Unbolting The Transmission Pan: Removing A 99 Blazer's Transmission Pan

Removing the transmission pan from a 1999 Blazer is a complex process that requires a range of tools and mechanical expertise. It is important to place the vehicle securely on jack stands to allow access from beneath, and to start and warm the engine to loosen various components. The transmission mount and mounting cross member must be removed, and the engine safely supported with a jack. The transmission must then be loosened and removed, taking care to address all electrical harnesses, hoses, and brackets.

Loosening bolts and removing the pan

To loosen the bolts and remove the pan of your 99 Blazer's transmission, follow these steps:

First, place your vehicle securely on jack stands to give you enough clearance to work underneath. Start the engine and let it warm up, particularly the exhaust system. The heat will make it easier to loosen the exhaust flange stud nuts and the oxygen sensors. You can even do this from beneath the vehicle while the engine is still running. If you've planned ahead, you will have already soaked the exhaust fasteners with penetrating oil. After the exhaust fasteners are loose, and while the transmission and drive line are still warm, loosen the transfer case adapter and any accessible transmission bolts. Don't remove them completely, just break them loose. Soak any other fasteners with penetrating oil.

Next, place the transmission selector in neutral, disconnect the battery, and isolate the cables to prevent accidental contact. If your vehicle has a mechanical radiator fan, you may want to remove either the fan or the fan shroud to allow the engine to tilt without interference. Drain the transfer case if your vehicle is equipped with one. On AWD and 4WD vehicles with a floor-mounted shift lever for the transfer case, remove the interior floor trim and disconnect the shift linkage.

Now, match-mark the universal joints at their differential ends so they can be assembled in the same orientation, then remove the drive shafts. The AWD front drive shaft has a detent locking ring on the splined transfer case output shaft, so it may require a light bump with a pry bar to disengage. Remove the oxygen sensors, marking the rear sensors if your vehicle has post-converter sensors as they are sometimes different from the main (front) sensors. Remove the exhaust crossover and pipes/exhaust assembly as necessary, especially if the crossover will interfere with the removal and installation of the transmission.

At this point, you can remove the transmission neutral safety switch wiring, main electrical harness, transmission cooler lines, shift linkage, and disconnect any clips or brackets mounted to the transmission. On some vehicles, the fuel and vapor lines and other electrical harnesses are attached to the transmission housing by clamps, so be sure to remove these carefully. Some vehicles will also have additional brackets or supports for the transmission and/or transfer case that need to be removed.

Now, you're ready to start loosening the bolts on the transmission pan itself. On a 99 Blazer, you'll need to remove 12 13mm bolts on the bottom of the transmission. You may also need to unbolt the transfer case skid plate and the cross-member bolts, but be careful not to let them fall inside the frame. Make sure you have a jack under the transmission to support it.

Once all the bolts are removed, carefully lower the transmission pan and remove it from the vehicle. Be prepared for fluid to drain out, so have a catch pan ready. With the pan removed, you can now access the transmission filter and gasket, which should be replaced.

Removing the filter

First, place a pan under one corner of the transmission pan. This will catch the fluid that will drain out. Next, loosen the pan bolts at the corner of the pan and then back the rest out partially so that the corner is lowered and the fluid can drain into the pan. Once the fluid has drained, take the pan loose and remove it.

Now, it's time to remove the filter. This can be tricky, as you will need to break the filter off by hand. Be careful, as it can be difficult to get the new filter in, so some people choose to simply toss the old one away. However, if you do want to try and reuse the old filter, be sure to clean it thoroughly before reinstalling it.

Once the filter is removed, you can install a drain plug in the pan. This will make future fluid changes much easier, as you won't need to remove the entire pan. Simply drill a 1/2" hole about 5" from the back, next to the second bolt from the passenger side. This will allow you to drain the fluid without removing the pan.

Finally, before reinstalling the pan, be sure to clean it thoroughly and inspect it for any damage or leaks. If there are any issues, it's best to replace the pan rather than risk further damage to your vehicle.

Removing the gasket

To remove the gasket of a 99 Blazer transmission pan, follow these steps:

Firstly, place the vehicle securely on jack stands to raise it and ensure there is adequate clearance on the side for transmission removal. Next, start the engine and let it warm up, particularly the exhaust system. This will make it easier to loosen the exhaust flange stud nuts and oxygen sensors. You can perform this step from beneath the vehicle while the engine is still running.

Now, loosen the exhaust fasteners. If you have planned ahead, you would have already soaked the exhaust fasteners with penetrating oil, making this step easier. Once the exhaust and drive line are still warm, loosen the transfer case adapter and any accessible transmission bolts on AWD and 4WD vehicles. Don't spin them out, just break them loose. Soak any other fasteners with penetrating oil.

At this point, you can remove the old gasket. To do so, place the transmission selector in neutral, disconnect the battery, and isolate the cables to prevent accidental contact. If your vehicle has a mechanical radiator fan, you may want to remove either the fan or the fan shroud to allow the engine to tilt without interference.

Now, you can proceed to remove the gasket. Take the necessary precautions and wear appropriate safety gear, including gloves and eye protection. Use a gasket scraper or a putty knife to carefully pry and remove the old gasket from the surface. Make sure to clean the surface thoroughly after removing the old gasket. Use a suitable solvent to remove any remaining residue or debris.

Once the surface is clean, you can prepare for installing the new gasket. Ensure you have a new gasket that matches the specifications of your transmission pan. Before installing the new gasket, refer to the vehicle's service manual or seek advice from a qualified mechanic to ensure you follow the correct procedure for your specific vehicle.

Raising the vehicle and placing it on jack stands

To raise your 99 Blazer and place it on jack stands, follow these steps:

First, park your vehicle on a flat, level surface. This is important to ensure your vehicle is on even ground and that the jack stands can't slip out from underneath it. Working in a garage or on a flat driveway is best. Activate your vehicle's parking brake and place chocks or tire wedges around each wheel if you're lifting the back end of your car. If you don't have chocks, you can use 2-inch by 4-inch boards in front of and behind your wheels.

Next, locate an area underneath your vehicle to place a floor jack. Use a hydraulic floor jack as it is the safest way to lift your vehicle. Slide the floor jack underneath so that the arm is underneath the frame of your vehicle or at a lift point. Consult your vehicle's manual to determine the best place to jack it. Common places to jack your vehicle include looking for tow hooks on the front or back of your vehicle or using the stabilizer bars directly behind the vehicle's wheels.

Now, raise your vehicle so that the tires are 2-3 inches off the ground. Continue cranking the handle up and down to lift your vehicle until the tire(s) closest to your jack are completely off the ground. Be careful not to lift your car higher than necessary, as it could become unstable.

Once your vehicle is raised, set the jack stand(s) underneath the pinch points of your vehicle. The pinch points are located on the sides of your vehicle, behind your front tires or in front of your rear tires. Slide the jack stand(s) in from the side and line up the divot on the stand with the part of the pinch point that extends down. If your vehicle doesn't have pinch points, set the jack stands underneath the vehicle's frame. Make sure to adjust the height of the jack stand(s) if needed. Lift the top of the jack stand(s) up until it's touching the pinch point, then secure it in place with the safety pin.

Now, slowly lower your vehicle onto the jack stand(s). Turn the lever on your floor jack counterclockwise to lower your vehicle. The jack stand(s) will now support the weight on the side of your vehicle, allowing you to safely work underneath it. Pull the jack out from underneath your vehicle, giving yourself more room to work.

Finally, push your vehicle slightly to ensure it's sturdy and doesn't move around or shift its weight. If it does, try placing the jack stand(s) in a new area. If it feels sturdy, you can now place additional jack stands to lift your vehicle completely off the ground. Make sure any adjustable jack stands are the same height so your vehicle doesn't sit crooked.

Remember, safety should always be your top priority when working on your vehicle. Never go underneath your vehicle without properly securing it with jack stands. Car jacks can slip, and your vehicle could fall on top of you. Always activate your parking brake and chock your wheels before beginning any work.

Removing the skid plate

To remove the skid plate from a 1999 Blazer, follow these steps:

First, it is important to note that the Blazer/Jimmy has little room to remove the skid plate due to the center cross member. This means that the transfer case will have to be twisted and tilted to clear the cross member when removing it.

Now, to begin the process, place the vehicle securely on jack stands to gain access to the underside. Remove the skid plate from the bottom of the case, and disconnect all electrical connectors and the vent hose.

The skid plate is attached with bolts, and there may be between five and nine of these, depending on the model. Some models have two parts to the skid plate, with two bolts holding the two pieces together. The bolts are usually 12mm hex bolts. Once the bolts are removed, the skid plate should come away, but you may need to wiggle it a little, or use a pry bar to loosen it, as they can get stuck.

If you are removing the skid plate to change the oil, it is possible to do so without removing the skid plate. You can stuff rags underneath the filter to catch any runoff, or cut a hole in the skid plate to access the filter.

Frequently asked questions