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-   -   My 2011 35d thermostat observations (https://xoutpost.com/bmw-sav-forums/x5-e70-forum/99439-my-2011-35d-thermostat-observations.html)

josiahg52 01-07-2015 11:36 PM

My 2011 35d thermostat observations
 
I was reading Stephen's (sgrice) thread concerning his 35d thermostat woes and correction and it got me thinking about my 2011 35d.

I notice on longer trips that the heat will get a little cool. If I go into iDrive and turn up the fresh air setting up one or two points from center, the heat will be fine. I don't drive my M5 much in cold weather like I have been in the X5 lately so I can't directly compare but I think this is similar to what I sometimes have experienced in the M5. I don't think this is a problem.

Since I got the BMWhat and Torque applications I have been able to easily view coolant temperatures. What I see is that on the highway down to about 2C, coolant temperature fluctuates between 85 and 86C.

At the temperatures that I have been driving in the past couple of days, -5C and down to -10C or even lower, coolant temperature fluctuates between 79 and 81C but I have not had an extended run at these temperatures; only about six miles highway and two miles stop and go every morning and night. Tonight, idling in -11C, I saw coolant temperature lower to 65C.

Fuel mileage is still good I think. As of late, 31+ MPG on the highway and 22+ in daily driving, approximately six miles highway and two miles stop and go every morning and night. I'm sure my drive cycle is enough to fully heat up the engine. If work wasn't so crazy I'd take it on a good long trip and see what it gets up to in this cold weather.

I can't believe that this vehicle may also have a thermostat issue, not that they last forever but I've had enough trouble with the M5s thermostat to last me a lifetime. The new OE thermostat I put in the M5 this past March was running cool when I put the car away in October. I hope I can get this one in the X5 licked. Thanks to Stephen's thread, we now know that the thermostat is marked "88C."

josiahg52 01-08-2015 03:14 AM

More information:

Ambient temperature -15 to -16C
Miles driven: 55 miles
Average speed: 65 mph
Coolant temperature: 80 to 83C, mostly 81/82C

As soon as I stop, coolant temperature goes down pretty quickly at idle. With the engine off, temperature drops almost 30C in less than 10 minutes.

bawareca 01-08-2015 01:19 PM

I honestly dont know what should be considered a normal temp at these conditions,but I know that diesel is very hard to warm-up and keep hot at low temperatures.There is no way it will hold over 80C idling at -15C with the heater working.This is the nature of the beast.I would say your temps are within the norm at this weather.

josiahg52 01-08-2015 06:47 PM

Thank you for the reply. I'm not getting too worked up about it at this point. I am new to owning a diesel but I'm aware of the their peculiarities to some extent. I will wait until more moderate ambient temperatures and then try a similar run again to see what changes.

TriX5 01-09-2015 02:12 PM

I just checked mine this morning and it would not go over 69C in suburban stop and go. Temp outside was a few degrees below freezing. (Car has over 80k miles)

Since it had just done a 40 minutes run with few stops on two lane roads I think it should be running above 80C. Tomorrow the wheather should be a few degrees over freezing and will check again but I suspect my T-stat is toast.

Diesels may not warm up fast but they certainly should be able to attain the T-stat stated temperature in moderate weather.

ZetaTre 01-09-2015 02:14 PM

Quote:

Originally Posted by bawareca (Post 1022896)
I honestly dont know what should be considered a normal temp at these conditions,but I know that diesel is very hard to warm-up and keep hot at low temperatures.There is no way it will hold over 80C idling at -15C with the heater working.This is the nature of the beast.I would say your temps are within the norm at this weather.

Totally agree!!!!

Last summer there were 90F outside and I let the car idle outside for some 5 minutes and the temperature hardly moved.

If it was my car I would say that josiahg52 are perfectly fine given the outside temperature. Based on my experience if the thermostat failed you would have read temperature in the 50s or 60s while cruising at 65 with -15 outside. That would indicate a problem even in a Diesel.

josiahg52 01-09-2015 08:53 PM

Thank you all for your input and observations. I would not even know that the E70 thermostat might be a particularly troublesome part were it not for this forum. It's just something that I will pay attention to and keep an eye on going forward.


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