'79 operating temperature
Thread Starter
Heel & Toe
Joined: Jul 2012
Posts: 20
Likes: 0
From: Bakersfield CA
'79 operating temperature
Hi all, I have a '79.
I read through several posts on running hot and I will get my cooling system checked out. The other day the outside temperature was 100+ degrees and I was on the highway and the temp reached close to the red mark @240 degrees. I'm concerned now because the coolant mixture was gurgling. I'm sure that's not good.
At one point when I stopped at a gas station the coolant was leaking on the ground. This has never happened before. I've only owned the car for two weeks though
The temperature did stabilize toward the middle of the guage ~220when I was just cruising.
At what temperature does damage begin to happen?
Is there a recommended coolant I should be using?
Thanks!
I read through several posts on running hot and I will get my cooling system checked out. The other day the outside temperature was 100+ degrees and I was on the highway and the temp reached close to the red mark @240 degrees. I'm concerned now because the coolant mixture was gurgling. I'm sure that's not good.
At one point when I stopped at a gas station the coolant was leaking on the ground. This has never happened before. I've only owned the car for two weeks though
The temperature did stabilize toward the middle of the guage ~220when I was just cruising.
At what temperature does damage begin to happen?
Is there a recommended coolant I should be using?
Thanks!
Drifting
Joined: Mar 2011
Posts: 1,886
Likes: 9
That's too hot.
The efficiency of the cooling system will determine the max operating temp. You definitely need:
A good flowing radiator (clean, inside and out),
A working fan,
All the factory shrouding and radiator seals,
The front air dam (to divert air up and into the radiator),
A working water pump. Sometimes a very old, neglected impeller can rust away so badly it will not actually pump any water (rare, but possible in a 30 plus year old car). If you open the radiator cap and it looks like mud in there, it's possible.
Bad ignition timing or a too lean carburetor might also make it run hot.
The efficiency of the cooling system will determine the max operating temp. You definitely need:
A good flowing radiator (clean, inside and out),
A working fan,
All the factory shrouding and radiator seals,
The front air dam (to divert air up and into the radiator),
A working water pump. Sometimes a very old, neglected impeller can rust away so badly it will not actually pump any water (rare, but possible in a 30 plus year old car). If you open the radiator cap and it looks like mud in there, it's possible.
Bad ignition timing or a too lean carburetor might also make it run hot.
Burning Brakes
Joined: Oct 2001
Posts: 1,241
Likes: 4
From: Okinawa Okinawa
Coolant leaking on ground - Have you found the source of the leak? Radiator, hoses, any connection into the engine (water pump, head gasket, intake)
220 is too hot. I was running 205 with my old engine and was worried. With my new engine I never run over 180. Do you have any idea how old the water pump is? I'd flush the system, change hoses, etc. and check the water pump. No special coolant needed. I still get the green coolan and mix 50/50 with water.
Congrats on the 79. Enjoy it.
220 is too hot. I was running 205 with my old engine and was worried. With my new engine I never run over 180. Do you have any idea how old the water pump is? I'd flush the system, change hoses, etc. and check the water pump. No special coolant needed. I still get the green coolan and mix 50/50 with water.
Congrats on the 79. Enjoy it.
Le Mans Master
Joined: Oct 2007
Posts: 7,442
Likes: 967
From: Tennessee/Rhode Island
I don't want to rewrite what I have posted on this topic before and again just recently. Do a search on jb78L-82 to view my full comments but here is the skinny: The 78/79 L-82 ran notoriously HOT from the factory for emissions reasons. My 78 L-82 4 speed A/C car and my buddies 79 L-82 4 speed, also bought new, routinely ran 225 degree normal operating temperature, 235-240 on the highway with the A/C on hot days. I have done everything posted above plus much more and the car now runs max 180 degrees on the hottest days. PM me if you want all the details.
Race Director
Joined: Apr 2003
Posts: 19,347
Likes: 654
From: Tampa, Florida
The normal operating temp of my C4 and C5 was upwards of 230...I think the high speed fan kick on in the 230+ range.
It's normal for a radiator to 'gurggle' over into the overflow tank when you turn the car off. it's going inot heat sink mode and that's just how the system works.
Do the basics first, change out the coollant to a 50/50 mix and make sure you the proper pressure rated radiator cap. Fill the overflow to the 'min' line when cold and refill as needed untill the systems done 'burping' all the all air.
It's normal for a radiator to 'gurggle' over into the overflow tank when you turn the car off. it's going inot heat sink mode and that's just how the system works.
Do the basics first, change out the coollant to a 50/50 mix and make sure you the proper pressure rated radiator cap. Fill the overflow to the 'min' line when cold and refill as needed untill the systems done 'burping' all the all air.
Burning Brakes
Joined: Apr 2009
Posts: 807
Likes: 2
From: VIRGINIA BEACH VIRGINIA
My 79 averages right around 180-200 normal driving. When there is a need to go very fast on the highway (>80mph) the temp will get up around 220 but never higher. I have a new water pump, radiator, hoses, 180 degree thermostat and most of the gaskets around the radiator.
Mine is a stock 350 and automatic with headers and dual exhaust.
Make sure you have the front air dam/spoiler on the front underneath......if you don't have it, your temps will be crazy high.
Mine is a stock 350 and automatic with headers and dual exhaust.
Make sure you have the front air dam/spoiler on the front underneath......if you don't have it, your temps will be crazy high.
Thread Starter
Heel & Toe
Joined: Jul 2012
Posts: 20
Likes: 0
From: Bakersfield CA
My 79 averages right around 180-200 normal driving. When there is a need to go very fast on the highway (>80mph) the temp will get up around 220 but never higher. I have a new water pump, radiator, hoses, 180 degree thermostat and most of the gaskets around the radiator.
Mine is a stock 350 and automatic with headers and dual exhaust.
Make sure you have the front air dam/spoiler on the front underneath......if you don't have it, your temps will be crazy high.
Mine is a stock 350 and automatic with headers and dual exhaust.
Make sure you have the front air dam/spoiler on the front underneath......if you don't have it, your temps will be crazy high.
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Le Mans Master
Joined: Oct 2007
Posts: 7,442
Likes: 967
From: Tennessee/Rhode Island
1. Make sure timing is set correctly according to the sticky on the forum.
2. No pollution control-no cat, EGR valve etc. The 882 emissions heads restrict coolant flow to raise head temps for emissions-cant be helped if you want to remain OEM
3. Aluminum Dewitts or other aluminum radiator
4. Dual 2.5 inch exhaust with free flowing mufflers. Headers a plus.
5. Stewart High Flow Aluminum stage 2 water pump or equivalent with 180 Robertshaw modified thermostat.
6. L-82 Rubber radiator spoiler extension to increase airflow to the radiator.
My car never shows a temperature of more than 180 degrees whether on the highway or in traffic. When new the car ran 225 normally and up to 235-240 with the A/C on the highway!
Last edited by jb78L-82; Jul 18, 2012 at 07:51 AM.
Race Director
Joined: Apr 2003
Posts: 19,347
Likes: 654
From: Tampa, Florida
Le Mans Master
Joined: Oct 2007
Posts: 7,442
Likes: 967
From: Tennessee/Rhode Island
Sometimes I think there's a huge misconception of what 'normal operating' temperature is. Running a 180 thermostat simply means 180 is your minimum operating temperature, there's nothing wrong with running hotter than that. 'Gurgling' into to the overflow tank is normal, it's a sign of a properly working system but it's relative as to what pressure and temps it's occuring. I dont think there's anything wrong with a street driven car running temps up to 220 or so.
1. The 79 temp gauge was changed so that the 12 O'Clock position of the gauge read 225 instead of 200 on the 78's.
2. The 79's had an auxiliary electric cooling fan added inside the radiator to help with cooling.
3. The 79's had a rubber lip extension spoiler added for cars with HD cooling since the 78 system was not meeting he task.
Clearly GM knew something was not optimal and that was the reason for the changes. These high temps were needed for one reason only-Emissions. Optimal operating temperatures when not concerned about emissions is 180-200, not 225-240. The high operating temperatures also contributed to head cracking on the L-82 882 emissions cylinder heads.
Simply put, these high temperatures are not ideal for a 78/79 L-82-different for modern days engines. Hope that helps!
Race Director
Joined: Apr 2003
Posts: 19,347
Likes: 654
From: Tampa, Florida
The 78/79 L-82s as stated previously routinely ran 225 as the normal operating temperature and as high as 235-240. GM knew that there was a problem in 79 and made 3 changes to help bring the temps down:
1. The 79 temp gauge was changed so that the 12 O'Clock position of the gauge read 225 instead of 200 on the 78's.
2. The 79's had an auxiliary electric cooling fan added inside the radiator to help with cooling.
3. The 79's had a rubber lip extension spoiler added for cars with HD cooling since the 78 system was not meeting he task.
Clearly GM knew something was not optimal and that was the reason for the changes. These high temps were needed for one reason only-Emissions. Optimal operating temperatures when not concerned about emissions is 180-200, not 225-240. The high operating temperatures also contributed to head cracking on the L-82 882 emissions cylinder heads.
Simply put, these high temperatures are not ideal for a 78/79 L-82-different for modern days engines. Hope that helps!
1. The 79 temp gauge was changed so that the 12 O'Clock position of the gauge read 225 instead of 200 on the 78's.
2. The 79's had an auxiliary electric cooling fan added inside the radiator to help with cooling.
3. The 79's had a rubber lip extension spoiler added for cars with HD cooling since the 78 system was not meeting he task.
Clearly GM knew something was not optimal and that was the reason for the changes. These high temps were needed for one reason only-Emissions. Optimal operating temperatures when not concerned about emissions is 180-200, not 225-240. The high operating temperatures also contributed to head cracking on the L-82 882 emissions cylinder heads.
Simply put, these high temperatures are not ideal for a 78/79 L-82-different for modern days engines. Hope that helps!
Le Mans Master
Joined: Oct 2007
Posts: 7,442
Likes: 967
From: Tennessee/Rhode Island
I understgand what your saying but I guess my point is that alot of people think anything over 180 is NOT normal when it is and the same with 200...IMHO 200 is normal, it may not be the ideal temp for maximum performance but it is normal. There's nothing wrong with running 200 all day long.
BTW-My gauge is accurate-checked it with a Infrared thermometer.
Le Mans Master
Joined: May 2002
Posts: 5,084
Likes: 786
From: Lebanon Township New Jersey
There is no need to run a 50/50 mix of antifreeze and water. 75/25 water to antifreeze will transfer heat better, 80/20 even more so. I don't think you're too worried about freezing.
