QuestionSir,
I recently asked you about the interchange of a transmission for my 93 Olds Cutlass Supreme. I've been able to locate a replacement in my area, but I can't help but wonder if there is a way I can repair the tranny without having to do a full rebuilt (More expensive than a salvage tranny, I know), so here's the info I can give you about how it:
93 Oldsmobile Cutlass supreme SL
3.4l V6
The reverse gear will not engage, and the transmission will not shift past low gear (around 20mph). I checked the fluid level with a warm engine before driving, and the tranny fluid is fresh and does not smell burnt. There is no grit in it. After driving the car for a short distance, I checked the fluid level again with the engine running, and the fluid has bubbles in it, and has been pushed up the dipstick, way past the level it would be if checked cold and not running. The gears don't sound like they're grinding at all, and I hope they are not damaged.
The former owner told me the transmission went out suddenly, but it's been my understanding that these things don't break down without any warning. There's always some gear slippage or something to warn you it's about to go out.
This car also sat for about 10 months before I purchased it.
Any help would be appreciated, and thanks for the help you gave me before.
AnswerHi Matthew,
I hope you're sitting down because this is too long to read standing up. Lol.
If reverse won't engage, the possibilities of a 'quick-fix' are about 1%.
Understand that the gears in a typical automatic transmission are not really gears at all in the normal sense of the word. An auto-trans uses a series (between 8 and 20 depending on the application) of small two-sided clutch discs with a thin steel plate between each set of discs. These plates and discs are arranged in a drum which is the actual 'gear' (called a clutch-pack). In your 3-speed w/OD (4-speed auto) there are only three drums (which is why it is classed as a 3-speed w/OD). First and reverse use the same drum as do 2nd and 4th (OD) and third has it's own drum because it is supposed to be the "most-used" gear even though everyone drives OD vehicles in OD and not Drive, which is third gear.
OK, when you shift from Park to any forward gear or reverse, you are moving a steel drift with small notches inside of a cylindrical housing inside of the valve-body of the transmission. The notches correspond with fluid-paths machined into the valve-body as well as the transmission case and when the front pump is operating (engine running) high-pressure trans-fluid is directed by the drift position inside the cylinder to the proper 'gear' fluid tunnel. When fluid reaches the actuator, it overcomes the spring pressure and activates the band that holds the drum of the specific gear being used/engages. If the clutch-pack has good discs and steels, the accumulator will compress the pack together allowing only a small amount of 'slip'. This slip is used to allow your car to be stopped at a red-light while still engaged in the forward or reverse gear. Once you hit the throttle, the front pump immediately increases it's output pressure to completely compress the pack and allow the vehicle to move.
If the pack is bad or glazed, it will still engage, but the pump just will not have enough pressure to overcome the amount of slip between the discs and steels. Glazing of the discs occurs from either low-fluid level, no fluid or LOFC (Lack Of Fluid Changes) which is by far the most likely cause of slippage. Since you state the gear is not even engaging, I'd have to say either the drift is bent or damaged in some way or there is a blockage in the reverse fluid tunnel somewhere stopping the actuator from moving. This to me can be confirmed by you stating that first gear DOES engage and operate.
If the trans doesn't shift out of first gear, you may want to pull the governor out and clean it. Sometimes minute pieces of debris can block up the miniature ports in it rendering it inoperable. This would also be an explanation of why the fluid was aerated. In first gear at 20+MPH, the engine is going to be turning some high RPM's which is forcing the front pump to operate well above it's normal capacity. This not only reduces the fluid level in the pan by pumping it out but it causes the inlet to cavitate and actually run out of fluid. In the absence of fluid, the pump is going to slip because air compresses much easier than liquid. This slippage causes the fluid level to rise and fall suddenly in the pan also increasing the amount of air in the fluid making it frothy-er.
You are correct in assuming most transmission problems occur over time but not always. A piece of debris can lodge itself into a port and instantly cause the trans to not operate correctly if at all. But when gears go out in transmissions, it typically is a slow process.
Ok, finally, the advice paragraph. I would pull the pan and make certain the filter is properly seated. While the pan is down I would make sure the magnet is clean and still in place at the corner of the pan. On the back of the transmission case, facing toward the rear of the vehicle, there should be a small cover being held on by a small wire spring-clip similar to the one used on old-style metal-topped master cylinders of yesteryear. Pull this cover and remove the accumulator valve. Spray it with some BRAKE KLEEN or any other instant-dry parts cleaner and re-install. Do the same for the governor which is located at the tail of the transmission (Right-side) under a small cap held on with 2 bolts. The cap will either have a speedometer cable coming off of it or a wire harness for the speed sensor. Either way, the governor is under this cap. Remove the cap, pull the governor straight-up and out. Clean it with BRAKE KLEEN also and operate the arms left and right a few times to make sure it is not sticking. re-install. I would refill with NEW fluid but if you are as unsure as I am about it functioning again, you can use old but clean and filtered fluid. New fluid would be the only cost you'd incur following this advice which is the way I like it.
Put four quarts of fluid in and while the vehicle is still off of the ground, start the engine and depress the brake pedal. Shift from Park to Reverse then to Neutral, O, D, 2 and then 1 without leaving your foot off of the brake and pause for a second at each location to allow fluid to flow. The gears 'should' slightly engage while you do this but don't allow the wheels to move. Shift back to Park and check the fluid level. If there is no reading on the dip-stick, add another full quart and follow the instructions given above. If the fluid is visible on the stick but low, add one PINT of fluid and get back in the car. Do the same shift proceedure outlined above but this time, when you get back to Park, you'll be going back to Reverse. This time remove your foot from the brake and allow the wheels to spin up to about 20MPH (use the throttle to get it going this speed). Apply the brake, stop the wheels (don't jam the brakes on, slowly apply them so you don't upset the balance of the car on the jack-stands or lift) and shift to neutral and then to O or highest 'drive' position. Remove your foot from the brake and let the wheels spin up using the throttle to attempt to reach 50MPH. If the trans shifts and allows you to reach 50MPH, maintain that wheel speed for about ten or fifteen seconds then slowly apply the brakes and stop the wheels. Shift back to Park and top off the transmission fluid while running. DON'T OVERFILL! Less is better than more when it comes to trans fluid level.
If the trans still doesn't engage reverse or shift out of first gear, it's junk. There is a mechanical issue somewhere deep in the system and it will need to be rebuild, re-manufactured or replaced with a used unit (from Knucklebusters).
Thanks for the question, I hope this information was helpful to you.
Fred
www.knucklebusters.us
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