How to Remove a Turbo 350by Christian Killian
Removing a GM Turbo Hydromatic 350 transmission from a truck, car or SUV can be accomplished by most automotive enthusiasts with a little planning and a few tools. The TH350 is a three-speed automatic transmission used in a variety of cars, trucks and 4x4s dating back to the mid 1960s. It uses a fluid-filled torque converter to transfer power from the engine through the transmission to the drive shaft or transfer case of the vehicle. It is a dependable transmission that is very easy to remove and replace.
Disconnect the battery so the engine cannot be turned over while your hands are around the torque converter and flywheel. Safety is always the first concern with a project like this.
Jack up the vehicle and place all four corners on jack stands. Be sure you are working on a solid, flat surface so the stands do not move, causing the car to shift or fall while you are working under it.
Remove the drive shaft from the vehicle. There will be four bolts that hold the shaft to the transmission output yoke. Do not remove the slip yoke at the rear of the transmission. This will allow fluid to escape from the transmission.
Locate the transmission cross member that runs across the vehicle. It is a boxed piece of steel that is bolted to the frame rails and holds up the transmission. In the center, there will be several bolts that go into the transmission mount from the cross member. You will need to remove them.
Place a floor jack or transmission jack under the transmission and remove the bolts that attach the cross member to the frame and remove the cross member. The bolts may be hard to get out if they have never been removed, so you may need to heat them with a torch or use a good penetrating oil on them.
Locate and remove the two steel transmission-cooler lines on the passenger side of the transmission. You will need an open end wrench or a flare nut wrench to remove the fittings. Be careful not to twist or crimp the lines so you can reuse them. Place a drip pan or bucket under the lines to catch any transmission fluid that may drain out.
Move to the front of the transmission and locate the inspection cover. Remove the bolts that hold it on. There are four 10mm bolts in the cover. You should now be able to see the torque converter and the flywheel.
Remove the four torque converter bolts that connect the torque converter and the flywheel together. You will need to rotate the engine to get to all the bolts, so a helper can save you a lot of time here. Have your helper put a socket and breaker bar on the crank shaft bolt in the center of the harmonic damper on the front of the engine. This will allow him to rotate the engine for you as needed.
Locate and remove the bell housing bolts from the transmission. There are four on most models, but depending on the vehicle there may be five. These bolts are the ones that surround the bell housing and secure the transmission to the back of the engine block.
Slide the transmission back slowly, making sure that the torque converter stays on the transmission. Once you are sure you are clear of obstacles, lower the transmission to the ground and slide it out from under the vehicle.
- Recruiting a helper will save you time and make the job easier. The transmission is heavy and you may need someone to help you steady it as you remove it from the vehicle.
- Always makes sure the vehicle is solidly supported on the jack stands before working under it.
Items you will need
- Jack stands
- SAE wrench set
- 1/4-inch drive socket set
- 3/8-inch drive socket set
- Transmission jack
- Oil-drain pan or bucket