Auto Gearbox Fluid Change Issue

[tricky1962]

Hi.
The gearbox was changing down unnecessarily downhill, only when cold so not knowing the service history, I decided to change the fluid first.


I drained the gearbox and got 3 litres of fluid out. Refilled with 3 litres of fresh, removed the level plug, started the engine and went through the gears as instructed. I looked underneath the car and it seemed the fluid was being pumped out under pressure. I let it run for a bit then stopped the engine. 3.5 litres of fluid had been pumped out.


I don't understand why the level plug should allow the fluid to come out under albeit low, pressure.


I'm going to put 3.5 litres back in for now and take it for a short drive, but does anyone have any ideas what's going on?


Thanks

[MissMoppet]

Do you mean the level plug?

[tricky1962]

Originally Posted by MissMoppet

Do you mean the level plug?

Thanks. Now fixed, I hope it makes more sense

[Matt_75]

The level plug should only be removed when the transmission fluid is between 35°C and 45°C, otherwise the level won't be correct. Also the instructions say to move through the gears before removing the level plug. Is this what you did?

[tricky1962]

Yes, that is what I did

[SD1too]

Originally Posted by tricky1962

I looked underneath the car and it seemed the fluid was being pumped out under pressure.

Just to add to Matt's question Richard, check that you have identified the correct location for the level plug. It's mounted on the underside of the gearbox next to the selector cable return spring (see photo 19.10 in Haynes page 1A.14).

If you have, then fluid draining under pressure suggests that the gearbox was overfilled.

Simon

[tricky1962]

This one point that puzzles me. There is only one bolt, behind the selector cable, but it does not the allen socket as shown in Haynes, merely a 14mm bolt head. There are no bolts in that area with allen socket heads.



I only drained 3 litres from the gearbox so didn't think it likely that the box had been overfilled (I was expecting 4-4.5 litres). Also it was still being forced out after 3.5 litres had come out and I switched the engine off.

[SD1too]

Originally Posted by tricky1962

There is only one bolt, behind the selector cable, but it does not the Allen socket as shown in Haynes, merely a 14mm bolt head.

Thanks for your reply Richard.

I have information from a Land Rover Freelander site that on later transmissions the 5mm Allen key was replaced by the 14mm hexagon bolt that you have identified. It's mounted on a raised boss.

Originally Posted by tricky1962

Also it was still being forced out after 3.5 litres had come out and I switched the engine off.

Was the coolant temperature gauge reading normal and the engine running at normal idle speed?

Simon

[tricky1962]

I started the car and drove it around the block to put a bit of heat into the gearbox. The car then sat for an hour while I went to buy a 24mm socket for the drain plug.


I drained the oil, measured it and refilled with just above the same amount.


Then I started the engine, and within two minutes I had gone through the gears and then went to check the level plug.


I doubt the engine temperature guage had moved in that time and I think it was operating at a fast idle - 1000 - 1200 rpm?

[SD1too]

Thanks for the extra detail Richard.

As Matt pointed out in post no. 3, MG Rover states that the engine should be run at idle until the fluid temperature reaches 35˚C. It's hard to be certain whether yours achieved this since driving it "around the block" doesn't sound very far then the transmission was allowed to cool for an hour. When you performed the level check, if your engine was running at a fast idle then that indicates that it and the transmission was probably quite cold, i.e. below 35˚C. You need to be less casual about this Richard!

For maximum accuracy you can stop the engine, separate a connector and measure the fluid temperature using a multimeter. Alternatively you can use the traditional method which worked satisfactorily for years before diagnostic equipment existed. That is to ensure that the coolant temperature gauge reaches the nine o'clock position when the engine idle speed should be around 800 rpm before attempting your level check. That should give a better result.

If you decide to do that, please let us know what happens.

Simon