Ok, since i'm new at this, i think i just found out my overheating problem. I just saw in some website that if you change your thermostat to a cooler one, you need to make changes to your computer, or prom, or whatever. Remember, i'm new.Bare with me! Ok, i changed my thermostat to the 160 degrees one. And i think, not sure, that ever since then, my fan won't start. My car has heated up several times already. I need to be careful not to sit still for a while, cuz my temp will pop up! But when i start driving, it will go back down. Can that be the problem, that i put a 160 degree thermostat? To fix it do i just buy the original one back? What's the degrees on the original one? I have a 92 Firbird 305 TBI. Thanx for any help guys!

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92 Firebird 305 TBI
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First of all, check to see if your fan switch sensor is hooked up properly(good connection), it is located in the passenger side cylinder head. I had a problem with my fan not coming on and it was because the wire had fallen off the sensor. Your car gets cooler when you drive because cool air is forced into your radiator, that is normal. The fan should come on at about 220 degrees. If it doesnt come on, i dont think it has anything to do with the thermo. The stock thermo is 195 degrees. You might want to put a 180 in your car, because 160 might not be a good idea in the winter.

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1990 5.0 TBI
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Yeah, if anything, the low-temp (160 deg) thermostat will keep your engine cooler... it doesn't really matter if it's warm (>50 degrees or so) out and there's no airflow to the radiator (i.e., your car's not moving and the fan isn't on). He's right, the problem is that your fan coming on, either b/c the motor is dead, the coolant temperature sensor is dead (not sensing >220deg), or the in-between wiring/fusible link is bad. Pray that it isn't the wiring. That can be a real b**ch to fix.

 

The purpose of a t-stat is to keep the engine WARM, not cool.

The t-stat stays closed until the set temp (160 deg.) is reached. It has nothing to do with how cool the engine stays. Once that t-stat opens, the coolant relys on the rest of the cooling system.

If your fan is set to -on@~220-, and -off@~200-, (factory setting) then that is what dictates wether or not the coolant stays cool.

If it's relatively cool outside, then the 160 deg. t-stat will keep the coolant from going below ~160 deg. It always keeps it warmer than that.

Now of course these all have to compliment each other. If you have a 160 deg. t-stat, then your fan switch should be -on@180-, -off@165-. But don't get a t-stat higher than the -shut off- on the fan. Otherwise that fan will run forever. A 180 deg t-stat won't let a fan with an -off@165- switch get a reading that's cooler than 165 deg. That will wear out that fan faster than a 2 bit *****.

That's why a lot off people think that a lower deg. t-stat will keep your engine cooler. It doesn't keep it cooler, it just doesn't warm it up as much. But if you increase the cooling effect on the rest of the cooling system (such as the pump or fan), then you have to lower the t-stat setting in order to see those benefits.

Make sense?

AJ

[This message has been edited by AJ_92RS (edited November 16, 2001).]

 

You really gotta be more specific on this whole issue.. with a 160 thermo, is your car even *getting* to 220 for the fan to switch on? You said it spiked, but going from 160 to 200 would look like a spike, and never get near your fan switch point. Also, are you running with a chip? If not, that 160 thermo is probably going to hurt performance and economy more than help by making it exceedingly difficult for your car to go into closed loop operation... might want to go up to a 180..

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[QUOTE]Originally posted by AJ_92RS:
[B]The purpose of a t-stat is to keep the engine WARM, not cool.

It doesn't keep it cooler, it just doesn't warm it up as much... ...Make sense?

Eh...no? Not to delve into physics or chemistry or anything, but cooling IS the removal of heat... when the stat opens, it allows hot coolant to start flowing out of the engine to the radiator, where the heat dissapates, right? And this flow allows cooler coolant to flow into the block, picking up heat, and so on... so if you have a lower temp (eg 160) stat, this coolant effect starts working at a lower temp, right?

I know this all also works to allow the engine to warm up faster (b/c coolant isn't flowing until it reaches temp.) I dunno, maybe we're just looking at it from two different perspectives...

 

First off, the stock T-stat rating on these cars is 195 degrees. The T-stat has no direct relationship with the fan. I just installed a 180 degree T-stat with no probs.

The bottom line is if your engine temp goes above 225 degrees, the fan should come on. I've seen the temp "spike" from 160-200, this is normal, its just your cooling system building up pressure...when the pressure hits a certain point the temp levels off.

A T-stat does not "cool" off an engine..air blowing from the fan or driving does that. What the T-stat DOES do is allow coolant from the block to merge with coolant in the radiator. Think of it as heat dissipation, but not enough to keep cool without a fan. Otherwise you wouldn't have an overheating prob in the first place.

 

If your thermo is broken then you'll have a temp change when sitting and driving. If it's a robertshaw thermo like mine was, it'll break in the open position. Does your car take abnormally long to warm up? If it does, then it's definatly a broken thermo, if it warms up right away, then it sounds like a fan motor, wire, or switch problem. All easy fixes.

 

First of all, what kinda attitude is that. Does that make you feel smart? Eh...like..does it dude?

Yea. Me right. You no understand.

Once the t-stat is open, it will close again (while the engine is running or not) if the temp of the coolant gets below the operational setting of the spring used in that particular t-stat. Therefore it keeps the coolant from getting too cool. I.E., it keeps it 'warm'. That is it's only purpose.

I can say that you don't ever want to run without a t-stat. The coolant would never warm up when it's cool/cold outside. Just the same, if you were to use a t-stat that is set at 220 deg. (do they even sell one? ) then the coolant wouldn't go below that temp. That's because the purpose of the t-stat is to keep the coolant above (or at least equal to) the temp that it's set at.

Now do you understand?

AJ

 

Hey Pukka did you see a benifit from the switch from 195 to 180?

 

Yes I did, the engine takes longer to get to 220 degrees. Before the swap, my temp while driving used to hang between 170-180...now it stays just below 160.

 

Minor addition here- the thermostat (whatever its temp. rating) if operating correctly (i.e. not stuck in closed position) has absolutely no bearing/effect on the maximum cooling of the system. I.e. once it's open, it's open and if your engine wants to sit at 220 degrees it is totally 100% irrelevant if your thermostat is a 160, 180, 195 degree unit. As stated by others above- it will control the minimum temperature the engine operates at (i.e. in cold weather conditions). You can vary the fan switch settings to anything you want over the thermostat rating to try and control the maximum temperature (i.e. a 160 stat. could have the fan switch set at 190-on 180-off to try and keep the temp at around 190 or so all the time, assuming the rest of the cooling system is up to the task).

As for the original question- thermostat in this case is irrelevant- check your switches and also check to see if the fan is operational (not seized). Also be sure your lower air deflector under the front is installed, if it came off you'll overheat consistently. Also, make sure your fan shroud is intact and installed correctly.

 

I meant did you get a power benefit, economy loss?