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#1
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Would a "bad" thermostat- run cool when cold out also run hot when warm out?
As I have mentioned before, I think I have a bad thermostat and so I am told by others, as my car (85' 380SE) was running very cool on the highway when it is cool out... the cars gauge is like @ 60°C. Now that it is warming up, I have noticed the gauge is going much higher than it did last summer when idling. Tonight, I was setting in a drive-thru and had to idle for about 5 minutes. It was 58° outside. When I looked at the gauge, it was up to about 105°C! It was not in the danger zone, as I would not have allowed that, but I "revved" up the engine to about 1500 RPMs (to get the fan to speed up) and the temp gauge went down almost instantly down to 85°C, which seemed odd it went down so quickly. With that, does it sound like the water pump getting weak, or will a faulty thermostat also make an engine run too hot when idling, when at the same time run too cool when cold out? Today, when I was driving when it was 67° outside, it was around 80°C, which seems normal, but it goes up and down quite a bit as I stop and go. Last summer, it never went above 95°C, even in 97°F weather, but seems like it may be worse this year.
I would like to add this info and be sure before I replace the thermostat. Thanks in advance! |
#2
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that is how it would run if it had no stat.
tom w
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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC] ..I also have a 427 Cobra replica with an aluminum chassis. |
#3
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Buy a thermostat and replace the old one. As stated above, there likely is not a thermostat installed. Do not run the engine without a thermostat.
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Ali Al-Chalabi 2001 CLK55 1999 Dodge Ram 2500 Cummins Diesel 2002 Harley-Davidson Fatboy Merlin Extralight w/ Campy Record |
#4
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Thanks. Well, its been like that since I have owned it (almost 2 years), so I bet the PO had removed it or something. Probably was getting too hot when the auxillary fan stopped working. It does not work (keeps blowing fuse). I am wondering if I put in a new stat without the fans working, will it likely overheat?
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#5
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I bet your gas mileage is low with that kind of temperature.
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#6
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you will probably find that the thermostat is broken partially open which will account for your symptoms.
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David S Poole European Performance Dallas, TX 4696880422 "Fortune favors the prepared mind" 1987 Mercedes Benz 420SEL 1988 Mercedes Benz 300TE (With new evaporator) 2000 Mercedes Benz C280 http://www.w108.org/gallery/albums/A...1159.thumb.jpg |
#7
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Your car will typically only need the aux fan during the summer with the AC on, and not moving (ie sitting at idle or in a traffic jam). Please replace your thermostat.
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1985 380SE Blue/Blue - 230,000 miles 2012 Subaru Forester 5-speed 2005 Toyota Sienna 2004 Chrysler Sebring convertible 1999 Toyota Tacoma |
#8
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Just about an hour ago, I replaced the thermostat on the 2003 E320 wagon. All is good now. Before the new thermostat, the temp would not reach 80 degrees Celsius. Now it goes there quickly and above it. The thermostat is rated for 87 degrees.
From my personal experience with Mercedes thermostats (4 of them), they tend to last for about 40k - 50k miles. After that they will stuck slightly in the open position. The symptom is that the temp will not go above 80. This results in too cold running in normal driving then too hot running in the summer. (A partially stucked in open thermostat probably cannot fully open either.) |
#9
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Quote:
Jeff Pierce
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Jeff Pierce Current Vehicles: '92 Mercedes 190E/2.3 (247K miles/my daily driver) '93 Volvo 940 Turbo Wagon (263K miles/a family truckster with spunk) '99 Kawasaki Concours Gravely 8120 Previous Vehicles: '85 Jeep CJ-7 w/ Fisher plow (226K miles)'93 Volvo 940 Turbo Wagon '53 Willys-Overland Pickup '85 Honda 750F Interceptor '93 Nissan Quest '89 Toyota Camry Wagon '89 Dodge Raider '81 Honda CB 750F Super Sport '88 Toyota Celica '95 Toyota Tacoma '74 Honda CB 550F |
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