I've been noticing a consistent noise. I haven't really paid too much attention to it until now, but I think what I'm hearing is a chirp from the sc clutch engaging. It only happens in 1st gear when I'm in manual mode. It doesn't matter how fast or slow I accelerate, but when I hit right around 3k rpm, I hear a chirp and feel a massive shove in torque. I think before I thought that it was just wheel spin from the surge in torque, but now I think it's the clutch engaging. If I rev over the 3k and it happens and then decelerate and try to hit 3k to hear it again it doesn't happen, unless I come to a stop and accelerate again. Now, I've read a thread or two over on mbworld and they said the chirp was normal as the clutch and pulley age, but I would assume the clutch should be engaging somewhere between 1600-1800 rpm. If what I'm hearing is my clutch engaging, I don't know why it's not engaging until 3000 rpm. Should I be concerned? Any thoughts are appreciated.

 

Try changing ur belt

 

I changed out the belt back in the winter when I installed my nw pulley saver kit. So I don't think it's that.

 

Belt tensioner

 

I read that the SC does not disengage until the car is stopped, Woody did a test to prove that. So you would not hear the chirp until you have stopped the car and start of again.
You are using the Polish 65 mm pulley from what I have read on your posts, is it possible that there is a problem somewhere on it? I am not saying there is but I would inspect it and see that the magnet has not been damaged like Red Dogs one was some time back and that it is affecting the clutch operation. Worth a look I would say.

 

The clutch engages at around 1,200 RPM initially, but the sound you are describing definitely reminds me of a failing tensioner. If I recall correctly, that's not a cheap part. Easy to replace though.

 

I guess I'll have to take the pulley and scattershield off so I can take a gander at the magnet. I never thought about it being the tensioner, but I don't really understand how it could be that. Why would a failing tensioner make a single chirp noise at 3k rpms, but not one at 2k or 5k? Isn't the tensioner at a constant tension all the time? Would the bolt being loose on the tensioner cause the chirp? Do you guys think too large of a pulley gap could cause this problem? Just thinking about possibilities.

 

Also, if it is a failing tensioner, then why is the chirp accompanied by a huge shove in torque?

 

I have had same problem for long time, I changed belt tensioner no luck, I'm thinking its the space between the pulley it needs to be shimmed out?

 

I changed belt with OEM and sway bar end links and chirp is gone now. I know with the belts they all different sizes cause the aftermarket one I had on was making chirping noise at low rpm

 

Morph: so u had the same symptoms I was describing? I have the nw 65mm pulley saver kit on mine with the belt that rob included in the kit. U had a single loud chirp followed by a great shove in torque?

 

Mine only makes 1 chirp when it hits 3k and then it goes away, until I stop and then go and hit 3k again.

 

Not so much of great shove of torque, but had chirp even when car would change gears between first and second gear it would chirp, i have 65mm but no psk, but I had to change pullies, idler, guide, belt tensioner, car has only 66,750 miles
Once I put new belt from dealer, and changed front end links it went away now. It was only making chirp below 2000
Hope this helps.

 

Thanks for the input morph.

 

It seemed like when car got 1600-1800 rpm or when sc engages I would get chirp, when I changed 2 things at same time belt from mb dealership, and front end links it went away. I used to a clicking noise cmg from front brakes, someone put pads on with no shims and they would slide around and click

 

FWIW, I installed the Polish 65mm pulley about two weeks ago. The factory pulley had 4 shims behind it. Code 3 specifies a .2mm to .3mm gap between the SC clutch and the back side of the pulley. Initially, mine required removing ALL those shims to get a gap just over .2mm (it was around .22mm or so).
I checked it yesterday, and the gap was now UNDER .2mm!! (The SC still spun freely with the engine off, and I could stop the SC clutch with my bare hands when the engine was running, but I didnt like that the feeler gauge was such a tight fit between the clutch and back of the pulley)).
As a precaution, I installed 1 shim (they're .1mm thick) and now I have slightly less than a .3mm gap, maybe .28mm or so. So far, the SC spins freely with the car off, and the car runs and drives very normally).

So Im wondering (since you have the same pulley, bbsrt6) if maybe you have too MUCH gap, causing the SC to engage abruptly? It certainly would explain the torque shove you describe if the SC is not engaging around 1200rpm or so.
(You didnt mention if the car is making "normal SRT power" under 3000rpm).

Just a thought from a Xfire noob.

 

Nikko: I don't have a feeler gauge but the pulley is damn close to the clutch from the looks of it. My factory pulley came with 1 shim, so when I installed the polish pulley, I just used the 1 shim. The incorrect gap theory makes the most sense to me, but I'm wondering about something. At what point is the gap too big to where the clutch won't engage at all? Now you asked if my car has the srt power below 3k rpms, and to be honest I can't tell because 1st gear is too short. It feels fast everywhere in 1st gear, but I do feel a noticeable shove at 3k.

 

Hey BB. The one thing I might be able to add to this is that about 2 months ago, the SC circulator pump in my SRT initially became intermittent, and then crapped out altogether. That, of course, made the SC initially engage intermittently, and it quickly went to not engaging at all, due to the higher intake temp. (It went from fully functioning, to intermittent to totally non-functioning in the space of about 15 minutes).

When it was intermittent, the dropping in and out of the power increase SC provides was EXTREMELY noticeable... like when it went out, a Prius would probably have blown my doors off, and that might not even be an exaggeration.
Before I changed the circulator pump, when SC would disengage abruptly at or near full throttle, even my wife said "what the #&(@ was THAT"??? I mean, it felt like I turned the key off, the dropoff was so dramatic.

It certainly SOUNDS like your blower is not engaging when it should, but based on how my car reacted when the pump was out completely, I'd think if the blower is not engaging at all below 3k rpm, the lack of power below 3k would be very obvious.
Measuring the gap with a feeler gauge seems to be of obvious importance, but even Code 3's instructions say "check the gap between the backplate and the clutch. It should be between .20 and .30mm. The important point is that once tightened, the pulley and clutch spin freely of each other, while being as close as possible".

Before I added a shim yesterday, the SC to backplate gap WAS under .20mm, but the SC did spin freely, and I could still stop the SC clutch with my bare hands when the engine was running. Makes me wonder if I really needed the shim at all?? Without the shim, the SC engagement was really smooth and undetectable when driving. It still is now that the shim is in, but it makes me wonder if there would be increased wear or stretching with the pulley springs.
I guess we'd also have to factor in some room to accommodate heat expansion, so who knows??


Anyway, I hope some of this might be of help.

 

You originally state that the gap was just over .20 mm maybe .22 mm and when you added a 1.00 mm shim it was just under .30 mm maybe .28 mm. From those figures we can calculate that the gap shrank from .22 mm to (.28 mm - 1.00 mm) = .04 mm which is .0015". I think that with such a small difference we can say that there was no change as it is very hard to measure that amount with feeler gauges on such an awkward part with a clutch plate that moves.
However if it is true then the springs have relaxed by more. As designed the springs hold the clutch plate against the stops, if the stops were removed the clutch plate would move even further away from the magnet, this is because the springs are preloaded to keep the clutch plate firmly against the stops. If the plate has moved and reduced the gap then there is now a gap between the plate and the stops.
If this is true then the gap will continue to get smalleruntil the plate rubs against the electromagnetic clutch. when the plate is not energized and the car idling.
One pulley was to be set up twice, an initial setting then when the springs had relaxed to set it up again, by this time the plate would not be sitting against the stops at all. I think that that would lead to the early failure of the springs because they were not springs at all. The OEM springs are much thinner than the after market springs because they are real springs, the others get their strength by being thicker only. I do not know if the springs on later pulleys were improved.
My prediction of the after market pulley spring failures are being born out.
Some people poo poohed me at the time and later, and after some springs failed, said that was the price of improvement.
The OEM springs have to fail and have failed in some rare cases but that is just something that happens after continual flexing, it will happen much sooner in non spring material.

 

I recall a post of Dave's (180) in which he added a page from the SRT6 tech's service manual I think it was. I tried to find it but struck out. It explained all the factors (parameters) that trigger the SC clutch lockup, and explains why it happens at different loads and R.P.M.'s. I recall it mentioning the "3k rpm" lockup point as well. DAVE, I hope you remember this; and could you please post that again. I thought it was very informative, and feel it would be very helpful here. Woody's old video that suggests it kicks on "at around 1,300" was informative, but I noticed that in his video it kicked on at a much higher rpm in one of his running tests. It does not just lock up at only a particular R.P.M.