Eliminating thermostat

[Inygknok]

I know what everyone will think at first, "oh, it's really going to suck to be him during Christmas season.". Doesn't happen in Puerto Rico where if the temperature drops below 64 degrees F, it has got to be the coldest night of the year with a heavy ass rain in which I wouldn't dare drive the Supra. So, no extreme cold start problems for me (and I have started the car while cold many times without any problems other than an odd idle problem it had, and someone explained it to me).


Anyhow, I was reading another thread around here somewhere (can't find it), and someone mentioned about the point of the thermostat during hot weather. This interested me. Being in a tropical island, we get plenty of sun. One user mentioned something about how the t-stat helped retain some of the water/coolant in the radiator for it to cool off before entering the coolant passages in the engine again. I believe that same user said something about the head absorbing all that heat due to the water not staying in the radiator long enough.


Now, is this correct, or just facts riddled among personal opinions?

 

[IJ.]

Leave it in there....

 

[Inygknok]

Leave it in there....

Aye aye, Cap'n! ::salute::


PS: More like, put it back in there.

 

[Doward]

Get you a 180 degree thermo, and a nice dual core aluminum radiator, and no more worries.

 

[fast 7m]

what kind of thermostat do you recommmed? I heard arc makes a pretty good one for our cars

 

[jdub]

Stant SuperStat...cut the jiggle valve off for a bit of constant flow.

 

[cnewingham]

Stant SuperStat...cut the jiggle valve off for a bit of constant flow.

thats what I run and do

 

[NA86.5]

Since Ive went NA-T I dont run a thermostat either.

 

[Burntz]

... Why?

 

[suprageezer]

I believe a constant temp what ever temp thermostat you choose prevents the cylinders from uneven wear aka egg shaped cylinder wear.

 

[jdub]

Geezer - excessive/uneven wear on cylinder walls is primarily caused by using hard rings or lack of lubrication. The 7m block is very hard, it would have to get pretty hot to see cylinder distortation contributing to uneven wear. The thermostat may or may not be the cause though.

One more time - running no stat will allow coolant through the radiator at full flow constantly. This will severely delay the coolant getting above the ops temp (176 deg F) the ECU needs to sense in order to transition from warm-up enrichment. Until the ECU sees this temp threshold, it will increase the amount of fuel supplied to the motor...you will run rich. The whole idea of running a coolant thermostat is to get the coolant to ops temp as quickly as possible...running a 160 deg thermostat will have the same effect, just not as severe time wise.

The temp rating of the thermostat has no effect on the car running cooler...the stat will simply open at the temp rating allowing flow to the radiator. The coolant will continue to get warmer (assuming constant running) until it reaches the thermal capacity of the radiator to get rid of the heat. At that point equilibrium is reached in the system. If you have coolant temps above ~210 deg F, the ECU will pull timing in order to prevent detonation.

The solution is to either fix the radiator, fix the fan, or upgrade to one with a larger thermal capacity if both of the former are good. A lower temp thermostat will not keep your coolant temps lower....however, using a 180 deg stat (like Dow suggested) will allow the radiator to get a "jump" on heat removal. Top coolant temps are determined by the radiator itself and the air flow through it.

 

[Inygknok]

Aight, let me see if I understood jdub correctly (correct me if I'm wrong, don't have to flame either).

Ok. Basically, the t-stat is specially important if the car is driven around in areas with cold seasons, or just an average cold season (doesn't happen where I live). The main role of the t-stat (which is kinda obvious at this point) is to simply coolant to get warmed up to operating temperature, just like oil needs to reach operating temperature. I'm sure that even warming up the coolant helps warm up the engine, warming up the oil at the same time (though I doubt it honestly helps THAAAAAAT much).


Anyhow, on the exempt case of where I live, the t-stat wouldn't help as much as a double core radiator would help out, like they mentioned previously. This being a factor even more important.


Am I right so far?


EDIT: Forgot to add something. Wouldn't running a MAFT actually help in the situation of the car running rich while warming up? Cuz I honestly don't mind running a bit rich while the car is warming up. I always allowed it to warm up for about 2 minutes before driving slow for about 5 minutes. That should have been more than enough for the engine to reach operating temp.

 

[jdub]

If you are running a stock ECU, the stat is important...not only does it get the coolant up to temp faster, it requlates flow to the radiator. The only difference between a cold/hot climate is the amount of time it takes to get to ops temp. I live in Phoenix...promise you it's hotter than PR and I run a 180 deg stat.

Don't know if the MAFT can override warm-up enrichment or not.

Highly recommend you listen to IJ, Dow, and myself...run with a stat.
A dual core rad will help keep your motor happy in a hot climate

 

[Inygknok]

Aight, fair enough. Just wanted to get all the questions out there. Didn't mean to appear to go against the experts.


Btw, if a dual core rad is not possible, will one of the Koyo OEM style ones suffice?


And yea, I've heard Phoenix is hotter, but it's the type of tropical heat we get over there that apparently, only us islanders can somehow survive (that's what all the tourists and foreign students say at least, and I have seen plenty! lol! I wouldn't know since I'm so accostumed to it).

 

[jdub]

Not taken that way...it's a common belief that a lower temp stat or no stat helps keep the motor cool. It's just that it causes more mischief than it's worth

I'm a big fan of a dual core in a hot climate...make sure your fan clutch is working well too.

A stock Koyo will basically be what you have...Koyo, CSF, Fluidyne and PWR all make dual cores for the MK III. Any one of them will work well, depends on what you want to spend.

Been to PR in the summer several times and lived in Miami...trust me, Phoenix is a lot hotter!

 

[supraguy@aol]

I second the recommendation of just getting a better rad. My temps would rise during the warm months of summer, and I had no BHG and I tried various rated Tstats. What cured it was getting rid of my 8 yr old radiator, and putting in a CSF. Temp never budges.

 

[King of Cleveland]

Also, a fluid moving past a stationary surface doesn't move uniformly, the layer of fluid right against the surface is actually stationary or nearly so, then as you get farther away from the surface the fluid moves faster. essentially, fluid "sticks" to the walls. This is called laminar flow. As the speed difference increases (like by removing the thermostat and allowing coolant to circulate faster) the thickness of the laminar layer increases, resulting in less net heat transfer from the walls to the fluid in motion.

http://en.wikipedia.org/wiki/Laminar_flow

Automotive engineers think about this stuff. don't mess with it. The thermostat is not only a temperature-actuated valve, it is also an intentional restriction in the cooling system. Run a 160 degree t-stat if it makes you feel better, but don't take it out.

 

[NA86.5]

Thanks for the info guys

 

[suprageezer]

King thats what I always understood also, if the water is flying through your engine it doesn't have a chance to remove heat properly and creates cold spots in some places and hot spots in other thus creating uneven cylinder wear, egg shaping.

 

[Kckazdude]

Back in the day, I ran restrictor plates in place of a t-stat. With the Fail-safe t-stats these are no longer needed as they go wide open in case of failure. The one other thing of note on cooling effeciency is that ethylene glycol has a tendecy to 'hold' heat and not treansfer it as well as distilled water. Using ditilled water also introduces other areas of consideration such as rust and other unwanted deposits that must be dealt with.