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**OU812** · 07-30-09, 10:28 AM

The thermostat does not control the engine temperature. Its purpose is only to allow the engine to warm up quicker by isolating the coolant in the block till it reaches running temp. A larger capacity radiator or a bigger fan is the way to control running temp.

**Guest** · 07-30-09, 10:42 AM

Originally posted by mybrokenjeep View Post

Would installing a lower temperature rated thermostat cause a motor to run hotter or cooler?

Here is the case in point... MyBrokenJeep has a Chev 350 in it... Running the factory recommended 192 degree thermostat today... at times the motor will run a bit hot... Someone mentioned that if I put in the alternate temperature 160 degree thermostat that the motor would run cooler as the thermostat would open earlier and allow water/coolant flow through the radiator quicker... Another person offered the opinion that I should go with a hotter ranged thermostat, maybe 210 degree would accomplish the same thing... I am confused!

Can someone, and I know there are people on this board that have forgotten more about this type of thing than I know, comment and offer your opinion?

I can only speak from experience. I have the 180* stat in ALL three of my car/truck/jeep. The 180* stat opens sooner than a 195*. Most of my cars run at 177-190* Why? I feel it opens sooner, thus cooling it sooner before it gets hotter. I also remove the brass plug, which allows 1/16" of coolant to pass regardless of the t-stat temp. If your t-stat has no brass plug, you can drill a 1/16" hole on the side. Not only does it flow more coolant, if it ever fails, you will still get some coolant flowing to get you home

So, again, these results are from my cars. As for the 160* stat. There I agree with Scott. Don't go with that one. Your coolant is always flowing and not enough time in the ratiator to cool down. Stick with the 180* stat. Most computer cars need to run at 177* to be warm. Also look into a bigger fan like I did. The one I put on may fit your application ($55 for a OEM fan blade)! Any more questions just ask.

**Guest** · 07-30-09, 10:46 AM

Originally posted by OU812 View Post

The thermostat does not control the engine temperature. Its purpose is only to allow the engine to warm up quicker by isolating the coolant in the block till it reaches running temp. A larger capacity radiator or a bigger fan is the way to control running temp.

I partially agree

Sorry buddy. The part I agree on is a bigger radiator and fan. I have went with a bigger fan. I went from a 5 blade to a 7 blade. So, far my temp has only reached 177* because of so much air on the motor. Link below on bigger fan I did.
It shows temp at 177* The part I disagree on is the engine temp. If the coolant flows sooner and can cool the motor down. Then temp then stays where it is at. Meaning, if the t-stat opens at 180* and the engine needs just that amount of coolant to cool it's self. Then your Jeep will remain at 180*. Although, if you have a 195* t-stat and it opens at 195* and the coolant flows to remain cool, thus your Jeep will remain at 195*. Does that mean you will never see 210* temp? Of course not. Some times you need all the coolant you can get to keep her cool like when I tow the Jeep with my Avalanche, she runs at 210* at times. Again, I can only go off experience I have with my cars I have a 180* in them.

My temp running at 177* (pictures included)
http://www.myjeeprocks.com/forums/sh...ad.php?t=15013
From a 5 blade to a 7 blade (pictures included)
http://www.myjeeprocks.com/forums/sh...ad.php?t=14977

**OU812** · 07-30-09, 12:49 PM

Originally posted by Jeep4cern View Post

I also remove the brass plug, which allows 1/16" of coolant to pass regardless of the t-stat temp. If your t-stat has no brass plug, you can drill a 1/16" hole on the side. Not only does it flow more coolant, if it ever fails, you will still get some coolant flowing to get you home

I like this idea. Next time I do a coolant flush I may be drilling a hole.

**Guest** · 07-30-09, 01:23 PM

Originally posted by OU812 View Post

I like this idea. Next time I do a coolant flush I may be drilling a hole.

I have replaced all three cars and have noticed all three have had the brass plug. I just cut the plug and I get my hole without drilling.

So, check before you drill.

**MyBrokenJeep** · 07-30-09, 09:33 PM

Guys... Thanks for the advice! I will look into replacing the one in there with the 180 degree thermostat.

If anyone else has ideas/advice/warnings, please voice them!

**aw12345** · 07-31-09, 04:37 AM

Randy a thermostat only controls the minimum temperature.
A colder thermostat on a hot day will nopt make a darn bit of difference since the engine runs hotter than 180 degrees anyways. Your Jeep or for that matter most Jeep CJ's and Wranglers are all struggling to run cool especially with a v8 in them. Making sure you have good electric fans that draw a lot of air and come on early sat around 205 degrees and can can reduce the engine temp when it gets up to 215 should be the ticket, also making sure that all air flow has to go through the radiator and cannot go around the outside of it helps also, so does a good fan shroud. To sum it up the biggest radiator and fan combo is the way to go for your setup. Once that is done you can look at other ways to try and get some of the heat out of the engine compartment.
With vents and such in the hood or opening up the inner fenders anything to get the hot air from the radiator and engine out of the engine compartment

**Double AA** · 07-31-09, 08:22 AM

As already stated, a cooler thermostat will do nothing to keep an engine from running hot.

When our Jeeps left the dealerships they didn't run hot, and larger tires and lifts aren't going to make a noticeable difference.

If your cooling system (fan, hoses, thermostat, radiator, pump, cap...) works properly, the engine block isn't obstructed and you have a fan shroud, there won't be any issues with a hot running engine.

When you swap to a V8 engine there's a good chance you'll need a larger radiator. On thing you also need to check is that your fan is not too far away from the radiator.

I would run the factory fan assembly whenever possible, unless you spend a lot of time in deep water. They draw a lot of air and last a long time.

I installed an oversized radiator in my CJ when I swapped to a V8. I modified the stock shroud to fit, used the V8 fan and never had an issue. Even when crawling at barely an idle in JV at 100* plus.

I recently modified my CJ and had to install a shorter, wider radiator. I still have the oversized radiator with the shroud and cap that i'm going to list along with a few other CJ parts. Let me know if you can use it.

**Guest** · 07-31-09, 08:58 AM

Originally posted by Double AA View Post

As already stated, a cooler thermostat will do nothing to keep an engine from running hot.

When our Jeeps left the dealerships they didn't run hot, and larger tires and lifts aren't going to make a noticeable difference.

If your cooling system (fan, hoses, thermostat, radiator, pump, cap...) works properly, the engine block isn't obstructed and you have a fan shroud, there won't be any issues with a hot running engine.

When you swap to a V8 engine there's a good chance you'll need a larger radiator. On thing you also need to check is that your fan is not too far away from the radiator.

I would run the factory fan assembly whenever possible, unless you spend a lot of time in deep water. They draw a lot of air and last a long time.

I installed an oversized radiator in my CJ when I swapped to a V8. I modified the stock shroud to fit, used the V8 fan and never had an issue. Even when crawling at barely an idle in JV at 100* plus.

I recently modified my CJ and had to install a shorter, wider radiator. I still have the oversized radiator with the shroud and cap that i'm going to list along with a few other CJ parts. Let me know if you can use it.

I respectfully disagree.

So, coolant doesn't cool the motor? Thus opening sooner wouldn't cool the motor sooner? The pictures I posted tell the tale

As for lifting and tires not making it run hot. I disagree there too. A body lift can make it run hotter (relocation of radiator and shroud). Also, bigger tires with a small gear ratio can too (motor works more to move the tires).

Remember, some people feel 210* and 220* are not a problem. While others like my self like a cool running Jeep

Now, I do agree, if you have a 4cyl radiator trying to cool your v8. Then yes. That is an issue. Likewise with your fan blade.

For $9 as I stated, try it

Don't forget to drill out the hole or remove the brass plug (it's a small plug).

Ron

**Double AA** · 07-31-09, 09:58 AM

Any properly functioning thermostat only effects when the coolant starts to flow, not how much. It's only job is to allow the engine to warm up faster and set the minimum temperature the engine will be allowed run at. If you have a 190* T-stat, once the coolant hits 190* and it opens, it's job is done and it's functioning the same as a 160* or any other T-stat of 190* or less.

Obviously if to have modified your Jeep and the fan is drawing air from around the radiator, it's going to effect the effectiveness of the system. Also if you obscure the front of the radiator with a object like a large/tall winch it will have an effect.

An engine is designed to run at a certain temperature range for it's maximum efficiency. It's cooling system and computer is design to keep it in that range. A colder T-stat wont affect it, but let's say you modified your system to run cold. Your computer will read it, go into warm up mode and lean out your fuel/air mixture. Not a good thing for your engine or performance. I'm sure you've seen simi's with covers over the radiators in cold climates.

**OU812** · 07-31-09, 10:04 AM

Ron I think you are right. Opening the thermostat sooner will keep the engine cooler. But only for the warm up period. Your thermostat will make you jeep take longer to get up to running temp because it starts circulating coolant before its gets to running temperature. But two of the same cooling setups( radiator, fan, shroud) one with a 160 thermostat and one with a 180 thermostat will end up running the same temp. Only the 160 thermostat will take longer to get there. They both have the same capacity to evacuate BTUs.

**Dezertdog** · 07-31-09, 11:29 AM

Fail-Safe

Originally posted by OU812 View Post

I like this idea. Next time I do a coolant flush I may be drilling a hole.

Just get a [COLOR="Red"]fail-safe [/COLOR]brand thermostat. They are designed to automatically lock in an open position if there is a problem. There is no plug to drill.

Have always run them. Never have I had a problem with a thermostat.

my :2:

Scott

**Guest** · 07-31-09, 04:08 PM

Originally posted by OU812 View Post

Ron I think you are right. Opening the thermostat sooner will keep the engine cooler. But only for the warm up period. Your thermostat will make you jeep take longer to get up to running temp because it starts circulating coolant before its gets to running temperature. But two of the same cooling setups( radiator, fan, shroud) one with a 160 thermostat and one with a 180 thermostat will end up running the same temp. Only the 160 thermostat will take longer to get there. They both have the same capacity to evacuate BTUs.

I know 180* and 195* is when it starts to open. It's not full open (so I was told). Also, what explains mine running at 177*? I was told 177* is the normal running temp for a computer engine?

Not trying to disagree, more understand. Meaning, I am going off what I know and have experienced. I mean geez I have included pictures showing it at 177* when it was 95* outside. Can someone else post what theirs is in 95* weather so I can compare?

**Guest** · 07-31-09, 04:11 PM

Originally posted by Double AA View Post

Any properly functioning thermostat only effects when the coolant starts to flow, not how much. It's only job is to allow the engine to warm up faster and set the minimum temperature the engine will be allowed run at. If you have a 190* T-stat, once the coolant hits 190* and it opens, it's job is done and it's functioning the same as a 160* or any other T-stat of 190* or less.

Obviously if to have modified your Jeep and the fan is drawing air from around the radiator, it's going to effect the effectiveness of the system. Also if you obscure the front of the radiator with a object like a large/tall winch it will have an effect.

An engine is designed to run at a certain temperature range for it's maximum efficiency. It's cooling system and computer is design to keep it in that range. A colder T-stat wont affect it, but let's say you modified your system to run cold. Your computer will read it, go into warm up mode and lean out your fuel/air mixture. Not a good thing for your engine or performance. I'm sure you've seen simi's with covers over the radiators in cold climates.

Correct. I agree. What is that? Is it 177*?

Why does hypertech have you run a 180* stat after you chip your car? They say it is better performance.

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