I know this has been asked to death but I see so many people with varying numbers as to what is normal. With the AC OFF while driving in town my car hovers right at 200 which seems pretty normal for 100 degree texas heat. In town with the AC on I can get up to the middle 230s. I have a 94 LT1 with headers everything else stock. I already blew out the radiator with compressed air which did help but still seems to be getting a bit too warm. My fans also seem to be working normally. Should I be trying like mad to get my temps down or just quit worrying?

 

Primary fan should activate around 228...... if your temps are not going above 230 in the conditions you cite, your cooling system is working as designed.

 

Question: When the A/C is on and the temps get to 230 as you mentioned...are you driving or sitting still???

Something to check when the engine is cold.

The 3/8" I.D. hose that is on the top passenger side of the radiator (where a radiator cap normally would be) and it runs to the expansion tank. It connects to a fitting just below the hose for your overflow...which is just below the cap. ****REPEAT**** DO THIS WHEN THE COOLANT AND ENGINE ARE COLD. Remove the radiator cap and when you crank the engine...using your finger...fell inside the expansion tank and feel for water flowing out of this port...into the expansion tank where the hose coming from your radiator is attached. This hose assembly that has crimped fitting and a aluminum block can get clogged. Thus NOT allowing air to get out of the radiator...even though you can loosen the fitting on the thermostat housing and get a stream of water...it the water can not flow out of the top of the radiator...you can have a air pocket. I run into this quite often where I have to blow out this line...which also sometimes requires me to remove the hose where it attaches to the tube at the back of the engine on the passenger side also.

Also...with the engine running (at idle) and your cooling fans come on at 226-228 degrees. How long does it take for the temperature to start to drop???...and the fans shut off???

Last but not least...you still have the air deflectors intact on the bottom of your front bumper....right??? IF they are not there...especially the center one...you are not scooping air into the radiator area...thus the air is passing under your car and not getting the air it needs.

How long has it been since the knock sensors where removed and ALL of the coolant has been drained and flushed out of the block and radiator??? The "Dex-cool" coolant is known to turn to a muddy thick glop and can effect the flow of the coolant and block passages. I deal with this issue often. You would be amazed on the "glop" that comes out when I flush a system. Make sure you test your radiator cap.

DUB

 

A functioning a/c results in lower coolant temps because the fan(s) come on sooner and stay on longer to maintain the temperature of the liquid it's making in the Condensor. For R134, that's in the area of 120 to 140 degrees, well below the thermostat, which will control Coolant temps. Unless the numbers you posted are reversed for a/c non a/c, it doesn't seem yours is working right. Usual causes are poor air flow and overcharged or plugged up systems. Checking operating pressures and Center Vent temp are a good place to start. You can also stick digital thermometer on the Condenser outlet (line to Evaporator at the Condenser) which will give you some idea of it's temperature.

 

I'm sorry, that's just plain incorrect for anyone outside a near perfect climate...like anywhere other than SD. Even the Ca desert is easy...move a bit further east and see what happens!

Maybe in SanDiego thats true, but in Az or New Mexico or Texas its absolutely NOT. I am comfortable that the rest of the gulp coast is the same way...because of the ambient, not anything else.

My motor is 'built' and makes a bunch of heat. I do have upgraded cooling enhancements to balance out the equasion...

Down the freeway in Houston today @ 70 mph I can cruise at 195-200 degrees with the a/c ON. It was about 105 on the concrete street.

Hit traffic and stop for a few minutes it goes to 235..more sometimes. As soon as I move again it falls, rapidly.

The same conditions without a/c get me the same temps on the freeway. T-stat manages the minimum temp, NOT the max.

However, in traffic without a/c I can sit there and idle all day and stay in the 200 range WITHOUT A/C. The minute that a/c is turned on the temps shoot straight UP and stay there and the fans are raising hell blowing like a hand held hair dryer.

A/c in extreme climates generates MORE heat. The radiator has to absorb the extra heat due to the design of the nose air box and how the ducts work. The condenser gives off a LOT of heat when its 105 degrees outside, that's the reflection of the heat that's been removed from the cabin, nothing else.
HOT like it was today, and the added condenser heat goes directly to the radiator to compound the engine operating temp. Heat is cumulative,...meaning it keeps adding up and driving the eng temp UP. The trans adds some more, so do the other coolers if so equipped.
If I want to make mine cool down faster when it gets up to 235-240 all I have to do is turn OFF the a/c for a few minutes...it drops within a couple minutes.

The desert and texas is a LOT different than the San Diego climate in every way...sorry, not trying to "call you out" but that statement just don't fly....
I can assure you that your car would behave just like mine or the Ops car does, IF you were in this climate... I am very comfortable with that after having lived with my current car in the SD area a few yrs ago...hell, back then it wanted to run at 163, I had to use a hotter
t-stat just to MAKE it get hot enough to pass smog in Ca...

BTW, my a/c system is firewall forward new, (less than 1 yr) pressures are right, radiator AND condenser are NEW. Its ALWAYS acted like this, just as everyone elses car does in extreme climates. A/c causes more heat...not less. In fact, I am building a better pusher fan assy to combat the a/c high pressure that come from extended idle time in Houston traffic...and loss of a/c from HP cut out.

To the original poster, Rawkmann....
your car is completely normal. Nothing to be concerned about. I saw 260 a few weeks ago during a blown hose incident and stuck on a 610 overpass with no shoulder...and didn't hurt anything.
Don't stress until it WON'T come down from 240+...that's when you look for a place to pull over and investigate. It should come down as you move, and rise the longer you sit. Vettes do not do well sitting still.

 

I decided to really test my 388 LT1 stroker install today.

I needed to drop some devices off to some fellow engineers about 30 miles away and rather than tanking my 2013 Armada I decided to heat test my 92 C4's engine transplant. In Dallas at 5:00pm about 100+ deg, AC is still not connected.

I was avg'n about 190 - 195 before summer really hit in my stock-ish 350 LT1, 220 if I was really ******* her.

TODAY I averaged 208 in stop and go traffic on the Dallas North Tollway. The highest I ever saw was 217 when I started to gain my confidence and started to have some fun.
Only really went above that if I decided to really rev it up.

Now I do have a New Radiator, Electric Water Pump, External Oil Cooler and I installed a temp switching fan relay and have it set to always on for the summer, the good news is that the factory main fan was not engaged or needed yet.

I am assuming the jump in avg temp is due to the engine displacement changing from 5.7ltr to 6.3ltr.

I will be installing my BigMouth Air Dam and I will report back in the next few days to see it also helps.

 

Whats been worrying me all along are all the other Vette owners saying their temps drop like rocks as soon as their AC is cut on. Growing up in Texas heat this goes against everything I've ever known lol. Yesterday the outside temp gauge on my Vette read 105 degrees, and these are pretty average temps for Texas in late August. If my coolant temp dropped while my AC was running I'd consider it a miracle! I'm going to check for air in the system and maybe a flush and refill, and TRY not to worry much about those hot temps.

 

Thats got to be a misprint or confusion.

The biggest difference is between OEM radiators and the aluminum aftermarket replacements.
The later controlling temps better. MUCH better.

 

SunCr is absolutely right, leesvet, on a stock or stockish, well maintained car. The cooling fans run w/the AC on and thus should cool better than w/the AC off in teh "around town" driving that the OP is talking about...PROVIDED that the radiator has the cooling capacity.

IN THIS CASE, the OP's radiator does not. His temps are climbing to above 230, which means that his cooling system isn't controlling the temp the way that it should be. "Mid 230's" isn't detrimental (it won't hurt anything), but the cooling system should be able to do better than that. The OP said that he blew out his radiator w/compressed air....I'm assuming that he is talking about the space between the AC condenser and the radiator. I suspect that the radiator is clogged/coated w/sludge internally and not providing the efficiency that it originally did. He needs to flush his radiator and coolant and/or buy a new radiator.

Driving "Around town" with the AC on, I expect temps to go no higher than 215.

 

Went out and inspected my radiator and there are many bent and damaged "fins" where the bottom air dam is. I believe I'm going to replace the rad and flush coolant and see what that does.

 

Well, the only thing I have to add, is that if your Condenser is pushing a crap load of heat, it's not making cold air. Granted, the OEM's had some difficulty coming to grips with what it takes to keep R134 under control once ambients hit the mid '90's and above. They started with 2 fans, then added multiple speeds, some now use 3 fans. I've seen some overcharging around here, but that's generally with conversions when too much gets crammed into it. And by the way, we have 100 plus out here; not everyday, but Santa Ana Season starts next week and none of my cars sees anything close to the 220's when it's 100 + (and thank god the last Emission's Test I had the tech forget to turn it off - a/c is exempt from the standards - it was 105!)

 

My bone stock '96 LT4 will run cooler with the A/C on during a hot summer day.
Only because the cooling fans are on.

With the A/C off, the fans won't come on until the coolant temps climbs to approx. 228°F
With the A/C on, it never gets that hot to begin with since the fans are running.

About 235°F is about as hot as my car has ever reached while sitting at a traffic light.
Oh, and I don't consider 230° - 235° to be too hot for a modern properly functioning cooling system.

Here in Missouri, the July-Aug temps can reach into the low 100's with over 90% humidity, so yes it gets hot and sticky here.

 

This statement fits my car to the T! I'm in the SoCa High Desert, and have seen Outside temps north of 110°.. In traffic,, A/C "on" I'll see 105-115° A/C "off" (only for testing purpose's) I'll see 230° before she cools back down with the Fans. I'm also at 3,000 ft MSL and in a fairly dry climate.

 

Well, now we know why the OP is confused, I see a lot of these but not much real agreement here.

 

I don’t understand the statement above. Air blows thru/across the condenser INTO the radiator. Without the A/C, the radiator sees ambient air temps. If the condenser is raised to 140 degrees, that will heat up the air as is blows thru it – on it’s way to the radiator. How does thermostat/coolant temperature factor into that process?

(Caviat: I don’t know if the condenser sits in front of an LT-x radiator – like it does on our L98 cars. I do understand that fans might be running longer and at lower temps (depending on ECM programming). But, I still never observed cooler temps with the A/C running. In fact, the opposite is true – as Leesvet described. I have a modified L98 myself…and am currently investigating radiator/condenser spacing, in addition to fan upgrades.)

 

But only because I'd like to be agreeable -- while asking questions!

 

How about this statement is this true? "The 3/8" I.D. hose that is on the top passenger side of the radiator (where a radiator cap normally would be) and it runs to the expansion tank. It connects to a fitting just below the hose for your overflow...which is just below the cap. ****REPEAT**** DO THIS WHEN THE COOLANT AND ENGINE ARE COLD. Remove the radiator cap and when you crank the engine...using your finger...fell inside the expansion tank and feel for water flowing out of this port...into the expansion tank where the hose coming from your radiator is attached" Mine seems to flow from expansion tank to radiator.

 

Without getting into thermodynamics and a bunch of physics I have long since forgotten, the Condenser always sits in front because it not only needs to be cooler than the Coolant; it also has to be rapidly cooled to prevent the gas from reaching a point that blows a hole in something. The spec I've seen is 1 to 1 and 1/2 inch. Ie, an inch to one and one half inches is all that's necessary for the heat that's been carried away from the Condenser to dissipate before that air is reused to cool what's in the radiator. The base temp of the Coolant will always be function of the thermostat. Actual temp is a function of capacity and air flow. Finally, if we ever get to an ambient that matches the thermostat, there's a mushroom cloud nearby and your Vette is the last place you will want to be.

 

That confirms/implies LT cars also have the condenser up front. I doesn't explain how raising air temp going through the radiator helps it to run cooler! Even if OEM spacing is near 1 1/2" (which is what I guessed based on pictures), you still have to assume air blowing across the radiator is warmer -- when the air is running. So, that increases the thermal load on the radiator. Once you get to a condition where it's hot enough for the fan to run, I don't get this discussion on the A/C making it cooler.

Yeah....Obvioiusly ambient will always be cooler than stat temp -- which is why ANY air moving across the radiator (and condenser) will aid in cooling. Often, you see reported running temps as a function of ambient + x-degrees. Put another way, you might see people posting that their car runs at 180...if 80 outside -- OR -- 200 if 100 outside. Heat up that condensor (by running the A/C) and the radiator should "see" hotter air -- and raise running temp.

Unless it's 50-degrees outside...or a mushroom cloud nearby.

 

I wouldn't mind seeing a link to that info.