I thought it was bad to run without a thermostat! I thought it was because with no restriction, the coolant circulates too quickly though the engine to pick up any heat. (Improper heat transfer..) And therefore, even though the coolant temp would be low, the engine itself would be hotter than normal.

Am I wrong? Isn't this why Moroso (and other companies) sell those waterneck restrictors, or that people make their own? Thanks!


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-Tom P (Hot rodded 1986 Firebird 2.8l) from http://www.f-body.net/mailbag/3rd/3rd_mailbag.html message boards
---Think your car could be pic of the week? Visit http://www.f-body.net for details!

 

You really want a thermostat. First, it brings the engine up to operating temperature, warms the oil to flow better. I have also heard the engine develops hot spots with no stat.
Now if you're only going a 1/4 mile at a time and it's only taking you 8 seconds or less to do this, maybe not

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Rob P
89RSconvtZZ4TPI
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[This message has been edited by Rob P (edited April 16, 2001).]

 

Yeah tom, like you said, the theory goes that if you want to run no stat you should still run a restrictor to simulate a thermostat so that the coolant will slow down as you said.
Of course, this is just theory and every so often you get someone who doens't understand the difference between theory and what might work, and will argue you till they're blue in the face that they don't run a thermostatt and do great.
...ed

 

The theory of coolant going too fast to effectively cool is complete horse hooey. This is an old wives tale and completely contrary to the principles of thermodynamics that moving "media" going so fast that it ceases to be effective to cool. The faster the "media" moves (along with a temperature differential), the more effective it cools to the temperature of the media; not the opposite. This is the same whether the media is a liquid or a gas. This is why if you put a fan on an ice cream cone, the faster moving air causes the ice cream to melt FASTER because the fast moving air is removing a cool thermal 'layer' over the ice cream with the temperature of the fast moving "media". In this example, it works the opposite.

With no thermostat, it just strips the "layer" over the internals of the motor. Increasing flow (like a faster pump) also causes an engine to cool quicker. If the "theory" was correct, then putting a SLOWER WATER pump would help cool a engine down. Trust me, it won't. Just like not having a T-stat will cause you to overheat...it won't. But it does cause a whole raft of other problems.

The problems with no t-stat is the risk of over cooling and possibly having your engine go into open loop if the coolant temperature falls below a certain temperature. Of course, there are the other problems with a computer controlled engine with too cool of coolant; the ecm thinks it is "warm up", runs too rich, too high of an idle, EGR may cease to function, etc. You would be amazed how many engine functions are controlled by the engine temperature.


[This message has been edited by Glenn91L98GTA (edited April 16, 2001).]

 

Well, barring the "dangers" of oil temp, closed/open loop, etc from running without a thermostat... Anyone else have an opinion on cooling? That's my main question; and so far the vote is split! Thanks guys!



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-Tom P (Hot rodded 1986 Firebird 2.8l) from http://www.f-body.net/mailbag/3rd/3rd_mailbag.html message boards
---Think your car could be pic of the week? Visit http://www.f-body.net for details!

 

I agree with Glenn91L98GTA! As long as you're sure that the engine and radiator are at full capacity, it only makes sense that the faster the coolant moves through the engine, the faster it will carry away some heat with it.

 

Well as far a cooling goes my friend has a sweet 72 Nova 350 bored over .30 and for some reason it gets into the 230's with any thermostat. He pulled his termostate out and the car runs 190ish on the street and about 210ish on the highway. This is with no water restictor. I thought the car would get to hot or to cold but it seems to run fine This is a very confusing subjet to say the least. SSC

 

What I'm describing could leave your coolant at a "normal" temperature, but have your engine block itself be at a "higher" temp. Know what I mean? The heat isn't getting pulled out of the engine by the coolant, because the coolant's rushing by too quickly. So the engine stays hot, and the coolant doesn't... and the coolant gauge shows the temp of the coolant.

But the ice-cream-cone analogy seems to put a different view on things!


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-Tom P (Hot rodded 1986 Firebird 2.8l) from http://www.f-body.net/mailbag/3rd/3rd_mailbag.html message boards
---Think your car could be pic of the week? Visit http://www.f-body.net for details!

 

TomP, living in a climate where we have cold and fast moving waters, our Search and Rescue have found that the faster the water moves, the quicker you die of hypothermia.

Same with your engine. The faster the coolant moves, the faster it pulls heat away from the block as no "thermal barrier" devolops just over the block's internal walls. Conversley, the slower the coolant moves, the larger this "thrermal barrier" becomes and thus the block itself gets hotter.

Glad you liked the Ice Cream analogy. I've pulled this trick on my nephews and nieces and they can't believe that a fan will cause the ice cream to melt faster, especially when I put the fan in front of their faces first...just to convince them how cool the fan makes their face feel. Again, its the "thermal barrier" from the radiating heat from their skin getting removed by the fan that makes them feel cooler.

 

Faster flow will cool the engine more. The problem with no t-stat is that coolant may not stay in the rad long enough to GET cool and then it can't absorb as much heat, not because it's moving too fast but because it's too hot already from the last pass. Once the coolant reaches the correct temp for the t-stat (eg 195) and the t-stat opens, the faster the flow the better up until the t-stat closes. Is that 72 computer controlled? Using no t-stat is IMO the lazy man's way to cool a monster engine like that. But with no computer and likely no egr it's not too big of a problem on those older cars.

 

i don't use a t-stat with my moroso eletric water pump. this allows water to flow freely when the pump is run without the engine running. i know it's a specialized application that most of you will never have.

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ICON Motorsports

1st & 3rd
MM Black Diamond 538 F&AM

 

run a 160 if you have any sort of high performance carb engine.

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89 firebird formula

356 10.5:1compression CURRENTLY DEAD!!! BEARING FAILURE!!
comp cams xe262 cam
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future mods: 406 roller REALLY REALLY REALLY RADICAL!!!!!

current engine underway..sucks not having a car!! Building the same engine but .060 over balanced and blueprinted..decided to get a little more serious this time around!!

 

Guess i should have explained deeper. Of course the fast moving coolant can cool the block, i don't doubt that, but the theory i have subscribed to is that the fast moving coolant will not get properly cooled in the radiator.
Also, another part of the theory is that the restriction i the water neck helps the WP build some block pressure, which helps with heat tranfer as well as ensuring a better cooling distribution. Otherwise the coolant has a tendency to rush right in, take the shortest route through the block/heads, and right out the water outlet. By restricting the water outlet the coolantends up taking a more circuitous route through the engine because the biggest restriction is now at the outlet, rather than the path itself.

Of course this is all theory and many people do fine w/o them. Thats fine. Thats why i had that disclaimer at the end of my post. In practice running w/o a thermostat can work, but that doesn't make it the most technically correct. Thus there's no point to arguing over it.
...ed

 

now we could probably fix that problem of "water not cooling down enough in the radiator" by getting a monster double fan, huh?

 

OK people heres the deal with thermostats.
1. You NEED ONE PERIOD. Without a thermostat your engine will NEVER warm up. And if you have a computer controlled car your computer will continually run in "full enrichment mode" meaning that you will be burning gas beyond beleif. This is because your cars computer is trying to warm up the engine.

2. Without a thermostat your engine will run cooler, PERIOD. You will lose your heating and defroster(as you have no hot or even warm coolant)

3. Running with no thermostat DOES cause hot spots on the cylnder walls. The same theory that the hot spots on brake pads develop. Some of the area just gets hotter faster than others, and while you have no thermo to regulate this cooling/warming there will be certain parts that will get hot while others can get flow through.


On another post tomp tred to tell a guy that running no thermo will cause his car to overheat. I do not mean to thrash tom but by saying this is the exact oppisite of what will happen. Tom you need to go get a repair manual and read it. You will learn alot.

 

The only reason to use a restricter without a thermostat is in a situation that the pump would pump too fast through the radiator(circle track of some kind) for an extend period of time. I certain amount of flow could maximize heat transfer.

The problem with this on the street is that the flow is always varying. At idle you wouldn't want the restricter. At 7000rpm you might want it. I can't see how in a street car the restricter would ever cool better compared to no restricter.


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82 camaro--original steering wheel, brake/gas pedals, seats--everything else modified
82camaro

 

I have to disagree with this. I had a 160 in my carbureted engine and it was too cold. I had poor driveability in general, LESS power, and worse fuel economy, all of which I attribute to poorer fuel atomization from the lower temp stat, and possible fuel puddling/dropping out of suspension. I switched back to the 180 that came with the engine and all of my problems disappeared.

I personally believe 160 is just too cold for any sort of wet flow system (carb/TBI) I have never tried 170 though, and since the 180 works and keeps it just as cool in the summer, I'll probably just stick with it.




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"Beware he who would deny you access to information, for in his heart, he dreams himself your master"

'84 Black Camaro ZZ4 M5 (V-6 in a former life) -- street beast
'91 Medium Blue Metallic Z28 A4 (UB-HSTRY's old ride) -- currently broken
'99 Navy Blue Metallic Firehawk #120 M6 (99.44% stock) -- daily driver

 

You don't mean to thrash me, but you say I need to go get a repair manual and read it? Hah, yeah, whatever, buddy. I never said the guy would overheat, I said he'd run HOTTER. (As you can see, a few other guys on here have said the same thing regarding unregulated coolant flow- Apparently, I'm not the only one!) Then, I went back, POINTED to THIS message, and basically said I was wrong. What the hell's your problem? When you do the things I've done, -then- you can tell me to go get a repair manual and read it.

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-Tom P (Hot rodded 1986 Firebird 2.8l) from http://www.f-body.net/mailbag/3rd/3rd_mailbag.html message boards
---Think your car could be pic of the week? Visit http://www.f-body.net for details!

[This message has been edited by TomP (edited April 18, 2001).]

 

Your engine doesn't always "over cool". You have to have a hell of a cooling system to do that. I ran no thermostat for the greater part of the summer months last year, the temp would keep around 200 - 210 (engine was breaking in). It can only over cool as much as the cooling system will let it.

Second, the fast moving theory is correct. Except, you missed one very important part. Moving water will "pick up" more heat, however, this still fast moving water (has to move quickly through the hole system, it's been drawn into the engine as fast as it is being push through and out) means there is less time for it to cool in the radiator before it is taken back by the water pump. So let's say....

1 gram of water that stays together moved through the thermostated engine picking up 88 kJ then went into the radiator and lost 76 kJ = net gain of the water would be 12 kJ.

1 gram of water that stays together moved through a non thermostated engine picking up 67 kJ (now, each gram gains less because time is a factor in reaching thermal equilibrium, higher speed, less time, less transfer), now it flys through the radiator and loses 55 kJ (even though less time in radiator, difference in temp is determining factor of how much energy gets transfered while trying to achive thermal equilbrium) = net gain of 12 kJ. So as you can see, the function that is coolant temp is determined by heat of the engine, speed of the coolant, specific heat of the coolant, and efficency of cooling system.

Bottom line, it probably doesn't hurt your engine to run without a thermostat aslong as you're not overcooling.

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1984 WS6 Hardtop Trans Am
Former L69 Car under restoration
1984 T-top Trans Am
4-bolt main 350, performer intake, headers, Holley 650, T-5, hayes clutch, dual elec. fans and 3.23's.
Daily driver and restoration
13.98 @ 101

 

Ok...It is a fact that running no stat at all will make your car run hotter. The coolant pauses in the radiator (due to a stat or restrictor) to be cooled by air flowing through it. If it is constantly free flowing, it does not have time to cool down properly. But on the other hand...it will take your "heater" longer to heat up due to the same reason....not enough time for the heater core to properly disperse the stored heat since it is constantly flowing. So both of you are right! Oh...by the way TOMP, I used to be a member on the board with the name of 1984L69Z28 about 7 months ago. Don't know if you remember, but your name is familiar to me. Good to be back at any rate!

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1984 Z28 - L69 optioned, 350HO w/ Trick Flow Heads, Drop Forged Lunati Crank, Crane Cam and 1.5 Roller Rockers, Stock Z28 Intake Manifold, Highly Tweaked Rochester Carb(700cfm), K&N Filter, ThermoMaster Chip w/ 160 Stat, Comp Headers, 3" Stainless Dual Exhaust w/ no Cat & Dynoflow Muffler, 4 wheel disc brakes, etc....

God bless us father, son, and holy ghost....whoever goes the fastest wins the most!!

 

I'm just adding my view on this.. I was running for quite a while with a thermostat that was stuck open.. it ran cooler than normal, but not too much (around 150 instead of 195), and burned plenty more gas (glad I replaced it now. hehe) I don't know if that was just the temp of the coolant or if the engine was a different temp or anything.. that's just what my guage said .. I'm not sure if it'll run like that on all of our cars, but that's what it did on mine .. hope that helps some.

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1991 Firebird 5.0L TBI

• K&N
• 2.5" Cat-back exhaust
• More coming soon

 

Tomp you still say that running no stat will make the engine run hotter...if that is so them why have I replaced 8 thermostats in cars that the owners have complained of no heat and very low coolant temps on the guage?...
I started and ran the car for 40 minutes at idle to try to get the temp gauge to go up...it didn't. Hell I didn't even wait 5 minutes before pulling the hoses and replaceing the thermostat the coolant was still only luke warm to the touch!. Now after I replaced the thermo the temp went up in a matter of minutes as it should have in the first place.
In fact I replaced one that a woman drove over 2 hours (from Springfeild Illinois to Carbondale Illinois) and the engine was still only showing 130ish on the guage and a infared thermometer read 139...AFTER OVER 2 HOURS OF DRIVING!!!! I'm sorry but unless you are running a VERY big engine and sitting idle for a LOT OF TIME(like days) then I will never see how running no 'stat will cause your car to run hotter. I have never seen this first hand and never will.(I simply just don't believe it ever will)
Now I replaced the 'stat in my car after it went bad after 9 years and I could not get any heat at all even after driving for 35 miles and sitting idle for 10 minutes to allow the engine to warm up alittle...with the old one that is. It was stuck full open(go figure huh?.) And by the way I got suspicious becuase the gauge never went above about 130 unless I was sitting Idle for a long time, like waiting behind 15 cars at a drive through line and even then it only hit 170. And by the way glenn (one of the moderaters can even see plain logic..why can't you?.


[This message has been edited by Camaro_hunter_d (edited April 19, 2001).]

[This message has been edited by Camaro_hunter_d (edited April 19, 2001).]

 

And as someone said that fast moving coolant cannot transfer temp throught the radiator because it is not allowed to slow any..this is true but if the coolant is cold to begin with and stays relitively cold due to the fast moving flow(by the way it will flow and cool the same as it the thermostat had opened) the coolant will stay perpetually much cooler than coolant that could warm up in a hot engine then flow to the radiator. I think this was a slight oversight only.

What I am saying is that ok the 'stat is installed. The coolant in the engine warms, the radiator coolant cold. 'Stat opens the coolant cools/warms perspectively.
Now the 'stat is not there. Cold engine coolant, cold radiator coolant. Now the cold radiator coolant will flow through the cold engine warming slightly granted. But remember the coolant in the radiator will still cool the same as if the 'stat was there and opened. So the coolant will remain cool throughout the entire system.
Tring not to step on anyone elses toes the coolant will cool at the same rate as an opened thermostat. Which will keep the coolant flow cold. To me this sounds like mere logic(tring not to sound high and mighty, but mechanics comes second nature to me, not to mention it just sounds more logical with the way that thermodynamics work) If someone has something else logical to add debate I will listen and reply accordingly but to me this just sounds like the way it is/works.

 

(yawn) I've run with an open thermostat too, and yes, my coolant temp was lower than normal, and I had no heat. But, we're not talking about coolant temperature! We're talking about engine temperature.

I'm not sure why you said I still think the engine runs hotter w/o a thermostat. Apparently, you didn't read my last few messages, where I already changed & said I was wrong; that's okay. However, I just noticed that you supported my argument that the engine will run hotter! You wrote:

Hot spots, eh? Well, in my book, if an engine has hot spots where it didn't previously, that means the engine's running hotter. You even say this is caused by a lack of a thermostat to regulate the cooling process- that's the exact thing we've been discussing on this message?? We've been talking about the use of a thermostat to regulate the system. Your whole argument has revolved around about coolant temperature. We're talking about the temperature of the engine. By the way, your attitude sucks, and I'm done with you- both here and on the thread in the V6 board.

In fact, I retract my "I'm wrong" statement. Looks like this is the same kind of debate as "MAF screen- leave in or remove?", where nobody has a 100% correct answer. Thanks to everone else that contributed sanely! Now I'm more open-minded towards the other side!

350HOZ28, is -that- who you are? Yep, that old alias of yours is very familar! Welcome back! Sorry you caught me in a pissy mood, heh heh...

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-Tom P (Hot rodded 1986 Firebird 2.8l) from http://www.f-body.net/mailbag/3rd/3rd_mailbag.html message boards
---Think your car could be pic of the week? Visit http://www.f-body.net for details!

[This message has been calmed way down by TomP (edited April 20, 2001).]


[This message has been edited by TomP (edited April 20, 2001).]

 

One point that has not really been brought up is that an important function of an engine thermostat is to allow the engine to quickly come up to operating temperature.

Depending on how far the vehicle is driven, the engine may never have a chance to come up to operating temperature with wintertime accentuating the problem. There are many reasons why an engine should be brought up to operating temperature quickly – burning off internal condensation is just one.

It will also take longer for computer controlled cars to go into closed loop (if the engine even gets hot enough).

I think everyone will agree that an engine will get hotter quicker with coolant that is stationary. The question seems to be what effect does coolant have on engine temperature at different circulating speeds such as would be obtained from a fully open thermostat (some restriction) or no thermostat (no restriction).

Remember that coolant circulation speed constantly varies according to engine speed (expect for the very few that use electric water pumps).

I do not believe that an engine will run hotter without a thermostat. While there may be hot spots (I don't know as I've never heard this before - how hot can it get if 160° coolant is circulating?), the overall engine temperature will be significantly lower when no thermostat is used. To say that an engine runs hotter (or warmer) w/o a thermostat is nonsense.

Perhaps the question should be “How hot can an engine get with a coolant temperature of 150° being circulated”?

Those that run 190-200° without a thermostat at highway speeds would indicate to me that (1) you have a small capacity radiator or (2) the ambient temperature is >95° or (3) there is blockage in the cooling system.

MADMAX – I agree with your point about using Redline Water Wetter. It increases the efficiency of the cooling system. I think it is under rated.

[This message has been edited by Stuart Moss (edited April 21, 2001).]

 

Stuart, I think you meant without a T-stat you may not get into closed loop. Open loop is when the engine does not rely on the 02 sensor to maintain 14.7:1.

But you are correct in the fact that without a T-stat it is possible for your engine not to go into closed loop as the coolant may not warm up enough to exceed the minimum temperature requirement. Also, the TCC may not lock (if you have an automatic) as it too has a separate minimum temperature requirement.

Temperature also affects various learn modes and functions like the EGR. And this is not a complete list. It is amazing how much the ecm relies on the CTS to control things. This is one of the reasons I stopped using a 160* t-stat when I saw how much was affected by it.

 

When water passes over a rough surface (ALL castings have this) it causes air pockets to be formed. This is much the same as in a fast moving river with lots of rocks, the air from the surface oxygenates the water and it does get down to the ground surface. I've seen this too many times in the lab in a 2' deep transparent water flume to count. Antifreeze will lessen this effect because it has much less of a tendency to hold and transfer air, but there is still water in there. Under pressure like in a cooling system, these effects become less apparent, but there is still a possibility.

The most important thing to start with is the water has to be able to carry the heat away. If its not touching the surface (air does a terrible job of heat transfer) and its moving so fast that it picks up relatively little heat from the surface in comparison to how much it NEEDS to pick up, then you run into a problem. Surface buildup of scale and rust and whatnot only makes this worse.

This is how the redline water wetter actually works, it takes the surface tension off the water, mixes better with it than coolant to make for a more complete contact with the surfaces inside the engine, and allows the water to pull more heat from the surface than it would normally because there are no air gaps (more correct would be less... they are always there).