Help, overheating???
Thread Starter
Instructor
Joined: Feb 2010
Posts: 112
Likes: 0
From: Gillette Wyoming
Help, overheating???
Have a 73 with 350 and automatic, The temp guage maxs out when I get on it some even after a short time driving, but will cool back down. I have dual electric fans and as soon as they kick on the guage goes down. Have done the normal things.
1. I check the guage by grounding it out when all the way up
2. Have new sensor
3. Flushed the radiator
4. pump is working can look and see flow in the radiator
5. Removed the thermastate, have none now
6. using 70/30 mix for coolant
7. Do not have heater hooked up, so plugged the line not just looped
back to the pump:*****
Does anybody have more ideas, Maybe have the wrong sensor(ohms)??
guage messed up???
1. I check the guage by grounding it out when all the way up
2. Have new sensor
3. Flushed the radiator
4. pump is working can look and see flow in the radiator
5. Removed the thermastate, have none now
6. using 70/30 mix for coolant
7. Do not have heater hooked up, so plugged the line not just looped
back to the pump:*****
Does anybody have more ideas, Maybe have the wrong sensor(ohms)??
guage messed up???
Burning Brakes
Joined: Aug 2006
Posts: 1,058
Likes: 27
From: Eastern North Carolina
Well judgeing from what you have told us, I see two things that might cause some problems. I would mix the coolant at 50/50 and maybe put a T-Stat back in it. How is you Radiator Cap? Is it holding pressure? Too much advance on your timing can also cause temp problems. With the two fans I would think you are getting enough air flow thru the radiator.
Hopefully other will respond to your post. Good Luck Tim
Hopefully other will respond to your post. Good Luck Tim
Melting Slicks
Joined: Dec 2006
Posts: 2,669
Likes: 3
From: Kingston Ontario
70/30 ? Do you live in Alaska? 50/50 is OK for most coolants. You are right on the limit with that ratio.
Put a thermostat back in. Your cooling fans are obviously do the job if driving down the temps.
What actual temperature does it peak at? Where are the sensors located for the fan. If the heater is disconnected then you should loop the bypass.
Tim types faster than me.
Put a thermostat back in. Your cooling fans are obviously do the job if driving down the temps.
What actual temperature does it peak at? Where are the sensors located for the fan. If the heater is disconnected then you should loop the bypass.
Tim types faster than me.
Thread Starter
Instructor
Joined: Feb 2010
Posts: 112
Likes: 0
From: Gillette Wyoming
The temp guage goes all the way 250... , The sensor is located on the block between #1 & #2 spark plug, thought it would run cooler with no thermostat, the cap holds presure if try to take of the cap when hot it sprays, the sensor for the fans is a probe in the radiator fins no problem if the fans kicking on, the only indication if running hot is the temp guage
Thread Starter
Instructor
Joined: Feb 2010
Posts: 112
Likes: 0
From: Gillette Wyoming
Maybe I will not forget something now, I plugged the heater hose not just looped it thought that would incress the flow though the main lines, if just a loop that fluid bypasses the block
Race Director
Joined: Mar 2006
Posts: 14,112
Likes: 28
From: Florida
You really need to know how accurate the gauge is reading. Test it with an ir gun, if possible.
You may be running very cold and the 250 may really be 195.
If you insist of running with no tstat, then gut one out and use the outer ring as a restricter, but an appropriate tstat won't cause overheating.
You are correct, plugging the heater outlets, reduces bypass to the radiator.
To test, put a tstat back in, wire your fans to run all the time and see what readings you get.
You may be running very cold and the 250 may really be 195.
If you insist of running with no tstat, then gut one out and use the outer ring as a restricter, but an appropriate tstat won't cause overheating.
You are correct, plugging the heater outlets, reduces bypass to the radiator.
To test, put a tstat back in, wire your fans to run all the time and see what readings you get.
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Thread Starter
Instructor
Joined: Feb 2010
Posts: 112
Likes: 0
From: Gillette Wyoming
when it is at idel it is OK they kick on , going by the guage , about 195 and cut out about 180 like I said going by the guage inside just running it, it goes so high then the fans have to catch up, maybe I will have to check more into see if the guage is even accurate.
Racer
Joined: Nov 2009
Posts: 384
Likes: 2
From: Tulsa OK
make sure your timing is correct, that turned out to be my problem.
I had to change my vac advance can to a B26 unit from a B1 due to low idle vacuum caused by a cam change.
Also, the static idle timing was only at 4 degrees.
When set at 12 degrees static, 36 degrees total, and another 16 degrees via a properly operating vacuum advance, my engine temp dropped dramatically.
Read the Timing sticky and Lars' paper on Vac advance units if you think this may be contributing to your problem.
Fred
I had to change my vac advance can to a B26 unit from a B1 due to low idle vacuum caused by a cam change.
Also, the static idle timing was only at 4 degrees.
When set at 12 degrees static, 36 degrees total, and another 16 degrees via a properly operating vacuum advance, my engine temp dropped dramatically.
Read the Timing sticky and Lars' paper on Vac advance units if you think this may be contributing to your problem.
Fred
Thread Starter
Instructor
Joined: Feb 2010
Posts: 112
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From: Gillette Wyoming
Do not know Fred, have the timing at 12 degree at idel now, startes good now hang-up and runs good, I am also thinking that may I need to flush the radiator again really good may be if part plugged it will cool ok at slow driving but at full speed it can not handel it, have flushed it once but maybe needs more cleaning. I have had a lot of that I think this car sat a while a lot of the parts needed a lot of TLC and cleaning before they were OK. check my "garage"
Racer
Joined: Nov 2009
Posts: 384
Likes: 2
From: Tulsa OK
I just wanted to make the point that timing has a bigger impact on cooling than many people realize. I never understood this until recently.
John Hinckley has a good article on C3 cooling issues. I downloaded it from Corvette Enthusiast website. I can email you a copy if you don't have it.
Some points:
Thermostat has little to do with overheating issues, Harrison aluminum radiator is key, getting good airflow through the radiatior is important (eg. proper installation of shroud, seals, air dam etc.).
John Hinckley has a good article on C3 cooling issues. I downloaded it from Corvette Enthusiast website. I can email you a copy if you don't have it.
Some points:
Thermostat has little to do with overheating issues, Harrison aluminum radiator is key, getting good airflow through the radiatior is important (eg. proper installation of shroud, seals, air dam etc.).
Thread Starter
Instructor
Joined: Feb 2010
Posts: 112
Likes: 0
From: Gillette Wyoming
Went out to the garage and looked at everything and did a littel thinking, I hope that it is just some thing with the gauge, when I putted the radiator to do some repaires on the frame I painted the they black do not if that was a good Idea maybe it is not letting it cool so good ??? Thanks fred will check out that article.
Thread Starter
Instructor
Joined: Feb 2010
Posts: 112
Likes: 0
From: Gillette Wyoming
Was reading anoghter forum and they were writing that it is very important to have the front air dam to dirrect air to the radiator, when I got this car the front end was busted up some and I have not replaced the air dam (now have none at all), they said it could make a big differance in air flow to the radiator may 40-50%, si this correct if so looks like it time for me to buy a air dam
Racer
Joined: Nov 2009
Posts: 384
Likes: 2
From: Tulsa OK
yes, the article I referenced above talks about the air dam and air flow importance.
Air flow and radiator were the major issues, as I recall. Many have replaced original aluminum radiators with brass/copper cheap replacements. They apparently don't cut it.
Air flow and radiator were the major issues, as I recall. Many have replaced original aluminum radiators with brass/copper cheap replacements. They apparently don't cut it.
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,112
From: Crossville TN
Here's the important question to answer: Is the temperature increase shown on the temp gauge real (engine is actually getting hotter), or is it 'virtual' (gauge is reading incorrectly when this event happens)? It could just be a fractured signal line going to the gauge. When you "step on it", that may create enough movement in the wire to "open" the fracture so that the gauge is maxxed out. Slow down, and the wire makes contact again and goes back to normal.
I'm not saying that's it...but it is a possibility. After you've been driving it and shut it down, leave the ignition key in the "ACCY" position so that battery power is getting to the gauges. Get under the hood and wiggle the temp sender wire to see what happens to the gauge reading.
I'm not saying that's it...but it is a possibility. After you've been driving it and shut it down, leave the ignition key in the "ACCY" position so that battery power is getting to the gauges. Get under the hood and wiggle the temp sender wire to see what happens to the gauge reading.
Race Director
Joined: Jul 2001
Posts: 15,892
Likes: 42
'73s (like the OP's) came with a brass/copper rad, no aluminum rads in '73 or later.
Drifting
Joined: Apr 2008
Posts: 1,305
Likes: 2
From: Lewisburg WV
thegazman
When you installed you electric fans did you make a cover for the top of your radiator? I had a similar problem after I installed my dual electric fans. I determined that the air coming off of my front air dam was escaping over the top of the radiator and not flowing through the radiator at highway speeds. I installed a cover over the top of my radiator forcing the air to flow through the radiator. It did okay at slower speeds with the fans running. The cover solved my problem.
Thread Starter
Instructor
Joined: Feb 2010
Posts: 112
Likes: 0
From: Gillette Wyoming
Thanks gazman and no I still have that 1.5" gap at ther top will seal everything up and get a air dam. Yes, Mike I have the original it is brass and copper have thought about a alum. one but will try the air dam and seals before I spend the $$ for a alum Rad. Thanks to everyone for the input, keep it coming have got some good iformation. Bill