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Lots of fan noise

T

Tx Surveyor

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Hey Everyone,

I have an '85 K5 with a 305 with a Holley Carb. When I am driving and I get to low/mid range RPM I have a crap load of fan noise coming from the motor, so much that it's deafening if I rev the truck up.
My question is this: If I were to pull my main radiator fan and replace it with 2 electric fans do y'all think I would generate enough airflow to keep the engine cool? Anyone have other suggestions for so much noise? Could it just be the carb sucking massive ammounts?
The carb does need to be replaced says my mechanic, says I need a new vacuum secondary and I had might as well replace with an edelbrock while I'm at it.


Thanks,
Surveyor
 
To check the fan clutch, with the motor cold and OFF, try to spin the fan. It should spin fairly easy. There should be some resistance but not a whole lot.

Tx Surveyor said:
If I were to pull my main radiator fan and replace it with 2 electric fans do y'all think I would generate enough airflow to keep the engine cool?
Click to expand...


It's a common swap to put dual electric fans on. Most people use Ford Windstar fans or Tauras fans. If you do a search you will find allot of info. I'm running some Windstar fans with great success.
 
Tx Surveyor said:
Extremely noisey when the motor is choked, because the motor is low/mid range RPM.



S
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When the engine is cold, the fan should only turn very slow at idle, in fact if you're brave enough grab it it shouldn't turn, BUT if it's bad and locked up, it will take a bite out of your hand. The fan clutch comes into play when the engine heats up and the cooling is needed. If it is noisy at idle when the engine is cold, it's bad and needs to be replaced.
 
Excellent, I will probably switch to electric fans. At least now I know, thanks for all the replies.



S
 
Whoa, I'm not a fan of a bunch of the advice given in this thread so far.


Electric fans are not quieter than mechanical fans when they are working.

Electric fans exist for two reasons: they are easy to mount (and are usually necessary for FWD applications) and they only turn on when they are needed (which is good for efficiency). They have to pull their power from the alternator/battery which is 90% efficient or so, there are really no significant efficiency gains to be had by electric fans.

The mechanical fans move more air than just about every electric fan out there, I don't understand why people think switching to electric fans is an upgrade.



As far as carbs go, I do not care for Edelbrock or Holley stuff. The carbs that they aim at the average person (and that they claim are "good to go" out of the box) need a bunch of tuning. There are tons and tons of people that think 8 mpg is acceptable for a K-series truck, but its not. If you bought a carb, put it on the truck and expected it to work then sure, 8 mpg might be expected.

Your $200 carb is hardly a bargain if the truck is getting 60% of the mpg's it should.

And the craziest thing? The Quadrajet that came on every carbureted K5 is probably the best carburetor ever made and people ditch them because they don't understand them. Sad, because their design is eons above Holly and Edelbrock stuff.

Better MPG, HP/torque and its the best performing carb at angles. Nothing else has ever compared. Oh, and there are a bazilion of them out there because GM put them on V8's from the 60's to the early 90's.

My 383, 4.56 gears on 37's, 4" lift, 5200 lbs averaged 12-14 mpg.


And I still run the Q-jet on my buggy, plenty of people here can confirm the angles that my Q-jet can handle; I generally run out of oil pressure before the carb cuts out (enough angle and oil pressure gets a bit low, any serious wheeler should probably have an oil accumulator and that's high up on my list).
 
Umm, every clutch fan I've ever had has been noisy on a cold start for the first minute or so, then it does it's job and quiets down.

Has someone mounted the blades backwards? If the blades are curved the wrong way for the direction the fan spins, it can get mighty noisy.
 
The fluid is thicker when cold, so a little warmth is necessary for proper operation. I'm no scientist though, so I could be wrong:crazy:
 
USSkoval said:
The fluid is thicker when cold, so a little warmth is necessary for proper operation. I'm no scientist though, so I could be wrong:crazy:
Click to expand...

Actually the fluid is the same viscosity hot or cold (silicon based oil). There is a temperature sensitive coupling that allows more fluid to enter a chamber that controls fan speed. More fluid means more fan speed.
Now, that being said, all that works IF he has a fluid coupled fan clutch. There is also a bi-metal clutch that works like a bi-metal thermostat. More heat more tension on the drive.
 
OK, take my S-10 for example. It seems to be an RPM thing at first, because it doesn't matter what the outside temp is. On any cold start, even in the summer, the fan is noisy all through first and second gears, then right after shifting to third the fan quiets right down. It is dead repeatable every cold start... wouldn't that be normal operation? It NEVER runs too hot or too cold either.
 
why don't you just bypass the clutch fan and put a spacer in between the water pump and fan so the fan spins all the time it shouldn't make any noise. i ran this set up on my blazer and i never had any noise or problems and my dad runs the same set up on his 72'. just my 2 cents.
 
You don't happen to have a solid fan do you? If you do then that's why it's loud. I have a solid flex-fan on my burb and it's noisy as hell.
 
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