Re: When should a 180* tstat start to open?
[Re: Mad Accountant]
#1498647
09/08/13 11:46 PM
09/08/13 11:46 PM
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Joined: Feb 2006
Posts: 2,262 Groveland, MA
SteveS
top fuel
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top fuel
Joined: Feb 2006
Posts: 2,262
Groveland, MA
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The normal Start to Open range for a 180° thermostat is 177° to 184°. The tricky part is that STO is defined as an opening of .003", which you can't measure. It will be open all the way by about 204°. You can't measure it that accurately on the stove, because it has to sit at that temperature for a few minutes. There is a lag as the water temperature changes.
The spring has absolutely nothing to do with the operating temperature, which is controlled by expansive wax inside the bronze cup.
Steve
Someday I'll have another C-body.
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Re: When should a 180* tstat start to open?
[Re: 360view]
#1498650
09/09/13 06:57 PM
09/09/13 06:57 PM
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Joined: Feb 2006
Posts: 2,262 Groveland, MA
SteveS
top fuel
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top fuel
Joined: Feb 2006
Posts: 2,262
Groveland, MA
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Quote:
If the initial opening is so small, and since most vehicles coolant temperature does stay pretty close to the 180 Tstat rating, not near the 204 degree full opening i guess that means that much of the time during lazy part throttle driving the annular opening is only ten to thirty thousandths "high" ?
Kinda.
A couple of things come into play. First, the wax expansion is non-linear. Second, the test dude is going to look at three temperatures: 177°, 184°, and 204°. I'm using some typical Stant numbers here. It shouldn't move at 177°. At 184° you will probably see something averaging about .030" to .060". As the temperature rises a little from there, the expansion curve gets steeper. A small temperature change means a larger amount of expansion. The expansion occurs over about 15°, and then the curve flattens out again. By 197° or so, it's done. At that point, the thermostat is no longer controlling temperature.
There is some lag with temperature changes, because the heat needs to propagate through the entire wax cavity. There is copper and/or other materials blended with the wax to help with heat transfer.
The same ranges apply to other temperatures, too. The wax is blended according to the desired temperature and expansion characteristics.
Steve
Someday I'll have another C-body.
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Re: When should a 180* tstat start to open?
[Re: Mad Accountant]
#1498652
09/09/13 08:21 PM
09/09/13 08:21 PM
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Joined: Jan 2003
Posts: 5,439 So Cal
Sinitro
master
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master
Joined: Jan 2003
Posts: 5,439
So Cal
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What many people do not understand is that the thermostadt is not just simply an open/close water flow switch. The marked temperature is when it starts to open, and typically it takes another 5-7% of increased water temperature to open fully... A 195 F degree thermostadt will start to open around 195 F but will not be fully open until about 205-208 F degrees. The real question is How much time? is required for the thermostadt to be fully open.. This is directly dependent upon several factors including: Outside air temperature Engine loads Engine compression Fuel octane rating Amount of timing Radiator capacity Airflow through the radiator Vehicle speed Just my $0.02..
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Re: When should a 180* tstat start to open?
[Re: Mad Accountant]
#1498653
09/09/13 08:24 PM
09/09/13 08:24 PM
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Joined: Feb 2006
Posts: 2,262 Groveland, MA
SteveS
top fuel
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top fuel
Joined: Feb 2006
Posts: 2,262
Groveland, MA
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Probably 99% of the "defective" thermostat returns work perfectly, regardless of whether they come from consumers and jobbers (NAPA, Carquest, etc.) or from new car dealers!
In other words, the problem is usually with another cooling system component, or the installer.
Steve
Someday I'll have another C-body.
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Re: When should a 180* tstat start to open?
[Re: SteveS]
#1498657
09/10/13 10:35 AM
09/10/13 10:35 AM
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Joined: Jan 2006
Posts: 8,162 USA
360view
Moparts resident spammer
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Moparts resident spammer
Joined: Jan 2006
Posts: 8,162
USA
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In Chryslers original press release about the then-new iron V10 Ram pickup engine, they made these claims about the $35 thermostat used: quote A heavy-duty truck engine block cooling system and thermostat minimized low-temperature piston wear and oil consumption by allowing the cylinder walls to warm up gradually and expand uniformly. The truck-type thermostat opened in a smooth continuous manner because it had four times the working area of a passenger car thermostat. A conventional thermostat released bursts of chilled water during warm-up that distorted the cylinder walls and causeed wear and high oil consumption. The thermostat had a cylindrical valve element with an O-ring seal to assure smooth consistent operation. It was mounted in a molded plastic housing at the front of the engine. unquote Is the V10 thermostat a better design? original at http://www.allpar.com/mopar/V10.html
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Re: When should a 180* tstat start to open?
[Re: 360view]
#1498658
09/11/13 10:24 PM
09/11/13 10:24 PM
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Joined: Feb 2006
Posts: 2,262 Groveland, MA
SteveS
top fuel
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top fuel
Joined: Feb 2006
Posts: 2,262
Groveland, MA
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I guess Ma was saying that all of their other cooling systems sucked? That top bypass design has been used by people like Mack and Detroit Diesel for years. The coolant flow is constant, and the thermostat directs the flow back into the engine, and into the radiator, and the percentage varies with the temperature. Pretty much just like any other thermostat. They might mix better, but I think they could have done the same thing with a more conventional bypass blocking thermostat.
Steve
Someday I'll have another C-body.
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