Question about Thermostats. - Page 4 - GM Forum - Buick, Cadillac, Chev, Olds, GMC & Pontiac chat


2000-2005 Discuss your 2000-2005 Bonneville SE, SLE, and SSEi Please use General Chat for non-mechanical issues, and Performance and Brainstorming for improvements.

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Old 06-05-2006, 07:41 PM   #31
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Quote:
Originally Posted by lash
Good post Curt! <snip..> As to the diameter of the Stant 'stat in our cras, I'll measure my 195* when I get home tonight, assuming no one else has posted an answer by then.
Thanks. It'* a 180, so if the diameter is right, it'* going in with the blower.

Actually, I found a lot of what the others were saying very reassuring. I was concerned that the Bonneville wouldn't have enough cooling capacity. Was even concidering getting a 4-core for it ( Which is what I had to do on the '87 F-Body to keep the 420 motor comfortable and not running the fans all the time.)

However, as ambient temps here in Daytona keep going up, the Bonnie is running a consistant temp, even with the AC going full tilt. That pretty much follows the observations of others. GM put a big enough radiator in them to handle the heat output of the 3800 motor, probably with some capacity to spare.
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Old 06-05-2006, 07:47 PM   #32
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Quote:
GM put a big enough radiator in them to handle the heat output of the 3800 motor, probably with some capacity to spare.
Wouldn't it be interesting to know if the Northstar Bonnies had the same radiator?
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Old 06-06-2006, 07:53 AM   #33
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So Curt, I measured the 'stat I have in the 180* box. Good news for you, it is a 44mm diameter. Also, for those interested, the 180* Stant thermostat Part Number is 13848.
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Old 06-06-2006, 08:15 AM   #34
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Cool! Thank you very much for that Slant PN.

For those of you wondering, Slant also offers a SuperStat which is their premium t-stat and it is PN 45848 available from Advanced Auto for $7.44. Their regular is $4.94 there as well.
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Old 06-06-2006, 09:36 PM   #35
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If I had an L67, perhaps I would go with the 180F T-stat, but my L36 runs at 187F (fans on) on a 100F day. And this is with the stock GM 195F T-stat. Winter time with the fans off, cruising the freeway, it'll get down to 180F.

You guys have to remember that the coolant needs to stay in the radiator in the path of on comming air for a certain length of time, to let go of its heat. If the coolant was constantly moving through the radiator without a thermostat, it wouldn't have enough time to cool off.
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Old 06-07-2006, 10:07 PM   #36
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Quote:
Originally Posted by MACDRIVE
You guys have to remember that the coolant needs to stay in the radiator in the path of on comming air for a certain length of time, to let go of its heat. If the coolant was constantly moving through the radiator without a thermostat, it wouldn't have enough time to cool off.
I'll dissagree with you on this in the strongest possible terms. Here'* why (I'll try to make this make sense, Thermodynamics wasn't my area of study)

Ok, first thing to remember: Heat energy can only flow from a high temp area to a low temp area. If both materials are the same temp, then no heat energy is transfered regardless of how long they remain in contact with each other.

The transfer of thermal energy from the coolant fluid to the aluminum is very efficient. Aluminum is a great conductor of heat energy. The transfer is instantaneous so long as the aluminum is cooler than the fluid. The transfer of heat from the aluminum to the surrounding air is poor. Air is a pretty good insulator.

Mr Science experiment for the doubters: Take a cheap aluminum funnel and toss it in the freezer. Takes a few minutes to get freezing cold because the transfer of energy from the funnel to the air in the freezer is poor. Now take the funnel, hold it in your hand, and pour boiling water through it. It will become too hot to handle in a mere second. The transfer of heat from the water to the aluminum funnel is that efficient.

The best analogy I can come up with is putting the family to work cleaning the house with little trash bags. Each person fills their bag with trash, then walks it to the curb and tosses it on the growing pile in the trash can. When the can is full, they can't put their trash bag in, and carry it back into the house like a lemming to try again. No mater how long they stand at the curb, staring at the full trash can, they still can't toss their little bag in. When the garbage truck comes along and empties out the trash can, they can resume dumping thier little bags of trash into it again. Ok, this is pretty silly.

That'* the way the coolant system works: Each droplet of coolant picks up energy from the engine till it is as hot as the metal it is in contact with. Then it imeadiately starts looking for a cooler material to transfer that energy to. If the aluminum of the radiator is cooler than the fluid, the energy get'* transfered. As soon as the aluminum is the same temp as the fluid, no energy is transfered and the droplet of coolant has no choice but to keep on moving. It doesn't matter how long it stays in the radiator...if it can't give up it'* energy to the aluminum, it just can't. And the speed of the flow through the radiator doesn't matter, cause it'* a contiunous bucket brigade of hot droplets trying to transfer their heat to the aluminum of the radiator. The only thing that matters is that the radiator can dissapate energy to the air faster than the engine can generate it. The coolant can be flowing at 10 gpm or 1000 gpm, it doesn't care. (Yes, the more time it has in contact, the more complete the transfer can be, but that'* not important because it'* a closed loop...there'* always another droplet of coolant in line behind it...so the net flow of thermal energy from the motor to the radiator is constant regardless of how fast the fluid is flowing.)

I hope this is making sense. I've heard this myth a few times, and at first blush and observation it does apear to be a truth, but what the observer is seeing and what was really happening were too different things. The no thermostat boil-over problem didn't begin in the radiator because of too fast a coolant flow not being able to dump it'* heat to the radiator'* aluminum. The real problem was hiding in the back of the block in the form of super heated steam created by zero coolant flow back there. When that steam finally filled the block, the super-heated steam bubbles went out the water neck, hit the cold radiator, where they expanded and popped the cap..too much thermal energy hit the radiator all at once..more than it could dissapate. All the while, the water pump is circulating the rest of the luke warm coolant like crazy...it just never came in contact with the hot parts of the block to transfer any heat energy from the block to the coolant and on to the radiator.

Same thing would happen if the water pump stopped moving coolant at all (like chucking a belt off the motor.) It would run along for another 30 seconds or so, then the temps would skyrocket as steam from the block finally hits the radiator.

If the system is circulating coolant properly, a boil over occurs only when the engines heat output outstrips the radiators ability to dissapate that heat. And it is a gradual problem...you can watch the engine temps slowly rise higher and higher, till steam starts forming everywhere and the cap on the radiator pops.
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Old 06-07-2006, 11:25 PM   #37
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Curt,

I have never been disagreed upon so strongly before in my life. Is there some place on this site I can go hide?

I need that smiley icon that is digging himself a grave right here > ( )

So can you expain to me and to the rest of the world the purpose of a thermostat and whether you are an advocate for the 180F or 195F t-stat?
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Old 06-08-2006, 08:21 AM   #38
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Quote:
Originally Posted by MACDRIVE
So can you expain to me and to the rest of the world the purpose of a thermostat and whether you are an advocate for the 180F or 195F t-stat?
No sweat. The engine has an operating temp range. The Thermostat controls the bottom end of that range by keeping coolant in the block when the engine temp is too low. The top end of the range is controlled by the radiator, fans, timing retard, and EGR valve (as a last ditch effort to keep the engine temps from getting too high.) Once the engine temp reaches the thermostat'* opening temp, it is no longer in play, it opened and will stay open. If the radiator is shedding heat faster than the engine is producing it, the stat will close again to let the temp inside the motor come back up again.

So yes, I'm an advocate of running a 180 stat if you are looking for more power out of the existing engine, and you are willing to live with the higher emmissions and poorer fuel economy.

If you want best fuel economy and the cleanest emmissions, leave the 195 stat in. That'* how they left the factory.

Another thought to add: I advocate drilling a small hole in the flange of the thermostat prior to installation, regardless of the opening temp of the thermostat. It'* purpose is to allow air trapped in the block to escape when filling the system with fluid. Typically, GM tries to put the thermostat at or near the highest point in the system so it is easy to service the coolant. They don't always succeed (like the Pontiac Fiero) So the little hole will help ensure you filled the radiator and the block with coolant, not just the radiator.
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Old 07-10-2006, 06:23 PM   #39
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I know i am reviving an old thread but after reading it I am kinda confused how much mpg would you lose after the 180 install if it is no more than one mpg isn't it worth the added power or benefit. I realize i am a newbie but I also live in a colder climate and so would the 180 stat be worth it or would it be detrimental to a l36 motor in the dead of winter. I have got told that a very base mod is the drilled tsat I am not looking for gobs of power I am just doing a tune up and well i am going to change the coolant anyway so why not get a new tstat. along with the fuel filter plugs and wires and pcv valve.
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Old 07-10-2006, 06:41 PM   #40
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@gojo83,

Welcome,

can you put your year and trim level in your sig.,,it'll help us help you...
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