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Discussion Starter · #1 ·
I serviced my 2009, 451 a few weeks and ago and topped off the radiator coolant level. Over a period of a week the car suddenly but slowly lost coolant and over heated.

For the purpose of this discussion, I don’t want to get into the cause of coolant loss but instead discuss what should happen if a sudden loss of coolant occurs (i.e., a sudden hose burst while driving).

In my case, the engine lost coolant and overheated but never gave me an over temperature indication on the instrument cluster. Only when the coolant temperature sensor failed due to excessive heat in the head, did I get any indication that something was wrong with the engine. Unfortunately by then it was too late and severe damage occurred to the engine.

Now I would think that the coolant temperature sensor would indicated a problem if the coolant operating temperature was too low or too high but the sensor has to make contact with the coolant to get an accurate measurement. In this case however, the coolant stops making contact with the sensor so I’m assuming that some intermediate dry air temperature was probably measured so no trouble was seen by the sensor.

I realize that quite a few of you reading this already have a scan gauge II plugged into your OBDII port and can read coolant temperature but isn’t that temperature coming from the same coolant temperature sensor that I’m currently having issues with?

I know that this is a very common single point failure on any car with a coolant system. As these coolant systems age, I expect a whole lot more engine failures in the future. I would think that Mercedes/Mitsubishi engineering would have a solution that would give some indication of a problem long before engine failure.

How about the 450’s? Have they experience coolant loss and engine failure in this same way?
 

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Unfortunately, yours is not the first one to do this. :(

It seems that in all the cases that "I" have read, they all said the same thing: the light did not come on until AFTER the damage had occurred !! :mad:

From what I've seen, MB is silent on this matter .............. :mad:

:sorrysign: it had to happen to you.

I have changed my coolant to EVAN'S ZERO PRESSURE NPG+ Engine Cooling Systems



Wishing the best to you.
 

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The OLD VW's didn't have this problem...
It needs a Low Level alarm sensor in the Coolant Bottle... That would take care of everything. Showing you ~Low Level~Boil Over~Boil Out~ telling you to Stop RIGHT NOW...!!!
NOTE: We were driving along with the Kid in front of us in her Yaris... The Cel Rings, and its her telling us the warning light on the dash just came on...!!! I told her pull over right now... I opened her hood, and checked the Water & Oil, they were OK... We were good to go... I didn't care what the light was about after that... She has 47,000 on it. The Dealer put a New CAT in it No Charge, because it was a Emissions Device...<:))
 

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I have changed my coolant to EVAN'S ZERO PRESSURE NPG+ Engine Cooling Systems

Chief, the Evans products are indeed interesting, but depending upon what happened to the the original poster's cooling system to cause the catastrophic overheating, I'm not sure that having previously converted to NPG+ would necessarily have averted the disaster (if that's what you're implying) as it could still potentially have pumped itself dry enough to overheat.
 

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trfellows, what actions have you taken with MB in regards to your problem??
Understandably the idiot light gave no warning to the overheating and that issue has cropped up here on SCoA before... so not a lone case...
 

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I attended a recent webinar with a smart tech guy. He stated that the coolant temp. light will come on at 244 deg. F. He also stated that the head gasket will fail at 248 deg. F. He did not elaborate, but I believe that the coolant sensor will only work if it is sensing liquid? If the system is empty, you will not see a warning light. smart needs to install a low coolant warning light and a coolant temperature guage and hopefully assist the owners who have damaged an engine due to coolant loss. The hoses, seperntine fan belt, water pump and thermostat should all be good from 2008 to present and smart should stand behind any failures with a good faith warranty.
 

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It seems to me that the cause of the coolant loss would be of much interest to this forum. Do you know why it happened?
I serviced my 2009, 451 a few weeks and ago and topped off the radiator coolant level. Over a period of a week the car suddenly but slowly lost coolant and over heated.

For the purpose of this discussion, I don’t want to get into the cause of coolant loss but instead discuss what should happen if a sudden loss of coolant occurs (i.e., a sudden hose burst while driving).

Since no reply, I just have to wonder if it was an issue of the op not properly sealing the coolant system after service.

But that is just a guess based on the fact he didn't want to discuss it
 

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trfellows, I just called MB this morning for resolution on the same issue. I have an '08 with 28k miles that has a fried engine. Same series of events... no warning lights came on until after the engine had already failed.

The dealer quoted me an $11,000 engine replacement.

My leak stemmed from the 'rubbing hose' issue that many of the early Smarts suffered from (I only just learned of it on this forum, after I started searching for answers to why my engine could have failed).

I have asked MB to replace my engine at no cost. The hose was a known defect, and the failure of a warning light is also a known defect.

I don't understand how a company that prides itself on being the 'eco-friendly micro car of choice' would allow thousands of owners to drive around in vehicles they know carry a serious risk of leaking coolant into the environment.

I think this is an issue that deserves some serious attention.
 

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Discussion Starter · #14 ·
Yes indeed, it was my fault. I didn't secure the reservoir cap and coolant boiled out over a period of two weeks. After thinking about it though, I realized that this is a future potential problem if any of our cars suddenly lost coolant. I'm quite concerned that I may be paying for another engine repair in the future if I don't add some sort of secondary sensor.

The max temperature of the coolant temperature sensor is 260F. Since it failed, the head temperature had to have severely exceeded that temperature. The service rep is trying to tell me that the sensor is made to fail during an over heating issue of this type. I’m challenging that statement and asked for the temperature specification of that sensor to prove to me that it’s made to fail at a certain temperature.
 

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Discussion Starter · #16 ·
trfellows, what actions have you taken with MB in regards to your problem??
Understandably the idiot light gave no warning to the overheating and that issue has cropped up here on SCoA before... so not a lone case...

I'm not sure what to do yet. I don't expect any sympathy from MB so my other option is to try to prevent this from happening again. I'm looking into maybe a head temperature gauge or even an amplifier temperature gauge with the sensor connected to the outside wall of the head.
 

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Engine damage due to lack of coolant is happening a tad more frequently now...and strangely it seems to be only on the 2008s...

I don't want to sound like Larry, but a recall (to ensure that hose isn't leaking and/or to replace it with the setup on newer models) does sound like a good solution, especially since they're charging these excessive amounts to replace the engines!
 
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Discussion Starter · #18 ·
Was this the original engine failure that was reported a couple of years ago? :)

PS - for help with that "temp sensor designed to fail" issue, try this contact at smart USA: [email protected], just mention "Quinn" in the subject line.
No, this just happened to me this week. Was there any follow-up on the email mentioned above? If that was a response from two years ago then wasn't that before MB took over from Penske group? I'd be surprised if that email is still valid.
 

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Was this the original engine failure that was reported a couple of years ago? :)

PS - for help with that "temp sensor designed to fail" issue, try this contact at smart USA: [email protected], just mention "Quinn" in the subject line.
jwight, I'm new to posting on this forum... what does the "original engine failure" refer to? is there a thread that covers the issue? thanks!
 
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