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Discussion Starter #1
My new Brutale S goes in for it's 600 mile service (900 miles in a week) and I have a question.

The bike seems to run cooler in cool weather than I would expect. Today when cruising with OAT in the 55-65 F range (13-18 C) the engine temp would stabilize around 150-160 F (65-70 C). In stop and go traffic of course it would go to 200F (93 C) but back at speed would quickly cool down.

New bike normal or stuck open thermostat?????

Tom
 

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Hey Tom, I am a new member also and I have a brand new 910 S.
Believe it or not, I was out riding today but my temperature was a little cooler, around 50 F. I noticed that my temperature guage was reading right around the 165 F mark. In the back of my mind I thought that to be rather low but my bike runs perfectly and I haven't thought any more about it until I read your post.
Hopefully the more experienced MV owners can help us both out.

Tim
 

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While riding the other day with temp at about 55 deg. and riding on the freeway, the temp was stable at 155 deg.
Once you hit the stop lights the temp rises very quickly to 190-200 deg
I have a little over 4000 miles and it has always done that and never had any problems
 

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I dream of those temps! :)

No need to worry - perfectly OK.
 

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Yeah, Greg is right. Downside is, when it's hot out the bike will get VERY hot, to the point of overheating in traffic. Engine Ice/Water wetter, etc. helps, but even for a naked, the Brute is a cold[hot]-blooded beast.
 

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Discussion Starter #7
spalding12 said:
both of your bikes are NORMAL
remember......

NAKED bikes run cooler
simple as that

in COOL weather, your bike will run COOLER
it is NOT a car, where the "operating temperature" will be the same in 30 or 100 degree weather

bikes are much more "cold blooded" in that their temperatures reflect that of their surroundings
Thanks for the reply. This isn't my first "naked" bike and although it may be normal for the Brutale it certainly isn't normal for the other water cooled naked bikes I've ridden and owned. It is the job of a thermostat to control the bottom end of the operating temperature and to not open until operating temperature is reached. Just like cars all the other naked bikes I've owned maintain a minimum temperature of about 180F (80C +) even with riding temperatures below freezing.

If you say it is normal for the Brutale we will have to agree the Brutale is both cold and hot blooded and I guess it just has a wider operating temperature range. :))

Tom
 

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I think the thermostat on the MV's have a slight problem. It seems they are either open or closed without any variation in between. On my Burtale, as the engine reaches 212F the fan comes on and the temp states to lower to about 200F. You can feel the hot air coming off the fan when it kicks in but when the temp gets to 200F the air coming off the fan is cool. To me, the thermostat should stay open on the cool down until about 190F than start the cycle again. This would have a better chance of keeping up with the coolant temp at low speeds.
 

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I was out 2 nights ago and it was a staggering 22 degrees F here in NY. My 910r displayed about the same temps as you are experiencing, it even dropped to 145F on a high speed blast. I dont think you have anything to worry about.

I too questioned the cooling system on these bikes, but am more concerned with the fan kicking on at an earlier temp, as it waits till 190F is reached. I have since learned that most new cars and motorcycles are running this high, even in race applications. From what I understand, its more efficient and as machining specs are tightened up, there is less chance of mechanical failure as a result of hight temperatures as in previous years.
 

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I'll have to investigate before I can say for sure how this works, but it seems that there are two temperature sensors. One appears to feed a signal to the engine control module (CPU in the shop manual diagram) and one sends a signal to the instrument panel display.

The manual is unclear about the function of the sensor to the engine control module - it only states the fan "functioning interval" is 100C (212F) 97C (207F) and this appears to refer to the same sensor that sends the instrument signal.

The sensor sending the signal to the instrument panel is located on the left side tank of the radiator. It won't necessarily correspond to engine temperature if the thermostat is restricting flow to maintain engine temperature.

Having said that, I'm still confused by the manual. In the electrical section parts list they show two temperature sensors: #22 Water Temperature Sensor - CPU and #36 Water Temperature Sensor for Instrument Panel Thermometer; yet the wiring diagram makes it appear as though it's one and the same sensor.

:confused:
 

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While exchanging my Brutale's coolant for distilled water/Waterwetter in preparation for this weekend at the track, I took a closer look at the cooling system. :moped:

There are two separate temperature sensors, both easily accessed. One on the left side tank of the radiator and one on the left front of the cylinder head at the thermostat flange.

The one on the radiator supplies the signal to the instrument panel. The one on the cylinder head supplies the signal to the Magnetti Marelli engine control module (ECM).

I connected my laptop VDSTS to the diagnostic port and compared the readings supplied by the ECM with the reading on the instrument panel display. This exercise explains the rapid fluctuation of the coolant temperature displayed. :nerd:

Both readings warmed up fairly rapidly, the engine reaching operating temperature quickly (within a few minutes on the stand). The engine temperature remained fairly stable at 98-102C (208 - 215F) as read from the ECM via laptop while I revved the engine. The radiator temperature fluctuated greatly, depending on the amount of air passing over it and the flow rate of the coolant through the radiator; from 74 - 94C (165 - 201F). I placed a fan in front of the radiator to simulate riding for this. Why MV decided to display radiator temperature rather engine temperature is a mystery to me. The fan is regulated by the ECM so it reads engine temperature, not radiator temperature. A stuck (closed) thermostat probably would not be indicated on the instrument panel because a stuck thermostat would result in lower radiator temperature while the engine temperature goes high. :mad:

So here's what happens when we ride down the road. The engine is apparently designed to run at ~100C. The thermostat opening will vary to maintain this temperature. When the engine temperature drops (cruising in a low load situation with plenty of air passing through the radiator) the thermostat restricts the flow to maintain engine coolant temperature. Meanwhile, coolant flow is stagnating in the radiator while high airflow through the radiator is sapping the heat from the coolant there. This temperature drop is displayed on the instrument panel even though engine coolant temperature is fairly constant. When we stop in traffic, the airflow through the radiator is reduced (or even eliminated) but some hot coolant continues to enter the radiator. The thermostat opens to increase flow as a thermal soak occurs (the cylinder retains heat from the work performed but the flow of coolant through the system is reduced at idle). The flow into the radiator now increases but there's no airflow to remove the heat from the radiator. Radiator temperature climbs and this is displayed on the instrument panel; but the engine coolant temperature doesn't change that much. :)
 

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Discussion Starter #13
Koop said:
........The one on the radiator supplies the signal to the instrument panel. .......:)
Thanks for the work - displaying the temp from the radiator to determine engine temp is kind of like determining your horsepower by counting the stalls in the barn! Only the Italians ......... :bash:

Tom
 

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Koop said:
There are two separate temperature sensors, both easily accessed. One on the left side tank of the radiator and one on the left front of the cylinder head at the thermostat flange.

The one on the radiator supplies the signal to the instrument panel. The one on the cylinder head supplies the signal to the Magnetti Marelli engine control module (ECM).
Would it be possible to hook up a second temperature gauge to the engine sensor or, perhaps install a second sensor in the engine, so that we could actually get an engine temp reading? Installing a second sensor would naturally require a second port for the probe, and I don't know if one is available.
 

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falcopilot said:
Would it be possible to hook up a second temperature gauge to the engine sensor or, perhaps install a second sensor in the engine, so that we could actually get an engine temp reading? Installing a second sensor would naturally require a second port for the probe, and I don't know if one is available.
I wouldn't get too worried about it. If the temp reads too cool and stays there when stopped, I would suspect a thermostat issue (stuck closed, no hot coolant entering the radiator). When the temp is reading high, the cylinder head is probably a few degrees higher. 220 - 225F (104-107C) wouldn't cause me to lose any sleep.

I think MV decided to read radiator temps on the display to keep owners from freaking out about constant 210F cylinder head temperature. People would be in the delearship saying "my bike runs hot" all the time. In reality, 210F is not an issue at all. I was concerned about running too cool! :jsm:
 

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Thanks Koop. I was just curious to know what the actual engine temp is, especially while driving in traffic. I learned real quick that this bike was not made for driving around town in the summer in places like Houston.
 
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