how long should take for thermostat to fully open?

[55Test]

I'm testing the thermostat that came out of my Dodge Spirit, and if I drop it into a pot of boiling water, after 15 seconds it hasn't opened a bit. 30 seconds and it's open maybe halfway. 45 seconds and it's still not open fully. 60 seconds and again it's still not fully open. Shouldn't a good thermostat open a little quicker than that?

 

[Donald]

Well in the vehicle the thermostat would be heating up along with the engine which is not happening in your test. I would say your thermostat is fine. But they really are a maint. item and I would replace it if its out.

BTW the test should be to hang with string the thermostat in the middle of the pan so it does not touch the sides or bottom of the pan.

 

[widman]

and you should put it in the water and then heat the water so it is heating evenly. The heat transfer through the tube to melt and expand the wax in it, pushing open the door.

 

[NHGUY]

I would just replace it with a good quality one (Mopar,Stant...etc).My Aries stat opens when the gauge gets just past 1/2 way and drops down to just less than 1/2.This is usually after around 5 minutes at interstate highway travel (65 mph).

 

[Papa Bear]

Get a good new one to put in the Dodge now that you have it apart. Give the new one the same test that you are describing and let us know how the new stat acted.

 

[hsd]

Originally Posted By: Papa Bear
Get a good new one to put in the Dodge now that you have it apart. Give the new one the same test that you are describing and let us know how the new stat acted.

I think you should always check new thermostats this way, because of the rate of failure out of the box.

 

[mechtech2]

Thermostats in a car are not subjected to instant boiling temps. They are heated up along with the coolant, gradually.

Note the opening temp on the thermostat. Suspend it with a wire [so it is not resting on the bottom of the pot]and heat up the water while you measure the temp. When it starts to open, then note the water temp. Another 5-10 deg F may be needed to be fully open. This is normal.

Buy the best PCV valves and thermostats that you can find. Spend the extra $2-5.
If I had one out, I'd get a new one almost every time.

 

[55Test]

I went and got a thermostat yesterday. All that was available on a Sunday afternoon in this town for my particular engine was a 180F Motorad. I couldn't even find a [censored] thermostat gasket so I had to cobble one together with Permatex RTV, which so far seems to be holding without leaking. I tested the new thermostat in boiling water before I installed it. Dropped straight into a pot of boiling water, the new one was fully open in less than 15 seconds, the old one wouldn't even open in the slightest in that amount of time. The engine runs much cooler now, below the midpoint of the temperature gauge while driving. I just hope no permanent damage was done to the head or headgasket while the engine was running hot with the old thermostat

 

[mechtech2]

Hotter thermostats have some benefits.
Cleaner oil, and more fuel efficiency due to better thermal efficiency. Also much better in winter conditions.
The burning mixture does not have to constantly waste heat/potential power by always heating up the engine/coolant as much. More MPG is the result.
This is why Ford and others have used dual temp thermostats. 215ish for cruising, and 195ish for power.

I balk a little at your 180. It is OK, but nowadays, I'd get the 192-195.

 

[SteveSRT8]

Many cars are shipping with over 200 degrees stock. Mine shipped with a 203.

One thing Mechtech didn't mention was wear. You'll get less wear in a HOT engine.

Yes, that's right. I said LESS.

 

[Colt45ws]

Yeah, Ford Ranger with 2.3L Duratec had heated 230F? thermostat. Depending on specific cooling requirements, the PCM would turn on the heater (PWM) to either cause it to open, hold it open, or allow it to run rated temperature.

I stick with factory 192 in my car. Many go 180 for more powder. I dont think the trade off justifies the extra couple ponies from the added timing.

 

[SteveSRT8]

Just depends on your cars controls. On my car a 180 stat is one of the best mods if you reprogram the fans correctly.

Our PCM pulls timing like crazy over 190, the performance difference is HUGE.

In my car the oil is quickly heated due to oil squirters shooting it at the piston crowns. One thing you do not want is cold oil!

 

[mechtech2]

We probably won't get any additional timing with a cooler thermostat.
It is all there by programming already.
It can retard , but no more advance is available.