Strange problem close to overheating

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1973 Mach 1 completely stock ivy green with silver stripes.
The problem I am experiencing is totally opposite of what I’m use to. I’ve just replaced the stock radiator because of it leaking. I replaced it with an aluminum radiator. When I’m driving the temperature goes almost to the overheat line. When I stop for a light it goes back to normal operating temperature. As I drive away from the light the temperature climbs back up. I have stock gauges and with the original radiator the temperature stayed consistent. When I say strange I mean usually the temperature would climb when stopped but go down when moving. Any suggestions as to why this is happening, I have the original radiator and one day plan to have it fixed but until that day I’m scared to use my car because of the high operating temperature.
 
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Is than an electric fan and they had it blowing out the front of the car instead of lucking air in?
No electric fan the guy put the stock fan on backwards instead of pulling air in it’s pushing air out. That’s why it cools while stopped and heats up when driving. I was thinking I created another problem by using an aluminum radiator. I was thinking that now I would have to get electric fans. I’m guilty of overthinking a problem instead of looking for the easy solution.
 
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A fan on backwards, wow!.
I hope that is not a 50 year old Flex Fan? If it is get rid of it as quickly as you can.
You might want to consider a clutch fan instead. I put one on my car and it works great.
If interested I or someone else will give you the part numbers.
 

Hemikiller

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I'm glad you got it figured out and thanks for posting the problem, I laughed out loud. I have never ever seen someone do that. Chuck

Even better - most Ford fans are marked FRONT as well....

the guy put the stock fan on backwards instead of pulling air in it’s pushing air out.

When you return to the garage, I'd insist that whomever worked on your car is to never, ever touch it again.
 
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Even better - most Ford fans are marked FRONT as well....



When you return to the garage, I'd insist that whomever worked on your car is to never, ever touch it again.
The work was done by a new mechanic at the shop. Usually the owner or the other mechanic work on my car but because it was a relative easy job they let the new guy do it. I’ve been using this shop for over three years and never had a problem . This new guy made a mistake and the shop is standing behind it. I’m not going to hold it against the mechanic everyone has to start some place and when starting out we all make mistakes. Hopefully he learns from this and goes on to be as good as the owner and the older guy who specializes in classic mustangs. I’m not going to let this damage the relationship I have with the shop. Their honest and reliable which are very hard traits to find these days. Over the last 3 years they have saved me a lot of money by being honest. I’m physically unable to perform most of the work needed on my car so it’s good to have a shop like this I can count on.
 
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The first thing I thought about when I read your post was a problem I've had in the past. If the lower radiator hose is missing the inner spring it may be fine at idle then collapse under acceleration. The first time a suspected this, I let the car idle and stood outside the driver's side. I put my left hand around the lower hose, then I used my right hand to hit the accelerator. As I applied a slight pressure on the hose, sure enough, it collapsed. This same thing can happen with an old hose where the spring is rotted away. Think about this if you ever have overheating when driving but normal temperatures at idle. This problem can be difficult to diagnose when it happens intermittently under different driving conditions.
 
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1973 Mach 1 completely stock ivy green with silver stripes.
The first thing I thought about when I read your post was a problem I've had in the past. A lower radiator hose that doesn't have the spring inside may be fine until acceleration and then it may collapse. The first time a suspected this, I let the car idle and stood outside the driver's side. I put my left hand around the lower hose, then I used my right hand to hit the accelerator. As I applied a slight pressure on the hose, sure enough, it collapsed. This same thing can happen with an old hose where the spring is rotted away. Think about this if you ever have overheating when driving but normal temperatures at idle. This problem can be difficult to diagnose when it happens intermittently under different driving conditions.
That’s a good point ! But I verified my fan was put on backwards because you can feel air being blown through the radiator towards the front of the car at idol. Besides that I have all new hoses, he’ll the whole system has been replaced. Heater core , blower motor , hoses, proper thermostat with restrictor plate and lastly a new radiator. The radiator was the last thing replaced and the car was running fine until that.
 

machphil

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oops! found my problem the fan was put on backwards. I can’t do my own work anymore because of medical problems. Fortunately the garage I use will stand behind their work and take care of the problem.
You are lucky you found it in time. I recall a time when my sister was going to MTI in Indy and they replaced a belt on her '77 Bird. They put the fan on backwards and she drove it home 170 miles. I saw what was wrong right off. Dad and I went to the junk yard and found a couple of heads, hers were toast, and some time after getting it back together she sold the car to me. It was a nice cruiser!
 

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AcesArneson

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Hope you didn't have any permanent damage from overheating. Warped heads, blown seals, oh boy. Keep an eye out for leaks and check your coolant for signs of oil.
 
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A fan on backwards, wow!.
I hope that is not a 50 year old Flex Fan? If it is get rid of it as quickly as you can.
You might want to consider a clutch fan instead. I put one on my car and it works great.
If interested I or someone else will give you the part numbers.
Hi, I've got original everything 108K 2V 351C and at times got my head under the hood. Did our cars come with flex fans and what is the issue with Flex fans other than the obvious? Is this an age issue, rust, detachment, etc Thanks!
 
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Hi, I've got original everything 108K 2V 351C and at times got my head under the hood. Did our cars come with flex fans and what is the issue with Flex fans other than the obvious? Is this an age issue, rust, detachment, etc Thanks!
I can't remember all the details off hand but I'm sure other members can elaborate. Most of us old guys that owned these cars in the early to mid 70s remember a recall on the flex fans. Some of the originals would crack and fly apart! I heard people were killed. I personally had one that did that and cut the paint up under the hood pretty bad.
 
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