Coolant / Operating Temp

[rwantin]

Forgive me in advance if this sounds rather dim and elementary. I have always done my own work, but it has been YEARS for some reason since I have addressed a cooling system.

I have not been able to drive it that much this season for various reasons (that will change now), but I have noticed it seems to be running a bit warmer than last year. It seems to get to 195 or above much quicker than before, and doesn't seem to lower much with cooler air going through the radiator while driving. I may just be imagining it, but it seems like I have to use the cooling fan more often, and it also doesn't seem as effective. Last night was pretty cool here, but even on a short drive it went to 195 and over, and I wasn't sitting.

Coolant level looks fine, as does the coolant itself. I bought this car, thus not sure of the thermostat situation. Stock compression 1989 HO 302, warmed over (cam, porting, manifold, 625 Demon carb), so nothing wild there.

What would a normal operating temp or range be for this? Thermostat hanging up (though I don't believe that to be the case)? Switch to a 180 degree? Cap not pressurizing the system properly? Am I just being an automotive hypochondriac?

Thoughts welcome, and again, sorry to sound like such a neophyte.

[Bob Cowan]

Stock 302 thermostat for a late model EFI/smog motor is 195*. In the olden days, the carbed motors ran at 180*. So it all depends on what thermostat is in there.

Personally, I prefer a 180* thermostat with a small hole drilled in it. Don't get worried about it until it hits 220* or so.

[68GT500MAN]

I would not be worried about 195. I also would not switch to the 180 thermostat since all it will do is open 15 degrees sooner than the 195. Drilling a small hole (1/8") positioned at the top of the opening can help with any air trapped in the system.
Doug

[walt mckenna]

I had a similar problem with mine early on. I have a 4.6 DOHC all aluminum mod motor that takes forever to warm up, but runs a little hot (in my opinion) during normal operation. I pulled the thermostat and put it in a pan of water on the stove (my wife wasn't happy about that) with a thermometer. The thermostat cracked open at 180 and was fully open at 195. My fan comes on at 200 and off at 195, so I guess 195 is where mine want to run so I stopped worrying about it. I did have a circumstance where the temperature went to 210 on a hot day in stop and go traffic so I installed a fan shroud, at the recommendation of this forum, and that problem went away.

[rwantin]

Thank you gentlemen, a bit less worried about it now. I'll keep an eye on things (actually, I need to get back behind the wheel some more!) Understood on the opening 15 degrees earlier, just throwing out some thoughts. The shroud sounds like a good idea, as I don't have one.

Much appreciated.

[skullandbones]

Hi rwantin,

If you don't have a shroud, get one. These radiators are not going to pull much air at rest without help. I have a dual fan with shroud from Summit. It also has rubber by pass flaps to let air escape the shroud when at speed. They close when you are at rest thus maximizing the pull on the fans. One thing I did was run the car at rest for several cycles of the cooling fans. It should get to the max temp under normal conditions and then cool to the minimum temp and then repeat each time. My cycle is from 185 to just over 200 degrees. You can also get a variable temp thermostat that fits in the fins of the radiator if your cooling cycle is a little too far out of the desired range. Fortunately, mine is just about right for my driving conditions. I also added a top shroud that mounts on the 3/4 inch tube running across the top of the radiator. It closes off the space between the body and the radiator to help force more air thru. Just a note about thermostats: it could be that it is getting a little contamination on the shaft that holds the spring/plate that moves on the thermostat. I would change that out just for peace of mind. They don't always go out at once.

Good luck,

WEK.

[CraigS]

I would put a 180 in there asap. Gives you a chance to replace an old part that may be starting on the end of it's life. T-stats do wear out. I disagree that this wouldn't be an improvement. We can debate what a max temp that can be reached w/o damage is but, whatever the number is, a 180 deg stat has you 15 degrees further from it. I notice w/ mine it is a lot easier to keep it close to 180 if I flip the fan switch on at 185 than if I let the sensor turn the fan on at 195. A lot of the time getting into a situation is as much about time idling as it is ambient temp. W/ that extra 15 deg cushion, you may be moving again before you need to worry.

[durk]

Have any of you guys tried or heard about Evans waterless coolant it is non corrosive boils at 350 degrees is a life time coolant and since it does not boil the cooling system is not pressurized. I am considering using it in my build. Check out the Jay Leno U-Tube Video

[Bob Cowan]

I'm not a big fan of Evans. You have to start with a completely dry system. So switching from one to the other is difficult.

The big goal is to keep a race from blowing it's top when the temps get too high. If they're running 280-300*, they'll keep going to finish the race even if it kills the engine. But in a street car, 280* is a bad thing, whether the coolant is boiling or not. If your temps are that high, you need to stop.

[durk]

You don't run the car that hot, the car still runs at the thermostat setting unless there is something is wrong which needs to be fixed. The reduced pressure is good, it is a lifetime coolant, no corrosion on aluminum plus you have a buffer when you are a ways from home

[rwantin]

Thanks a ton guys, as I said, it has been eons since I have messed with a cooling system. Nice (relatively cool) day here in MI, may go out for a run and observe some more. I'll probably pick up a new thermostat sometime this week. Oh, and forgive my relative lack of familiarity with the car, turns out there is indeed a shroud.

Really appreciate it.

Robert