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Thread: How to remove the engine from the bottom - LS1 fbody

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    How to remove the engine from the bottom - LS1 fbody

    Engine Removal from Underneath

    This how-to is meant as a guideline for removing your engine from the bottom of your f-body. There are many ways to do this, this is just a walk through of how I did it. This removal is being performed on a 1999 Firebird Formula A4, however since f-bodies have remained very similar from 93-02, you can adapt this how-to to suit your own needs.

    I am using a lift to make things easier; however several people have performed this type of install in their home garage, by using a cherry picker to lift the car off of the front end. I am also doing a few other modifications at this time. For that reason, you may see additional things removed in the how-to pictures and text that are extra. This took me about 4 hours to do by myself.

    Before beginning your removal, decide whether you want to leave the a/c compressor with the body (and unmount it from the engine) or leave it on the engine (keep in mind you will need to have the refrigerant evacuated from your a/c system). I decided to leave the compressor with the engine and recover the refrigerant, so this how-to covers removal of certain a/c components and lines.

    First things first. Remove key from ignition and make sure the steering wheel is locked. Set the car up on the lift or jack stands by using appropriate jacking points. Leave the vehicle in neutral.

    1. Disconnect the negative and positive battery posts. 8mm bolt on a stock battery setup. There is also a 10mm ground that needs to be removed, right behind the battery.


    Body ground.

    2. Inside the car, on the passenger side, remove the plastic kick panel. It is held on by four Philips head screws, and then pops out. Pull back the carpet at the top right corner and you will see a couple harnesses. Unplug the upper connectors (2) so that later on you can pull that harness through the firewall.


    X marks the spot for the phillips head screws.


    Body connectors.

    3. If you have a manual, remove the shift knob. Removing the shift boot is helpful also so it doesn’t get torn during re installation.

    4. Remove radiator cap, set aside. Open petcock valve (bottom of the radiator, passenger side) drain coolant (either set aside or recycle).

    5. While coolant is draining, unplug the IAT sensor, MAF sensor, and TPS sensor. Remove your air lid or stock air intake by loosening the ring clamps with a flathead screwdriver. Pull the lid and MAF off.



    6. Remove the small coolant hose that is attached to the coolant pipe under the intake manifold. Lay over top of radiator.

    7. Remove the throttle body cable from the throttle body. To do this open the throttle body cam all the way and slide the cable out the side. Pry a flathead screwdriver between the plastic piece and bracket to remove it completely.

    8. There will be a few clips holding the throttle body cable & ASR cables (if applicable) to the engine/air conditioning lines. Pull the cables loose so they are not attached to the engine. They do not need to be removed from the ASR module, just detached from the engine. It is helpful to remove the ASR module from the body by taking out two 13mm bolts. Then you can tie it up out of the way and it won’t be all up in your grill later when you are wrestling with the engine harness.

    9. At this point the coolant should be just near finished draining from the petcock. Re-tighten it so it doesn’t mess the floor, otherwise plan on keeping a pan under it the whole time.

    10. Detach the upper and lower radiator hoses from the engine. Use pliers to squeeze the hose clamp and slide it towards the radiator. Twist the hose to loosen it off of the engine block. Pull off and lay them out of the way. Also detach the coolant hoses that run from the water pump to the heater box. Beware fluid from lower hoses.



    11. On the driver’s side of the engine – disconnect the fuel line. You will need a fuel line disconnect tool to do this (3/8”). You may need to unplug injectors/coil harness to get enough room. Also disconnect the fuel evap line from the small black canister lying on the intake manifold. Do this by squeezing the top and bottom of the plastic ring, and slide it off. Swivel fuel lines out of the way and wrap with a rag so gasoline is not potentially dripped onto the shock tower.



    12. Remove steering shaft. There will be bolts on both ends, 7/16”. These are often tightened by gorillas from the factory and are doused in loctite so have fun with them. When the bolts are removed, remove the shaft from the rack first. A pry bar works well to loosen it. Then pull it off of the steering wheel side. Re-install the bolts into the shaft so you don’t lose them.

    13. Remove the brake booster hose at the booster.



    14. Detach the master cylinder from the brake booster. There is a 15mm nut on each side that needs to come off. Then pull the master straight towards you. It will be stiff, but you will be able to pull it forward enough to get it off of the booster studs. Once it’s off, push it up above the windshield cowl so you will have room to remove the shock tower bolts.

    15. On the driver’s side shock tower, there are two bolts that are T50 torx. There are also two 15mm nuts. On the passenger side shock tower, there are two 15mm nuts and two 13mm bolts. Remove all, set aside. Then you can put the master cylinder back in its location so the brake lines are not stressed.

    16. Locate your Electronic Brake Control Module, an aluminum block on the driver’s side. The front brake lines need to be removed, and are marked if you look closely (LF and RF). They are ˝”. Be careful of dripping brake fluid, it eats paint.



    17. Follow the lines down the side of the frame area. There is an aluminum heat shield there held on by 4 10mm bolts. Two can be removed from the top, the other two you can get from the bottom. When you pull it out you will see a black/gray bracket that holds the brake lines. Pop the front brake lines from the bracket. Also remove the nearby black cable from the bracket by undoing the clip.

    18. Remove the positive cable from the post on the fuse box. 15mm bolt, pull ring terminal off.



    19. Below the fuse box on the driver’s side, there is a ground strap held on with a 10mm bolt that needs to be removed.



    20. At the a/c accumulator, remove the thick a/c line by loosening the 10mm bolt. Remove the accumulator itself from the bracket by loosening the 10mm bolt. Now disconnect it from the heater box side by removing the 13mm bolt. Pull it completely out of the car. Also disconnect the smaller a/c line that runs to the condenser.



    21. Remove the PCM. The connectors, red and blue, are each held on with a 7mm bolt that does not come all the way out. Then there is a black bracket that is held on with two 10mm bolts, remove them. The PCM and bracket can come out as one unit. Twist the top of the PCM so that it is facing the passenger side, and pull it out towards you (bending the windshield shroud out of the way). Now you can pull the body harness through the firewall, including the grommet. Also remove it from any clips on the firewall.


    Firewall grommet, clips holding harness.

    22. Follow the PCM harness to the heater box, where you will see a vacuum line coming off of it. Disconnect the vacuum line from the heater box. Also unplug the pressure switch connector from the evaporator tube.


    Vaccuum line.


    Pressure switch connector.

    23. Disconnect the connectors that run along the passenger side fender.



    24. You can now start flipping the harness onto the engine to clear the way. You will see that the passenger side harness runs down the body to the o2 sensor, underneath the small a/c line…while the rest of it is above the same a/c line. Brilliant, GM. But that’s ok - the reason for disconnecting the a/c lines at the heater box is so that you can untangle that harness without pulling it out from the top (which would involve disconnecting it from the k-member, behind the starter, and from the oil level sensor). Just manipulate the a/c line until the entire harness is sitting on top of it.

    25. Remove the front wheels. After removing the front wheels, look on the k-member on both sides to find the wheel speed sensor connector. Disconnect it, and pop the connector out of the k-member.

    26. Underneath the car on the driver’s side there is a thin rubber dam. Remove this by pulling it off of the clips. Remove the other 2 10mm bolts from the brake line heat shield if you haven’t already.


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    27. There are two harnesses running behind the electric fan. One actually has connectors going into the motors; you do not need to disconnect that one. The other is fatter and is attached to the shroud with clips. Pull this harness loose from the clips.

    28. Using the access panel underneath the driver’s side, follow that same harness and unplug the necessary connector from the AIR pump.

    29. Underneath the car on the passenger side, the thin a/c line enters the condenser. Remove this line by loosening the 13mm nut and slide it off. Beware of dripping PAG oil.

    30. If you have an automatic, remove the transmission cooler lines, both stock and aftermarket (if you have one). The line that goes into the radiator is held in with a 13mm nut. Beware dripping transmission fluid.


    31. Also for an automatic, remove the shift selector cable by prying it off with a screwdriver. Then remove the two 13mm bolts that secure it to the transmission pan so that it dangles.


    This naughty looking thing is the gearshift selector cable.

    32. For a manual car, detach the clutch hydraulic line that runs into the side of the transmission. There is a white ring that needs to be depressed with two flat tip screwdrivers (or an appropriate tool). When pushed in, the line pops out.

    33. Detach the sway bar from the mounts. On the driver’s side, there is a 13mm nut that comes off to reveal a bracket. The bracket comes off by removing two 10mm bolts on the body. Then remove the two 13mm bolts holding the sway bar on. On the passenger side, there are two 13mm bolts also.


    Swaybar mounts...on both sides.

    34. Disconnect and remove o2 sensors. It’ll be a few less harnesses to worry about tangling when the engine comes out. O2 sensors are 7/8ths.

    35. Remove your y-pipe. The socket sizes you need depend on your type of exhaust. I typically unhook the over the axle pipe and pull it out of the muffler to let it hang. Then work your way up to the headers/stock manifolds taking off pieces as you go. A good rubber mallet will be handy. If your exhaust is stock you may break a few clamps trying to take it off. The headers/manifolds can remain on the vehicle.

    36. Remove your driveshaft. Because you’re smart you left your car in neutral so you can spin the driveshaft. There are four 7/16” bolts. If the driveshaft is stuck in the yoke, lightly pry it. Try and keep the caps on the u-joint so that you don’t have needle bearings going everywhere. After it’s out of the yoke, lift up and pull back to slide it off of the tail shaft.



    37. The torque arm can now be disconnected from the transmission. Taking it all the way out is not necessary unless you are installing a new one. If you have an automatic, pry the vent tube clips from the torque arm. It then has a clamshell type mount on the transmission end, held on with a 15mm nut/bolt. Remove the nut and push the shell off of it. The torque arm will want to spring upward so be careful and try and guide it slowly with your hand. If you are replacing the arm – the nuts on the rear end are 13/16th”.



    38. At this point, do a quick check of the vehicle. Besides the k-member and transmission brace, look for any wiring harnesses, brackets, etc that may still be attaching the body to the engine.

    39. Now make a decision about what your engine and transmission are going to rest on when you take them out of the car. I am using a handy dolly. Very simple to set up, and then the engine/trans can be wheeled around as necessary. You can also use jack stands. Take care when setting them, using appropriate jacking areas. Get the vehicle set up the way you like it, and lower it down until it rests on the stand heavily.

    40. Remove the bolts from the transmission brace. Four 15mm bolts. The brace can stay attached to the transmission.



    41. The k-member is the final thing we will be dealing with. There are six robust bolts attaching it to the body. I have tried to capture their location in photographs, but it was difficult to show them all at once. It should be fairly obvious which ones they are, three per side, and they are all 18mm. You will need a breaker bar or impact gun to remove them. Before doing this, double check that your engine and transmission are appropriately supported.


    Driver's side.


    Passenger's side.

    42. After removing the bolts, you can start taking the body off. Do a final check that there are no other harnesses/etc attached. Initially, bring the body up slowly. Sometimes the k-member is sort of stuck. If so, use a pry bar and it should detach itself abruptly.


    Ready for removal.

    43. From here on out, continue lifting the car, stopping every few inches. Even though we have removed everything attaching the engine and transmission to the body, the harnesses and lines will still want to hang up as you go. Take special care of the brake lines, they are hooked and thus want to grab everything. GO SLOW. You will thank yourself later when you are not doing un-fun things like repairing broken wiring harnesses or brake lines.



    44. As you lift the car up, the engine and trans will want to shift a little. When the body gets high enough for the shock tower studs to slip out, the rotor/a-arm assembly will want to lay over to the side pretty violently – that is a lot of weight, so take it slow.



    45. Once the body is off of the engine and transmission, you are now free to do as you like with them. But first complete this very important step. You must climb into your now barren engine bay, strike a pose, and have your friend take a picture. Everyone does it and you should be no exception.




    Ta-da!!


    Notes concerning reinstallation:

    You can basically read this how-to backwards to remind you of how the vehicle will go back together. When lowering the body back onto the engine/trans, take your time and guide it so that the k-member and shock towers are lined up correctly. Once they are, reinstallation is a breeze. You can consult a repair manual for appropriate torque for bolts/nuts, here are a few:

    Brake master cylinder nut – 21 lb/ft
    Shock tower nut – 32 lb/ft
    Shock tower bolt – 37 lb/ft
    Sway bar bolts – 41 lb/ft
    Driveshaft bolts – 16 lb/ft
    Steering shaft bolts – 35 lb/ft
    K-member bolts – 92 lb/ft (lower) 107 lb/ft (upper)
    Transmission brace bolts – 66 lb/ft
    Brake lines in EBCM – 11 lb/ft
    A/C Accumulator bolt – 12 lb/ft
    A/C Evaporator tube bolt (at condenser) – 12 lb/ft
    Throttle body bracket bolts – 89 lb/in
    Wheels – 100 lb/ft


    After all of your bolts, nuts, harnesses, etc are in place, don’t forget to top off any missing fluids. The brakes will need to be bled after the lines are reattached to the EBCM. Transmission fluid may need to be topped off if it’s leaked through the tail shaft. The engine coolant will need to be refilled and bled also. To bleed an LS1, reattach all of your coolant hoses except for the small one that runs to the coolant tube under the intake manifold. Place a small paper towel underneath the line and cap off the rubber line with your thumb.

    Refill the coolant through the radiator. You will hear air rushing out of that tube, which is the highest point of the coolant system. Once a stream of coolant appears out of the tube, reattach the rubber line and start the car. From there you can top it off as necessary (should not need much more at all).

    Do a final once-over before starting the vehicle, and enjoy!

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