I have an issue with my car wanting to run very hot and push the limits of overheating while at idle or in traffic. However when I get up and rolling the car cools right of and no isues are noticed. I was lookin for some help. the car has DEXCOOL in the cooling system. Thats how it was when I bought it. I need to take care of this soon before i take it across the desert southwest here in the dead of summer! Any help is appreciated!

 

How hot does it get? Mine gets to around 230 or so before it starts cooling down. I mentioned this a little while ago and the person who helped me said that these cars run hot and that there wasn't anything wrong. Mine won't overheat, it just gets up there.

Also, if you change from Dexcool to the green stuff, flush the system COMPLETELY before the switch.

 

If it still has the original radiator, replacing it with a stock aluminum one will help. Also, fabricating a fan shroud for a single fan or going to dual fans will pull more air through the radiator in traffic.

 

My 85 Camaro was spiking to 235 degrees or so in hot weather at Idle and then cool off when moving. Changed to a dual fan with 200/185 on and off switch and a 180 themostat. Solved the problem even on real hot days in slow heavy traffic. Has never got much over 200 degrees. It works great in cold weather too. Heater works fine... I installed a 350 H.O. and it still works fine.
Hope that helps.

 

The car hit about 235ish, then I got rolling in traffic so it wasnt an issue. The car was doing this in 50-60 degree weather. I was just concerned that when it hits 110 here in June that the cooling wont be able to keep up. Ill look into switching fans and to a cooler thermostat, just dont have a ton of cash now. Trying to do economical, long lasting, good fixes. Also, is there really a difference in how DexCool vs. the green stuff in how they cool the car? Thanks for the advice so far!

 

Well you might wanna see when like temp wise when the fans turn on and also check the water to coolant ratio in your rad and me personally use the cheap coolant and im fine But you might just wanna check your fans and then if they are fine and actually turn on then just flush your system and that should fix it.

 

is your water pump good? how about your fan? I installed a 160 degree t-stat on my 3.1L V6 and it just about NEVER gets above 200. check yours, too.

 

I did a complete system wring out. It turns out that the gauge is highly inaccurate (Go figure). I replaced the fan relay before I checked eveything out....just in case, but everything works like a champ. As of now im not too worried anymore!

 

Also, 230 is not abnormal. the stock fan temp switch doesn't turn on until upwards of 235 anyway. Never EVER EVER use dexcool. For more info on why, just search for "dexcool"
anywhere. If you haven't changed the radiator cap in a few months, it would be nice to see a picture of the underside of it. 10:1 says that it will be caked with orange crud ...and so will the rest of the coolant system.

Dont put a 160 degree t-stat in unless you like not running in closed loop mode. Without major changes to the ecm, a 160 degree t-stat will do much more harm to performance than good. Unless you like replacing a catalytic convertor every year from running wayy too rich all the time.


but you're right to not really be worried. It sounds like normal operation. For now anyway, it's just a matter of time with that dexcool crap in there.

 

QUOTE:
Dont put a 160 degree t-stat in unless you like not running in closed loop mode. Without major changes to the ecm, a 160 degree t-stat will do much more harm to performance than good. Unless you like replacing a catalytic convertor every year from running wayy too rich all the time.



abt the t-stat: the ECU does not switch into closed loop according to coolant temp. It goes into closed loop when the O2 sensor is fully heated. until then, it stays in open mode until it has voltage from the O2 sensor. during that time is when you have the WORST fuel mileage. the reason I run a 160 is to reduce detonation. I have 12:1 pistons with ported and polished heads. Iv'e already lost a complete set of pistons because of it. when i changed the t-stat to a lower temp, it helped out ALOT. then i started runnung VP 114 gas, and it went away. I let mine warm up for abt 10-15 mins. before taking off. I like to go as far as I can on my tankful of VP for as long as I can. thats **** is expensive now. and as far as the cat goes, ditch the thing. i hate em' with a passion. the day i got home with mine the first thing i did is cut that thing off and weld a pipe in place. The throttle response i got was a night and day difference. later on i got a 3.5" mandrel bent exhaust system installed.

 

I don't care where you live 235 is hot!! i know these cars tend to run on the "high side of everyones normal" but in AZ that may lead to problems later the 160 thermostat should help. speaking of which anyone know what thermostat came in the 1994 3.4l v6 by chance? mine is doing the same thing with a brand new stat of "oem" specs (so says the pimply teenager at the auto store anyway =) )

 

It's at the upper limits of the designed operational temperature the engines were made to run at. That's why the fan only comes on at that point, and why the thermostats are 195 degrees. It's "Normal". Everyone gets it in their head that cooler == better and figure, cooler air == better, so cooler engine == better so i should try to make the engine as cool as possible, that's not the case. The engine's efficiency is highest at these high temps, it's the limitations of the fuel and oil that limits your ability to run at even higher temps.

You want to run the engine as hot as you can before running into issues like detonation. 160 degree t-stat for most people not running heavily modified engines (really high compression), is too cold. The ECM will never kick the engine into closed loop mode because it never gets hot enough unless you're just sitting still. The engine, since it's running cooler, is running significantly less efficiently than it could be running, resulting in loss in fuel mileage and power.

Another thing, since we're worried about AZ temps. If the car is at 235 degrees, the t-stat is open whether it's 195 degree or 160. So moving to 160 if you have a 195 (stock) wont help you at all. The radiator and fan is all that can help you if your temp is up at 235 degrees. If the fan can't lower the temp, then you need to investigate coolant restrictions, clogged radiators, or non-functional fan or insufficient fan power.

It's important to remember, the temp when you are just sitting idle, will be whatever the fan temp settings tell it to allow the car to be. It turns on around 235 and turns off around 200'ish i believe. Also important is that the fan turns off when the speed of the car is over 40mph, so a bad air dam would cause problems for you. But 160 or 195 or 180 degree thermostats wont save you from high idle temps if you are still using the stock fan temp switch to control when it comes on.


edit: i know it's counter-intuitive for some people to say hotter == better. It's correct to think that cooler air == denser which means you can shove more fuel at a time into the cylinder and get more power than with hotter air. That is true, and because it's very hard to insulate the intake air from the heat of the engine, a very hot engine tends to heat the intake air more than a cooler engine, so at some point you have to reach a compromise. Aside from that, with cars not equipped with a MAF sensor, intake air must be within a given range that the ECM has been programmed with and which the sensors can handle. Too cold, and the computer has no clue as to how much air is really in the cylinder. That's why those types of cars have that thermac vent in the intake to heat incoming air. In the winter, not having the intake air heated to the correct range yields poor perfomance, that might be masked by the fact that you'll likely be running too rich. So yes, while it may feel more powerful, and you may not notice the decrease in mileage, your cat is probably getting ruined.

 

no i have the fan on a manual switch but i found out that when i did the wiring i crossed wires and the fan spins the wrong way. well duh lower=/=better, all a lower temp does is make you feel better about running a low temp it doesn't gain you any performance , but 235 is still a little high normal for these cars is 200-210 isn't it?

 

195 is the t-stat. The fan switch is set at around 235. So the correct range is between 195 and 235. Though, 180 is still plenty hot to get you into closed loop.

 

QUOTE:
Aside from that, with cars not equipped with a MAF sensor, intake air must be within a given range that the ECM has been programmed with and which the sensors can handle. Too cold, and the computer has no clue as to how much air is really in the cylinder.

no, these cars don't have MAF's, but they do have IAT sensors to tell the ECU what temp the intake air is. The ECU uses inputs from the TPS, IAT and MAP sensors to tell it how much fuel to feed the engine. so yes, the ECU does know how much air is in the cylinders. BTW, SCREW CATS!!

 

They have sensors for the temp, but the equations used to determine how much air actually is in the cylinder (the temp isn't the same in there as it is where the temp sensor is in the TB) depends on a given temp range. Outside of that, and the equations no longer give "correct" outputs. That's why thermac exists. It's not there to punish you, it's there to make the intake air warm enough for the equations to work if the intake air is initially too cold.

With a MAF, you know the air that passes it equals the volume of air entering the cylinder. Plain and simple. The mass doesn't change. Not true for our system, which is why the equations have to assume certain characteristics to remain simple, and that required them to maintain a specific range of air temp. Go outside of it, too cold, too hot, and even if the sensors still give accurate readings, the ECM wont be able to give you the correct AF ratio due to the limitations in the equations.