Opinion's On 180 Thermostat

[DieselMike29]

I'd have to disagree with you on the heater not putting out any heat till the thermostat opens.The heater is actually tied in ahead of the thermostat on pretty well every vehicle built. Put your hand in front of the heater when the temp gauge is saying 130/140'ish,you'll feel heat coming from it,and the thermostat should not be open at those engine temps.BTW i'm in Alberta so I know cold too,lol. It's not wise to totally remove the T-stat unless you add a restrictor plate in it's place,full flow means the coolant is circulating to fast to actually absorb any heat from the engine block

Oh, I agree with what you said and have experienced that myself, but remember also that I said "the thermostat temperature is when FULL flow is allowed" Unless they have COMPLETELY changed how the cooling system on vehicles works since I played with them on my 1967 Chevelle SS396 (WHY OH WHY did I ever sell that car????), the heater hoses connect outside the circuit that allows the block to heat before opening to the radiator.

There are several little "tricks" I learned about the heating system (that part of the overall COOLING system for the vehicle) when I was much much younger.

First, how do you check to tell if the thermostat is "locked"/"frozen" shut? You grab the heater inlet hose - if it is cold when the engine is hot, the thermostat hasn't opened. (NOTE: "cold" and "hot" are relative terms in that 120 degrees is "cold" compared to "220" degrees.) This works because the heater supply (hot) connection is after the thermostat.

Second how to you check to see if the thermostat is "frozen" open? There are actually two ways, but by combining them you get a fairly accurate answer. They are: 1)put your hand on the radiator tank or (preferred method) upper inlet hose right after (within a minute of) starting the engine and/or 2) put a hand on the heater inlet hose. If the hoses warm up immediately and get hotter as the engine heats up, your thermostat is open. In this case, the thermostat could be partially open which would allow immediate flow to the radiator and the heater.

Why would you consider making those checks in the first place? The stuck shut thermostat is more easily noticed because the engine almost immediately overheats. It will take longer to notice that the engine is not heating to operating temperature as quickly as it should (because of a stuck open thermostat, but a loss of power or unresponsiveness should alert you to making the check.

Again, yes, you will feel some heat coming from the heater when the temperature in the engine has reached a certain temperature (how high depends on the (call it) full open temperature, ie the rated temperature of the thermostat).

And exactly why do you want the thermostat to open slowly and not pop wide open all at one time? The water in the cooling channels of the block is a fairly small part of the total amount of water in the entire cooling system. The radiator, on the other hand, contains MOST of the water (Okay, okay - it is "coolant" and NOT pure water) in the cooling system. (The heater actually contains quite a bit of the water too.)

If the thermostat were to pop wide open you would introduce that (relatively) LARGE amount of much colder water from the radiator into the hot block or the engine. Such a happening would cause (if not all at once, over time) a brittle fracture of the block - the walls of the cooling channels are quite thin in places and VERY susceptible to brittle fracture. To prevent this from happening, the thermostat is designed to open slowly to allow the water in the radiator to heat up as it starts to flow into the block.

 

[Hemi395]

Good point about getting a tune to enhance the t stat, because in some trucks the cpu will resist the new temps. Does anyone have info on the best way to use the tuner to adjust for the cpu not getting used to the 180f?

I don’t have the exact answer for this but I can tell you Sean did revise my tune when I put the 180 in. I even asked him if I could just change the fan settings and he said he needed to change some other things as well.....

 

[Wild one]

Oh, I agree with what you said and have experienced that myself, but remember also that I said "the thermostat temperature is when FULL flow is allowed" Unless they have COMPLETELY changed how the cooling system on vehicles works since I played with them on my 1967 Chevelle SS396 (WHY OH WHY did I ever sell that car????), the heater hoses connect outside the circuit that allows the block to heat before opening to the radiator.

There are several little "tricks" I learned about the heating system (that part of the overall COOLING system for the vehicle) when I was much much younger.

First, how do you check to tell if the thermostat is "locked"/"frozen" shut? You grab the heater inlet hose - if it is cold when the engine is hot, the thermostat hasn't opened. (NOTE: "cold" and "hot" are relative terms in that 120 degrees is "cold" compared to "220" degrees.) This works because the heater supply (hot) connection is after the thermostat.

Second how to you check to see if the thermostat is "frozen" open? There are actually two ways, but by combining them you get a fairly accurate answer. They are: 1)put your hand on the radiator tank or (preferred method) upper inlet hose right after (within a minute of) starting the engine and/or 2) put a hand on the heater inlet hose. If the hoses warm up immediately and get hotter as the engine heats up, your thermostat is open. In this case, the thermostat could be partially open which would allow immediate flow to the radiator and the heater.

Why would you consider making those checks in the first place? The stuck shut thermostat is more easily noticed because the engine almost immediately overheats. It will take longer to notice that the engine is not heating to operating temperature as quickly as it should (because of a stuck open thermostat, but a loss of power or unresponsiveness should alert you to making the check.

Again, yes, you will feel some heat coming from the heater when the temperature in the engine has reached a certain temperature (how high depends on the (call it) full open temperature, ie the rated temperature of the thermostat).

And exactly why do you want the thermostat to open slowly and not pop wide open all at one time? The water in the cooling channels of the block is a fairly small part of the total amount of water in the entire cooling system. The radiator, on the other hand, contains MOST of the water (Okay, okay - it is "coolant" and NOT pure water) in the cooling system. (The heater actually contains quite a bit of the water too.)

If the thermostat were to pop wide open you would introduce that (relatively) LARGE amount of much colder water from the radiator into the hot block or the engine. Such a happening would cause (if not all at once, over time) a brittle fracture of the block - the walls of the cooling channels are quite thin in places and VERY susceptible to brittle fracture. To prevent this from happening, the thermostat is designed to open slowly to allow the water in the radiator to heat up as it starts to flow into the block.

You better go look at where your heater hoses tie onto the engine,"they are ahead of the thermostat",not behind it as you claim. The thermostat opens slowly to minimize thermal shock to the engine block.If it opened fast at operating temp,the thermal shock could possibly break the cast iron engine block.You have some decent points,but you're out to lunch on a few of your theories,lol.

 

[seabrook]

You better go look at where your heater hoses tie onto the engine,"they are ahead of the thermostat",not behind it as you claim. The thermostat opens slowly to minimize thermal shock to the engine block.If it opened fast at operating temp,the thermal shock could possibly break the cast iron engine block.You have some decent points,but you're out to lunch on a few of your theories,lol.

My titan cooling system had a small bypass around the t stat so it was never at zero flow- does the hemi have a similar set up?

 

[Hemi395]

You better go look at where your heater hoses tie onto the engine,"they are ahead of the thermostat",not behind it as you claim. The thermostat opens slowly to minimize thermal shock to the engine block.If it opened fast at operating temp,the thermal shock could possibly break the cast iron engine block.You have some decent points,but you're out to lunch on a few of your theories,lol.

If I remember correctly, the heater hoses are completely separate from the tstat? As in they are right off the water pump and are always circulating coolant through them?

 

[Hemi395]

My titan cooling system had a small bypass around the t stat so it was never at zero flow- does the hemi have a similar set up?

Sort of, the Hemi tstat has (or should have) a jiggle pin that is mainly for bleeding air our of the system. But it does allow a small amount of coolant to pass through it....

 

[ScLeCo]

Sort of, the Hemi tstat has (or should have) a jiggle pin that is mainly for bleeding air our of the system. But it does allow a small amount of coolant to pass through it....

Huh, so that's what that thing is. When I put my new T stat in I was all WTF is this??? The old one had it so I left it alone.

 

[Hemi395]

Huh, so that's what that thing is. When I put my new T stat in I was all WTF is this??? The old one had it so I left it alone.

LOL yeah I thought the same thing when I first saw it

 

[joshuaeb09]

I don’t have the exact answer for this but I can tell you Sean did revise my tune when I put the 180 in. I even asked him if I could just change the fan settings and he said he needed to change some other things as well.....

I didn't ask Jay specifically what he changed in my tunes, but the usual suspects are typically the same for speed density engines.

For example something along the lines of the following formula being used to calculate fuel :

Load x TPS x ECT x IAT x BAT x LT x O2 x ST = Pulse Width

Going back through my tuning logs I do notice I got a degree or two more of timing out of the 180 so there's that as well.

 

[VB712]

If you install a 180 or lower thermostat without a custom tune, you will get a CEL for coolant temperature threshold not met. Also your fan temp will need to be adjusted to 195 degrees.

Running without a thermostat on these motors isn’t smart either because the coolant having a constant flow will not allow time to cool going through the radiator.

 

[crazykid1994]

I love this post. So much back and forth. I’ll probably get hell for what I’m about to say... I’m untuned. I switch between a 180 and a 190 depending on the weather here in Florida. I could probably leave the 180 since it’s only cold 1 week of the year and I don’t think 45° can really be called cold... Ags has been deleted since 10,000 miles on the truck. I’m at 26,000. I’ve never had a cel. I have never had an issue with running lean. I have a S&b intake and a borla catback exhaust. Moes tb. Soon I’ll get a custom tune. But deleting the clutch fan and the lower temp thermostat was the most noticeable improvement on this truck by far. Better off the line response and butt dyno says more torquey. Waiting for some cold weather for track times. Last year stock I ran a 15.2