68 C20 with 327 excessive fan noise
 

I have a 1968 family owned since new. It is a C20 327 v8 3OTT I have have finally got the truck going after many years. It has a terrible fan noise very loud like you thought the tranny was howling. I took of the fan belt and drove it for a quick drive through the gears and it made such a difference I couldn't believe it. Currently it has the factory fixed blade fan. I am wondering if anyone else has ever noticed this on these trucks? Can I run a clutched fan on the truck?
I would like to know what to order as I know that the fan has to sit in the radiator fan shroud correctly so it draws the correct amount of air.
any suggestions on what to try?

Re: 68 C20 with 327 excessive fan noise
 

yes you can use a fan clutch on the 327. I went from 4 blade fixed to the 5 blade asymmetrical fan with fan clutch

looks like you will need a short flange fan clutch as you have a long WP to keep your pully alignment the way it is now. My 327, in my 67 Camaro, has a short WP so needed the fan clutch with the longer neck flange (pic)

You need to get the right fan center opening size (it will note that in specs of fan) to match the fan clutch mount side. Ideally someone running the truck pully set up like yours can note part # but rockauto typically is very good about noting for short or long WP relative to clutch fan. Many prefer Hayden brand clutch fan. LMC, etc, likely has the 5 blade fan if rockauto does not

You want the fan 1/2 in/out of shroud

But before you do anything, confirm its not the WP itself making the noise as you won't know by removing the belt. Turn WP by hand, it should spin easily. If it hangs up slightly, your WP bearing is failing

Fixed fans are noisy in general as they always spin at same RPM engine does. Clutch fan only spins fully when engine temp is at a point it engages fully. Typically, they are not fully engaged when driving at Hwy speeds as air flowing through radiator is enough to keep engine at operating temp

Re: 68 C20 with 327 excessive fan noise
 

Direct drive fans are very noisy . Yes you can run a fan clutch on your truck. My 68 with the 327 has a fan clutch

Re: 68 C20 with 327 excessive fan noise
 

the next step will be to take the fan blades off and run the water pump. It didn't seem right and made a little sound when I turned it by hand. It is very possible that the WP is original equipment. This was the farm truck and it only has 48,000 miles on it yes that is correct it has never rolled over I know for a fact it is original miles. Truck sat for 40 years in my dads barn and Grandpa never drove it much when he had it.

Re: 68 C20 with 327 excessive fan noise
 

I have a fixed 4 blade on my inline 6, not loud at all and even in 100 degree days runs normal temp. I would otherwise put a clutch fan and more blade fan on but am taking the position of if it ain't broke, don't fix it for me relative to going to a fan clutch

I suspect your WP may be more the source of noise given your findings it makes a noise just spinning it and that the truck sat for so long

Re: 68 C20 with 327 excessive fan noise
 

My K20 with A/C is running a Hayden 2747 fan clutch with a 7-blade fan. It's a heavy duty thermal fan clutch made by Four Seasons in Lewisville, Texas, and is a perfect replacement for trucks with factory A/C. It should do the trick for your 327.

A heavy duty clutch will cool better than a standard duty, and severe duty is overkill for normal use, even in hot climates. I'll guess you're running an 18" fan -- look for a six-blade or better yet a seven-blade fan.

Differences between standard duty, heavy duty, and severe duty clutches can be seen here: https://www.haydenauto.com/en/produc...-types/thermal

Re: 68 C20 with 327 excessive fan noise
 

4 season makes good stuff. I have one of their radiators in another 383 car using twin EL fans (stock to that car)

run a 7 blade (18") on my 357 with fan clutch in a 67 Camaro which did the trick to stop temp creep the 5 blade just would not do along with a Cold Case radiator

If OP otherwise has a cooling issue, I would go with a fan clutch and 7 blade set up.

what gets me on my 72 C10 is even with the stock fixed 4 blade....there is no shroud at all. and my temps are fine. IDK if the 6 cyl had shrouds, all I have a a small piece basically intended to keep hands out of a moving fan which appears "stock"

Re: 68 C20 with 327 excessive fan noise
 

Yup, that's all they had was the finger guard on the six cylinders, unless you had AC.

Re: 68 C20 with 327 excessive fan noise
 

I have an original 68 327 fan blade set up. It's not noisy that I've noticed. I'd suspect your WP. Have you posted any other pictures of your truck in another thread????

Re: 68 C20 with 327 excessive fan noise
 

Grab the ends of the fan blades across from each other and see if there is any wobble. That will tell you if you have a bad bearing in the water pump. Another thing to think about- unless this truck had a good load of antifreeze when it sat all that time (and even so), there could be a fair amount of corrosion on the inside of the block. Freeze plugs would be suspect, as well. Look at them for weeping or blisters. If one is leaking, replace them all, even if it means pulling the engine. Better now than cranking down the freeway and springing a leak.

Re: 68 C20 with 327 excessive fan noise
 

Many can tell the sound of a water pump rumble from the fan whirl.
However, removing the fan and running the motor for a short time is a great idea.
Eliminate one issue at a time.
Issue was noted and address by others
The symmetrical fan blade positioning is a bad idea for noise reduction.
The auto fans are asymmetrical for a reason, noise.
Changing the fan will make a big difference if the blades are evenly spaced on the existing fan. Adding a clutch will also help. These fans can drain as much as 30hp.
The addition of the clutch will help. However on your rig it isn't likely to be a measurable difference in performance.

https://www.youtube.com/watch?v=Hz0ebc6XkFE

Re: 68 C20 with 327 excessive fan noise
 

here is a picture from our drive on Saturday, I should have mentioned that around 1990 the engine was rebuilt because it didn't run well once we opened it up we found that 2 or 3 of the cam lobes were rounded out. Bad cam's from the late 60's is what we were told. we couldn't believe it at that time as it only had 43,000 miles on the truck. We took off the big side mirrors and put the ones on it now looks so much nicer. also removed the split rims and hub caps. Original split rims and tires still look great just not a good option.

Re: 68 C20 with 327 excessive fan noise
 

knowing my dad at the time of the engine rebuild I am sure he put the original water pump back in it same as he did with the clutch and pressure plate. I am pretty sure that it why it takes off so hard in first and rev. lots and shimmy if you don't ride the clutch. Drive shaft and carry bearing have been rebuilt and replaced. trying to decide if I want to put an automatic in it or try replacing the clutch. I seem to remember that my dad and my brother had a horrible time getting the engine in and aligning the clutch I almost think they bent the fingers on the pressure plate. I have not dug into it to much as I have put enough money in the truck and my dad is 88 and the truck technically isn't mine. I hate to keep sinking money in if one of my other siblings swoop in and take it. Parents say it is my truck but until I get the title it makes it tough.

Re: 68 C20 with 327 excessive fan noise
 

Nice pic and a beautiful truck!

Re: 68 C20 with 327 excessive fan noise
 

thank you we went for a nice drive just to get to this location I was teaching my son how to drive a 3 OTT

Re: 68 C20 with 327 excessive fan noise
 

OP

what likely caused the cam lobe fail was using oil that did not have enough zinc in it. The 327 had a hydraulic flat tappet cam as did all motors back then. If it still has a hydraulic flat tappet cam you still need to use either a high zinc content oil like Valvoline VR1, Joe Gibs, or use a zinc additive in regular oil

Shops saying "bad cams of the 60's" was BS.

While at 43k mi the clutch should have been ok to reinstall if it didn't see hard use prior, ideally it would have been replaced and the flywheel should have been turned. Engagement on a stock clutch should be as smooth as butter

Nice truck

Re: 68 C20 with 327 excessive fan noise
 

Am I just seeing things or is that a short water pump with a spacer using a long water pump type crank pulley?

Re: 68 C20 with 327 excessive fan noise
 

You right went up and snapped a few of my 68 327 . Water pump and alternator are driven by the same belt on the inner crank pulley and the power steering on the outer .

Maybe the OPs engine has all long pump brackets ?

Re: 68 C20 with 327 excessive fan noise
 

I want to say I remember hearing that the truck didn't have power steering new and it was added on at the dealership when my grandfather bought it. I will ask my dad to clarify.

Re: 68 C20 with 327 excessive fan noise
 

My bet is that it is the harmonic balancer. It is slipping on the rubber isolation mounts.

I chased that howling and screeching sound. I replaced the water pump, fan clutch, all new belts and nothing fixed it.

It went away when I replaced the harmonic balancer. If you take the balancer off you can see where the rubber isolation mounts were broken, but hard to see in the truck. You may be able to take a photo of it in the truck.

Re: 68 C20 with 327 excessive fan noise
 

The sound went away when I took the fan belt off. I am pretty sure I am down to the water pump/ fan blades ran super quite with the belt off. drove 1/4 mile through all gears then back home. no noise

Re: 68 C20 with 327 excessive fan noise
 

Ok, great job. Now pull the fan off and bolt the pulley back onto the water pump and reinstall the belt.
Repeat the drive. By the time you get back from a short drive you will know for sure which is the culprit.
Cheers

Re: 68 C20 with 327 excessive fan noise
 

yes that is the next step just have not done it yet.

Re: 68 C20 with 327 excessive fan noise
 

I would take this opportunity to put correct short pulleys on it. I have never seen a short pump with that spacer like that. Or put a long water pump and get the correct upper pulley. Either way I would get rid of the spacer.

Re: 68 C20 with 327 excessive fan noise
 

question for me is what is the correct parts do I need to fix this problem and ad a fan clutch