I've said before that I dont like how hot the BMW V8 setup runs at normal temps in terms of coolant and gearbox. I tow fairly regularly and at the end of the journey even the wife says that the engine smells hot. I've even had the gearbox go into overheat modes ... I hate the thought of that having shelled out a fortune getting the gearbox reconned a few years ago.

It crosses my mind all the time that the gearbox oil temp is kept artificially high by the engine coolant, and that when you hit a hill towing, this reduces the overhead you have before you hit the overheat range.

What if you removed the existing heat exchanger and replaced it with a standard oil cooler? I was thinking along the lines of a P38's oil cooler which looks like it would fit in the space in front of lower rad just underneath the electic fan.

Are there any measurements of how much cooling is needed? and how much a cooler can cool?

I was figuring that if a P38 can manage with a single cooler, then so can the L322 ... or is there something that makes the L322's geaerbox much more demanding?

I'm aware that the heat up time would be longer, but thats an acceptable consequence.

any thoughts, ideas suggestions and comments are welcome... like I say .... lets talk about gearbox cooling!  V8 or else ...

Wait for the ECU to scream and die  Land Rover Addict
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Fisha,
I had an external oil cooler fitted to mine last year when I had gearbox done. Sits in front of the main engine radiators, behind electric cooling fan.

No way of telling the temperature, but is large, and sits in airflow, not buried in the engine bay.

Rich

was that in addition to the exchanger or as a replacement V8 or else ...

Replaced, as they cant guarantee any debris from gearbox failure will not be in original cooler, plus it's an upgrade and keeps oil cooler.

Here's a link.

http://www.autotransgloucester.co.uk/ATGL/Coolers.html

As well as gearbox cooler, they fitted upgraded pump to gearbox and sleeved the valves in valve block.

My car has just had 6 month oil flush last week, and again, they don't just drop contents of sump, they purge the gearbox to change as much of the old oil as possible.

Interesting ... and confirms it can be done.

So what did they do about the coolant pipes at the section where they meet the exchanger? Did they just replace them with straight pipes or leave the exchanger in place with the oil not connected. V8 or else ...

Mine were disconnected, although at first it was joined with a length of pipe to complete the curcuit, this caused over cooling (mentioned in another thread), I removed this tube and blanked the ends, to stop the flow and the over cooling.

I suppose the coolant pipes could be left connected, thier is an internal thermostat in the original oil cooler, which only opens up when gearbox oil temp rises, or remove from cooler and blank the ends like I have.

Fisha:
Are you planning to exchange the L322 gearbox cooler for a P38 version?

The transmission oil is hotter than the engine coolant, so it will dump heat into the coolant.
I thought the point of this new system was to extract the heat even when you're sitting still.
As you know, the P38 version will only cool effectively when you're moving.

You could add the P38 trans cooler (installed where it goes in the P38), then plumb that back to the existing device; so you'd cool the trans oil, then probably re-heat it! But you'd still have cooling when stationary.

As far as "amount of cooling", 1 of those laws of thermodynamics says (more or less), the greater the difference between the 2 temperatures, the faster the heat transfer.
So the L322 version, at standard operating temperature, is always cooling the trans oil with engine coolant at 205F.
Running the P38 version, ambient air temperature is more important, and the vehicle moving keeps a steady stream of cool(er) air moving across the oil cooler.

I have yet to encounter 200F temperatures where I live.
Although, sitting still on the highway in a giant summertime traffic jam, I've seen my outside temp display at 105F. Jim
2000 NAS HSE
2005 NAS HSE

Quote:

Are you planning to exchange the L322 gearbox cooler for a P38 version?

Quote:

The transmission oil is hotter than the engine coolant, so it will dump heat into the coolant.

fisha wrote:

Was actually considering 2 of them plumbed in series, one above the other sitting at the bottom front area of the radiators.

Quote:

Pushing heat into the coolant is what I dont want. A seperate mod I am considering is to change the thermostat to an BMW M5 one to bring the stat temp down from 105°C to the more normal 90° range to give me more temperature overhead for towing.

Quote:

Reading the RAVE manual, warm up mode is below 60°C and high temp is in the 120-124°C range - thats quite a range that the gearbox considers as normal temp. I think I would have to do a significant amount of cooling to bring it down anywhere near 60°C. At the same time, I dont see the point of heating it up to 105°C by the coolant if the gearbox isn't working the fluid to that temp.

Quote:

That's a pretty big temperature change.
Presumably, the ECU will deal appropriately with the change?
Why does it run so hot? An emissions thing?

RAVE wrote:

The electrically heated thermostat is used to regulate the engine coolant temperature. The thermostat regulates the coolant temperature depending upon engine load and vehicle speed. This allows the engine coolant temperature to be raised when the engine is operating at part load. Raising the coolant temperature while the engine is at part load has a beneficial effect on fuel consumption and emissions.
If a conventional thermostat with higher constant operating temperature is used, poor response when accelerating and in traffic could result.

the M5 stat is different. the L322 stat is all one part of the hose connector bit that bolts onto the water pump. an M5 stat is like a normal engine stat which sits sandwiched inbetween the hose connector and the pump.

a search of the web brings up a couple of how-to's on how to change it. You need to get a spacer machined that holds the new stat in place and also need to cut out sections of the old stat. Not a difficult job in the grand scheme of things, but until recently, I've struggled to find a machining shop near me. Might have found one recently though.

Quote:

Removing the heat source caused by the trans oil "cooler" should reduce the engine coolant temperature.
Just doing this might give you a bit more temperature headroom for towing.

fisha wrote:

It'll remove a heat source, but wouldn't stop the stat keeping the temp at 105°