Changing oil in P38 autobox

[Simon_CSK]

Have the kit and oil to to service the box on my 4.6 P38.

When I look at the service book it says the capacity of the gearbox in 11.5 litres. When I look at the sump it doesn't look like it has the capacity to take all of that oil. I am guessing that the oil capacity is therefore distributed amongst the gearbox, torque converter and sump. If that is the case then I am also guessing that the gearbox needs topped up with the engine running. Can someone give me the procedure in a simple list please?

Thanks.

[Bowie69]

You won't able to change the whole lot unless your torque converter is empty, you will perhaps change half of it using the following method:

Replacing oil:
1. Ensure that gearbox is cool. Apply
handbrake and securely chock front and rear
wheels.
2. Place a suitable container beneath gearbox.
3. Clean area around oil filler/level and drain
plugs.
4. Remove oil drain plug, remove and discard
sealing washer.
5. Allow oil to drain.
6. Fit new sealing washer to oil drain plug.
7. Fit automatic gearbox drain plug and tighten to
15 Nm (11 lbf.ft).
8. Remove oil filler/level plug, remove and discard
sealing washer.
9. Fill gearbox with recommended oil to bottom of
oil level/filler plug hole.
+CAPACITIES, FLUIDS AND
LUBRICANTS, Lubrication.
10. Select 'P' (Park).
11. Ensure handbrake is applied.
12. Start engine and allow it to idle.
13. Apply footbrake.
14. Move selector lever through all gear positions,
while continuing to fill the gearbox. Select 'P'
(Park).
15. With engine idling, continue filling gearbox until
a 2 mm bead of oil runs from oil filler/level plug
hole.
16. Fit new sealing washer to automatic gearbox
filler/level plug, fit plug and tighten to 30 Nm (22
l b f . f t ) .
17. Stop engine.
18. Remove all traces of oil from gearbox casing.

[Blanco]

You are correct I think in your assumption that much of the oil capacity,.... between 40 and 50% is in the hydraulic circuits/valves/TC etc. I got the tip from here that the longer you leave it to drain the more you get out, mine is the HP22 box and I got about 8 litres by leaving it overnight.

If you have the whole kit then after No.5 in Bowie's sequence above, remove the sump and replace the pickup filter etc. 

[Simon_CSK]

Progress

Oil drained, sump off, filter changed, sump back on gearoil added and cycled gearbox three times with the third time the gearbox wanting to move the car. Next time I am back out I will do the final check of the level, one final cycle and then try and move the car. 

I take it that the movement of the car is evidence that the gearoil has reached the places that the gear oil needs to reach and that we are not far away from actually getting my car to drive. 

[Escape]

Good work Simon! As you say, once you feel the car wanting to move, oil is getting where it needs to be, mainly the torque converter.

One thing I would do differently compared to the list above, is remove the filler plug first. That way you're sure it can be removed (they can be pretty stuck on if not removed for some time), and it will give you a more steady flow when draining. I also think it doesn't matterif the gearbox isn't cold when draining, just be careful with hot oil spilling (just like you would when draining the engine). Letting it sit overnight definitely helps, 7 to 8 litres is what I usually get out.

Filip

[Simon_CSK]

7 hours ago, Escape said:

Good work Simon! As you say, once you feel the car wanting to move, oil is getting where it needs to be, mainly the torque converter.

One thing I would do differently compared to the list above, is remove the filler plug first. That way you're sure it can be removed (they can be pretty stuck on if not removed for some time), and it will give you a more steady flow when draining. I also think it doesn't matterif the gearbox isn't cold when draining, just be careful with hot oil spilling (just like you would when draining the engine). Letting it sit overnight definitely helps, 7 to 8 litres is what I usually get out.

Filip

Filip

The gearbox was more or less empty amd I left it 48 hours with the sump plug out. Didn't intend to leave it that long just happened that way. So I think I can safely say that the gearbox is now good to go. Only a few more problems to fix with the car and I can put it back on the road.