79 L42 Continuously running hot
08-09-2019, 10:07 AM
#1
Intermediate
Thread Starter
79 L42 Continuously running hot
I’ve tried everything and the car still runs around 220-230* with AC on and 215*with it off. I live in central FL and try not to drive it much in the summer. So far i have done the following:
1.) Champion 4 row Aluminum Radiator.
2.) Aluminum Radiator shroud.
3. 5500+CFM cooling fan.
4.) Stewart Stage 1 hi-flow water pump.
5.)180 and 160 degree hi-flow thermostats (no difference in temp with each).
6.) Zip corvette oil filled correct temp sender, wrapped in exhaust tape to keep out side temps from interfering.
7.) Wilcox corvette temp gauge resistor to make sure temp is accurate to my gun.
8.) Too Cool water wetter added to radiator.
9.) Synthetic Blend Oil in engine.
10.) full coolant flush.
i have a set of 1.75” SS headers to go on next to let it breath more.
At at this point I’m baffled on what i can do to make it run cooler. I have the lower valance so it should be getting required air, i also removed factory engine fan. All work has been done by two very reputable corvette specialist in town.
Any suggestions?!?
1.) Champion 4 row Aluminum Radiator.
2.) Aluminum Radiator shroud.
3. 5500+CFM cooling fan.
4.) Stewart Stage 1 hi-flow water pump.
5.)180 and 160 degree hi-flow thermostats (no difference in temp with each).
6.) Zip corvette oil filled correct temp sender, wrapped in exhaust tape to keep out side temps from interfering.
7.) Wilcox corvette temp gauge resistor to make sure temp is accurate to my gun.
8.) Too Cool water wetter added to radiator.
9.) Synthetic Blend Oil in engine.
10.) full coolant flush.
i have a set of 1.75” SS headers to go on next to let it breath more.
At at this point I’m baffled on what i can do to make it run cooler. I have the lower valance so it should be getting required air, i also removed factory engine fan. All work has been done by two very reputable corvette specialist in town.
Any suggestions?!?
08-09-2019, 03:02 PM
#2
Team Owner
Never heard of an L-42... If you mean an L-48, that is the stock small block Chevy V8 engine.
The first order of business is to verify that your vehicle's water temp gauge is [approximately] correct. Buy/borrow an infrared temp measuring device and compare its readings to the car's gauge. You may find that you gauge reads too high. If it agrees with the engine running in 210 or higher range, first check out ignition timing. A engine with retarded timing will run hot. Also determine if the vacuum advance can on the distributor is being fed by timed/ported vacuum (as it came from the factory) or by manifold vacuum (what the engine really needs). If you satisfy those issues, look to the hi-flow water pump generating too much heat by pumping too much fluid through the radiator with little time to allow the water to cool. The inlet to outlet temps on the radiator should show around a 20*F drop if you are to expect decent cooling. If you have less than 10*F temp drop across the radiator, get rid of the high-flow pump. Those are intended for higher rpm racing use...not street use.
The first order of business is to verify that your vehicle's water temp gauge is [approximately] correct. Buy/borrow an infrared temp measuring device and compare its readings to the car's gauge. You may find that you gauge reads too high. If it agrees with the engine running in 210 or higher range, first check out ignition timing. A engine with retarded timing will run hot. Also determine if the vacuum advance can on the distributor is being fed by timed/ported vacuum (as it came from the factory) or by manifold vacuum (what the engine really needs). If you satisfy those issues, look to the hi-flow water pump generating too much heat by pumping too much fluid through the radiator with little time to allow the water to cool. The inlet to outlet temps on the radiator should show around a 20*F drop if you are to expect decent cooling. If you have less than 10*F temp drop across the radiator, get rid of the high-flow pump. Those are intended for higher rpm racing use...not street use.
Last edited by 7T1vette; 08-09-2019 at 03:03 PM.
08-09-2019, 03:58 PM
#3
Dr. Detroit
Member Since: Mar 2012
Location: New Braunfels Texas
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Yes.....check your timing!
Jebby
Jebby
08-09-2019, 05:18 PM
#4
Intermediate
Thread Starter
Never heard of an L-42... If you mean an L-48, that is the stock small block Chevy V8 engine.
The first order of business is to verify that your vehicle's water temp gauge is [approximately] correct. Buy/borrow an infrared temp measuring device and compare its readings to the car's gauge. You may find that you gauge reads too high. If it agrees with the engine running in 210 or higher range, first check out ignition timing. A engine with retarded timing will run hot. Also determine if the vacuum advance can on the distributor is being fed by timed/ported vacuum (as it came from the factory) or by manifold vacuum (what the engine really needs). If you satisfy those issues, look to the hi-flow water pump generating too much heat by pumping too much fluid through the radiator with little time to allow the water to cool. The inlet to outlet temps on the radiator should show around a 20*F drop if you are to expect decent cooling. If you have less than 10*F temp drop across the radiator, get rid of the high-flow pump. Those are intended for higher rpm racing use...not street use.
The first order of business is to verify that your vehicle's water temp gauge is [approximately] correct. Buy/borrow an infrared temp measuring device and compare its readings to the car's gauge. You may find that you gauge reads too high. If it agrees with the engine running in 210 or higher range, first check out ignition timing. A engine with retarded timing will run hot. Also determine if the vacuum advance can on the distributor is being fed by timed/ported vacuum (as it came from the factory) or by manifold vacuum (what the engine really needs). If you satisfy those issues, look to the hi-flow water pump generating too much heat by pumping too much fluid through the radiator with little time to allow the water to cool. The inlet to outlet temps on the radiator should show around a 20*F drop if you are to expect decent cooling. If you have less than 10*F temp drop across the radiator, get rid of the high-flow pump. Those are intended for higher rpm racing use...not street use.
Timing was check by mechanic and it’s 48 not 42. It had same issue prior to water pump replacement. I went with the stage 1 over the recommended 3 because i knew I’d never race the car. I installed the Wilcox resistor and dialed the gauge in with that and my IR gun. It’s roughly 3* off. That’s why I’m so stumped. I’ve run thru all the above and it’s still running hot.
08-09-2019, 05:35 PM
#5
Racer
Member Since: Oct 2001
Location: Portage La Prairie Manitoba
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I’ve tried everything and the car still runs around 220-230* with AC on and 215*with it off. I live in central FL and try not to drive it much in the summer. So far i have done the following:
1.) Champion 4 row Aluminum Radiator.
2.) Aluminum Radiator shroud.
3. 5500+CFM cooling fan.
4.) Stewart Stage 1 hi-flow water pump.
5.)180 and 160 degree hi-flow thermostats (no difference in temp with each).
6.) Zip corvette oil filled correct temp sender, wrapped in exhaust tape to keep out side temps from interfering.
7.) Wilcox corvette temp gauge resistor to make sure temp is accurate to my gun.
8.) Too Cool water wetter added to radiator.
9.) Synthetic Blend Oil in engine.
10.) full coolant flush.
i have a set of 1.75” SS headers to go on next to let it breath more.
At at this point I’m baffled on what i can do to make it run cooler. I have the lower valance so it should be getting required air, i also removed factory engine fan. All work has been done by two very reputable corvette specialist in town.
Any suggestions?!?
1.) Champion 4 row Aluminum Radiator.
2.) Aluminum Radiator shroud.
3. 5500+CFM cooling fan.
4.) Stewart Stage 1 hi-flow water pump.
5.)180 and 160 degree hi-flow thermostats (no difference in temp with each).
6.) Zip corvette oil filled correct temp sender, wrapped in exhaust tape to keep out side temps from interfering.
7.) Wilcox corvette temp gauge resistor to make sure temp is accurate to my gun.
8.) Too Cool water wetter added to radiator.
9.) Synthetic Blend Oil in engine.
10.) full coolant flush.
i have a set of 1.75” SS headers to go on next to let it breath more.
At at this point I’m baffled on what i can do to make it run cooler. I have the lower valance so it should be getting required air, i also removed factory engine fan. All work has been done by two very reputable corvette specialist in town.
Any suggestions?!?
Cooling fan correct rotation?
Correct timing?
08-09-2019, 05:44 PM
#6
Intermediate
Thread Starter
Both in town and on highway, fan is sucking not blowing, timing was checked by prominent corvette shop in town. I’m going to replace upper and lower radiator hoses with stiffer ones as I’m not 100% sure if they were replaced. I’ve read of some being old and squishy and restricting flow.
08-09-2019, 06:11 PM
#7
Dr. Detroit
Member Since: Mar 2012
Location: New Braunfels Texas
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Timing was check by mechanic and it’s 48 not 42. It had same issue prior to water pump replacement. I went with the stage 1 over the recommended 3 because i knew I’d never race the car. I installed the Wilcox resistor and dialed the gauge in with that and my IR gun. It’s roughly 3* off. That’s why I’m so stumped. I’ve run thru all the above and it’s still running hot.
Jebby
08-09-2019, 06:26 PM
#8
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Thread Starter
08-09-2019, 06:29 PM
#9
Dr. Detroit
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08-09-2019, 06:38 PM
#10
Le Mans Master
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Every time I see a aftermarket W.P. (Stewart Stage 1) has been added, I wonder if its a serpentine system running the pump the wrong direction or a V belt W.P. running the wrong direction.
Last edited by HeadsU.P.; 08-10-2019 at 06:25 PM.
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Engage (08-09-2019)
08-09-2019, 06:42 PM
#11
Le Mans Master
Email @lars for his timing papers (his email address is all over this Forum), and ask for his timing papers. You might want to ask for his HEI and Carb setup papers as well. You'll need a timing light, but then you'll know if your car's timing is correct. A Corvette Specialist mechanic should know better, but if they just follow what is in your owners manual, with a low idle advance and ported vacuum, your car is absolutely not set up correctly, and will run hot and have less power.FWIW, check your octane, too. An L48 should run fine on 87 octane, except when it doesn't. My 80 had run-on (dieseling) at shutdown the one time I tried 87. Both of my L48s get 93 every time.
08-09-2019, 10:32 PM
#12
Intermediate
Thread Starter
Email @lars for his timing papers (his email address is all over this Forum), and ask for his timing papers. You might want to ask for his HEI and Carb setup papers as well. You'll need a timing light, but then you'll know if your car's timing is correct. A Corvette Specialist mechanic should know better, but if they just follow what is in your owners manual, with a low idle advance and ported vacuum, your car is absolutely not set up correctly, and will run hot and have less power.FWIW, check your octane, too. An L48 should run fine on 87 octane, except when it doesn't. My 80 had run-on (dieseling) at shutdown the one time I tried 87. Both of my L48s get 93 every time.
08-10-2019, 06:40 AM
#13
Le Mans Master
Ive heard or Lars, I’ve seen his papers talked about in a bunch of other threads. I run only rec 90 (non ethanol) with a Lucas upper cylinder lubricant in every other tank. I’m going to bring the car back to the shop that worked on it Monday and have them double check all their work and replace both radiator hoses. The guy i brought it to (Stan’s cocoa corvettes) is known for being the man in town for vettes.
I'd still suggest reading Lars' timing papers before you go. But even if you don't, please ask your mechanic what total mechanical (without vacuum) advance he is setting you to, and what RPM that occurs at. And if your vacuum advance is plugged into manifold or ported vacuum.
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Aarond (08-10-2019)
08-10-2019, 07:48 AM
#14
Race Director
Buy a timing light. Less than the price of one trip to the guy. They frequently set idle at spec and tell you whatever they think you want to hear.
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Aarond (08-10-2019)
08-10-2019, 08:25 AM
#15
Dementer sole survivor
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Does your lower radiator hose have the anti collapse spring in it? squeeze it and you'll feel it. If your car is hot at idle and on the highway its a flow problem, not an air problem if youre looking at a coolant solution.
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Aarond (08-10-2019)
08-10-2019, 08:37 AM
#16
Intermediate
Thread Starter
Email @lars for his timing papers (his email address is all over this Forum), and ask for his timing papers. You might want to ask for his HEI and Carb setup papers as well. You'll need a timing light, but then you'll know if your car's timing is correct. A Corvette Specialist mechanic should know better, but if they just follow what is in your owners manual, with a low idle advance and ported vacuum, your car is absolutely not set up correctly, and will run hot and have less power.FWIW, check your octane, too. An L48 should run fine on 87 octane, except when it doesn't. My 80 had run-on (dieseling) at shutdown the one time I tried 87. Both of my L48s get 93 every time.
08-10-2019, 08:40 AM
#17
Intermediate
Thread Starter
It feels like a normal hose, i can squeeze it very easily with my hand with car being cool. (Just went out to make sure). It’s hot weather im moving or at idle, it maybe drops a few degrees when I’m underway but nothing substantial.
Last edited by Aarond; 08-10-2019 at 08:41 AM.
08-10-2019, 11:08 AM
#18
Melting Slicks
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You should be able to feel the spring in the bottom hose , it will feel like solid " ribs ". Most of the hose apart from just near the end fittings should have "ribs"
08-10-2019, 12:12 PM
#19
Race Director
Hose gets softer as it gets hotter. Come home hot. Open hood. Rev engine up to 3k-3500. Hold it there 5 seconds or so while watching hose.
Last edited by derekderek; 08-10-2019 at 12:13 PM.
08-10-2019, 02:53 PM
#20
Intermediate
Thread Starter
I changed both hoses this morning, went with reinforced spring bottom (luckily ecklers is a close drive) and brand new top, kept car at consistent 222* with AC on At 2800RPM’s doing 65 on highway. It was around 217* with AC off under same conditions. Could it be an exhaust blockage? Cats are off and it has 2 inch + exhaust going into magnaflows.
Last edited by Aarond; 08-10-2019 at 02:56 PM.