Will your engine survive when a sudden loss of radiator coolant occurs?

We’ve all been there or seen it happen at some time.  Driving down the road maybe on a vacation trip and a radiator or heater hose suddenly bursts and you’ve run out of radiator coolant.  Often times you won’t even notice the problem until a warning lights up on the instrument panel.

In my case, my smart car lost coolant and the engine 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 cylinder 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. Other manufactures provide at least a low coolant indicator.  Others may have a secondary sensor monitoring the head temperature.  I would think that Mercedes/Mitsubishi engineering would have a solution that would give some indication of a problem long before engine failure. 

Tags: coolant, engine, failure, loss

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The coolant temperature lamp lights up at 118°C (244°F).  From what I have been told the cylinder head gasket could be damaged at 120°C (248°F), so there is not much margin.

I would agree that a level indicator would be ideal.  If you are in for your regular services, the coolant level is checked at the 2 year/20K visit and replaced at the 4 year/40K visit.  At this time the hoses would be observed as well.  In most cases I would think this should catch impending issues.  A quick visual check of the coolant level when you are in to top off your washer fluid would also be a good idea.

Robert, thanks for the info.  Long discussion on a similar incident on SCoA: http://www.smartcarofamerica.com/forums/f25/coolant-loss-dilemma-44...

Robert Weingart said:

The coolant temperature lamp lights up at 118°C (244°F).  From what I have been told the cylinder head gasket could be damaged at 120°C (248°F), so there is not much margin.

I would agree that a level indicator would be ideal.  If you are in for your regular services, the coolant level is checked at the 2 year/20K visit and replaced at the 4 year/40K visit.  At this time the hoses would be observed as well.  In most cases I would think this should catch impending issues.  A quick visual check of the coolant level when you are in to top off your washer fluid would also be a good idea.

In addition to the lack of a warning light, early 2008 Smart owners face excessive coolant loss from a faulty hose issue (read about it here: http://www.smartcarofamerica.com/forums/f25/451-hose-info-radiator-...).

This just happened to me at 28k miles, where the rubbing of the coolant hose against the metal of the frame caused it to slice open, draining the coolant out as I drove.  It seems the damage can be done in a matter of minutes, and with no warning indicators, it leaves owners with no ability to intervene in what quickly becomes a catastrophic engine failure (and in my case, an $11k engine replacement).

So in my case, no, there was no way I could have survived this.  It was too immediate, and I was given no warning until the engine was already ruined.

I'd add to this that, in addition to the excessive repair cost that stems from such a minor faulty part such as a sensor or hose, this creates a physically dangerous situation.  My car literally stalled out while I was driving on the highway.  I was very lucky no one ran into me.  The next person might not be so lucky.

Thanks Robert,

We’ve been hearing that a loose coolant reservoir cap is becoming a common problem.  With a loose cap the system is unable to pressurize which causes the coolant to boil at normal engine operating temperatures.  Basically that’s what happened to me.  The system wasn’t pressurized and the coolant boiled out over a period of a week. 

I regularly service my car but don’t check the radiator coolant on a daily basis.  Much to my demise the coolant level dropped to a point where the temperature sensor could no longer produce accurate temperature readings so no over temperature indication occurred.  The engine over heated then the temp sensor failed.  Only when the temp sensor fail did I get any indication there was any problem with the car.

Basically, what I’m trying to say is, you can never predict when you might have coolant loss.  Hopefully it can be caught before catastrophic engine damage occurs but if there was some indicator that told you there was a problem long before engine damage occurred, would certainly provide a lot of benefit to all smart car owners.


Robert Weingart said:

The coolant temperature lamp lights up at 118°C (244°F).  From what I have been told the cylinder head gasket could be damaged at 120°C (248°F), so there is not much margin.

I would agree that a level indicator would be ideal.  If you are in for your regular services, the coolant level is checked at the 2 year/20K visit and replaced at the 4 year/40K visit.  At this time the hoses would be observed as well.  In most cases I would think this should catch impending issues.  A quick visual check of the coolant level when you are in to top off your washer fluid would also be a good idea.

Hi Jennifer, I’m sorry you had to experience this problem too.

Whether it’s a burst hose, leaky gasket, week hose clamps or unpressurized system, the end result is the same, catastrophic damage to the engine. A secondary sensor needs to be retrofitted to these cars that will give some warning indication that there’s a coolant level problem long before engine damage occurs.

I was blissfully ignorant to this problem until last week when it happened to me. Before, I didn’t question taking a long trip in my smart car but now I question the car’s reliability and will no longer take long trips with it until I or MB comes up with a secondary sensor for this low coolant problem.

Everyone who currently owns a smart car is susceptible to this problem and will more than likely fall into this same fate of engine failure and pay thousands of dollars for repair or replacement of the engine. No car should suffer such catastrophic failure for such a simple and common mode of car trouble.


Jennifer W. said:

In addition to the lack of a warning light, early 2008 Smart owners face excessive coolant loss from a faulty hose issue (read about it here: http://www.smartcarofamerica.com/forums/f25/451-hose-info-radiator-...).

This just happened to me at 28k miles, where the rubbing of the coolant hose against the metal of the frame caused it to slice open, draining the coolant out as I drove.  It seems the damage can be done in a matter of minutes, and with no warning indicators, it leaves owners with no ability to intervene in what quickly becomes a catastrophic engine failure (and in my case, an $11k engine replacement).

So in my case, no, there was no way I could have survived this.  It was too immediate, and I was given no warning until the engine was already ruined.

I'd add to this that, in addition to the excessive repair cost that stems from such a minor faulty part such as a sensor or hose, this creates a physically dangerous situation.  My car literally stalled out while I was driving on the highway.  I was very lucky no one ran into me.  The next person might not be so lucky.

It's only fair to point out that most cars' engines would not survive a sudden massive loss of coolant.  Once the coolant is lost any warning lights are basically saying "time for a new engine."

Well, I got the bad news today.
After the MB service department replaced the coolant temperature sender for $500, they then told me I needed a new thermostat for an additional $800. I convinced the service manager today that a compression test and leak-down test of the cylinders should be done before any additional work was done. The tests all came back severely low indicating a bad head gasket and possible warped head. They told me I need a new engine at a cost of $4000 plus labor. They won’t replace the head only the whole engine.

Needless to say, I’m very distraught right now.

Yikes, I am going to my dealer next week to get mine checked out!

This is so very true.  This is one of the more important reasons I installed an UltraGauge in my little Munchkin.  They are now only $69.95, and they deliver peace of mind in so many ways.  http://www.ultra-gauge.com/ultragauge/index.htm

Jim
 
jwight said:

It's only fair to point out that most cars' engines would not survive a sudden massive loss of coolant.  Once the coolant is lost any warning lights are basically saying "time for a new engine."

Exactly.  Do a thorough checkup every 10k miles (check the hose connections and condition) and the chances of catastrophic coolant loss and engine failure will be extremely slim.  There's no need to worry.  I'm at 167k and still don't worry even with outdated coolant and in SoCal deserts that are creeping up near triple digits just in time for Summer.

Jeff Edmondson said:

Yikes, I am going to my dealer next week to get mine checked out!

From what I’m experiencing, a scan gauge or UltraGauge won't help you with loss of coolant.  The temperature measurement through the OBDII port comes from the same coolant temperature sensor that is supposed to warn you when the engine is over heating.  The sensor has to make contact with the coolant in order to get an accurate measurement.  A secondary sensor either sensing coolant level or head temperature is necessary to avoid catastrophic failure due to coolant loss.

Jim and Ann Brown said:

This is so very true.  This is one of the more important reasons I installed an UltraGauge in my little Munchkin.  They are now only $69.95, and they deliver peace of mind in so many ways.  http://www.ultra-gauge.com/ultragauge/index.htm

Jim  
jwight said:

It's only fair to point out that most cars' engines would not survive a sudden massive loss of coolant.  Once the coolant is lost any warning lights are basically saying "time for a new engine."

Very disturbing, to be relying on something which is not reliable.  Back to the drawing board.

Jim

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