I was wondering if anyone know how and if at all possible to reset the rad.'s ffan turn on and off temp settings. I replaced my stock stat with the 180 and when sitting in traffic notice how the temp rises back to the highs that are associated with the stock stat. I read that the coolant has to have an on temp of 207 and off of 199. I would like to take that down to 190 on and 185 off. Can anyone help?

Thats a PCM setting-- best you could do without getting an aftermarket chip is put in the fan switches. Then just turn them on when you feel you want the cooling. PFYC has 'em.

ferb!

QUARKMAN SAYS: I read that the coolant has to have an on temp of 207 and off of 199. I would like to take that down to 190 on and 185 off.

MY QUESTION: I've seen several people trying to lower their normal operating temperature. Since lowering a car's operating temperature decreases it's thermal efficiency (the ability to convert the energy stored in gasoline to mechanical energy), I am curious; why do you want to do this?

Regards, Gary in Sandy Eggo

My primary reasoning on lowering the temperature by 15F was increasing cooling due to the high heat generated by the Supercharger, which adds to the overall temperature of the reaction in the chamber and by the time the coolant flows by the cylinder to take the heat away, the cylinder walls are supeheated. I entertained a few options on how to lower the temperature of various components due to punching the car a bit harder then I used to and all the modifications that I did were reactive. Addition of an intercooler would be most preferable for me but that is way too expansive.
I looked at the efficiency drop and gas milage drop and I think this 15 deg decrease is fairly reasonable.

So, what you really want to do is carry heat away from the cylinder walls as quickly as possible. There are two ways of doing that. One is to increase the temperature differential between the cylinder wall and the coolant. This is what you're trying to do by lowering the overall operating temperature. The other is to increase the conductivity coefficient between the coolant and the cylinder wall. Running a higher percentage of water in your coolant mix (60-70% water instead of 50-50) might do this. Water has a higher heat capacity per pound (or gallon) than does glycole, and, it "wets" the cylinder wall better than does glycole. Perhaps a combination of the two would give you your best results. To accommodate the lowering of the coolant boiling point due to the lower percentage of glycol, you might want to install a radiator fan by-pass switch that would keep the fan going all the time while you're "in the heat of battle."

Since new pontiacs do not use glycol but the orange stuff which escapes my name right now, would the addition of water to it be as effective as its addition to glycol? Since the summers here are very warm and winters very very cold I was not certain if I should use a 50/50 mix and stuck with a 70/30 mix of coolant to water. What do you suggest. Should I drain a few liters and fill up the system with water?

It's still ethylene glycol with a touch of diethylene glycol. So it is a possibility. However... I would look around in the market for other, more worthwhile products.

Design Engineering Inc. has a product which claims to fight head hot-spots and lowers overall coolant temps. And of course you have the slurry of products from Red Line, Amsoil, etc, claiming to lower temps as well.

Frankly, i think the switch from a 195 to a 180 thermostat is a good call. I, however, am going with a drilled 195. Small holes drilled around the main 'port' allow coolant to constantly flow. This doesn't really lower overall coolant temperatures, but does allow constantly circulating liquid.

ferb!

QUARKMAN SEZ: Should I drain a few liters and fill up the system with water?

RESPONSE: Beyond the "engineering principles" of heat exchange, I really don't have any advice for what you're trying to do. Just a side point, however, whenever you introduce water into your cooling system, make sure its distilled water, not water from your garden hose. Tap water contains various minerals which "plate out" in your cooling system and supports the formation of scale - both of which reduce your cooling system's heat transfer capability.

Regards, Gary in Sandy Eggo

When it comes to bonding energies stored in intermolecular bonds, Hydrogen bonding is the strongest, so its not only that the water molecule itself has a tremendous amount of energy absorption in the covalent bond of O-H (492kJ/mol) but the but Hydrogen bonding has an additional 23kJ/mol to add to the total amount of energy required to break the bonds within the lattice of water. Now as everyone always says this energy system is specifically designed for H2O and any addition would become an impurity and decrease the ability of water to absorb the heat transferred to it. This means that even the cooling system's additives decrease the efficiency by allowing higher then 100C and lower then 0C operating temps. I was trying to use as much water for the very hot summers and very cold winters.

Also anyone who visits this thread, what ratio of coolant and water do you use? Any additives like radiator relief from DEI?

Thanks

QUAKMAN SEZ: When it comes to bonding energies stored in intermolecular bonds, Hydrogen bonding is the strongest, so its not only that the water molecule itself has a tremendous amount of energy absorption in the covalent bond of O-H (492kJ/mol) but the but Hydrogen bonding has an additional 23kJ/mol to add to the total amount of energy required to break the bonds within the lattice of water.

I RESPOND: WOW!!! Notwithstanding the "shooting fish in a barrel" exercise we just concluded in Iraq, this is my first true opportunity for "shock and awe". My dog just brought my hip-waders, so tell me more. ;-) That was a hoot.

Gary in Sandy Eggo

I have a question regarding this topic. When I first got my 98GT the temp would stay steady (+/- 5 deg) regardless of driving conditions. I've had other vehicles that did not fluctuate in the temp at all no matter how old. Last summer through present I've noticed my pontiac is fluctuating 20 deg under normal driving conditions. 190 while moving to 210 when sitting. Up/down/up/down the gage is like it's on a bungee cord. Fans come on around the 210 mark. Had the thermostat changed last summer. What gives? Is this typical of this car.

I do not know about GT's but when it comes to punching the GTP the S/C will increase the temperature of the coolant.I have changed my stock Stat and now with the new stat the increase is even bigger. The reason for this is that I do not have a bypass for the fans even though the PCM has decreased the temperature of the on an off of the fans as per the readout that I was able to scam of the CJ2 unit. The fan on is now at 195F vs. 208F that my unit displayed.

Hello,

190 is when the thermostat opens, the coolant runs through the engine at its peak, but, since the fans are running, the temperature still rises. It continues to rise until the fans turn on to let cooler air through the radiator. This cycle repeats itself over and over. It does it to a greater extent when it's hot out, and, it's not as noticable when moving, because air is being driven through the radiator by motion.
I don't know why it's all of a sudden more noticable to you, I noticed mine doing that the first summer I had it.
Later now,
Clint

thanks for the replies.....i guess i won't worry about it unless the temp goes above 210 and stays..then we've got a problem! Like I said before, it's odd because it didn't start happening until last summer and i've had the car since it rolled of the truck in late 97. I just bought a new xterra and it's temp gage stays in one local even when I go offroad. The 87 pathfinder I traded it in for never fluctuated at the gage either and that thing was put through hell. Maybe thermo's in suv's have higher full flow temp settings. i don't know. thanks again!