( I know there are other threads about cooling at the moment, but I think this merits a different thread )

OK , lots of recent talk about lowering the temp of the 105°C opening on the 4.4 V8 engine. A very kind chap off here sent me up a used thermostat which I was going to use as a template to get a spacer made so I could fit a different, lower temp stat in its place. ( Search google for "M62 thermostat mod" to get the idea ).

Anyways, whilst the wife was watching horse and country TV garbage ... ... I was measuring up the stat and looked at the BEHR markings on it and wondered if I could find the catalogue to get true dimensions. I could ... I found a catalogue which listed all BEHRs part numbers ... and it calls it a 2.547 type stat.

Towards the end of catalogue, it even puts pictures up ... here is 2.547 :



Looks right, even has the electric connector pictured for the bit that forces the stat open under heavy load.

But then I looked at the next picture, type 2.548 :



Same shape, no electric connector.
The trawled the catalogue for 2.548 type stats. They list as diesel stats:

BEHR Part Number
2.548.88

BMW Part Numbers:
11 53 2 248 542
11 53 1 715 254

A quick search of the first part number brings up:

http://www.teilehaber.de/thermostat.-kuehlmittel-id15347081.html



Angebot-ID: 15347081
Artikel-Nr.:8620 24388
OE-Nr.: 11 53 1 715 254, 11 53 2 248 542, 2.548.88 (nur zu Vergleichszwecken)
Hersteller: TRISCAN
Thermostat, Kühlmittel
Öffnungstemperatur: 88 °C

And further searches of the various part numbers all seem to point to it being the same housing with an 88°C opening.

So could it be that easy to simply try and find one of those part numbers and bolt it on to get a lower temp? A quick search online seems to point to it being in the 140 euro range price wise ...

any thoughts? worth a punt? can anyone find it cheaper? V8 or else ...

Here are some alternative part numbers:
Analogous \ Similar Parts of BEHR THERMOT-TRONIK 2.548.88

( Manufacturer )
( Number )

BGA
CT5003

BMW
11 53 2 248 542

BMW
11 53 1 715 254

FIRST LINE
FTS473.88

MOTORAD
603-88
Thermostat, coolant

TRISCAN
8620 24388

VEMO
V20-99-0161


Added so I dont lose the link: found VEMO at the top of the page here:

http://www.buycarparts.co.uk/thermostat/bmw/7-saloon-e38

Seriously thinking of just ordering one and trying it. Its gonna cost me £50 to get a spacer machined and £30 for a stat ... plus the time and effort. V8 or else ...

Hi mate,
Sorry I ment to pm you when I got back of holiday. Do you still need the template of water pump? I've got a friend who works for Unipart, when he's back in work next week will give him the part numbers and see what he can find. [img]http://www.fuelly.com/driver/rob2529/range-rover[img/]
04, 4.4V8, Vogue Oslo Blue with LPG.
"You can sleep in your car, BUT you can't race your house!!!!"

If something can't be fixed with a hammer....... You have yourself an electrical fault!

Rob, no worries. Its OK at the moment.

I'm going to sleep on the idea, but I imagine tomorrow I'm going to bite the bullet and just order one of those thermostats. The more I look at the picture of it compared to the stat i have on the desk in front of me, the more I'm convinced its an exact same housing but with just a different wax insert to open at the lower temp and where the electrical thing goes in, its just blanked off.


I also think that you should be then able to just get an alternate wax insert for a lower temp as they just pop in and out ( but thats another story for another day. ) V8 or else ...

Well, its ordered ... lets see what arrives in the post eh?

 V8 or else ...

Just out of interest, what are you intending to achieve by this?

Won't it just lead to the engine management system assuming that e engine has not warmed up properly and therefore running sub-optimal settings for fuelling etc, or worse, a fault being generated as the thermostat will appear to be open circuit and the engine going into limp home mode?

In short, I tow a horse box, and run large tyres in the winter. The high nominal temp of a standard stat does not give me much overhead before cooking the engine. dropping the stat temp gives me more temp space fir when I really work the engine.

I've also had the autobox go into overheat protection mode a couple of times. Lowering the coolant temp increases the cooling if the transmission as well.

I don't think the ecu will bother. 88 deg c is still a fully warm engine and other conversions like this report no errors V8 or else ...

You won't fix a gearbox overheat by reducing the engine coolant temperature, because the gearbox is not cooled by the engine coolant.

If the engine coolant is getting hot, then having the stat open earlier won't fix that assuming the stat is opening at the moment. Are you sure you don't just have a stuck stat? It'll delay the onset of high temperatures but if the existing system can't cool things down then neither will the new system, because once the stat is open the new and old systems are the same.

Messing with the design of the system like that, particularly removing the ECU's ability to control the position of the stat, sounds a bit iffy to me. Are you sure you don't just have a fault?

ric355 wrote:

You won't fix a gearbox overheat by reducing the engine coolant temperature, because the gearbox is not cooled by the engine coolant.

If the engine coolant is getting hot, then having the stat open earlier won't fix that assuming the stat is opening at the moment. Are you sure you don't just have a stuck stat? It'll delay the onset of high temperatures but if the existing system can't cool things down then neither will the new system, because once the stat is open the new and old systems are the same.

Messing with the design of the system like that, particularly removing the ECU's ability to control the position of the stat, sounds a bit iffy to me. Are you sure you don't just have a fault?

If that is the case then why is there a Gearbox Cooler plumbed into the Coolant system??

Take a gander under the boonet on the Drivers side (RHD) near the bottom, small ali heat exchanger with a plastic manifold plumbed to the coolant system! 

I do wonder if there is an underlying fault somewhere. I tow a two horse trailer and a twin axle caravan (not at the same time) that's nearly two tons all up. Never had a problem with overheating of either the engine or gearbox. That include towing all over the Welsh mountains in the summer.

I'd be checking the state of the rad and the current stat before moving away from spec on these engines.

If the rest of your cooling system is in good order, the engine will run below its design temperatures with the stat that opens earlier.

Good luck with what you're doing, but I think you're trying to solve the wrong problem.

I dont get a dash error thrown, its that the gearbox goes into its thermal protection mode by holding lower gears to increase flow of fluid through the cooler and other parts. It does this as a means to protect itself before hitting a full overheat and errors thrown.

The RAVE manual says that the electronic stat controls the engine running between 80degC and 103decC ... but normally has it sitting high for better emissions. Lowering the stat temp to 88degC is still well within the engines normal operating range ... i.e. not out of spec so to speak.

Its a well discussed topic on BMW forums. V8 or else ...

Be interesting to see if it solves your problem. I'd just be a bit concerned if it was me, as the car is designed to tow heavy trailers across the Sahara without overheating! I've never had my gearbox go into any cooling mode - seems to just do the job it's supposed to without complaining.

Saint.v8 wrote:

If that is the case then why is there a Gearbox Cooler plumbed into the Coolant system??

Take a gander under the boonet on the Drivers side (RHD) near the bottom, small ali heat exchanger with a plastic manifold plumbed to the coolant system!

fisha wrote:

its that the gearbox goes into its thermal protection mode by holding lower gears to increase flow of fluid through the cooler and other parts. It does this as a means to protect itself before hitting a full overheat and errors thrown.

RAVE wrote:

Cooling Strategy
The purpose of the cooling strategy is to reduce engine and transmission temperatures during high load conditions, when towing a trailer for example. Under these conditions the engine and transmission may generate excessive heat.
When in any gear other than 5th or when in 5th gear at a speed of 38 mph (61 km/h), if the transmission fluid temperature increases to 124C (255F) or higher, the EAT ECU employs the cooling strategy.
The strategy uses a specific shift and torque converter lock-up clutch map. This map allows torque converter clutch lock-up and gear shifts to operate outside of their normal operation. This will reduce the engine speed and/or slip in the torque converter, therefore reducing heat generated by the engine and the transmission.
The cooling strategy is cancelled when the transmission fluid temperature decreases to 120C (248F) or below.

Quote:

The EAT ECU monitors the output from the transmission fluid temperature sensor in the transmission and also receives an ECT sensor signal from the ECM on the CAN. When the transmission fluid and/or the engine coolant temperature is less than 60C (140F), the EAT ECU initiates the shift maps used in sport mode, when driving after a cold start.
The sport mode shift points raise the engine speed. This, in turn, promotes faster transmission fluid warm-up and also decreases the warm-up time for the catalytic converter to reach optimum temperature.

Quote:

Hill Mode
Hill mode is initiated by the EAT ECU when high engine torque, high throttle angle and low engine speed is detected via ECM signals on the CAN. The EAT ECU defines this combination of signals to determine when the vehicle is travelling on a steep gradient.
In response to these signals, the EAT ECU modifies the transmission shift pattern to raise the shift points to prevent repetitive up and down shifts. This mode can also be initiated when the vehicle is at very high altitudes.

Ric355:
The P38 RR had an air-cooled trans oil cooler, mounted just below the engine oil cooler, in front of the radiator.
Another of Fisha's thoughts on keeping his trans fluid cool was to either add 1 of these in-line, or swap out the water-cooled version for the air-cooled version.

I'm doing nothing to my truck, but I'm enjoying reading RAVE to tell Fisha how crazy he is.
Or isn't.
I'm really not sure if he's crazy like a fox or just crazy.
 Jim
2000 NAS HSE
2005 NAS HSE