Why won't the transmission separate from the engine?

Hi. You will need a shop setting to remove this transmission. On a 2015 Nissan Quest the vehicle is raised with a two post car lift. The A/C charge is reclaimed, coolant is drained, brake calipers and struts are disconnected, steering column, motor and transmission mounts are disconnected, any necessary hoses, EVAP tubes and fuel lines and all related cables and harness connections. Raise the minivan up and place either multiple jack stands or heavy duty roll around table underneath the main chassis support frame. The Engine, transmission, steering and suspension get lowered down onto the chosen table or stands and the main mounting bolts are removed. Finally the vehicle is carefully raised separating the entire drivetrain from the vehicle. A cherry picker (engine hoist) is then used to remove and separate the engine and transmission. I hope this helps. Please let me know if there is something else you need answered. GoodLuck.

Freeze plugs are located at various points around the engine block and sometimes the cylinder head assemblies as well. Some are accessible while others may be behind bolted-on components such as power steering pumps, water pumps, alternators. Others are located at the rear of the engine against the firewall where replacement may be impossible. Still others are at the rear of the engine block, often requiring separation of the engine and the transmission to access them. If you are planning to replace ALL of them, expect to have the engine removed from the vehicle and separated from the transmission to be able to do them all. This, as you can imagine, is relatively expensive.

To replace the flex plate you should purchase an inexpensive repair manual first off, then purchase an inexpensive tool set with Metric sockets and wrenches. You will need a good jack and good blocking or jack stands to hold the vehicle up while you perform the task. Basically you must separate the engine and transmission move the transmission rearward far enough to reach the bolts which attach the flex plate to the engine. once you have the bolts removed and have matched a replacement flex plate you will need to torque the bolts back into the crankshaft and then reverse the procedure used to remove the transmission. It is a pretty big job but can be performed by a diligent worker with minimal experience following basic instruction from a simple manual. If you have a library near you you may be able to find a repair manual to outline the procedure.

Above all be safe when working under a vehicle so as not to be squished to death. A transmission jack may be helpful but may not be necessary if you have good stable blocking with which to support the transmission while allowing you to move it rearward away from the engine.(rear wheel drive only) This is not a super technical job but will require hard work.

The transmission is transversely mounted in these vehicles. The mount that secures the transmission to the body is also supporting the engine. If you want to remove the transmission without also removing the engine you will have to support the engine once you remove the transmission mount. You will need to remove the drivers side wheel, caliper, and rotor. You then need to remove the drivers side CV shaft. You will need to separate the lower ball joint in order to remove the shaft and to provide working room to separate the transmission from the engine. You need to disconnect the Shift cable (automatic) or slave cylinder (manual) from the transmission. You must separate the passengers side CV shaft from the transmission, but you do not need to full y remove it. Ensure that you do not separate the inner CV joint when pulling the transmission free from the inner splines. Remove the flywheel shield plate. If automatic transmission, unbolt the torque converter from the flywheel. Disconnect any electrical connections from the transmission. If automatic transmission, disconnect the hydraulic lines running to the radiator. Unbolt the transmission from the engine at the bell housing. Automatic transmissions will come out fairly easy...manuals you must pull back to disengage the transmission splines from the clutch disc.

remove the transmission torque converter ,,that seems like your hold up from what you explained

Won't accelerate on highway? At what speed (estimate) are you traveling before you "punch it". Is the engine a 3.4 or a 3.8? Is the check engine light on? Is it flashing?

These are a few questions I need to know to try to isolate the problem, but to put you in a ballpark of possible causes, causes could be (but not limited to):
poor grade of fuel
faulty secondary ignition components (spark plug wires, plugs)
clogged fuel filter
insufficient fuel pressure
a partially blocked catalytic converter (will aslo cause the floor to be a little warm)
a faulty map sensor
a faulty egr valve
a faulty transmission shift soleniod
a faulty vehicle speed sensor
low transmission fluid level
partially or blocked transmission fluid filter
transmission fluid has weaken due to age (needs flush)

1. Remove the hub cap and bolt the wheel back in.
2. Punch out the spindle nut lock and loosen the spindle nut.
3. Raise and support the vehicle and block the rear tires.
4. Remove the wheel.
5. Drain the transmission.
6. Remove the all the damper fork nuts and all the brake hose nuts on the damper fork and on the shock absorber.
7. Remove the damper fork.
8. Remove the driver side and passenger side front suspension flange nut inside the engine bay and slide the upper arm out
9. Turn the steering wheel all the way to the passenger side and remove the passenger drive shaft spline from the hub.
10. Separate the inner driveshaft from the transmission with a large screw driver (or crow bar).
11. Remove the passenger side drive shaft. Do not pull.
12. Remove the front radius rod.

Under the car.

1. Remove the center beam.
2. Remove the torque converter cover, the control cable holder and remove shift control cable.
3. Remove the drive plate bolts and four transmission housing bolts.

Inside the engine bay.

1. Place a transmission jack or several small jacks under the transmission.
2. Disconnect all the electrical connectors.
3. Remove the speed sensor gear shaft but leave the hoses on.
4. Remove the distributor and mark the distributor shaft with a razor or a diamond etcher, usually on the head side or both.
5. Remove the throttle control lever cable.
6. Remove the transmission cooler hoses mounting bolts and their 4 washers.
7. Remove the starter.
8. Remove the all the transmission housing bolts.
9. If the transmission won't come out remove a horizontal side engine mounting bolt and raise oil pan (with a wooden block between the oil pan and jack) until the transmission clears.
10. Lower the transmission into the transmission jack.
11. With the driver side front suspension flange out of the way, turn the steering towards the right then remove the driver side inner drive shaft with a large flathead screw driver.
12. Lower the low profile transmission jack and slide the transmission and the jack from under the car. Don't loose the two dowel pins.
13. Block all transmission fluid ports from leakage and dust and dirt.
14. If repairs are being done repair the transmission in a dust, sand free environment.
    

Start the engine and let it idle for four minutes. This will help to remove as much loose particles from the transmission as possible Turn off the engine. Raise the front of the vehicle using a floor jack, and support the vehicle with two jack stands Apply the emergency brakes and block the rear wheels with two wooden blocks .Place a large drain pan underneath the transmission pan. Loosen the front and side mounting bolts from the transmission pan using a crisscross pattern. Then remove the bolts. Use a ratchet, ratchet extension and socket.Loosen the rear mounting bolts from the transmission pan about 4 turns each. Pry the transmission pan open at the front using a screwdriver and let the oil drain onto the drain pan. Hold the transmission pan from underneath, using a shop rag as you remove the remaining pan mounting bolts. Separate the transmission pan from the transmission, and tilt it over the drain pan to remove the remaining oil. Discard the transmission pan gasket. This is were the filter will be located remove and replace filter and then. Clean the transmission pan with spray carburetor cleaner and a shop rag.Install a new gasket over the transmission pan flange Set the transmission pan in place and start the pan mounting bolts by hand. Start tightening the transmission pan bolts in a crisscross pattern, a little at a time, until all the bolts are tight. Use the ratchet, ratchet extension and socket. Just tighten the bolts enough to create a seal between the pan and the transmission to avoid damaging the pan gasket.

Don't have manual but here;

the clutch is located between the engine and transmission. Therefore you must separate the engine from the transmission to gain access to the clutch.

This is much more difficult on a front wheel drive vehicle.

On most front wheel drive vehicles the easiest way to this is to remove the engine and transmission as a unit. However on a front wheel drive vehicle the engine and transmission come out from the bottom. You disconnect all of the hoses, wiring, linkage, etc just like on a rear wheel drive vehicle. You disconnect the suspension and steering. You disconnect the front "K" member (front sub frame). Then if you have everything disconnected properly you lift the body off of the drive train. You can then separate the engine from the transmission and service the clutch. You reverse your steps to reinstall the engine.

As you can see this is much more involved than accessing the clutch on a rear wheel drive truck where the transmission can be removed without removing the engine.

There are a few front wheel drive GM vehicles I have seen where the "K" member can be removed in pieces. On these vehicles you only remove half of the "K" member and you can remove the transmission without removing the engine. Not sure if this is possible on a Ford.

3.8L Engine - There's a lot of stuff here.

1. Take the vehicle to a reputable repair shop to have the refrigerant discharged and recovered.
2. Disconnect the negative, then the positive battery cables.
3. Relieve the fuel system pressure.
4. Remove the A/C compressor and condenser hose from the accumulator.
5. Raise and safely support the vehicle.
6. Remove the front wheel and tire assemblies.
7. Drain the coolant and engine oil into suitable containers.
8. Remove the 3-way catalytic converter.
9. Remove the front fascia lower deflectors.
10. Remove the stabilizer bar bushing bolts.
11. Disconnect the radiator inlet hose from the radiator.
12. If equipped with an automatic transmission, perform the following:
    1. Remove the transmission converter bolts.
    2. Disconnect the transmission oil cooler lines from the radiator.
    3. Remove the transmission range selector lever cable from the transmission.
    4. Remove the left and right transmission support brackets.
13. If equipped with manual transmissions, perform the following:
    1. Remove the transmission control lever handle.
    2. Remove the clutch actuator cylinder line from the actuator.
14. Remove the propeller (drive) shaft.
15. Remove the torque arm from the transmission.
16. Remove the steering gear coupling shaft from the rack and pinion.
17. Remove the electrical ground strap from the engine block.
18. Remove the starter motor.
19. Remove the A/C compressor and condenser hose from the compressor and from the condenser.
20. Remove the negative battery cable from the rear compressor bracket mounting stud.
21. Remove the engine coolant heater cord from the block.
22. Carefully lower the vehicle.
23. Remove the A/C compressor and condenser hose from the vehicle.
24. Remove the heater hoses from the drive belt tensioner.
25. Remove the air cleaner outlet rear duct. Remove the resonator duct.
26. Disconnect the fuel lines from the fuel rail.
27. Disconnect the cruise control cable from the throttle body. Disconnect the accelerator control cable from the throttle body.
28. Remove the radiator outlet hose from the thermostat housing.
29. Disconnect the brake booster vacuum hose.
30. Remove the bracket lines and the clips from the ABS hydraulic modulator.
31. Remove the right-hand body hinge pillar trim panel.
32. Detach the engine wiring harness connectors.
33. Remove the forward lamp wiring harness connectors.
34. Remove the Powertrain Control Module (PCM) and the wiring harness and place them on top of the engine.
35. Remove the engine wiring harness through the front of the engine, then place on top of the engine.
36. Disconnect the positive lead from the alternator.
37. Remove the lower shock attachment nuts and bolts from the lower control arms.
38. Remove the upper control and ball stud from the steering knuckle. Use the upper control arm in order to secure the struts to the outboard.
39. Remove the wheel speed connectors from the engine frame.
40. Position a suitable engine support table under the engine and frame.
41. Remove the engine frame and transmission support bolts.
42. Raise the vehicle from the engine, the transmission and the engine frame.
43. Remove the transmission.
44. If equipped with a manual transmission, remove the clutch housing and the clutch.
45. Remove the engine mount though bolts.
46. Remove the engine from the engine frame. To install:
    
47. Position the engine to the engine frame.
48. Install the engine mount through bolts.
49. Install the transmission.
50. Position the engine lift table. Lower the vehicle to the crossmember in order to install the engine, transmission and engine frame.
51. Install engine frame and transmission support bolts, then remove the engine lift table.
52. Attach the electrical connectors to the wheel speed sensors.
53. Install the upper control arm ball stud to the steering knuckle.
54. Install the lower shock attachment bolts and nuts to the lower control arm.
55. Connect the positive lead to the generator. NOTE: When routing the engine wiring harness through the front of the dash, the rubber grommet must be installed properly to ensure correct sealing. If the rubber grommet is damaged, replace it.
    
56. Install the engine wiring harness through the front of the dash.
57. Install the PCM and PCM harness.
58. Install the forward lamp wiring harness connectors and the engine wiring harness connectors.
59. Install the right-hand body hinge trim panel.
60. Install the brake lines and clips to the ABS hydraulic modulator. Connect the brake booster vacuum hose.
61. Connect the radiator outlet hose from the thermostat.
62. Connect the cruise control and accelerator cables to the throttle body.
63. Attach the fuel lines to the fuel rail.
64. Install the air cleaner outlet rear duct and resonator duct.
65. Connect the heater hoses to the drive belt tensioner.
66. Attach the A/C compressor and condenser hose.
67. Raise and safely support the vehicle.
68. Connect the engine coolant heater cord to the block.
69. Connect the negative battery cable to the rear compressor bracket mounting stud.
70. Install the A/C compressor and condenser hose to their respective components.
71. Install the starter motor.
72. Fasten the electrical ground strap to the engine block.
73. Install the steering gear coupling shaft to the rack and pinion.
74. Connect the power steering inlet and outlet hoses to the steering gear.
75. Install the torque arm to the transmission.
76. Install the propeller shaft.
77. Connect the shift linkage to the transmission.
78. Attach the radiator inlet hose to the radiator.
79. If equipped with a manual transmission, attach the clutch actuator cylinder line to the actuator and install the transmission control lever.
80. If equipped with an automatic transmission, perform the following:
    1. Install the left and right transmission support brackets.
    2. Install the transmission range selector lever cable to the transmission.
    3. Attach the transmission fluid oil cooler lines to the radiator.
    4. Install the transmission converter bolts.
81. Install the stabilizer bar bushing bolts.
82. Install the front fascia lower deflectors.
83. Install the 3-way catalytic converter.
84. Install the wheel and tire assemblies.
85. Carefully lower the vehicle.
86. Refill the engine with the proper amounts of coolant and engine oil.
87. Connect the positive, then the negative battery cables.
88. Properly bleed the brake system.
89. Take the vehicle to a reputable repair shop to have the A/C system charged and the wheels aligned.