There seems to of been an unfortunate trend lately with people having transmission related issues, causing them to have to drop theirs. I've installed and removed the 4L60E a handful of times now on several GMT360's. During my times spent doing so, I've learned a few key things to look out for or take care of while the trans is already out. So I decided that I wanted to make a helpful thread here to list some key things to look out for and remember when removing/installing our transmissions.
-Leave the top two bolts in partially before you drop it, to make sure all transmission and fuel lines are clear, wiring harnesses are clear, and you've got the transmission steadily balanced on a jack. For reassembly do the top bolts first again, but this time making sure you've got the bolts through the two brackets (see picture below) on the line running parallel across the top of where the engine and transmission meet. This is highly important! You will not be able to seat the transmission to the rear of the engine properly if you fail to do this.
Alignment Guides:
-There are two "nipples" that are located on the each side, on the rear of the engine where the transmission seats, they mate right with the bell housing. If you've got those "nipples" seated in the bell housing, everything is lined up properly.
Rear Main Seal:
If you've got the transmission out and you've never replaced the rear main seal, now is a good time to go ahead and replace it if yours is leaking. More than likely than not your GMT360 has the original one still. These are known to be one of the more common causes of oil loss on the 4.2L GMT360's.
-Clean any gunky/burned up oil at the rear of the engine real good with some engine de-greaser, "Gunk" de-greasers especially, they work wonders. I marked the areas that needed typically need cleaning. Be sure to sand down the gasket surface area as well with light grit sand paper. You want as smooth an area as possible for the best seal.
-It doesn't hurt to add RTV sealant below the rear main seal area, to further reduce the chance of any oil leaking from this area.
Torque Converter installation key point:
When reassembling, make sure the torque converter is fully seated as far back as it can go by turning it until it slides back, then rotating it around again until it slides back once more. If it's not seated properly, it'll break the plastic piece on the pump(can't recall the name of this piece)! You'll know it broke if the vehicle isn't moving in any gear you put it in.
Broken plastic:
You can see how the plastic part of the pump here keeps all those small pieces in check and in a certain position (left) vs. the right, where half of it is all cock-eyed:
Healthy unbroken plastic:
Retaining Clips:
-Make sure you do not lose any retaining clips for the transmission cooler lines. They can be easy to lose track of among all the tools and parts lying under the truck. You'll need them to make sure the return and feed lines are locked in place. They can be quite a pain to remove and re-install, so just be patient.
-To remove the retaining clips; Insert a pick between the indent on the cooling line connection (refer to red arrows below) and the small raised portion on the retaining clip, then pry upwards.
Transmission dipstick seal:
-When reassembling, make sure the transmission dipstick seal (refer to picture above) is in place, as well as make sure you fully seated the dipstick in place before you jack the transmission up fully and put the cross-member in. It's a PITA to put it in place once everything is bolted up already. It's doable, but it's difficult because of lack of space and not being able to see what you're doing. If the seal isn't there or if the dipstick isn't in all the way it'll spew transmission fluid all over the exhaust pipe every time you take a sharp left turn. Transmission fluid is highly flammable; exhaust systems can range between 689°F (no load/ no throttle) - 1,533°F (100% throttle)
Dipstick seal:
Paint Marking:
-Use a paint marker on all the torque converter bolts as well as the flex plate to check for any walking themselves out after installation; had it happen before with a torque converter.
-Use a paint marker to identify the position of the driveshaft to the differential yoke for reassembly. It's important to make sure the driveshaft is reinstalled in the same position in order for it to preserve balance.
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-Putting a latex glove with a bunch of electrical tape around the end of the transmission tail shaft will hopefully keep any transmission fluid from spilling all over the floor.
-When reassembling, bolt the transmission mount (see picture above) on the tail shaft before you put the cross-member in, makes everything much easier.
-Blue Loctite is your friend, add to all bolts on the drive shaft straps, flex plate, and torque converter. This will keep vibrations from loosening any bolts.
*Convenient Torque Specs located at the bottom*
Two Top Bolts:
-Leave the top two bolts in partially before you drop it, to make sure all transmission and fuel lines are clear, wiring harnesses are clear, and you've got the transmission steadily balanced on a jack. For reassembly do the top bolts first again, but this time making sure you've got the bolts through the two brackets (see picture below) on the line running parallel across the top of where the engine and transmission meet. This is highly important! You will not be able to seat the transmission to the rear of the engine properly if you fail to do this.
Alignment Guides:
-There are two "nipples" that are located on the each side, on the rear of the engine where the transmission seats, they mate right with the bell housing. If you've got those "nipples" seated in the bell housing, everything is lined up properly.
Rear Main Seal:
If you've got the transmission out and you've never replaced the rear main seal, now is a good time to go ahead and replace it if yours is leaking. More than likely than not your GMT360 has the original one still. These are known to be one of the more common causes of oil loss on the 4.2L GMT360's.
-Clean any gunky/burned up oil at the rear of the engine real good with some engine de-greaser, "Gunk" de-greasers especially, they work wonders. I marked the areas that needed typically need cleaning. Be sure to sand down the gasket surface area as well with light grit sand paper. You want as smooth an area as possible for the best seal.
-It doesn't hurt to add RTV sealant below the rear main seal area, to further reduce the chance of any oil leaking from this area.
When reassembling, make sure the torque converter is fully seated as far back as it can go by turning it until it slides back, then rotating it around again until it slides back once more. If it's not seated properly, it'll break the plastic piece on the pump(can't recall the name of this piece)! You'll know it broke if the vehicle isn't moving in any gear you put it in.
*----Interesting fact:----*
Why did GM make this part plastic? As a fail-safe, to save the rest of the transmission pump from an issue that would otherwise cause catastrophic failure to the pump as a whole.Broken plastic:
You can see how the plastic part of the pump here keeps all those small pieces in check and in a certain position (left) vs. the right, where half of it is all cock-eyed:
Healthy unbroken plastic:
Retaining Clips:
-Make sure you do not lose any retaining clips for the transmission cooler lines. They can be easy to lose track of among all the tools and parts lying under the truck. You'll need them to make sure the return and feed lines are locked in place. They can be quite a pain to remove and re-install, so just be patient.
-To remove the retaining clips; Insert a pick between the indent on the cooling line connection (refer to red arrows below) and the small raised portion on the retaining clip, then pry upwards.
Transmission dipstick seal:
-When reassembling, make sure the transmission dipstick seal (refer to picture above) is in place, as well as make sure you fully seated the dipstick in place before you jack the transmission up fully and put the cross-member in. It's a PITA to put it in place once everything is bolted up already. It's doable, but it's difficult because of lack of space and not being able to see what you're doing. If the seal isn't there or if the dipstick isn't in all the way it'll spew transmission fluid all over the exhaust pipe every time you take a sharp left turn. Transmission fluid is highly flammable; exhaust systems can range between 689°F (no load/ no throttle) - 1,533°F (100% throttle)
Dipstick seal:
Paint Marking:
-Use a paint marker on all the torque converter bolts as well as the flex plate to check for any walking themselves out after installation; had it happen before with a torque converter.
-Use a paint marker to identify the position of the driveshaft to the differential yoke for reassembly. It's important to make sure the driveshaft is reinstalled in the same position in order for it to preserve balance.
-Putting a latex glove with a bunch of electrical tape around the end of the transmission tail shaft will hopefully keep any transmission fluid from spilling all over the floor.
-When reassembling, bolt the transmission mount (see picture above) on the tail shaft before you put the cross-member in, makes everything much easier.
-Blue Loctite is your friend, add to all bolts on the drive shaft straps, flex plate, and torque converter. This will keep vibrations from loosening any bolts.
Torque Specs:
- Driveshaft U-Joint Straps - 15lbs
- Front Crossmember - 37lbs
- Park/Neutral Position switch - 18lbs
- Flex Plate - 18lbs, followed by an additional 50° of rotation
- Rear Main Seal oil seal housing bolts - 89lbs
- Torque Converter-to-Flexplate - 44lbs
- Transmission-to-Engine Block - 37lbs
- Transmission Heat Shield - 13lbs
- Transmission Mount - 18lbs
- Transmission Pan - 8lbs, star pattern method
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