XSeries-forum

As there are some threads running at the moment about coolant leaks and mention of very high coolant running temperatures, well over 100 degrees, with the consequent additional pressure that this creates.  Having done a bit of reading it would appear that BMW done that to improve emissions and fuel consumption at idling and low revs. There are thermostats out there that can be fitted to lower running temperatures ie down to what the engine runs at, at speed, in the mid to low 90's. Is this a good mod, it would certainly reduce the pressure and likely hood of busted pipes. I'm thinking of fitting an electric fan in place of the viscous so whilst there was wondering about the thermostat mod. Anyone have any reasons why I should be discouraged?

I would check you actual temperature first via the hidden menu. I would also look at the cost for replacing all the hoses, as a perished hose will burst eventually even at a slightly lower temperature.
I have just replaced the thermostat on my X3 3.0d, the hardest part was refitting the EGR cooler as the bolts are tricky to get back in without dropping them, so not a problem on the V8. Once the fan is out there's loads of room.
Fan only took 5 minuites to remove.

Re electric fan - v - Viscous fan...
The electric fan will likely use more energy over all due to losses in fan blade efficiency against the OEM fan.
Energy losses via alternator to produce the power & additional losses thru another motor again.

The fan can ONLY cool the water the thermostat allows thru the rad matrix... regardless of the fan fitted.

Pumping even more air thru the rad will not effect anything or reduce the running temperature one jot, as the thermostat will open or close as it requires to maintain the temperature it was designed to run at.

Unless you have overheating problems caused by high altitude, an electric fan will not affect the running temperatures one tinsy bit. The viscous fan is more than capable of cooling the engine.... & the engine does not even need a fan at all if you are rolling at 50mph or more.
The fan keeps your machine cool at slow speeds or with exceptional pulling loads - ie towing a loaded horse box.

Pipes.... if the pipes are so fragile that a few degrees higher temperature may cause them to fail, then you simply need to change ALL YOUR PIPES.

The ideal running temp of these engines will see the gauge in your vehicle display cluster sitting at approx the mid point..... if it sits much higher or lower, then you have a faulty thermostat or a blown head gasket or losing coolant from your vehicle, or you are driving slowly at 2,000 feet altitude or more.

Viscous fans absorb power all the time, and a considerable amount at full lockout, BMW have moved away from them, I believe even the 4.8 facelift is electric, electric can be controlled and will not run at all at speed, the switch on voltage spike can be reduced with PWM controller  I'm not asking about this because I have any inherent problems with my system, I just want to make it more efficient. The load will be removed from the water pump bearings and if you look at most fans they have a bit of a wobble which multiplies the load.
I wouldn't necessarily agree that the manufacturer has the engine running at the most efficient temperature all the time, Politics and emission laws played their part. I will look at the running temp' at speed ( I believe to be in the mid to low 90's) and try and aim to keep it in that area at idle. That will be in the area of 20 degrees below what it is now.

Hijacking the post slightly ...... where s the thermostat located, what is approx cost of part, is it easy to replace and how do I access the hidden menu

Smee

the thermostat is fitted to the water pump, if you follow the rad bottom hose up it connects to the thermostat. The easiest way to access the hidden menu is to ask google when your sitting in you car "how do I access the X5 hidden menu"  It's easier to read than try to explain.

Sorry Smee I didn't read all of your questions, not completely sure of cost, think around £70/80. I think I'm going to go for the modified one at £60 which opens at 80C. I know that is a whopping 28c below present opening. Howls of derision I can accept. I will of course let everyone know how it goes even if I have to revert to original. Don't expect a report any time soon, I  haven't sent for it yet

Well I was wrong about a couple of things. Got into the hidden menu and set it on temperature. Anything below 60mph the temp was in the mid to high 90's. Above 60, high 90's to 100c, 80mph and above it's over 100 nearer 105c. Slowing and stopping, the temp quickly dropped to mid 90's for 2/3 minutes before starting to climb again to 100/102 area. If you switch off, within seconds the temp is reading max ie 107c.
Anyone like to comment on these findings bearing in mind that I'm not aware of any problems with my cooling system.
Interestingly the temp gauge is central at below 95 and still central at 107c

[quote="henrym3"]
Well I was wrong about a couple of things. Got into the hidden menu and set it on temperature. Anything below 60mph the temp was in the mid to high 90's. Above 60, high 90's to 100c, 80mph and above it's over 100 nearer 105c. Slowing and stopping, the temp quickly dropped to mid 90's for 2/3 minutes before starting to climb again to 100/102 area. If you switch off, within seconds the temp is reading max ie 107c.
Anyone like to comment on these findings bearing in mind that I'm not aware of any problems with my cooling system.
Interestingly the temp gauge is central at below 95 and still central at 107c
[/quote]
I'm assuming your quotation of "80mph and above it's over 100 nearer 105c" is purely theoretical  :biggrin: being the law biding citizen you are  :drive:
go on bite the bullet and fit it, I'd like your feedback before thinking of doing mine  :biggrin:
IT'S ALL GOOD FUN ISN'T IT!!

Of course anything above 70mph was done on my private estate, with the butler on standby in the ambulance.

A while back while I was researching the coolant temperatures due to my 4.6 popping hoses, I came across an interesting fact. Not sure if its true or not, but the reason the temperature gauge sits in the middle over a fair temperature range, is due to our American cousins.
Apparently they complained when the gauge moved around (as it would when correctly recording the changing temperatures), so BMW changed things to have the gauge in the middle under normal conditions.
With my unfortunate experiences with pinhole leaks in the coolant pipes, I relied more on the oil temperature gauge, which would rise even before the low level warning from the coolant tank activated.

Well, shy7g I have bit the bullet and sent for the 80c thermostat. Don't know when it'll get fitted as I'm up to the elbows in rebushing the Golf.
IanP. When I first got mine I was forever topping up, my indie told me to put enough coolant in so that you could just see it in the header tank and ignore the float level. It solved me having to top up?

Well I was wrong about a couple of things. Got into the hidden menu and set it on temperature. Anything below 60mph the temp was in the mid to high 90's. Above 60, high 90's to 100c, 80mph and above it's over 100 nearer 105c. Slowing and stopping, the temp quickly dropped to mid 90's for 2/3 minutes before starting to climb again to 100/102 area. If you switch off, within seconds the temp is reading max ie 107c.
Anyone like to comment on these findings bearing in mind that I'm not aware of any problems with my cooling system.
Interestingly the temp gauge is central at below 95 and still central at 107c

Ok. so got round to fitting the 80 degree thermostat today. Found lots of other little faults whilst in there Vanos solenoids cam position sensors weeping oil, minor little weeps from coolant pipes, couple of poor vacuum pipes. Anyway, stat fitted and out for a long run. Under 60 pretty consistent between 89/91. Above 60 between 89/92. Above that other figure sometimes well above never seen higher than 93. Idling afterwards saw a high of 99. When switched off it stayed around what ever it was when switched off and then started to drop. So, early days but I'm pleased with the results, don't seem to be living as near the edge of overheating. BTW gauge was central at 78 degrees.
Next is to monitor the fuel consumption which at present is 17.2mpg. I will also take it to a mate and get an emission test done just for interest.     

Not done this on mine, however my Škoda Superb shows temps within the on board computer and the pattern you are seeing is pretty much matched.  Mine sits between 85°C and 107°C and the temp gauge (like BMW) sits bang in the middle all the time.

There will be a lag between things changing (called hysteresis) and driving type.  High speeds mean high turbo (mine's a Diesel) temps and it takes a while to get from the oil to the water.  Water also cools faster than oil, more so given the nice radiator provided.

When you switch off there is no circulation then the temp will get local hot spots and climb rapidly.  It all looks normal, or at least 'expected' to me.

Am suffering considerable confusion with the mod. Had a small leak from one of the pipes which needed the fan and cowl removed to get at. Leak fixed, topped up and decided to run engine without fan fitted to see if the aux/ac fan would cut in. It cut in at 90c and kept the temp at 89/90c for 20 mins. Only runs foe 30 sec at a time. Yet on my test run yesterday I saw idling temps of up to 99c with both fans fitted. My main reason for wanting to get my head round this is I want to fit an electric fan but need to decide what temperature I want it to cut in. To low and it will run unessarily