Strange problem close to overheating

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Joined
Sep 12, 2015
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Location
SW Ontario
My Car
1971 Mustang Mach 1, M code, 4 speed.
I'm not exactly sure when flex fans were introduced on our cars, I wasn't this side of the pond yet!
I've told this before, but from march of 73, I worked at Canadian Fram in the prototype department hand building air cleaners and some controls devices, egr's egc and the like.
While I was not involved with the fan department, Fram made a great many fans for all the manufactures. I can't say with any certainty when the flex fan fiasco started, but I can say I've seen them blow up on the test rigs and bury blades into 4" of oak or maple. Imagine if that were your neck!!
Ok, so many will say " there are thousands out there without any problems", yes but do you want the one that does? You may never know until it blows up. Used fans from a junk yard should be very suspect and be avoided at all cost. The only sure way to prevent a possible problem is NOT to use one in the first place. Ok, if you have a trailer queen concours car that never drives, maybe you need the correct flex fan. Other than that no way Jose'.
I wouldn't even want one of those aftermarket flex fans, no telling what engineering went into them. If a company like Fram can do all the engineering and testing and still find field failures, what's the chance other companies got it right, I'll pass thank you.
Since I recently installed a clutch fan on my 71, I can say it has never gone passed the 190 degrees the t/stat is operating at. The one I bought is the Derale DER-17118 fan and a Haden HDA-2710 fan clutch from Summit Racing. Very happy with this set up.
 
Joined
Apr 14, 2019
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254
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59
Location
center Valley , pa 18034
My Car
72 Vert 351C White
Thanks for the detail. I'm sure I have an original fan and maybe I could get my hands on the blades to feel for something or tap on it. Probably best to remove and inspect at some point. I'm at cross road with my car as it drives and but sure would like to rebuild the engine and transmission..and and.....
 
Joined
Jan 2, 2019
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Location
Wisconsin
My Car
1972 Mustang convertible, 351C 2V with FMX (#'s matching)
Currently equipped with 351C 4V 4BM, .060 over, roller cam, Sanderson block huggers, -AC
Thanks for the detail. I'm sure I have an original fan and maybe I could get my hands on the blades to feel for something or tap on it. Probably best to remove and inspect at some point. I'm at cross road with my car as it drives and but sure would like to rebuild the engine and transmission..and and.....
Yes, inspecting it is the way to go. When I swapped out my 2V for the 4V mine checked out just fine and I couldn’t determine if it was OEM or a recall replacement. It does say “Front” on it though, and pulls plenty of air through the 3 core Al radiator and keeps everything at an even 180.
 
Joined
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Location
SW Ontario
My Car
1971 Mustang Mach 1, M code, 4 speed.
Thanks for the detail. I'm sure I have an original fan and maybe I could get my hands on the blades to feel for something or tap on it. Probably best to remove and inspect at some point. I'm at cross road with my car as it drives and but sure would like to rebuild the engine and transmission..and and.....
So I take you do have a flex fan. Best advice, don't even touch it. Chance are you have a good one, but trying to "test" the blades is asking for trouble. NEVER get your head anywhere near the fan when the motor is running, NEVER! Oh, and a warning to others, NEVER sand blast these blades to remove paint or rust.
The grain in the stainless steel used for those blades was very directional. It will bend in one direction, but will break in the other. I actually have a couple of blades in my stash that I cut and use for little springs (fixed our clothes dryer that way). Great material for that, but when heat treated incorrectly, that's when the problems start.
 
Joined
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Location
Pittsford, NY
My Car
My all time favorite vehicle is our 1969 Shelby GT500
Honest and reliable mechanics are indeed VERY hard to find. Good decision to stay with them, the new guy will learn. Chuck
That is one of the reasons I got into auto repair for a living years ago. I knew I could do better than those that were basically “parts changers.” Most techs I met were honest. I did find a few who did “shotgun replacement” of any and all parts with higher than usual labor times.
 

machphil

Active member
Joined
Feb 23, 2018
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24
Location
Illinois
My Car
'71 and '73 Mach 1's.
Dig that Opra Window!
That '77 was a beautiful body style. It was a boat at 4750# but great on long cruises and the 429 I later transplanted avoided several opportunities for speeding tickets. I installed a 140 mph certified speedo from a '79 LTD II police car but don't recall ever pushing it that hard. And in '88 or '89 when we had that blizzard it went from Janesville down to central Illinois busting 12" drifts without getting stuck while there were probably 5 cars and one semi in the ditch every mile. I often wondered what that car would look like, and feel like inside, if it were scaled down to the size of the '71 Mustang.
 
Joined
Dec 14, 2017
Messages
146
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119
Location
NW Pennsylvania
My Car
1972 Grabber Blue Mach One 351 Q code orig 4 speed. Now: 427C Titus
That '77 was a beautiful body style. It was a boat at 4750# but great on long cruises and the 429 I later transplanted avoided several opportunities for speeding tickets. I installed a 140 mph certified speedo from a '79 LTD II police car but don't recall ever pushing it that hard. And in '88 or '89 when we had that blizzard it went from Janesville down to central Illinois busting 12" drifts without getting stuck while there were probably 5 cars and one semi in the ditch every mile. I often wondered what that car would look like, and feel like inside, if it were scaled down to the size of the '71 Mustang.
Thanks for the great info. Also, concerning your 140 mph speedo comment; often times non-car people ask me what's the fastest I've driven in my Mach One, I just say "I can never recall going too fast in it" 😀
 
Joined
Jan 2, 2019
Messages
287
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Location
Wisconsin
My Car
1972 Mustang convertible, 351C 2V with FMX (#'s matching)
Currently equipped with 351C 4V 4BM, .060 over, roller cam, Sanderson block huggers, -AC
So I take you do have a flex fan. Best advice, don't even touch it. Chance are you have a good one, but trying to "test" the blades is asking for trouble. NEVER get your head anywhere near the fan when the motor is running, NEVER! Oh, and a warning to others, NEVER sand blast these blades to remove paint or rust.
The grain in the stainless steel used for those blades was very directional. It will bend in one direction, but will break in the other. I actually have a couple of blades in my stash that I cut and use for little springs (fixed our clothes dryer that way). Great material for that, but when heat treated incorrectly, that's when the problems start.
 
Joined
Jan 2, 2019
Messages
287
Reaction score
183
Location
Wisconsin
My Car
1972 Mustang convertible, 351C 2V with FMX (#'s matching)
Currently equipped with 351C 4V 4BM, .060 over, roller cam, Sanderson block huggers, -AC
Could that have been the genesis of the “caution fan” sticker, or were too many people just so excited to place their hands all over a performance engine while it was running and losing their fingers? 🤔
 
Joined
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Location
SW Ontario
My Car
1971 Mustang Mach 1, M code, 4 speed.
Could that have been the genesis of the “caution fan” sticker, or were too many people just so excited to place their hands all over a performance engine while it was running and losing their fingers? 🤔
Hmmm! I don't think so. Some people are just too dumb or stupid to know better and need a sign. "Here's your sign" (quote from Jeff Foxworthy)
Oh wait, this is from a guy who stuck his fingers under the deck of a running lawn mower. Fortunately, I only lost the tip of one finger. Yeah guys, don't laugh too hard, we all do stupid things at times. That by far take the cake for me.
 

machphil

Active member
Joined
Feb 23, 2018
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Location
Illinois
My Car
'71 and '73 Mach 1's.
Thanks for the great info. Also, concerning your 140 mph speedo comment; often times non-car people ask me what's the fastest I've driven in my Mach One, I just say "I can never recall going too fast in it" 😀
Yes, the 85 mph speedo sucked. I want to know that my speedos can handle 85 mph without losing them at that speed. o_O🤣
 
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