How many of you out there run only an upper pulley? and how many of you get the "cavetation" (sp), or "diesel" sound at idle?

Im thinking about ditching my lower pulley, the sound is annoying...plus a local guys who had the same sound had to get his blower replaced.

 

Great explanation of the problem:

I have had several L and had the diesel sound with all of them. I always raise the idle about 100 rpm's and that will make the sound go away. The sound is a type of cavitation because the bypass valve is sized to fit the Eaton with a stock pulley. With a larger pulley it is pumping more air and the bypass valve can't spin all of it back to the front end. Raising the idle helps use some of the extra air being pumped and also puts the motor in a better idle range to just help it smooth out.

My new computer will be programmed to fix this.

Before you ditch your lower pulley get your idle increased by 100 rpm's on your next reflash/tune.

When we take my stock blower apart this weekend we will see if the rear bearings have any damage.

 

I have played with the idle, it doesnt make the sound go away. You just dont hear as much of it because the engine/exhaust noise is louder.... watch my blower freeze up on the way to Jon's

 

Konig, For what it's worth, I get massive cavation when using my 4lb bottom pulley ONLY. When ever I add the 2lb Upper in the mix, the cavatation goes away (or maybe a better way to say it is, it's so less noticable that you don't hear it)

As Tampa just said, it has to do with the amount of air coming in, (maybe even the temp of the air) RPM of idle, RPM the Eaton is turning, etc. I also agree with him that a higher RPM should eliminate the problem, (or lessing it to a point you won't even notice it). If it doesn't, my guess is you may have another issue and it's not cavation. I've been living with it since day one, and when I took my Eaton apart recently @ 12K, it looked brand new Don't know what your friend experienced needing to replace the Eaton, but it's been addressed a million times and if it is true cavatation, it causes no damage, only a annoying noise.

 

Rob: well the diesel sound is the best description I can give....only hear it at stop lights while in drive. It started the day of or the day after we installed the lower pulley. I expected it...but the frozen blower stroy has me a little worried. Maybe I should add an upper pulley on the next tune.... I would much rather add power to cure it then take the pulley off.




Steve: That exhaust blurp or "dragging" feeling when I let off after 40+mph.... Im thinking its the trany....I smacked it into nutral and it was smooth as silk..... I wonder wtf it could be

I think Im going to drop my pan and check the torque settings on the valve body.

 

Yup, diesel sounding is exactly how I would explain it too.
I guess when you think about it, raising the idle, or adding
an upper pulley both acheive the same results, --> spinning the
Eaton a little more on Idle. In my case that extra RPM seems to be just what the Doc ordered to quiet it down.

I've been switching back and forth from 6 to 4lbs and back to 6 for all 12K now, and I always have the same results, cavatation with 4lbs lower only, but un-noticable when I add the upper.
Strange but true ?

 

I am the one that trashed a blower with a 2lb lower. Part of it was due to polishing the blower and getting metal dust in some of the bearings. But, part was also due to having a belt that was way to tight for the pulley. I am back to stock and my truck makes even more noise than when I had the 2lb lower pulley installed. There are other factors involved in the noise, it's not just the valve in the blower. Removing the lower pulley filled with rubber is a big factor.

 

WUSSS!!!!

Keep it on there and floor it!! LMAO

Just kidding!!

 

Yeah you too...but I was refering to the guy who posted about the problem on NLOC... you posted on his thread as well


it just seems like I have all sorts of noise these days.... blower, exhaust studder...and I have recently aquired some of the floor board vibration I have always heard so much about.....

 

I just don't care anymore.... it helps to have 2 blowers.

 

Thats the number one answer! Thats why Ford put it there in the first place. How many of us would have taken delivery on a new truck that sounded like that at idle?

NONE

I'll take the noise along with the added boost

 

YA MAN, I AGREE

 

thats a first

 

 

so wich is worse for the cavitation the 2# or the 4#?

All the suppliers of pullies that I've seen say that the 2# can use the stock belt. Is this too tight?

How much power does one think a 2# with no chip add? 4#?

thanks