That would have been an appropriate hose. :D

From memory, my engine temperature is like 2 degrees lower than the transmission. The only time it goes to 100 or more, is on very hot summer days, or when I tow and drive 120kmh. Just going to work in normal traffic, it is around 82 - 84°C.

I am a bit confused. I know m62 and n62 have the operating temperature at about 108C. Does the 4.8 run at the same temp as the 3.0 ?

What are you confused about?

Is the 4.8 running cooler than 4.4? I was under the impression they would both run at around 108C. It looks like TB runs much lower than us.

Probably does run cooler. The ME 7.2 used on the 4.4 in our cars was amost a left-over "operating system" if you will by the time it was used in the 2000 X5 4.4i. It does not have the sophistication of, say, the then current Japanese systems employed. For example, my Toyota V8 from that era maintains active control of the engine operation from idle to WOT, whereas your X5 goes into open-loop at the drop of a hat (which is not a bad thing if you like to tinker with parameters and sensors, BTW)

Anyway, the high operating temperature on our 4.4i engines is a band-aid to help the car deal with increasing emissions requirements, and maybe a token throw at a little bit of economy. The previous iterations of this same engine ran 30 degrees cooler. The 4.8 is the same basic architecture, but uses the ME 9.2 engine management system. While I have a great deal of familiarity with the ME 7.2, I have not delved into the 9.2. However, it is likely that engine management system has evolved sufficiently that BMW can run a more optimum 195 or so coolant (& cylinder wall temp), and still maintain emissions compliance.

Thanks civdiv.
Here are the new values using the tranny cooler. The weather conditions were pretty much the same. 4C outside temperature.

The engine temperature shows 104C.
INPA engine temp 219F = 104C
INPA tranny temp: 203F = 95C
While cruising I got 189F = 87C

So the cooler works well but I still have a small harsh downshift 2-1.
Although I thought was related to the temp, most likely it's something else. It could be timing. It just happens at the same time the gearbox temperature reaches 200+F degrees.
I will keep an eye on it.

http://i695.photobucket.com/albums/v...-12-37_158.jpg

http://i695.photobucket.com/albums/v...-12-31_402.jpg

I know I'm digging up an old thread here, but I'm about to add a transmission cooler. What size are the factory hoses between the lines and the exchanger? I want to be sure I have the correct fittings on hand when I attempt to splice into these lines.

Well, with caveat that the term "correct" is a reach in this situation, i think a 5/8 barb will work.

Just be sure you are comfy with this - you are going to cut both of the rubber lines about 10 inches or so before the factory cooler, splice in with a coupla adapters you preassy from the hardware store, use some higher end hose clamps, and add your aftermarket cooler of choice to the path. Pay attention to which hose is in, and which is out. Have the fluid go through the factory cooler, then your add on cooler.

Have clamping pliers handy to pinch off the factory hoses before you cut or you will be laying in a puddle with fluid dripping in your eye the whole time.

I personally don't find anything sacred in a 12 yr old car, but this kind of thing can make some folks a little concerned. Just so you know you are basically forging the path that seems right to you, under the car, with oil dripping in your eye. This isn't a well traveled road.

Excellent, thank you! I'm going to bypass the factory cooler completely. I'll have some 5/8" barb adapters, and some FI clamps ready when I chop those hoses.