Fan noise

[twostickmutt]

I just put on a GM alternator which also runs the fan on the 39. Alternator works fine just as I was told and I want to leave it on . Charges great at any speed after it's excited. Problem is ,is the fan noise even at idle. The pulley is smaller than the gen pulley and I realize its turning quite a bit faster . Even at idle the fan noise is loud like a piper cub taking off. Could there be some kind of turbulence between the radiator fan and alternator fan. If I take the radiator fan off of the alt. pulley it's nice and quiet,normal, when running even at high rpm. Any ideas for a fix. The radiator fan is the 4 blade 16 inch. Thanks !

[51 MERC-CT]

Thought that on a '39 the stock fan was down on the end of the crank.(could be wrong)
This leaves a lot to the imagination so a few pic's would help to see what your set up looks like.
Perhaps adapting a fan with more blades would eliminate the noise.

[twostickmutt]

Originally Posted by 51 MERC-CT

Thought that on a '39 the stock fan was down on the end of the crank.(could be wrong)
This leaves a lot to the imagination so a few pic's would help to see what your set up looks like.
Perhaps adapting a fan with more blades would eliminate the noise.

The 39 standard fan was mounted to the generator. I should have said it was a standard. I think the deluxe's were mounted lower. sorry bout that.

[drolston]

First, lay the fan face down on a table and be sure all of the blades are level. But at idle, bent blades will not make much of a fuss. It could be the alternator bearings. They are used to the radial load from the belt, but not the axial load of the fan pulling forward on the shaft. To listen for bearing noise, put the business end of a very long screwdriver or breaker bar on the alternator housing, and the handle end to your ear. You will hear the bearings and not the aerodynamic noise. Then try that with the fan removed; I am guessing you will find the bearings much quieter. If that turns out to be the problem, you have a problem! Maybe some bearing expert could recommend replacement bearings designed to take the axial load as well as the radial load.

[twostickmutt]

Originally Posted by drolston

First, lay the fan face down on a table and be sure all of the blades are level. But at idle, bent blades will not make much of a fuss. It could be the alternator bearings. They are used to the radial load from the belt, but not the axial load of the fan pulling forward on the shaft. To listen for bearing noise, put the business end of a very long screwdriver or breaker bar on the alternator housing, and the handle end to your ear. You will hear the bearings and not the aerodynamic noise. Then try that with the fan removed; I am guessing you will find the bearings much quieter. If that turns out to be the problem, you have a problem! Maybe some bearing expert could recommend replacement bearings designed to take the axial load as well as the radial load.

ok thank you. I could put the generator back on and it would be normal.....no noise. the alternator is brandy spankin new but that doesn't mean there can be a bearing problem. I will check the blades on the fan tomorrow.

[Charlie Stephens]

Sponsored Links (Register now to hide all advertisements)

Originally Posted by twostickmutt

I just put on a GM alternator which also runs the fan on the 39. Alternator works fine just as I was told and I want to leave it on . Charges great at any speed after it's excited. Problem is ,is the fan noise even at idle. The pulley is smaller than the gen pulley and I realize its turning quite a bit faster . Even at idle the fan noise is loud like a piper cub taking off. Could there be some kind of turbulence between the radiator fan and alternator fan. If I take the radiator fan off of the alt. pulley it's nice and quiet,normal, when running even at high rpm. Any ideas for a fix. The radiator fan is the 4 blade 16 inch. Thanks !

Be sure the front bearing on your alternator is strong enough to carry the load of the fan.

Charlie Stephens

[B-O-B]

Can you make an adapter to just hold your fan & use a offset mount for the alternator? I'm sure I have seen them (fan mounts) for sale.

[Kerk]

I ran a fan on the alternator on my 32 & 35 with a std. size pully. I did not have a problem with it charging except at a very slow idle.. I did not idle enough to to have a problem with the battery. Optima works fine for me. kerk

[ford38v8]

Originally Posted by twostickmutt

I just put on a GM alternator which also runs the fan on the 39. Alternator works fine just as I was told and I want to leave it on . Charges great at any speed after it's excited. Problem is ,is the fan noise even at idle. The pulley is smaller than the gen pulley and I realize its turning quite a bit faster . Even at idle the fan noise is loud like a piper cub taking off. Could there be some kind of turbulence between the radiator fan and alternator fan. If I take the radiator fan off of the alt. pulley it's nice and quiet,normal, when running even at high rpm. Any ideas for a fix. The radiator fan is the 4 blade 16 inch. Thanks !

twostick, you answered your own question. Increase the pulley diameter to bring down the fan revs closer to stock. You may be able to adapt the original pulley to the Alternator? Keep in mind also, get the fan close to the radiator for cooling efficiency.

[Lawson Cox]

If you are by chance using a 6 bladed fan on a generator/alternator, it will make noise like a hurricane. Don't ask me how I know.

[jimvette59]

Take the fan of and put a electric fan on.

[twostickmutt]

Originally Posted by jimvette59

Take the fan of and put a electric fan on.

Yup that's just what i'm going to do Jim. I wont have to worry about the load on the bearings either. Was just going to thank everyone here for the replies and tell them i'm going electric so...…...thanks everybody.

[twostickmutt]

Originally Posted by Lawson Cox

If you are by chance using a 6 bladed fan on a generator/alternator, it will make noise like a hurricane. Don't ask me how I know.

No it's 4 blade Lawson and plenty loud too but not as bad as a 6

[twostickmutt]

Originally Posted by ford38v8

twostick, you answered your own question. Increase the pulley diameter to bring down the fan revs closer to stock. You may be able to adapt the original pulley to the Alternator? Keep in mind also, get the fan close to the radiator for cooling efficiency.

Thanks alan

[JSeery]

With the alternator you should have the current to run an electric fan with no problem.

[Lawson Cox]

You'll be sorry. All they do is block whatever air flow you are getting, These vehicles operated for years as designed. Fix the problem. Don't put a band aid on it. If you want modern technology, buy a NEW car.

[twostickmutt]

Originally Posted by JSeery

With the alternator you should have the current to run an electric fan with no problem.

Yes I think I should be fine there jerry. thanks

[Gene1949]

X2 on the electric fan. You will be glad you did. A big plus; most of the time around town the low speed cycles (off and on) and the high speed only comes on pulling a hill or 100 degree days.

I think you are "overdriving" the fan because of the smaller delcotron pulley. You can get a bigger pulley but you defeat the alternator's low rpm charging ability.

Besides, the delco front bearing isn't designed for a longitudinal load. It will last for a while but if you are going to drive it that's just another headache to worry about.

I have a Ford Taurus SVO 2 speed fan and shroud. The Ford fans have about the most cfm. Many different shroud configurations are easily available at any repurpose facility (wrecking yard). The fan is controlled by a Volvo 2 speed fan relay and 2 (high and low) temp switches soldered into the lower tank.

Since we drive the car a lot every thing we do has to be fixable with readily available parts from a NAPA (or some such) store.

[Ol' Ron]

I like running an electric fan Some of the newer cars have very quite ones.