[C2] 1966 over heating solved
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Intermediate
Joined: Jun 2015
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1966 over heating solved
Running down the highway on a 90 degree day with factory AC on, temp would run about 215 degrees and when i exit at a red light, would climb to 235. Forget about idle would redline. Checked gauge with infrared thermometer, new thermostat, water pump, fixed vacuum on distributer and set timing with zero results. I replaced 5 blade fan with a 7 blade using the same clutch and BINGO. Now with the same conditions, runs 170 on highway and 195 at idle.1966 with ac and automatic. hope this helps.
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From: Arlington TX
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I thought 7 blade fans were made for engines with air conditioning.
Team Owner
Joined: Jul 2006
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From: Kannapolis NC
I think you'll eventually find something else is going on. The change in air flow between a 7 and 5 blade fan isn't enough to make that much difference. It makes no difference at highway speed. The air flow at speed is determined by volume of air pushed through the radiator from the front. I'm glad it's better, but just don't think that's why.
Thread Starter
Intermediate
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That is why! Definitely the problem. I would not try to discourage people that fast. The car is working great for 3 weeks now. If I would have changed clutches it could of been a facter. I was told to do this by a
retired GM service writer. He told me back in the late 60"s when people would bring over heating problems they would go to a 7 blade fan immediately. I have been fighting this problem since I purchased the car.
retired GM service writer. He told me back in the late 60"s when people would bring over heating problems they would go to a 7 blade fan immediately. I have been fighting this problem since I purchased the car.
Team Owner
Joined: Jul 2006
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From: Kannapolis NC
I'm really glad you're happy and that the temp is down on your car. But a drop in temp from 215 to 170 at road speeds cannot possibly be the addition of two blades on the fan. Idle and slow speed is possible to get some extra air flow, but a 45 degree drop when driving is more than a miracle. A fan does not lower temp at speed, and in fact can slow air flow slightly, thus the use of a clutch fan by GM. Unless your other fan was in backwards and pushing air against the radiator and reducing flow from the front at speed, the fan didn't reduce it that much. Sorry that you think that's discouraging, but facts sometimes are. Again, I am truly glad your problem has gone away, everyone else with temp problems is not so fortunate.
Thread Starter
Intermediate
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The tech also told me that they went to a 5 blade fan in mid 1966. Thats when the problems started. returned back to 7 blade a couple years later. I do not know if this is true but I think he knows a lot. I forgot to state 327 300 hp
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Team Owner
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From: Kannapolis NC
My 65 with 300hp and a/c came with a 7 blade fan. I changed the stuff you did plus added a $900 aluminum Dewitt's radiator. It never idled less than 215 without a/c. (180 on the road). Turn on the a/c at idle and after 10 minutes it was over going past 225. Highway speed of 70 mph on a hot day with a/c and it would also climb over 220. That's with a 7 blade already installed.
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Intermediate
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I have been around 40 years working on cars and put on many fan blades. good though but it was on right. he has been telling me to do this but I was to stubborn, would have bet anything it would of not worked.
Race Director
Joined: Apr 2015
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From: Fresno California
I'm with 65GG, but am glad the problem is fixed. Two more blades on the fan, all else being equal, would matter zero going down the road at speed. Zip. UNLESS the new fan is sitting at a more optimal depth into the fan shroud.....if the previous 5 blade fan was too deep into the shroud, the turbulence would negatively affect cooling. So if the 7 blade is shallower, and less intrusive into the shroud, that would indeed make a difference. I have the optional 5 blade clutch fan on my '61, but since it's a 383 and likes to run hot when it's 100 degrees outside, I would love to install a 7 blade fan. Every little bit helps.
Race Director
Joined: Apr 2005
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From: Bowling Green, Kentucky
My 1967 327/350 HP has a seven blade fan installed. They were used for factory AC cars early in the C2 period, changed back to 5-blade around 1967, and then the C3 with AC cars eventually got 7-blade fans again.
It is am improvement.............but not certain it can/will make the difference that the OP indicates, unless something else changed along with it.
But I would recommend it (7-blade) for the factory AC cars based on my own experience over the years. Glad it helped the OP.
The condition and lock-up setting of the fan clutch is probably more important than the number of fan blades.
FWIW.
Larry
It is am improvement.............but not certain it can/will make the difference that the OP indicates, unless something else changed along with it.
But I would recommend it (7-blade) for the factory AC cars based on my own experience over the years. Glad it helped the OP.
The condition and lock-up setting of the fan clutch is probably more important than the number of fan blades.
FWIW.
Larry
Melting Slicks
Joined: Apr 2006
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From: Sunnyvale CA
I don't know what the pitch angle of the blades was for the 7-blade fan, but the 5-blade A/C fan had a steeper pitch than the non-A/C fan. 34.5 degrees vs 24.5 degrees. or something like that.
Instructor
Joined: Sep 2015
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is it possible that the fan clutch was not engaging but after you fussed with it is freed up. What temp does the clutch stiffen up at? was it hard to start the car after you idled at 235? I am fighting the same issue, ordered new DeWitt radiator installing over the weekend