ok so this is now the third thermostat ive gone through... im running a stock fiero thermostat on a 4.9. tonight it decided it would over heat and seize again... i am sick and tired of my car overheating...everything smells like coolant everywhere. now for a car thats only driven in the summer... is it OK to drive it without a thermostat. i need to know so i won't have to go by another one of those things... oh and installing a fail safe is just about as good as no thermostat because its going to break regardless... so it will be stuck open running like it had no thermostat anyway.... pluses for all who can help.

Thanks!

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Im not running one and my engine runs fine, It will take longer to reach operating temp tho.... So your gas mileage might be worst.

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My 4.9 runs fairly cool (cooler than the 2.8 ever did) without
a thermostat it'll overheat in the highway.
A thermostat serves 2 functions, it regulates the coolant/engine
temperature and acts as a flow restrictor when its open.
(so that the water doesn't flow too fast thru the radiator)
I don't know if you are running PFI or not, but if you are,
you are going to have problems with the ecm .
I was having trouble with the Fiero thermostat too, sometimes it would
open and stay that way, when the temp went down my ecm would
make the mixture richer thinking the motor was cold.
after 2 Fiero thermostats (both doing the same thing) i installed
a AutoZone brand 195degree thermostat For the Caddy motor.
No more problems.

Ed

Thanks for the responses guys! now ive run the highway with a stuck open thermostat once and it actually ran cooler then usual... i changed my coolant tonight and the results are as follows... when the thermostat is in it over heats and hits temps of up to 125 C. when its out it runs at normal operating temperature then the fan comes on and then once the fan does its job it shuts off. is this for the most part normal. oh and pluses for you both

Thanks!

I use restrictors rings in my car and I have no problems with that unless you are in a cold winter situation you bshould be able to run with a restrictor ,take out the thermostat and clip off the piece that holds the float and toss it just leaving the hole where it came from in this way it will slow down the water flow going through the system enough to keep your engine cool .

I'm running a caddy 195 degree thermostat but I drilled a 1/8" hole to bypass some coolant...
No overheating, no problems with closed loop or anything...

Dragon1/Brian

my 2.5 didnt have a thermostat in it for a whole summer it ran nice and cool didnt have any driveabily problems. just once the fall rolled around it took it a little longer to warm up,

but if it reaches it normal opt temp then there shouldnt be any problems

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Chris 85 Fiero SE 2.5L of fury
second one in the garage undergoing surgery
See the progress

http://www.cardomain.com/member_pages/view_page.pl?page_id=347941&page

You can run a thermostat without worrying abotu it failing and overheating. Motorad makes thermostats that fail open. I always forget how to link... http://www.motoradusa.com/products/failsafethermo/

I'd recommend just changing to a non fiero thermostat -
heck in the fiero 2.8 i've removed the little handle from a fiero stat and use it to hold a non fiero stat into place. worked great and was a lot more reliable

Thanks for all the reply's guys. i appreciate the advice. ive also found a small leak beetween the coolant line that runs from the thermostat at the engine to the coolant tube. would radiator stop leak work or do i need to flush the whole thing and put a new hose in?

i would NEVER use stopleak in a coolant system unless it was a junk with pinholes int eh radiator and it only needed to last me a few weeks

DON'T USE STOP LEAK...

I'd only use it on a junker to get me past a week before I trash it.

That stuff is horrible for your car.

quote Originally posted by Scythe: DON'T USE STOP LEAK... I'd only use it on a junker to get me past a week before I trash it. That stuff is horrible for your car.

GM service manual cut and paste for cadiliac

Failure to use the engine coolant supplement (sealant) and the approved coolant antifreeze could result in major engine damage. When refilling the cooling system, add three pellets of the engine coolant supplement sealant GM P/N 3634621 to the lower radiator hose.

good call pete! but now where do i get the good stuff... is it diffrent from the stuff canadian tire carries?

quote Originally posted by Saber49: now where do i get the good stuff... is it diffrent from the stuff canadian tire carries?

I know the GM stuff is in solid form and needs to be broken up, I don't know if its the same as the premixed liquid stuff at CTC. I can tell you the GM stuff is <$5.00 at the GM dealer. Sorry, not much more help.

Pete

thats ok pete. ill make a few calls and see whats around. ill try to get the offical stuff if possible

Thanks!

The myth that coolant flowing 'too fast' doesn't have 'time' to cool fails the basic physics test. It seems to be a popular myth, but it is neither possible, nor the experience of those that run without a thermostat. If the water is flowing 'too quickly' it only means it will be back sooner -- the total 'time' the water spends in the radiator will be the same, as the system is a closed loop. And the physics that determines how much heat gets dissipated works back at the accumulation end too ... the net effect is exactly the same.

A thermostat closes so that the coolant gets up to temperature in the block -- as soon as it is too hot it lets some out until the target temperature returns ... and that is a 'good thing', as proper operating temperature is what the engine is designed for. I see no advantage to running an engine 'too cool', though there is a disadvantage to running one too hot ... but the engine that runs too hot won't be 'fixed' by removing the thermostat, assuming it was a working thermostat, as the same physics governs the heat dissipation, thermostat or no.

Cheers,
GB

GB,
I don't understand your explaination of coolant flow.

quote If the water is flowing 'too quickly' it only means it will be back sooner -- the total 'time' the water spends in the radiator will be the same, as the system is a closed loop.

If the water is leaving the engine faster and gets back to the engine sooner, how could it not spend less time in the radiator?

Jon

quote Originally posted by PBJ: GM service manual cut and paste for cadiliac Failure to use the engine coolant supplement (sealant) and the approved coolant antifreeze could result in major engine damage. When refilling the cooling system, add three pellets of the engine coolant supplement sealant GM P/N 3634621 to the lower radiator hose.

Damn Pete you beat me to posting this. It's about the only thing I have learned so far and now you neat me to the punch\.

Because if it leaves sooner, it will be back sooner ... and the total time spent in the radiator is the same. Think of it as rpms -- if the coolant is 'rotating' at one rpm, then one degree of arc of the coolant spends 1/360 of a minute at TDC for every minute. If the rpm is increased to 100 rpm, then one degree of arc still spends 1/360 of its time at TDC -- it gets there faster, gets out sooner but it all adds up to the same total per minute.

In truth, the laws of thermodynamics that matter here are related to mass -- the heat is transferred from the block to the coolant (which I refer to casually as water), and the temperature rise of the water is determined by the mass of water. If the water is circulating adequately, you calculate the cooling capacity based on the total mass of water factored by the surface area of the radiator, which is nothing more magic than another heat exchange, this time from the closed loop (and fixed mass) coolant system to an infinite loop (and so infinite mass) air. The air mass is infinite only in that is not a closed loop -- the limitations of what mass of air can be moved across the surface area of the rad are governed by air flow and rad size ... but no where in this equation is 'time' of the closed loop coolant system a factor.

Now the reverse could be a problem -- the water in the block gets very hot, hotter than it would be if it could get exposed to the surface area of the rad ... but because the circulating pump doesn't move it fast enough the block reaches the limit of possible heat exchange to the water before the water is replaced with water that is below the maximum. But this is because the water runs out of the ability to absorb the heat. As long as the pump can move the water away from the heat source before it is at maximum, the system continues to function.

There is no disadvantage -- beyond some impossible system where the pump itself was so incredibly powerful that the pumping force added more heat to the water than the block did ... but such a pump would have to be powered by something other than the engine, or it would become itself an energy 'source' instead of an energy consumer ...

HTH

GB

So to speak, no thermostat in itself is not a big problem. It does restrict the flow to aid in cooling but not by making it slow down. It forces the water into passages that would not flow much if the rest was freeflowing. This will happen because not all openings for the water to flow are the same size. Some may be an inch or so, others may be 1/8" and the water will naturally try to follow the path of least resistance (bigger holes). Your gauge may indicate coolent temp is lower, because its measured at the sending unit. But there may be real hot spots in the water jacket that you will never know about untill that part fails by cracking or breaking. I will never run without some kind of restriction or thermostat except in a total emergency.

[This message has been edited by rogergarrison (edited 11-19-2004).]

Well, I'm not sure that the flow down restricted passages is affected so much by the thermostat as by the pressure inherent in the system itself. Most of the time, thermostats are either 'open', so have no effect on circulation at all, or closed -- in which case the circulation is entirely within the block & the cockpit heating system.

The real job of the thermostat is ensure that the block gets as quickly as feasible to the operating temperature, at which point the thermostat opens & in short order the entire 'cooling' system gets up to the operating temperature -- in the extremes of my winter driving, the thermostat might close again at highway speeds, as the ambient might be hovering around -20 and the cooling system becomes too efficient, but the thermostat closes the loop to a smaller capacity and the operating temperature stays where it was designed.

I am only speculating, but I'd guess that at 50 degrees F and warmer once the thermostat opens it likely stays open. Maybe there is a little oscillating at temperatures down to 20 or so & at the extremes of cold there is enough direct from block to ambient exchange the the thermostat might stay closed almost indefinitely.

If everything is working, a thermostat is a good thing -- but there is no way that the absence of a thermostat can lead to _more_ heat.

GB

Wow thanks for the uh... science lesson guys. that should help. now im sorta worried that coolant isn't getting everywhere like roger said... maybe ill just run with one. i don't know im gonna see how it runs with and without one and see which is the best course of action.

Thanks to all who have helped!

quote Originally posted by RGBaker: Because if it leaves sooner, it will be back sooner ... and the total time spent in the radiator is the same.

RGBaker, you left out one important part of the equation, the efficiency of the radiator is affected by the materials that is constructed, air flow across it and mass flow of the coolant in mass/time so yes time is in the equation.

At higher flow rates it's true that the delta T will be lower...the fluid will have less time to transfer heat and the temperature change will be lower. However you will move a larger quantity of heat. Everything else being equal flow is more important than delta T anyway. Back when I used to work at the Kennedy Space Center we had the ground coolant hooked up to the shuttle before liftoff. We would get the system as cold as we could but when the orbiter started powering up for launch we would increase flow rather than attempt to lower the temp. With higher flow you can get the heat back to the heat exhanger more quickly.

[This message has been edited by jscott1 (edited 11-20-2004).]

It would be incorrect to suggest that time has no place in the equation -- but the important fact here is that there is no circumstance where speed through a radiator reduces the efficiency -- if the thermal capacity of the coolant is not exceeded, cooling will always take place; if the thermal capacity of the coolant is exceeded, the 'problem' will occur at both the increasing & decreasing stages and so be a non-factor.

Cheers,
GB