P38A torque converter lockup

kermit_rr · Mar 7, 2020

Hi
Never really noticed before, so not sure if it's normal or the beginning of the end!
Particularly noticeable today, didn't get lockup until I'd done a couple of miles and the engine was warm, irrespective of the speed i was doing.
Normally, it'll lock anywhere from 35-40mph and up depending on conditions
What's normal on these?
Cheers

Datatek · Mar 7, 2020

kermit_rr said:
Hi
Never really noticed before, so not sure if it's normal or the beginning of the end!
Particularly noticeable today, didn't get lockup until I'd done a couple of miles and the engine was warm, irrespective of the speed i was doing.
Normally, it'll lock anywhere from 35-40mph and up depending on conditions
What's normal on these?
Cheers

Lock up in 4th gear normally happens at around 50 mph and around 40/45 in 3rd depending on throttle opening. If yours is locking at 35-40 it's not normal.

wammers · Mar 7, 2020

kermit_rr said:
Hi
Never really noticed before, so not sure if it's normal or the beginning of the end!
Particularly noticeable today, didn't get lockup until I'd done a couple of miles and the engine was warm, irrespective of the speed i was doing.
Normally, it'll lock anywhere from 35-40mph and up depending on conditions
What's normal on these?
Cheers

In D high range torque lock occurs at around 50 MPH after this speed has been maintained for a minute or so, it will drop out of torque lock when the speed has reduced to below 35 MPH for a minute or so. The engine operates at reduced power until the engine and gearbox have reached working temperature.

Henry_b · Mar 7, 2020

Mine used to lockup at 45 and stay there until 20mph, usually requiring me to change down manually..

Changing the fluid a few times, helped it significantly..

kermit_rr · Mar 7, 2020

Datatek said:
Lock up in 4th gear normally happens at around 50 mph and around 40/45 in 3rd depending on throttle opening. If yours is locking at 35-40 it's not normal.

Maybe it is actually at 40 (in 3rd) and then I'm dropping back down a bit, is a bit hard to keep an eye on the speedo while driving.

kermit_rr · Mar 7, 2020

wammers said:
In D high range torque lock occurs at around 50 MPH after this speed has been maintained for a minute or so, it will drop out of torque lock when the speed has reduced to below 35 MPH for a minute or so. The engine operates at reduced power until the engine and gearbox have reached working temperature.

If it's at reduced power for a while that would explain it i think
I shall keep calm and carry on!
It tends to snatch 2nd gear when changing up on a light throttle, but nice and smooth with a bit more pedal, but at 125000 miles on the clock i don't expect perfection. In guessing it's the original box
Changed the oil and filter when i got the car, oil was dark but didn't look 'bad'

wammers · Mar 7, 2020

kermit_rr said:
If it's at reduced power for a while that would explain it i think
I shall keep calm and carry on!
It tends to snatch 2nd gear when changing up on a light throttle, but nice and smooth with a bit more pedal, but at 125000 miles on the clock i don't expect perfection. In guessing it's the original box
Changed the oil and filter when i got the car, oil was dark but didn't look 'bad'

If it's snatching second gear the valve block is sticking, get yourself a bottle of Lucas. Snake oil that actually works.

Datatek · Mar 7, 2020

kermit_rr said:
If it's at reduced power for a while that would explain it i think
I shall keep calm and carry on!
It tends to snatch 2nd gear when changing up on a light throttle, but nice and smooth with a bit more pedal, but at 125000 miles on the clock i don't expect perfection. In guessing it's the original box
Changed the oil and filter when i got the car, oil was dark but didn't look 'bad'

Lucas Transmission fix with a second oil change might help. Only about half the oil comes out when you change it, so a second and maybe a third change after at about 1K mile intervals can be beneficial.

kermit_rr · Mar 7, 2020

Datatek said:
Lucas Transmission fix with a second oil change might help. Only about half the oil comes out when you change it, so a second and maybe a third change after at about 1K mile intervals can be beneficial.

Do i just leave that stuff permanently? Or oil change after x miles?
When i did the oil change, i bypassed the oil cooler and let it pump until it started to come thru a bit cleaner. Ran out of fluid at that point

kermit_rr · Mar 7, 2020

Next silly question, assume i suck a bottle full of oil out of the box, then pour the comments of the 'fix' into the box job done?

Henry_b · Mar 7, 2020

kermit_rr said:
Next silly question, assume i suck a bottle full of oil out of the box, then pour the comments of the 'fix' into the box job done?

you substitute a litre of ATF for the lucas.

4.2 litres whould drain from the sump..

kermit_rr · Mar 7, 2020

Henry_b said:
you substitute a litre of ATF for the lucas.

4.2 litres whould drain from the sump..

Cheers. If i recall i got thru around 2 bottles, don't remember if they were 4 , 4.5 or 5L. Just made sure it was up to the level afterwards

dubbleRR · Mar 7, 2020

The green sensor on the head ,can affect how long it takes to change gear ,,On mine the gearbox held the gear for longer got better as it warmed up ,changed the green one and it was fine again

, ...RR

wammers · Mar 7, 2020

dubbleRR said:
The green sensor on the head ,can affect how long it takes to change gear ,,On mine the gearbox held the gear for longer got better as it warmed up ,changed the green one and it was fine again , ...RR

Correct, the green sensor is the engine ECU sensor so any lag in that would give problems.

RangeRoller dt · Mar 7, 2020

He has a 4.0v8

wammers · Mar 7, 2020

RangeRoller dt said:
He has a 4.0v8

I was answering dubbleRR who does have a diesel. Also 4.0 L petrol and diesel are the same box.

RangeRoller dt · Mar 7, 2020

Is always worth changing green sensor on diesel.

kermit_rr · Mar 7, 2020

Thought the green one was no longer available? Or am i thinking of something else

RangeRoller dt · Mar 7, 2020

They are all available, blue can be tricky to source not silly money, is V8 not different sensors?
I have spare new brown (no aircon) if anyone needs one.

wammers · Mar 7, 2020

RangeRoller dt said:
Is always worth changing green sensor on diesel.

The ECU restricts fuel availability at low temps for emission purposes. So engine power is limited until working temp is achieved and a clean burn is possible..

P38A torque converter lockup

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Think outside, no box required.

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