future designs. Hope this helps.
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Wednesday, August 18th, 2010 AT 10:08 PM

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