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Discussion Starter #1
HELLO BOARD please chime in

Fist and for most i want to say thanks before hand.

my question is in this cooler weather say 28-32c what is your engine temp sitting. it seems my car doesnt want to go over the 1/4 mark on the guage and on the cluster test 7 i belive its not going over 72-74c while im cruseing on the hwy at like 70- 80 mph is this normal operating temp? How ever if im in traffic it will come up to just under half mark. i had the thermostat replaced last febuary under cpo and the fan clutch. thanks agian
 

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HELLO BOARD please chime in

Fist and for most i want to say thanks before hand.

my question is in this cooler weather say 28-32c what is your engine temp sitting. it seems my car doesnt want to go over the 1/4 mark on the guage and on the cluster test 7 i belive its not going over 72-74c while im cruseing on the hwy at like 70- 80 mph is this normal operating temp? How ever if im in traffic it will come up to just under half mark. i had the thermostat replaced last febuary under cpo and the fan clutch. thanks agian
My car behaves the same way. Low 70's temp, slightly higher oil temp when cruising in the 60's in south Florida. Temp comes up when sitting in traffic or city driving.
Regards,
Jerry
 

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Me too, though I have been wondering if I'm up for a thermostat replacement soon. Cruising at 100 mph with ambient temperatures of 5-10 degrees C sees about 75-77 degrees, while hammering it with lots of 3rd and 4th gear action brings it up to 84-87 degrees, which leads me to believe it could be normal.

In my case, maybe a recent oil change (10W/60) coinciding with the colder ambient temperatures has resulted in lower temperature readings?
 

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Hi , my M5 E39 regulate at 78°Celsius. the mark on my g
The coolant thermostat is calibrated at 78-79°C. It's less than most of poupular cars.
 

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Normal - I'm in Massachusetts and ever since cold (30F or so) my car has been running cooler oil and water temps. Normally straight up (or down) on both, now to the left of center on both...

d-
 

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I just tested this when I went to nearby city today. Weather was around -5C (23F) and the "secret menu" -test said the temp was between 66-71C at the highway, between 72-74C in the city, standing in the traffic lights.

Seems like I definitely need some thermostat replacing :3:

(Somebody just said in the other topic that under 78C the car doesn't go to closed loop or something and creates excessive carbon build-up..??)
 

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I replaced my thermostat once because I thought it ran on the cool side. The new one consistently yields temps in the 72-75˚C range. Only twice, on summer runs in the high desert country in AZ and UT has the temp gauge needle briefly gotten to the 6 o'clock position
 

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the thermostat starts to open at 79C so theoretially, the engine should never be under 79C once it's warmed up. These 75+/- temps indicate that the thermostat is not closing fully or there is an issue with the sending unit.
 

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I just replaced mine.

It would sit at the first dot, and the panel showed temps in the 68-70 range with outside temps ranging from 10F-30F

Now it sits between the first dot and halfway, and the panel shows 78-79 with the same outside temps. It did hit 83 when I was idling once - gauge was straight up
 

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xr4tic, did you do the thermostat swap yourself? I was thinking of ordering the parts and having Nikolas do the swap and coolant flush. Hoping the termostat replacement will be the answer to a SES/CBU light I've been having.

Thanks!
 

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Discussion Starter #11
like i said in my first post i had my thermostat replaced last feb and my father is a tech for bmw he seems to think my aa cai has alot to do with it. And says im craming cold air int othe combustion chamber and thats why im seeing lower number. my responce was ya ya your just to lazy to replace the thermostat for me agian lol
 

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the replacement wasn't too difficult, but I've done a ton of work on a lot of cars.

the big problem is the $#@%# O-rings on the 3 tubes going into the housing, I ripped one on reassembly, didn't find out until it was all back together again. Had to take it all back apart.

I think it took me a little over 3 hours to do it the first time, and I was taking my time.
 

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It's funny that some people have changed thermostat and still seeing only 70-75C and some do have that 79-80C after replacing.

I'm just wondering, is there different types of thermostats out there? :dunno:
I dont think there are different thermostats out there, but there might be some variance in the production of them by a degree or two.

I think outside temps have a lot to do with it also, along with how you're driving (freeway vs. stop-go traffic vs. driving hard)
 

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M5 runs cool

Mine runs cool too. Like you I had my thermostadt replaced and it still does the same thing. Unfortunately I had to pay out of pocket for my replacement to the tune of about $600. I guess these darn things just run cool.
 

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Hi!

I guess this info is pretty valuable for all of us.

I spoke with my friend from official BMW dealership today. He told me that there is major difference between the real OEM BMW thermostat, and the non-original thermostat from car accessory shop, u know the cheaper ones without bmw logo on it. :)

Difference is that the cheaper ones work just fine as well and have that same 79C opening point, but these DON'T fully close-up when cold!

OEM BMW thermostat has some special part in it to fully close the water circulation in cold temperatures, which warms the engine to that 79C at winter and in slow cruising.

He told that usually with these cheaper ones car can run at 70-75C sometimes, but with original BMW thermostat running temp should always be over 78-79C or the thermostat really is broken.

Hope this helps, I just bought the original one today, part costed me $192 but let's hope it's worth it. :)


By the way I also got diagnose for my car that idle hunting problem could be because of my broken thermostat, as the car jumps between cold and hot programs or something when it's pretty cold (68-72C) when I come from highway and stop to the traffic lights, and it then warms up few degrees - it can mix up the DME they said.
 

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My replacement thermostat was done at a BMW dealership. The car runs great, I'm just not used to seeing the temp gauge running just to the left of vertical. I've owned 7 BMW's and the temp gauges never moved on any of them most of the time. But this is my first M5...
 

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My replacement thermostat was done at a BMW dealership. The car runs great, I'm just not used to seeing the temp gauge running just to the left of vertical. I've owned 7 BMW's and the temp gauges never moved on any of them most of the time. But this is my first M5...
true that the gauge will run a touch to the left when it's cold outside and you're just cruising, what is more important is what the temp is on the obc when you pull up test #7 (do a search for 'unlocking the obc', if you're interested).

There is also a metal ring with a rubber seal on it that can fail, it goes into the housing behind the thermostat (my tech said it was a pain to remove the old one). I'm not sure what would happen if that failed wrt engine temps and such.
 

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Discussion Starter #20
ok so since bmw cpoed my thermostat on 3-20-2007 at 58k they are going to replace it agian under the 2 yr parts warrenty haha got to love it so the car is going to the dealer my father works at and now he got forced to do it for me agian lol any how thanks guys for all your imput. i knew i wasnt crazy
 
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