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Buick LeSabre Transmission



  • dbaurerdbaurer Posts: 2
    I have a 2002 LaSabre with 181,000 miles. It has the original 3.8 liter engine and the original transmission. I’m hearing a thud sound (it sounds like hitting a bump in the road) and it feels like there is a loss of power for just an instant. This has happened at slow speeds, highway speeds (70 mph) and while accelerating. The cv joint “seems” OK as there is no unusual sound or feel when shifting from park to reverse or forward.

    Many thanks for any ideas.
  • wheeldealswheeldeals Posts: 5
    Check your transmission mounts.
  • imidazol97imidazol97 Crossroads of America I70 & I75 Posts: 21,511
    Your description isn't enough. This is something that depends on the feel of what happens when that thud sensation occurs. Do you feel it in the steering wheel? In the floor?

    I'd vote for checking movement in the transmission/engine mounts. Raising the hood and gently acceleration in reverse and forward with the brake on will normally show some movement up and down in the front and back of the motor. If it's a lot (hard to define that) and if you hear sounds when it's moving you might want to have the mounts checked further.

    Because you say it seems to lose power for a second but recovers makes me think there's a misfire. The thud might be movement in the engine as it loses power and maybe even too much movement due to a worn mount.

    I would check for the plugs and wires. How's the maintenance been? When were they last changed? I had a new set of wires and plugs on a 3100 Buick. After a while I got a repeated hard miss. A single miss under just the right amount of load: just a little uphill where I applied just a little more gas or the cruise did. That's the highest requirement for the spark in the cylinder. The spark was jumping to the metal shield that surrounds the plug wire part that goes onto the plug. But my replacement wires weren't quite compatible and the metal shield was too close to the metal of the engine and there an arcing through the wire to the metal to the engine.

    The engine never misfired twice. It seemed like it adapted the mixture to cure the misfire. So I'm wondering if your loss of power is the computer adapting to the misfire.

    An old rule is that lots of transmission problems are actually engine driveability problems.

    2015 Cruze 2LT, 2014 Malibu 2LT, 2008 Cobalt 2LT

  • imidazol97imidazol97 Crossroads of America I70 & I75 Posts: 21,511
    Does the Traction Control system or Stabilitrak give a message on the Driver Information Center that it has kicked in? That might give the sensation that power has been reduced if one of the brakes is being applied by pulsing in order to keep the car from twisting if the Stabilitrak system thinks the car is skidding or a drive wheel is slipping and it applies the brake to try to keep traction on the other wheel instead of the one it thinks is slipping under acceleration.

    A sensor for yaw in the Stabilitrak or a speed sensor on the wheel might be giving a bad reading, either due to a worn hub bearing or bad connection at the clip or a break in a wire.

    2015 Cruze 2LT, 2014 Malibu 2LT, 2008 Cobalt 2LT

  • wheeldealswheeldeals Posts: 5
    I have a 1999 LeSabre that's doing that right now. It's a transmission mount. The check for a broken motor mount won't work for the transmission. It may be a different problem but I would check the cheapest one first.
  • dbaurerdbaurer Posts: 2
    Thank you very much for the tip. I'll have the mounts checked.
  • I have a 93 lesabre that is using transmission fluid. I go through about a pint of fluid every 100 miles, there are no visible leaks and I cant figure out where its going or why. I have checked the trans seals for leaks and the pcv valve to see if there were any signs of fluid, none. There isn't any getting into the radiator via the cooler either. can anyone give me any suggestions?
  • imidazol97imidazol97 Crossroads of America I70 & I75 Posts: 21,511
    edited September 2013
    Without checking my factory service manual for the 93 I had, isn't there a vacuum module on the transmission for shift adaptation? Those can leak and fluid can be sucked into the tube and burned through the intake manifold on the engine. So no drips.

    Look for a modulator about the size of a small fist on the outside of the trans with a vacuum line.

    Part #32 in this diagram.
    Check vacuum line to it for fluid.
    About $15
    Good luck.


    2015 Cruze 2LT, 2014 Malibu 2LT, 2008 Cobalt 2LT

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