77 C3 running hot HELP!
Thread Starter
Burning Brakes
Joined: Apr 2009
Posts: 828
Likes: 2
77 C3 running hot HELP!
Hi,
On my 77 C3 I just took it straight home as the temp gauge started shooting up and I wanted to make sure that the gauge was working. (it was)
In June I put in a brand new water pump, all hoses (3 to heater core separated by new heater vacuum switch and 2 main and new hoses to fill canister), all new anti freeze, thermostat and pre flushed out and back flushed) the radiator and system.
When I got home, I just got my IR temperature gun and checked the car out.
This is how it read.
Top Hose off radiator 210
Lower hose off radiator 174
Water pump body 214
Can I have a defective thermostat?
Help please.
Thanks
Jack
1977 C3 L-82
On my 77 C3 I just took it straight home as the temp gauge started shooting up and I wanted to make sure that the gauge was working. (it was)
In June I put in a brand new water pump, all hoses (3 to heater core separated by new heater vacuum switch and 2 main and new hoses to fill canister), all new anti freeze, thermostat and pre flushed out and back flushed) the radiator and system.
When I got home, I just got my IR temperature gun and checked the car out.
This is how it read.
Top Hose off radiator 210
Lower hose off radiator 174
Water pump body 214
Can I have a defective thermostat?
Help please.
Thanks
Jack
1977 C3 L-82
Thread Starter
Burning Brakes
Joined: Apr 2009
Posts: 828
Likes: 2
I had to replace the water pump as it sprung a leak, so I replaced all hoses, etc too. The new one kept it a solid 170-180 with a/c on all summer till today. It is a 180 thermostat. I was at a light 2 blocks from my house when I saw smoke coming from my ac ducts that smelt like anti freeze but nothing when I opened the hood and no leaks from core. The inside gauge was in the 210-220 range
I didn't check fan. (what's the best way to do that?)
I have 2 fans with clutches in basement from my 67 GTO.
I will wait till car cools.
Thanks
Jack
Race Director
Joined: May 2006
Posts: 18,734
Likes: 2,582
so are you saying you installed a 180 thermostat? If you have smoke coming from a/c ducts that smells like antifreeze you may have a heater core leak. Check the carpeting on the passenger side footwell for antifreeze.
For the fan, with the engine off, try spinning it by hand, it should not turn more than maybe a half to full turn when hot. When cold maybe a full turn. In addition look for excessive play by grapping opposite fan blades and moving and signs of leakage of fluid from clutch.
For the fan, with the engine off, try spinning it by hand, it should not turn more than maybe a half to full turn when hot. When cold maybe a full turn. In addition look for excessive play by grapping opposite fan blades and moving and signs of leakage of fluid from clutch.
Le Mans Master
Joined: Apr 2011
Posts: 6,284
Likes: 1,171
From: Hermosa
My 77 with the original fan set up ran 220 all the time. If the air was on and at highway speeds 230+.
Now I have electric fans and it runs 185 in town and still 210 on the highway or if the a/c is on and 95+ out side 230. The 230 is worrisome but not anything it can't handle.
So 210 to 220 I wouldn't worry about. The thing that puzzles me is how you got 180 with stock fan configuration. Maybe your temp gauge was wrong in the past? Ever double check that 180 temp with an IR gun?
I guess assuming nothing else is different I would look to the fan clutch or the "new" water pump. You never with Chinese quality these days.
Had another thought. Did you notice any performance changes? I'm thinking failed vacuum advance diaphram causing ignition timing to be come suddenly retarded at cruise or low throttle openings.
Now I have electric fans and it runs 185 in town and still 210 on the highway or if the a/c is on and 95+ out side 230. The 230 is worrisome but not anything it can't handle.
So 210 to 220 I wouldn't worry about. The thing that puzzles me is how you got 180 with stock fan configuration. Maybe your temp gauge was wrong in the past? Ever double check that 180 temp with an IR gun?
I guess assuming nothing else is different I would look to the fan clutch or the "new" water pump. You never with Chinese quality these days.
Had another thought. Did you notice any performance changes? I'm thinking failed vacuum advance diaphram causing ignition timing to be come suddenly retarded at cruise or low throttle openings.
Last edited by REELAV8R; Aug 28, 2012 at 04:20 PM.
Thread Starter
Burning Brakes
Joined: Apr 2009
Posts: 828
Likes: 2
My 77 with the original fan set up ran 220 all the time. If the air was on and at highway speeds 230+.
Now I have electric fans and it runs 185 in town and still 210 on the highway or if the a/c is on and 95+ out side 230. The 230 is worrisome but not anything it can't handle.
So 210 to 220 I wouldn't worry about. The thing that puzzles me is how you got 180 with stock fan configuration. Maybe your temp gauge was wrong in the past? Ever double check that 180 temp with an IR gun?
I guess assuming nothing else is different I would look to the fan clutch or the "new" water pump. You never with Chinese quality these days.
Had another thought. Did you notice any performance changes? I'm thinking failed vacuum advance diaphram causing ignition timing to be come suddenly retarded at cruise or low throttle openings.
Now I have electric fans and it runs 185 in town and still 210 on the highway or if the a/c is on and 95+ out side 230. The 230 is worrisome but not anything it can't handle.
So 210 to 220 I wouldn't worry about. The thing that puzzles me is how you got 180 with stock fan configuration. Maybe your temp gauge was wrong in the past? Ever double check that 180 temp with an IR gun?
I guess assuming nothing else is different I would look to the fan clutch or the "new" water pump. You never with Chinese quality these days.
Had another thought. Did you notice any performance changes? I'm thinking failed vacuum advance diaphram causing ignition timing to be come suddenly retarded at cruise or low throttle openings.
my 69, 72, 76 & 77 all ran at 180 all year long, so I am going by that number.
My inside gauge was the same temp as my upper large hose off the radiator.
Why is my lower hose about 30 degrees cooler than my upper?
Thanks
Jack
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Burning Brakes
Joined: Oct 2008
Posts: 1,037
Likes: 14
From: Mobile Alabama
Car usually kept a solid 180-190 for the past 3+ years driving or in traffic (since I have owned it).
I had to replace the water pump as it sprung a leak, so I replaced all hoses, etc too. The new one kept it a solid 170-180 with a/c on all summer till today. It is a 180 thermostat. I was at a light 2 blocks from my house when I saw smoke coming from my ac ducts that smelt like anti freeze but nothing when I opened the hood and no leaks from core. The inside gauge was in the 210-220 range
I didn't check fan. (what's the best way to do that?)
I have 2 fans with clutches in basement from my 67 GTO.
I will wait till car cools.
Thanks
Jack
I had to replace the water pump as it sprung a leak, so I replaced all hoses, etc too. The new one kept it a solid 170-180 with a/c on all summer till today. It is a 180 thermostat. I was at a light 2 blocks from my house when I saw smoke coming from my ac ducts that smelt like anti freeze but nothing when I opened the hood and no leaks from core. The inside gauge was in the 210-220 range
I didn't check fan. (what's the best way to do that?)
I have 2 fans with clutches in basement from my 67 GTO.
I will wait till car cools.
Thanks
Jack
Thread Starter
Burning Brakes
Joined: Apr 2009
Posts: 828
Likes: 2
It has all of the IR readings!
The anti freeze (of course) is full and no leaks from core.
Thanks
Jack
Le Mans Master
Joined: Apr 2011
Posts: 6,284
Likes: 1,171
From: Hermosa
Back in the day,
my 69, 72, 76 & 77 all ran at 180 all year long, so I am going by that number.
My inside gauge was the same temp as my upper large hose off the radiator.
Why is my lower hose about 30 degrees cooler than my upper?
my 69, 72, 76 & 77 all ran at 180 all year long, so I am going by that number.
My inside gauge was the same temp as my upper large hose off the radiator.
Why is my lower hose about 30 degrees cooler than my upper?
Lower rad hose cooler after water passes through radiator.
Can't explain the the "smoke" from a/c ducts that smells like antifreeze unless it's leak in or near the heater heat exchanger (core).
Race Director
Joined: Mar 2006
Posts: 14,112
Likes: 28
From: Florida
Yes it does sound like the tstat is not opening fully or the fan not pulling enough..
You're coolant out temps seems a little low and the pump temp is too high..
They should be really close with the pump being just a tad higher. Maybe 5°
Seems like it's mostly circulating thru the bypass in the pump.
You should get a temp diff of about 20-30 degrees on the oem rad
Current tstats are notoriously prone to failure.
You're coolant out temps seems a little low and the pump temp is too high..
They should be really close with the pump being just a tad higher. Maybe 5°
Seems like it's mostly circulating thru the bypass in the pump.
You should get a temp diff of about 20-30 degrees on the oem rad
Current tstats are notoriously prone to failure.
Burning Brakes
Joined: Oct 2008
Posts: 1,037
Likes: 14
From: Mobile Alabama
I read all of the posts. You didnt say the coolant level was full. I was trying to comunicate (not very well, I guess) that you should open the radiator to look for circulation (that you wouldnt have with a stuck thermostat) when the IR readings say the thermostat should be open.
Thread Starter
Burning Brakes
Joined: Apr 2009
Posts: 828
Likes: 2
Please forgive me. I am terrible at typing and I usually think that I am understood if I don't dot every I and cross every T.
The smoke came out of the A/C duct 5 minutes before I shut down the car. I was running the car with the windows open and 10 minutes before I put the A/C on and I saw the smoke that smelled like anti freeze. I then shut it off and drove home. I just wanted to cool down a little as it was 95 degrees outside and the gauge was close to the red. No leaks and when I opened it, the rad was topped up.
When I got home the upper rad hose was in the 210 - 215 range and the lower rad hose was in the 174-180 range with an IR temp gauge.
I did have to wait close to 8 minutes from the time I shut the car down to the time I found the IR gun and used it.
So the temps must have dropped down a little.
I am totally thinking that I might have not changed the old thermostat on the 77 as I did my 63 & 77 on the same day.
The 63, I know that I flushed and changed everything, due to it being in the high 90's that day, it does weird things to all of us and I did find a Stant 180 in my tool box in it's box.
I might not have changed the 77.
That could do this, am I right?
Thanks
Jack
77 C-3
The smoke came out of the A/C duct 5 minutes before I shut down the car. I was running the car with the windows open and 10 minutes before I put the A/C on and I saw the smoke that smelled like anti freeze. I then shut it off and drove home. I just wanted to cool down a little as it was 95 degrees outside and the gauge was close to the red. No leaks and when I opened it, the rad was topped up.
When I got home the upper rad hose was in the 210 - 215 range and the lower rad hose was in the 174-180 range with an IR temp gauge.
I did have to wait close to 8 minutes from the time I shut the car down to the time I found the IR gun and used it.
So the temps must have dropped down a little.
I am totally thinking that I might have not changed the old thermostat on the 77 as I did my 63 & 77 on the same day.
The 63, I know that I flushed and changed everything, due to it being in the high 90's that day, it does weird things to all of us and I did find a Stant 180 in my tool box in it's box.
I might not have changed the 77.
That could do this, am I right?
Thanks
Jack
77 C-3
Burning Brakes
Joined: Oct 2008
Posts: 1,037
Likes: 14
From: Mobile Alabama
When I got home the upper rad hose was in the 210 - 215 range and the lower rad hose was in the 174-180 range with an IR temp gauge.
I did have to wait close to 8 minutes from the time I shut the car down to the time I found the IR gun and used it.
So the temps must have dropped down a little.
I did have to wait close to 8 minutes from the time I shut the car down to the time I found the IR gun and used it.
So the temps must have dropped down a little.
Last edited by 74modified; Aug 31, 2012 at 04:19 PM.
Thread Starter
Burning Brakes
Joined: Apr 2009
Posts: 828
Likes: 2
This doesn't necessarily mean the thermostat is stuck. The upper hose is hotter when thermo opens and the hot coolant flow to the rad. The bottom is returning (hopefully) cooled liquid to the engine. Many times a stuck thermo will cause overheating coolant in the engine (boiling) and with no escape out the top it will back out into the bottom of the rad. This could result in a hotter bottom hose and cooler top hose. All this said, you could change it out quicker than reading thru all of this.
Going to my supply store Tuesday after holiday.
Radiator boiled out, motor flushed, fan good, new anti freeze and water pump. All hoses replaced. Rad topped up and side can at full line. No leaks anywhere.
I will do thermostat again.
I am stumped
Jack
Melting Slicks
Joined: Aug 2010
Posts: 2,487
Likes: 10
From: Palm Beach Florida
St. Jude Donor '12
Either way, you should NOT have smoke OR anti-freeze smell from the ducts. That indicates a heater core going bad. You can simply by pass that with a hose. Then re-check to see if it still smells.
Thread Starter
Burning Brakes
Joined: Apr 2009
Posts: 828
Likes: 2
Hi All,
I am sorry, Mia Culpa-please forgive me.
It happened again and there was a light smoke coming out of the center ducts and I did smell anti freeze. I quickly pulled over and I saw that the fan was blowing a small amount of green from the cap towards the motor and that's what I smelled inside the car.
I just bought a new correct pressure cap too. The one on the car had a cracked seal under the cap.
I think that the smokish air is a bad O ring from going to 134 from R 22 without changing anything. I did a gamble by just changing the 2 hi & low pressure caps to 134. It held up all summer and is still blowing cold air in 90 degrees.
When I get the money I will do it correctly, but i am very cash tight as I have my 67 GTO convertible almost ready to lift off frame too.
I am using a pump and taking out of the radiator top about a gallon of green so I can replace the thermostat while the fluid is below the thermostat housing.
Fan is not wobbly and good.
Thanks
Jack
I am sorry, Mia Culpa-please forgive me.
It happened again and there was a light smoke coming out of the center ducts and I did smell anti freeze. I quickly pulled over and I saw that the fan was blowing a small amount of green from the cap towards the motor and that's what I smelled inside the car.
I just bought a new correct pressure cap too. The one on the car had a cracked seal under the cap.
I think that the smokish air is a bad O ring from going to 134 from R 22 without changing anything. I did a gamble by just changing the 2 hi & low pressure caps to 134. It held up all summer and is still blowing cold air in 90 degrees.
When I get the money I will do it correctly, but i am very cash tight as I have my 67 GTO convertible almost ready to lift off frame too.
I am using a pump and taking out of the radiator top about a gallon of green so I can replace the thermostat while the fluid is below the thermostat housing.
Fan is not wobbly and good.
Thanks
Jack
Le Mans Master
Joined: Oct 2007
Posts: 7,453
Likes: 976
From: RI, Now Franklin/Nashville TN
In the last 30 years I have known 2 cars that had "smoke" coming from the A/C ducts-74 L-82 corvette and a 72 caprice with a 350. Neither was a bad heater core! Both times, the thermostat was stuck closed and the engine was overheating.
Thread Starter
Burning Brakes
Joined: Apr 2009
Posts: 828
Likes: 2
Car sat idling for 20 minutes and inside gauge was at 12 o'clock once thermostat opened.
I saw smoke immediately from A/C duct, it has to be from the humidity outdoors. No smell just like when you breathe outside in winter, you get a smokish cloud from your mouth, same.
Tomorrow I will clean out radiator front and drive it a bit and see.
Thanks
Jack