Overheating Issue....
Thread Starter
Intermediate
Joined: Mar 2015
Posts: 28
Likes: 1
Overheating Issue....
Hello,
I have a 1967 with a 327 (350hp) which is running very hot. It had a flex style fan with a clutch eliminator installed previously. I never had a temp. issue with this set up. This winter I installed a correct 5 blade fan with a GM replacement fan clutch. Now when I am at a stop light or the car is not moving the temp climbs up to 210. Is the clutch bad? I read on here that there was a trick to adjust the round spring in the front which I did. Is it possible that’s the issue? The fan does spin and the temp is fine while driving. Thank you all in advance for any help.
I have a 1967 with a 327 (350hp) which is running very hot. It had a flex style fan with a clutch eliminator installed previously. I never had a temp. issue with this set up. This winter I installed a correct 5 blade fan with a GM replacement fan clutch. Now when I am at a stop light or the car is not moving the temp climbs up to 210. Is the clutch bad? I read on here that there was a trick to adjust the round spring in the front which I did. Is it possible that’s the issue? The fan does spin and the temp is fine while driving. Thank you all in advance for any help.
Intermediate
Joined: Apr 2005
Posts: 46
Likes: 8
I had the same issue with my 66 with same motor. I kept the original fan, but added the direct drive(fan clutch elimination). No more issue. Someday, i may get a correct clutch again, but no hurry.
I checked the clutch and it seemed to be working correctly, but something was wrong.
I changed everything else out first, water pump, thermostat, radiator, checked timing, used a infrared heat gun to ensure guage was correct, etc.
I checked the clutch and it seemed to be working correctly, but something was wrong.
I changed everything else out first, water pump, thermostat, radiator, checked timing, used a infrared heat gun to ensure guage was correct, etc.
Thread Starter
Intermediate
Joined: Mar 2015
Posts: 28
Likes: 1
Spacing?
To answer a few questions. I purchased the Fan Clutch as a replacement NOS part for a C2. I belive it was marked CJ as all the GM replacments were? I do recall there may be an 1/8 difference between the CJ and CK? Is there a way to add a 1/8 spacer? Would adding a washer do it? Are you asking because you think it may be to close to the shroud? The issue I had the the flex fan is that it hit the shroud and took a small chunk out of it. I have coverd the missing portion with tape for now until I can find a replacement. I can not tell but I was thinking the fan may be hitting the shroud, but its about an inch away from it.
Last edited by haaron; May 11, 2015 at 09:56 AM.
Team Owner
Joined: Mar 2003
Posts: 26,118
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From: Greenville, Indiana
Stand by for someone who knows or has done it.
Melting Slicks
Joined: Aug 2004
Posts: 3,078
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From: Riverhead New York
Check your Distributor Timing to start. What Thermostat is in the car and is it opening fully? Have you tried Water Wetter? Cars with AC have extra Gaskets around the Shroud to keep air Flow coming threw the Radiator without leaking in from behind it. You could install this. How old is Radiator? Drain Down system and refill properly with Distilled water and anti Freeze. Never buy "Pre Mix" as you do not know if Mix was with Distilled water or Chlorinated Mineral water from a Municipal Well. Your report of a Max Temp of 210 is not harmful in itself even though it is annoying. The Radiator in my 67 AC car is original and car runs cool even with AC engaged. Keep us Posted please, Al W.
Team Owner
Joined: Aug 2007
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Army
Confirm your dash gauge reading with an I/R temp gun...C1/C2 temp sending units are notorious for being off -- sometimes 20 degrees or more. And, you can reclock your fan clutch to engage at a lower temp - several posts on here about how to do it....
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Thread Starter
Intermediate
Joined: Mar 2015
Posts: 28
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Check your Distributor Timing to start. What Thermostat is in the car and is it opening fully? Have you tried Water Wetter? Cars with AC have extra Gaskets around the Shroud to keep air Flow coming threw the Radiator without leaking in from behind it. You could install this. How old is Radiator? Drain Down system and refill properly with Distilled water and anti Freeze. Never buy "Pre Mix" as you do not know if Mix was with Distilled water or Chlorinated Mineral water from a Municipal Well. Your report of a Max Temp of 210 is not harmful in itself even though it is annoying. The Radiator in my 67 AC car is original and car runs cool even with AC engaged. Keep us Posted please, Al W.
Team Owner
Joined: Mar 2003
Posts: 26,118
Likes: 1,874
From: Greenville, Indiana
The car ran fine temp. wise with the other flex fan and fan clutch eliminator. Seems like all the other stuff really did not change, so it leads me to think its the clutch, or the fan. Maybe I put the fan in backwards? The fan has a flat straight edge, I put that facing down, is that wrong?
See post #6.
Le Mans Master
Joined: Feb 2014
Posts: 8,892
Likes: 5,429
From: Richardson Texas
What is the ambient temperature when your temp gauge is showing 210 degrees and you're idling at a stop light? 210 degrees is not overheating and could be operating completely normal. I can't tell from your profile what part of the country you're in, but down here in Texas 210 when the ambient is 90 degrees or more, idling at a light with the A/C on is perfectly normal.
Thread Starter
Intermediate
Joined: Mar 2015
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Ambient temperature...
What is the ambient temperature when your temp gauge is showing 210 degrees and you're idling at a stop light? 210 degrees is not overheating and could be operating completely normal. I can't tell from your profile what part of the country you're in, but down here in Texas 210 when the ambient is 90 degrees or more, idling at a light with the A/C on is perfectly normal.
Safety Car
Joined: Feb 2006
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Burning Brakes
Joined: Aug 2013
Posts: 1,071
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From: palm springs ca
To answer a few questions. I purchased the Fan Clutch as a replacement NOS part for a C2. I belive it was marked CJ as all the GM replacments were? I do recall there may be an 1/8 difference between the CJ and CK? Is there a way to add a 1/8 spacer? Would adding a washer do it? Are you asking because you think it may be to close to the shroud? The issue I had the the flex fan is that it hit the shroud and took a small chunk out of it. I have coverd the missing portion with tape for now until I can find a replacement. I can not tell but I was thinking the fan may be hitting the shroud, but its about an inch away from it.
Dom
Team Owner
Joined: Oct 2000
Posts: 38,897
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From: Washington Michigan
Here's some more Corvette cooling system information that's essential to understand:
http://www.lbfun.com/warehouse/tech_...em/cooling.pdf
The tip of the fan blades should be half-in/half-out of the rear edge of the shroud for best fan efficiency; the further forward you go from there, the less air the fan's going to move.
http://www.lbfun.com/warehouse/tech_...em/cooling.pdf
The tip of the fan blades should be half-in/half-out of the rear edge of the shroud for best fan efficiency; the further forward you go from there, the less air the fan's going to move.
Thread Starter
Intermediate
Joined: Mar 2015
Posts: 28
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Udate
Here's some more Corvette cooling system information that's essential to understand:
http://www.lbfun.com/warehouse/tech_...em/cooling.pdf
The tip of the fan blades should be half-in/half-out of the rear edge of the shroud for best fan efficiency; the further forward you go from there, the less air the fan's going to move.
http://www.lbfun.com/warehouse/tech_...em/cooling.pdf
The tip of the fan blades should be half-in/half-out of the rear edge of the shroud for best fan efficiency; the further forward you go from there, the less air the fan's going to move.
Drifting
Joined: Dec 2014
Posts: 1,752
Likes: 137
From: Chantilly Virginia
Several decades ago I had an Oldsmobile with a thermostatically controlled fan. It eventually developed a severe overheating problem while towing a trailer. The fan appeared to be working fine when hot, but easing several sheets of rolled up newspaper into the blades brought it to a complete stop. It's a messy test, but if your car is really hot at idle, the fan should be just about locked to the shaft.
Le Mans Master
Joined: Feb 2008
Posts: 5,214
Likes: 447
From: NJ Hockey beer league
You have removed a constantly spinning fan (probably one with more blades as well) and replaced it with the original design which is not designed to be spinning constantly. I think by doing this, you have exposed a problem that lies elsewhere in your cooling system as the old fan was compensating some for another problem. First thing I would do is check the thermostat and take a good hard look at that radiator. If the radiator is an old copper replacement, that could be your problem as well. 
Pilot Dan
Pilot Dan
Team Owner
Joined: Jun 1999
Posts: 41,792
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From: Houston,Texas USA
Yes. There is a clock spring on the front of the clutch. The are two notches to hook the spring. You move the spring to the other notch but I can't remember whether you tighten the spring or loosen it a half turn. That will make the clutch tighten up about 15* sooner.
Stand by for someone who knows or has done it.
Stand by for someone who knows or has done it.
Thread Starter
Intermediate
Joined: Mar 2015
Posts: 28
Likes: 1
I moved the spring counter clockwise the other night. last night I took the car for a quick spin but I am not sure it was long enough for the car to fully heat up. It did seem to be better, but I will have to take it out for a longer drive to confirm. One question when I shut the car off the fan basically stopped, it did not spin to a stop. Also the tension/drag felt about the same as when the car was cold. Again, I may need to get the engine temp. up higher to confirm.