Seven Blade Fan Issue

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bobscuda67

bobscuda67

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I have the steel seven blade clutch fan on my car and having an issue with it bending at the trailing edge. It cools the car great, even on the hottest days, but all the blades are bent a lot and it's got me worried. Do you think the blades could come apart?
I'm thinking of switching to the MP five blade fan and I wonder if it will cool as well.
 
I was driving my Dart with it's 318 and 7 bladed clutch fan to the shop to pull the motor and put in my 408. I never made it. I thought I had a flat, but what actually happened is two of the blades broke off, hit the hood lightly and landed on top of the power steering pump. I was lucky. One small scratch on the underside of my newly painted hood, a deep gouge in the shroud, and that was it. If the fan isn't true it can stress the structure and break, or at least unbalance it enough to put undue pressure on the water pump shaft.
 
I'll post a pic as soon as I can. The reason I noticed it was that the paint was coming off in flakes. It doesn't seam to be out of balance as it doesn't vibrate that I can feel.
 
Those blades do have a odd little bend near outer ends. All that I have seen come apart failed at the rivets.
 
Here's a picture of the engine side of the fan. Notice all the chipped off paint, that's where it's bending.
 

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I think air flow, along with water, sand, etc.. took that paint off.
 
.................looks normal to me.......there is always a certain amount of flex to a fan blade...........kim............
 
I had a 7 blade fan on my 340 when I took it to the chassis dyno shop. During the power pull, the water pump snout broke off! Fan blade imbalance! These things are heavy!I would purchase a new MP 5 blade clutch fan package. It should cool fine for all engines with a good radiator. I put on the 7 blade because I was overheating with a 4 core desert cooler radiator. Couldn't understand why the engine overheated all the time and thought it was the fan. Turned out I needed the radiator rodded out. I had it boiled out a while ago, but that isn’t sufficient to clean out built up deposits.So, the moral of the story is, check everything out before you go with heavy power robbing parts like a huge 7 blade fan that was made to cool a BB station wagon towing a trailer.
 
Here's another view looking down a blade. The crappy camera phone doesn't show the blade in full but it is bent. I put a straight edge on the length of the blade and it's about 1/2 inch gap at the tip on the worse one. Some of them are not as bad.
I guess I'll be looking for a MP 5 blade fan now.
Thank's for the reply's guy's.
 

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is it contacting the fan shroud, when you rev the engine, (and the engine rocks to the passenger side of the vehicle) ?
 
fanofpetty said:
is it contacting the fan shroud, when you rev the engine, (and the engine rocks to the passenger side of the vehicle) ?
Click to expand...

Not touching the shroud, that would be really loud to bend a blade that much, and there's no marks on the shroud.
 
Whats a rough cost on that 5 blade MP kit and where can you buy a factory fan shroud for a 26" rad?
 
The 5 blade fan kit from MP is an awesome part. You have made an excellent choice. Put it on and don't look back.
 
when a fan flexes , it is drawn towards the radiator because it is pulling air. it would have to be on backwards and flex the depth of the pulley plus the spacer if it has one. I think it would come apart before it would hit the belt. I would assume if the pump bearings were that bad , the belt would come off before the fan would hit it. this is why we don't ever want our fans less than an 1 1/2" or so from the radiator .... my 2 pennies
 
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