Allpar Forums banner

1 - 12 of 12 Posts

·
Registered
Joined
·
476 Posts
Discussion Starter · #1 ·
Happy New Year to Everyone!

I just have to ask, WHY on God's Green Earth would Dodge pick a thermostat that does not open until it reaches 220 degrees?

This does not make sense to me. Most thermostats are built to open around 195 degrees.
Does anyone know of another thermostat that will fit inside the housing on a 2011 Dodge Grand Caravan. I went up to O'reilly's and took my housing and looked for a fit, but they had none.
I do not want my coolant to reach 220 before the thermostat opens.

303,000K Miles and still going

:rolleyes:
 

·
Super Moderator
Joined
·
32,320 Posts
Rockauto says that the thermostat opens at 203F, not 220F. So does Advance Auto. Who is telling you 220F?
 

·
Super Moderator
Joined
·
37,852 Posts
This is not uncommon on newer engines. The thermostat is probably a 192°/195°. The thermostat likely starts opening at that temperature but may not be fully until well over 200°. For another car where this was discussed (in that case it was a Dodge Charger) and the service manual noted the thermostat would not reach wide open (unrestricted) flow until 220° despite the fact it starts opening around 195°, so it sounds yours is designed the same way.
You could swap to a cooler thermostat, but why?
1) If you swap to a cooler thermostat, you may cause the engine to use more fuel as the computer would richen the mixture for the cooler temp.
2) If there is an overheating problem, swapping to a cooler thermostat does not fix the overheating problem. It only masks it.
 

·
Registered
Joined
·
476 Posts
Discussion Starter · #4 ·
Rockauto says that the thermostat opens at 203F, not 220F. So does Advance Auto. Who is telling you 220F?
Hi Bob, No one told me. I put in in the water in a pan and it did not open until over 214 degrees. I replaced it like 3 times last weekend and I used to could look at the temp readout and see when the thermostat came open and it came open around 209 but, now it opens arund 219. All 3 thermostats open at different temps.
 

·
Registered
Joined
·
476 Posts
Discussion Starter · #5 ·
This is not uncommon on newer engines. The thermostat is probably a 192°/195°. The thermostat likely starts opening at that temperature but may not be fully until well over 200°. For another car where this was discussed (in that case it was a Dodge Charger) and the service manual noted the thermostat would not reach wide open (unrestricted) flow until 220° despite the fact it starts opening around 195°, so it sounds yours is designed the same way.
You could swap to a cooler thermostat, but why?
1) If you swap to a cooler thermostat, you may cause the engine to use more fuel as the computer would richen the mixture for the cooler temp.
2) If there is an overheating problem, swapping to a cooler thermostat does not fix the overheating problem. It only masks it.
I will not switch but, it seems to use more fuel anyway now that it has 330k miles on it.
 

·
Registered
Joined
·
1,291 Posts
Taxigirl; I don't mean to burst your bubble [sorry, sometimes I can't help myself] but water can only reach 212 deg without being pressurized. And even when you see water bubbling in the pot it may be less than 200 deg. A lid covering the pot will help raise the water temp.

The 3 thermostats opening at different temps doesn't surprise me. I put three 180 deg thermostats in the same pot of boiling water and watched them open. They were all different. Probably 5 to 10 deg difference. After putting a lid on the pot and heating more, they all opened fully.
 

·
Virginia Gentleman
Joined
·
15,010 Posts
In a pressurized system the boiling point is higher. And of course in the case of antifreeze, it has a higher boiling point than water. (It also has a lower freezing point). At least that's what I remember from my college chemistry class.

I'll bet, as Mark posted, the thermostat starts to open at 203 F and fully opens at ~220 F. Unless the temperature gauge is reading higher than normal I wouldn't worry about it.
 

·
Registered
Joined
·
476 Posts
Discussion Starter · #9 ·
Taxigirl; I don't mean to burst your bubble [sorry, sometimes I can't help myself] but water can only reach 212 deg without being pressurized. And even when you see water bubbling in the pot it may be less than 200 deg. A lid covering the pot will help raise the water temp.

The 3 thermostats opening at different temps doesn't surprise me. I put three 180 deg thermostats in the same pot of boiling water and watched them open. They were all different. Probably 5 to 10 deg difference. After putting a lid on the pot and heating more, they all opened fully.
Thank you, i did have a thermometer in the way but, i see what you are saying
 

·
Registered
Joined
·
3,681 Posts
Try another thermometer. I have seen those off also 5 degrees and more!
 

·
Registered
Joined
·
5,423 Posts
The Manufacturer that designed and tested your engine knows best what temperature the engine will run best at. Engine parts will expand with temperature, the spec temp to run the engine will have the parts expanded to their spec dimensions for the best fits and wear. Run at another temp, the fit and tolerances of the parts all change. Run an engine too cool, deposits will form, especially on the valves. Run an engine too hot, you'll get detonation or premature wear, especially on valves.

There have been plenty of tests, and if anything, using scientific methods found engines made better mileage or power when they ran hotter, NOT cooler. But still, the guy that ran that motor on a dyno for a million miles, and tore it down a dozen times and inspected all the parts, figured out what is the best temp to run the engine at for best mileage/performance and wear. So why would you think you know better and use a different engine temp. Get thermostat with the OEM temp spec.

Sorry someone led your wrong with the wrong spec, good you asked if he was right with such an unusaully high temp, cause it sounds like he is wrong. And 203°/205° degree thermostats are becoming more common these days.

And I call BS on the lower thermostat fools the ECM/PCM into using more aggressive spark tables. Has anyone ever proven that with a before and after dyno figures? I'm pretty sure most PCM's go to the warmed up Tune well before the engine temps gets anywhere near the temp of the lowest available thermostat. There was one aftermarket PCM for the Neons that soldered a resistor into the temp sensor pin of a stock PCM. Mopar Muscle magazine did a test with Dyno's, 0-60 and 1/4 mile times, the other aftermarket PCM's offered improvements, but the one with the resistor in the temp sensor pin (to fool the PCM like you're running a lower temp thermostat) actaully performed worse than the stock PCM.
 
1 - 12 of 12 Posts
Top