Normal operating temperature
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7th Gear
Joined: Dec 2006
Posts: 7
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Normal operating temperature
I just recently bought an 88 vette. i noticed the other day that the temp gauge got up to 230 deg. is this normal?
it mostly does this around town, but it has done this once on the freeway. it usually stays around 200 deg on the freeway. i was concerned because 230 deg just seemed a little high. i remember reading somewhere that that's a normal temp for a vette (C4 anyway). is this true?
would it hurt to change the thermostat to a lower temp?
it mostly does this around town, but it has done this once on the freeway. it usually stays around 200 deg on the freeway. i was concerned because 230 deg just seemed a little high. i remember reading somewhere that that's a normal temp for a vette (C4 anyway). is this true?
would it hurt to change the thermostat to a lower temp?
Melting Slicks
Joined: Nov 2000
Posts: 2,469
Likes: 6
From: Winchester Ontario
That is the normal stock settings. If you choose to run it cooler, as many forum members do, you can grab a 180 degree T-stat and also get your pcm "tuned" to turn your fans on at an earlier temperature.
You can also get a manual fan switch, thus allowing you to manually turn on your fans whenever you choose to via a toggle switch. This item can be purchased through many corvette magazines and if you're an electronic wiz, you could probably even wire one up yourself.
You can also get a manual fan switch, thus allowing you to manually turn on your fans whenever you choose to via a toggle switch. This item can be purchased through many corvette magazines and if you're an electronic wiz, you could probably even wire one up yourself.
Le Mans Master
Joined: Dec 2000
Posts: 7,839
Likes: 22
From: San Diego, Ca
Seems a bit high at 230, but your gage may not be accurate. Main fan should come on at 226 and that should cool it down. Signal is from the Coolant Temp Sensor and not the gage sender, so to see/verify it, you need to hook up a scanner. If there's an aux fan - in front of the radiator. It should come on at 228. Plenty of Vettes came without that option and it should rarely if ever come on.
Above assumes the a/c is off. With it on, main fan control switches or is supplemented by a switch on the high pressure line. That switch is normally grounded, but when the pressure rises to 220 psi (about 120 degrees at the condensor), it opens and the main fan should come on. It will keep turning until the pressure drops to 170 - 190 psi. These pressures are considerably lower in temp than a/c off operation and a clean cooling and a/c system will result in lower operating temps as long as the a/c is on.
When you're cruising and above 40mph or so, the main fan doesn't come on at all and it should run at or near the thermostat - 195 degrees from the factory.
If you want to verify all of this, you need a scanner to check the Coolant Temp Signal and a manifold gage set to monitor a/c operating pressures while you observe the main fan. At the same time, you can monitor alternator output and make sure it's got battery voltage at idle. Anything less and the temps will climb because that will cause the fan to slowdown. Without any testing, it's all a big guess.
Above assumes the a/c is off. With it on, main fan control switches or is supplemented by a switch on the high pressure line. That switch is normally grounded, but when the pressure rises to 220 psi (about 120 degrees at the condensor), it opens and the main fan should come on. It will keep turning until the pressure drops to 170 - 190 psi. These pressures are considerably lower in temp than a/c off operation and a clean cooling and a/c system will result in lower operating temps as long as the a/c is on.
When you're cruising and above 40mph or so, the main fan doesn't come on at all and it should run at or near the thermostat - 195 degrees from the factory.
If you want to verify all of this, you need a scanner to check the Coolant Temp Signal and a manifold gage set to monitor a/c operating pressures while you observe the main fan. At the same time, you can monitor alternator output and make sure it's got battery voltage at idle. Anything less and the temps will climb because that will cause the fan to slowdown. Without any testing, it's all a big guess.
Le Mans Master
Joined: Feb 2006
Posts: 8,753
Likes: 9
From: Louisiana
I posted this in C4 Gen for a different situation, but most should apply to you.
If you are seeing 238* before the main fan comes on then there could be a problem. The main fan is controled by the ECM that gets it's coolant reading from the CTS (coolant temp sensor) in the front of the intake manifold (very important sensor). You may and may not have a auxillary fan located on the front of the radiator. You can see if from looking under the front bumper. It is controled only by a temp switch located between #1 and #3 spark plugs in the driverside cylinder head. That fan come on at ~238*. The temperature you see on the dash is not from the ECM, but from a coolant temp sender located between #6 and #8 in the passenger side cylinder head.
Factory setting for the main fan are burnt into the memcal (chip) in the ECM. Usually ~226* is when the main fan should come on. Depending on where you live...a 160* might be good and might not. If your t-stat is stock then it is a 195*. Here I use a 180* t-stat and have my fan programmed (in the chip) to come on at 200* and off at 180*. When driving MY temps stay around 179-181* and when idling it gets to around 201* before the main fan comes on. In my opinion I think the 180* t-stat is the best all around for the L98 Corvette.
Check between the A/C condenser for trash (bird nests, leaves, plastic bags, anything that will block air flow to the fins). Make sure the air is out of the coolant system as temps will stay on the hot side do to air pockets. Make sure the coolant level is full and there are no leaks in the system. Make sure the fan(s) are operating as they should. Use only the coolant the manual says. The L98 cooling system hold about 14 quarts total.
Factory setting for the main fan are burnt into the memcal (chip) in the ECM. Usually ~226* is when the main fan should come on. Depending on where you live...a 160* might be good and might not. If your t-stat is stock then it is a 195*. Here I use a 180* t-stat and have my fan programmed (in the chip) to come on at 200* and off at 180*. When driving MY temps stay around 179-181* and when idling it gets to around 201* before the main fan comes on. In my opinion I think the 180* t-stat is the best all around for the L98 Corvette.
Check between the A/C condenser for trash (bird nests, leaves, plastic bags, anything that will block air flow to the fins). Make sure the air is out of the coolant system as temps will stay on the hot side do to air pockets. Make sure the coolant level is full and there are no leaks in the system. Make sure the fan(s) are operating as they should. Use only the coolant the manual says. The L98 cooling system hold about 14 quarts total.
Drifting
Joined: Oct 2006
Posts: 1,934
Likes: 3
From: Citrus Heights California
230 is not considered hot for a C4. They were made to run at that temp. I installed a 160 thermostat, a Dewitt's radiator and a new chip to make mine run cooler. The chip kicks the fan on @ 175. You may not want to go through your 88 and do all these mods. As long as you don't go over 235, I wouldn't worry. Wait until summer. If your 88 does not overheat in traffic with the AC on you are good to go.
Le Mans Master
Joined: Jun 2006
Posts: 5,642
Likes: 5
From: One day you're a Comet...the next day you're dust... Arkansas
Determine IF you have an Aux. fan. If you do, you can install a sensor/ switch to turn it on at 200* instead of 238*. That sensor is less that $20 for a 1988. You can simply unscrew the old switch and screw in a new one between plug 1 and 3 in the drivers side head. I did this to my 1989. I also went to a 180* thermostat at the same time. Solved my problem for under $30. If you are running 230 on the highway in my opinion that is too high.
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Race Director
Joined: Sep 2000
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From: The Top of Utah
Originally Posted by brownhornet
would it hurt to change the thermostat to a lower temp?
RACE ON!!!
Le Mans Master
Joined: Sep 2006
Posts: 6,050
Likes: 147
From: Phoenix AZ
2021 C4 of the Year - Modified Finalist
temps
first, take the radiator out of the car, and clean out the debris that may be in the cavity between the radiator and the air cond. condenser.
then use reduced air pressure, blow out the radiator fins if there's a lot of bugs or tiny pebbles in there.
Otherwise, use a strip of aluminum .020 thick, 3/16 " wide, about 3 " long to push out the dead bugs n stuff.
If you use high air pressure, the fins will bend over and block the air flow.
THEN drive the car for a week, and then determine you need to do anything. The cars just run warmer than you have beeen accustomed to.
I put a 180 t-stat in mine, and it runs 189 on the freeway at 105 degrees in the summer.
I also wired my aux fan relay coil positive wire to my main fan power wire so that when the main fan kicks on, it energizes the aux fan relay, and starts the 2 fans together. it cools down pronto. The extra milliamp draw on the main fan circuit is negligible.
then use reduced air pressure, blow out the radiator fins if there's a lot of bugs or tiny pebbles in there.
Otherwise, use a strip of aluminum .020 thick, 3/16 " wide, about 3 " long to push out the dead bugs n stuff.
If you use high air pressure, the fins will bend over and block the air flow.
THEN drive the car for a week, and then determine you need to do anything. The cars just run warmer than you have beeen accustomed to.
I put a 180 t-stat in mine, and it runs 189 on the freeway at 105 degrees in the summer.
I also wired my aux fan relay coil positive wire to my main fan power wire so that when the main fan kicks on, it energizes the aux fan relay, and starts the 2 fans together. it cools down pronto. The extra milliamp draw on the main fan circuit is negligible.
