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I'm getting weird symptoms from my 560sl with 53k miles. White smoke from exhaust but now I don't have it. My oil is still normal. I was working on my coolant system and removed the thermostat housing and found no thermostat so I just order one waiting for it to come. The thermostat housing is closed without a gasket so water is leaking out but I'm not driving the car. The reservoir has no bubbles when running. Any other way to find out if the head gasket is actually blown ?
 

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Your cooling system thermostat is a 3-way valve. It will not work properly without the thermostat. Check to be sure the bypass hose has not been blocked by who ever took out the thermostat.

You can use coolant combustion gas checker such as-

 

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When I find a thermostat which has been removed, it suggests someone has had an overheating problem. How sure are you of the mileage on the car? Do you have documentation? These cars are notorious for broken odometers and showing much less miles than actual. You will also want to check the radiator for clogging.
 

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When I find a thermostat which has been removed, it suggests someone has had an overheating problem. How sure are you of the mileage on the car? Do you have documentation? These cars are notorious for broken odometers and showing much less miles than actual. You will also want to check the radiator for clogging.
The radiator was clogged I unclogged the radiator. The car had the wrong coolant so I got the right coolant haven't put it in the engine yet. But the mileage is correct on that car not only from the condition of the car but from past state inspection documentation. I bought it from the first owner and came with all original paperwork.
 

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Can you think of any other reason you'd get white smoke out the back? I can't. Blue = oil, black = incomplete combustion, white = steam.
You said it had the wrong coolant. Was it the green stuff? Green stuff has a distinct sweet smell when coming out the back. It's hard to miss.
Just curious... how did you "unclog" the radiator?
 

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Can you think of any other reason you'd get white smoke out the back? I can't. Blue = oil, black = incomplete combustion, white = steam.
You said it had the wrong coolant. Was it the green stuff? Green stuff has a distinct sweet smell when coming out the back. It's hard to miss.
Just curious... how did you "unclog" the radiator?
Well I flushed out the green coolant with water from a hose and now the coolant system has just water. I unclogged the radiator with just water from the hose for about 5 minutes. The system was flowing fine after. But today was a hot day and I found no smoke. Ran the engine well over 5 minutes
 

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Well I flushed out the green coolant with water from a hose and now the coolant system has just water. I unclogged the radiator with just water from the hose for about 5 minutes. The system was flowing fine after. But today was a hot day and I found no smoke. Ran the engine well over 5 minutes
Is well over 5 minutes less than 6 minutes, or is it more like 10 or 15 minutes? The reason I ask is because 5 minutes doesn't seem like enough time for the engine to come up to full temperature.
Forgive me if I'm telling you something you already know but the Mercedes thermostat is a bit more complex than the average automotive thermostat. In the Mercedes the thermostat directs coolant in two directions. When cold, the coolant bypasses the radiator and is recirculated through the engine. This is done to promote faster warmup. As the coolant comes up to temperature the thermostat redirects more and more of the coolant through the radiator. However, with the thermostat removed, coolant will flow through the radiator regardless of temperature and as such the engine will take a very long time to come up to full temperature and indeed will never come up to full temperature.

This long winded explanation can be summed up in 7 words.... "don't run an engine without a thermostat". The reason should be obvious... the engine was designed to operate within a specific temperature range, one that takes into account thermal expansion among other things. If the engine is run for any length of time either cooler or hotter than the designed range, bad things can happen.

Second point... notwithstanding the direction of flow, it is highly unlikely, that a clogged radiator can be remedied by running water from a garden hose through it. Water, much like electricity, will follow the path of the least resistance, any clogged passages by definition will offer much higher resistance to the water flow than the unclogged passages resulting in the water flow simply bypassing the clog. It may be emotionally satisfying to run water from a garden hose through a clogged radiator but such action is not likely to yield meaningful results.

Install the new thermostat when it arrives and then you can perform more meaningful tests at full operating temperature. I might suggest using water alone for your intitial tests and if no problems are found, replace the water with the good stuff... green is definately not the good stuff. Hopefully that's all you'll need.

Good luck. :)
 
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