P38A over cooling

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I've not got an automatic but many of the Nanocom screens allow you to take a trace. Be interesting to see what the autobox sees.

Does the box itself have a temperature sensor?
 
Mark Piercy said:
The gearbox functions very well, cold or hot. When the temp gauge is at twelve o'clock the torque lock up is guaranteed, a bit before twelve o'clock it wont do it. It is a consistent occurrence. When I first changed the thermo' it was behaving brilliantly, then its gone back to the same behaviour as the old thermostat. The gearbox I have no doubts about.
Click to expand...

Torque lock is a function of road speed and engine speed and certainly should not be effected by a slight engine temp drop. I suggest you get some dedicated diagnostics on the car otherwise you are chasing your tail.
 
Grrrrrr said:
I've not got an automatic but many of the Nanocom screens allow you to take a trace. Be interesting to see what the autobox sees.

Does the box itself have a temperature sensor?
Click to expand...

Other than an over temp sensor on the oil cooler no. I have told him to get dedicated diag on it and look at the ECM and gearbox ECU interfacing. I cannot see how a small engine temp drop can effect torque lock.
 
On my Jaguar (XK8 with 4.2 V8 & six speed auto box) the gearbox is heated/cooled via the radiator.

I wonder, therefore, if the over cooling is causing the gear oil to thicken up enough to create this problem??
 
Check engine coolant temperature sensor readings with proper diagnostics, gearbox warm up mode should only be activated when engine is really cool, below normal temperature zone on guage.
 
That's sorted! Both coolant sensors replaced. Torque lock up at lower temperature and a more accurate temp gauge. One sensor was green from leaking into its own plug and the second had started to turn on the brass fitting as well as being fuzzy green. 33mpg av' at 70mph! Brilliant.
 
Update. All is good and a niggling water pump has raised its head, put it on the list along with the lower steering colum, headliner and brake sphere... What's your list?
 
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