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  #1  
Old 04-25-2007, 01:42 PM
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C90 Thermostat

Anyone know where to get a C90 rated thermostat for a 1981 300D? I want to run my WVO MBZ a bit hotter (good or bad idea ) to allow for a quick warm-up and switch over to vegetable oil.

VM

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  #2  
Old 04-25-2007, 02:14 PM
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the higher temp thermostat will not get your water hotter any quicker... it will just take longer for the thermostat to open.
John
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John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
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  #3  
Old 04-25-2007, 02:56 PM
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IIRC, the NAPA ones are 90c by default.
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70's Southern Pacific #5608 Fairmont A-4 MOW car

06 VW Jetta TDI 133K miles-replaced the other '06 that quit after 300k miles. (did not catch the bad cam in time)

91 W124 300D Turbo replaced, Pressure W/G actuator installed. 195K

90 Dodge D250 5.9 Cummins/5 speed. 400K
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  #4  
Old 04-25-2007, 03:04 PM
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Hmmm

Quote:
Originally Posted by vstech View Post
the higher temp thermostat will not get your water hotter any quicker... it will just take longer for the thermostat to open.
John
The C80 rating is when the thermostat is fully open. However, while the car is heating up the thermostat partially opens at temperatures below the rated temp. If you can delay this partial opening then would not the car reach operating temp faster? Maybe the difference in time would not be noticable, but in theory it sounds good.

VM
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  #5  
Old 04-25-2007, 03:12 PM
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if that is so, they your theory may be sound, I was unaware of this. I doubt there would be any measurable difference. make sure that whatever temp tstat you put in, it does not have bypass holes in it.
John
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John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!
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  #6  
Old 04-25-2007, 03:15 PM
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A partially opening t-stat would take the car longer to heat up, IIRC, especially in winter. Driving them heats them up faster.
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RRGrassi


70's Southern Pacific #5608 Fairmont A-4 MOW car

06 VW Jetta TDI 133K miles-replaced the other '06 that quit after 300k miles. (did not catch the bad cam in time)

91 W124 300D Turbo replaced, Pressure W/G actuator installed. 195K

90 Dodge D250 5.9 Cummins/5 speed. 400K
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  #7  
Old 04-25-2007, 04:34 PM
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Exactly. If the partial opening of the tstat occurs at a higher temp, then the car will reach operating temp faster (right?). It is my understanding that tstats do not spring open at their rated temp, but slowly open as the temp rises. If this slow opening is delayed, the vehicle will start cooling later in its warming up process.
VM
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  #8  
Old 04-25-2007, 10:53 PM
ForcedInduction
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Use an electric heater.
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  #9  
Old 04-26-2007, 12:25 PM
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Quote:
Originally Posted by VegeMan View Post
The C80 rating is when the thermostat is fully open. However, while the car is heating up the thermostat partially opens at temperatures below the rated temp. If you can delay this partial opening then would not the car reach operating temp faster? Maybe the difference in time would not be noticable, but in theory it sounds good.

VM
Buy a new proper "C80" t-stat and boil it on your stove and see when it opens. You'll be surprised. 80 is not the temp at which it is fully open, but rather when it begins to crack.
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1984 300D 225K
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  #10  
Old 04-26-2007, 03:47 PM
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Quote:
Originally Posted by sailor15015 View Post
Buy a new proper "C80" t-stat and boil it on your stove and see when it opens. You'll be surprised. 80 is not the temp at which it is fully open, but rather when it begins to crack.

That is correct. I did this experiment on a new one last weekend and 80C is when it begins to open. It is not fully open until well above 90C.

With a brand new radiator and new Tstat my car is running between 90C and 100C so I would like to find a Tstat that begins to open at around 70C. But all the parts stores I've been to seem to only have 80C or 90C available. Anybody know a source for lower temp tstats?
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86 560SEL
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  #11  
Old 04-26-2007, 09:55 PM
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if your car is getting to 100 with new radiator and tstat, I would verify the tstat is opening, at the correct temp, then look into a bad water pump, or a dirty block water jacket. I would also test the head for a blown gasket.
John
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John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!
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  #12  
Old 04-27-2007, 08:43 AM
Craig
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Quote:
Originally Posted by vstech View Post
if your car is getting to 100 with new radiator and tstat, I would verify the tstat is opening, at the correct temp, then look into a bad water pump, or a dirty block water jacket. I would also test the head for a blown gasket.
John
I agree, mine runs a 80 - 90C or just a little above, it shouldn't be getting close to 100C unless it's under a heavy load for some amount of time (i.e., big mountain on a hot day).
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  #13  
Old 04-27-2007, 09:17 AM
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I'm pretty sure it's an issue with the tstat, though I won't know for sure until I pull it and check. I will be curious to see how the one in there now compares to the new one that i tested last week.
The car was actually running too cool prior to installing the new tstat. This past winter I had to go with cardboard in front of the radiator in order to get up to decent operating temp.

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Joe

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
1980 300SD - 495k miles - 'The Ambassador'
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Former Family Members
95 C280
73 280SEL
90 300D
87 300SDL (X2)
86 560SEL
84 300D
80 300SD

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