My Kenne Bell needs a rebuild: Recommendations?

trinity_gt

10 Year Member
Jan 31, 2003
3,125
80
99
Canada
I've been getting some noise from the supercharger for a long while now. This noise occurs at certain points on the tach (typically at ~2K and quite noticeably at ~3K). I don't hear it at all at, say, 2500. It's worse when the blower/engine is hot. It's generally at its "worst" when at part-throttle although blipping the throttle when downshifting often results in a sharp sound too. I don't hear it when the throttle is closed and the engine RPM is dropping through 3000.

The sound is hard to characterize. If I had to describe it I'd say it's a "howl" or maybe a "hum" of moderate frequency. Interestingly, the frequency stays about the same at 2K and 3K but the intensity goes up at the 3K point. I'm guessing the rotors may be contacting the case ever so slightly, causing it to resonate. The blower doesn't make any bearing-type noises and still builds good boost. As far as I can tell, the drive coupling in the snout is fine and the blower feels smooth to rotate by hand.

I bought the kit used about 3 years ago and, aside from the sound, the blower has been trouble free. I've changed the oil several times now and check it pretty much every time I take the car out (maybe weekly) and when I fill up I check the engine and blower oil. I think it might have a small leak as the manifold behind it develops a sheen of oil but the level never seems to go down.

Anyway, I'm thinking of taking the assembly off the car and having it reconditioned. The sound is plain embarrassing and I may be mistaken but I believe it's getting worse; I'd rather not risk doing irreparable damage by driving it much longer like this.

I've found three candidates for rebuilding it: The Highspeed Lab, Jon Bond and PSE.

I'd appreciate any feedback anyone has who've dealt with these or who have alternate ideas.
 
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Yep... that's the right stuff.

Next: Remove and plug the bypass valve (if equipped) and drive the car to ensure that the noise is coming form the screws and not boost pressure forcing it's way past some other component.
 
Yep... that's the right stuff.

Next: Remove and plug the bypass valve (if equipped) and drive the car to ensure that the noise is coming form the screws and not boost pressure forcing it's way past some other component.

Here's a video on Youtube showing the sound it's making.

It's doing it under both light and moderate throttle angles during which the bypass would be open and closed respectively. This is a "ringy", "chirpy", "whirry" noise (the vid speaks for itself.) It's not a boost leak.

The blower otherwise sounds good (no grinding noises, normal whine sounds great etc...) and is making good boost.
 
Hmmmm... Sounds like a harmonic vibration from something. Do you get the same noise if you're stopped and rev through those ranges?

I can't say with 100% certainty that it's NOT the blower but I don't see how the screws could possibly make that noise. They sit in an oil bath.

That sound there, sounds to me like a harmonic vibration from a piece of billet with decent size surface area.

Have you checked the security of the pulley?
Looked for something, anything that might be bumping up against a moving part?
Checked the torque on the blower housing itself?
Aluminum drive shaft
flywheel against the bell housing
Damper and pulleys for security

I'm tossing stuff out there because I obviously don't get any directional sense about where the noise is coming from.

I just can't see an oil bathed set of screws coming together to make that noise. Try sending that link to Kenne Bell and see what they have to say.
 
Hmmmm... Sounds like a harmonic vibration from something. Do you get the same noise if you're stopped and rev through those ranges?

I can't say with 100% certainty that it's NOT the blower but I don't see how the screws could possibly make that noise. They sit in an oil bath.

Actually, just to clarify, they don't. The screws draw air in from the rear compress it and discharge it below. They run dry. The shaft has bearings at either end and the drive gears are in the oil bath but the screws themselves just run in air.

The screws also run with very close tolerances, both with each other and with the housing. It wouldn't take much warpage or bearing slop or a phasing issue with the drive gears for contact to occur.

I just can't quite figure out the resonance; why it only happens at certain RPM. I will say it appears to be getting worse though, that the sound is spreading out slowly from the peaks at 1K, 2K, 3K etc. At least I think it is...

That sound there, sounds to me like a harmonic vibration from a piece of billet with decent size surface area.

Ironically, that describes the billet blower housing to a T :)


Have you checked the security of the pulley?

Yes. Tight and secure.

Looked for something, anything that might be bumping up against a moving part?

One thing I haven't done is check to see how the blower turns by hand when it's hot. I've only ever done this cold. I'll try running it hot and then removing the belt and see if I notice any roughness or noise from it when turning it by hand.

Checked the torque on the blower housing itself?

Unfortunately the blower seems to bolt to the lower manifold from the inside (i.e. above the intercooler.) This also makes removing it for service more of a pain.

Aluminum drive shaft

Still the stock piece.

flywheel against the bell housing
Damper and pulleys for security

Hadn't considered these. I'm going to rule out the flywheel because if something was baffed enough for contact to be made here I'd know it from other symptoms. I'm not getting any MILs for misfires so the crank pulley is fine. The damper was bought new for this install.

I'm tossing stuff out there because I obviously don't get any directional sense about where the noise is coming from.

I appreciate the ideas.

Try sending that link to Kenne Bell and see what they have to say.

That's a good idea. I don't know if they'll look at it but I can try.

:nice:
 
I run the 2.2L blower on my Fox and the setup is a little different from yours. It still pulls air in from the back but my blower is upside down from yours with the exit ports on the top.

I have difficulty accepting that the noise is from the screws banging together or from coming in contact with the housing. By having a self contained oil bath at each end of the screws and being torqued down the intake, I can't see that ringing noise resonating like it does from your blower housing.... Unless something has broken away inside but your blower sounds pretty healthy when it winds up.

Definitely interested in see what KB says. If it's something they've come across before, they should know it immediately.

Good Luck and post back with what they say.

Oh... and if you do in fact end up having to rebuild it, see if they can put the larger displacement screws in it. They made several different displacement blowers out of same housings (though there are different housings as well).
 
I heard back from KB today to an email I sent Sunday at 5pm. How's that for quick service? :)

This is what I was told:

"I doubt the rotors have contacted each other you would feel it when you spun it by hand. If everything has checked out okay next would be to check the belt and tensioner, make sure they are in good operation. We do offer rebuilds but I don’t think that is what you need at this time."

In my car's case the belt, both idlers and the tensioner are all brand new. But I'm going to heed their advice for the time being and just keep an eye on it. If the noise gets worse I might take it off for some exploratory examination...
 
I heard back from KB today to an email I sent Sunday at 5pm. How's that for quick service? :)

This is what I was told:

"I doubt the rotors have contacted each other you would feel it when you spun it by hand. If everything has checked out okay next would be to check the belt and tensioner, make sure they are in good operation. We do offer rebuilds but I don’t think that is what you need at this time."

In my car's case the belt, both idlers and the tensioner are all brand new. But I'm going to heed their advice for the time being and just keep an eye on it. If the noise gets worse I might take it off for some exploratory examination...


If I were in your shoes, I would do the same thing. Keep an eye on it, but if I thought things were getting worse, the only place I would send my KB Unit for rebuild would be Kenne Bell. I dont think their prices are much more expensive than the 3 sites you listed in the first place, and it is their product any how. I trust their work, the only thing I am wondering about their product (since i have a 2.1 myself) is porting the actual lower intake manifold. I know they recommend not porting their blower, but I wonder what would happen if I actually port matched the lower manifold to the heads... They definitely dont match...
 
Well... if you get a lazy weekend, pull it, check everything you can physically touch, and reinstall.

For what it's worth... I've heard some strange noises from KBs over the last few years. None of them sounded like your video and one of them actually DID have screws that touched. That noise wasn't NEAR as charming as the one in your vid. :D

Have you tried changing pullies? Just for grins and a short test drive.
 
Well... if you get a lazy weekend, pull it, check everything you can physically touch, and reinstall.

For what it's worth... I've heard some strange noises from KBs over the last few years. None of them sounded like your video and one of them actually DID have screws that touched. That noise wasn't NEAR as charming as the one in your vid. :D

Have you tried changing pullies? Just for grins and a short test drive.

That's a good idea. I've got a few pulleys I could swap in and look to see if the RPM points move around. If they do, the noise pretty much has to be coming from the blower.

Thanks.
 
That's a good idea. I've got a few pulleys I could swap in and look to see if the RPM points move around. If they do, the noise pretty much has to be coming from the blower.

Thanks.

Quick follow-up to this: I did change the pulley to an 8# unit and found that the sound occurs slightly higher on the tach which tells me that the sound is indeed coming from within the blower.

Interesting observation. After a drive I removed the pulley with the blower still quite hot to check for roughness when turned by hand. I didn't notice any rough feeling per se but I did observe a decent amount of what appears to be backlash somewhere. I can rotate the pulley back and forth and hear a distinct knock or tap from within the case (hard to tell exactly where it's coming from as it sounds equally loud over the entire length; it might be louder at the rear...I don't know. Maybe I need to rent a stethoscope and dig more...) Rotating in one direction or the other was smooth but there's definite backlash when hot... I don't know if this is characteristic of the spider coupler or a problem or if it's normal. Anyone else noticed this with a hot KB?

When cold it doesn't do it: No perceptible backlash and same smooth rotation by hand. Oil is correct and up to the full mark on the 'stick.

I made a vid and will put it up later.
 
The only [oddity] that I can remember is that for a time, (I'd almost forgotten about it) I had a small, "ting" sound coming from the blower when I shut down the motor. Since then though, I've replaced the Blowzilla manifold(s) with the Flowzilla manifolds. No idea if that had anything to do with it or not. What I do remember is that I've not heard the sound since then.


Have you retorqued the blower housing bolts at all? Oh wait... you said before that the bolt heads were INSIDE the housing?
 
I have had to completly dismantly my 2.1 to fix a seal that KB didnt do for me. The spider coupler is a nylon/plastic piece that sits between the drive shaft and the gear set. I highly doubt that sound is coming from the spider coupler. What it really sound like, a bad bearing and it is resonating through the housing.

Test this. Go for a drive, get it nice and warm so it is making the sound. Go home, leave it running, and pop the hood. From under the hood slightly rev the engine. This will put out no boost or load, just spin the supercharger. This will give you a better idea. Is it only under load conditions? Is it anytime the engine is between those RPMs? It might not be as noticable when under load, thats why I say get your head under the hood. If it is happening anytime, you can track it down to which portion of the blower. If you put your hand on the top front by the oil check (yes it will be HOT), you should feel a vibration that goes with the sound. Then check on the back of the inlet, between the throttle/cruise cable holder and the vacuum ports. Is the sound louder near the snout, or near the back of the inlet?

There are 3 sets of bearings to worry about. First, the snout bearings. Second, the front gear/rotor bearings. And lastly, the rear bearings.
 
Here's a vid of the backlash-knock I heard when it's hot:

KB 1.7L backlash & knock when hot - YouTube

Noobz, after I've put it away hot I get the odd "ting" that sounds a bit like an exhaust cooling down. If it's the same noise you heard I don't worry too much about it.

verti, the noise is quite loud when there's a bit of throttle angle and airflow moving through the blower. For example, I don't really hear it as the engine drops through 3K, 2K and 1K as I decelerate. Under the hood when I rev it I don't really hear the noise either, at least not to the extent I do on the road. As I noted earlier, the pulley change proves to me it is coming from the blower. One thing I might try is to put the car on a dyno and load it up slightly for some underhood noise hunting...
 
any update on this?

Funny you should ask right about now. The noise got progressively worse, I was hearing it earlier (i.e. when the blower/engine was cooler) and it was very slowly spreading out in terms of the RPM ranges I'd hear it. This past weekend I was listening to the blower case and noticed that it sounded, to my ears, that the rear bearings in the blower were making a rumbling type noise. An auto stethoscope confirmed that the rear of the blower was definitely making noise not heard nearer the front. The blower was still making good boost and, when not making that noise, wasn't making any untoward noises at all, at least that I could hear from the driver's seat. But man...when it was hot and I hovered near 3K it howled.

The car is in the shop having the blower/manifold removed. My plan is to then bring the assembly back to my garage for disassembly, some photos and then it will be off to Jon Bond for a diagnosis and rebuild.
 
I can't say with 100% certainty that it's NOT the blower but I don't see how the screws could possibly make that noise. They sit in an oil bath.

Really? Care to enlighten us as to how the air moves THROUGH the rotors since they sit in an oil bath? Sorry but this couldn't be further from the truth or wrong.

The bearings sit in oil as do the gears. There are ports in the blower case that allow the oil to flow to the back of the blower to keep the rear bearings lubricated.

To the OP. I would continue down the path that you are going and eliminate everything you can before sending the KB off for a rebuild. If you do end up having it rebuild I wouldn't recommend anyone but KB.