Took the family up camping this weekend in the mountains and have a new noise to figure out on the truck. I'm pulling a 10K fiver. I can only get the truck to make the noise when I'm going up a steep incline and pushing the truck to keep speed or accelerate with the trailer on it and the boost gets up above 20 for an extended period. The noise is a fast pace chirping for about 2 seconds and stops. Sounds like a bearing to be honest. It might do it once per hill, might do it 2 or 3 times per hill or might not do it at all if I'm not quite as hard on the gas pedal. I haven't noticed the noise before this trip, but we haven't had the truck that long nor have we pulled the camper up the passes before. I can't push it hard enough to reproduce it with the same trailer down in the city or up the shorter hills around us. Only on those long steep passes in the mountains. The noise sounds like it is coming from right in front of top center dash panel, the turbo. The truck is an '05 and only has 80K miles on it. Stock except for the exhaust and a K&N intake. Is this something to worry about or is it normal for the turbo under such a high strain?

Something else I noticed, might be related, probably not. Before this trip, I put the CAT back in for for a stupid reason and haven't had a chance to take it back out. The truck has very little acceleration from a dead stop with the trailer on it. I get most of the way through an intersection before it kicks in. The truck almost doesn't want to move when pointed uphill from a dead stop. Takes fooooreeeeever for the turbo to spool up. Didn't notice this when the CAT was off, but I hadn't pulled anything for a while before putting the CAT back on. So, maybe something has headed south in the meantime. I know the CAT creates a lot more back pressure and causes the turbo to spool slower, but didn't think it'd be this dramatic. I did notice a difference just driving around without a trailer immediately after putting it on and didn't think anything of it knowing that the CAT would affect the turbo spool up. Just didn't think it'd be this dramatic with the trailer though. So, just pointing out an additional observation with the turbo that probably doesn't have anything to do with the chirping and is probably 100% normal(and why everybody takes out the CAT in the first place!).

 

Sounds to me it's your fan clutch locking up. It's either slipping the belt a little or the clutch itself is going out. What's the condition of the belt?

 

I'll have to check the belt tonight. The serpentine was replaced about 20K miles ago supposedly, before I got my hands on the truck. Is it ok to put belt dressing on them on these trucks?

 

Don't disguise the sound. You need to find what is causing it to avoid being left on the side of the road with your family and camper in tow.

 

I definitely don't want to disguise it, I would definitely like to fix it! I can only reproduce the chirping/ringing sound under a certain circumstance and there's no way I can be under the hood when doing it that I can think of, how can I narrow in more? Is there a procedure to tell if the fan clutch is bad? How hard and expensive is that replace? Don't want to just throw money at parts though.

Now that you guys got me thinking about the fan clutch, I have noticed that the fan spins up to higher RPM's as I accelerate but drops off after reaching speed, regardless of the oil/coolant temps. I don't remember that it use to do that but the outside temps are now getting hotter and I just assumed it was because of that. They aren't going ballistic, just going from it's usual

 

When you say "fast paced chirp" might it be a high pitched whistle, like maybe a tea kettle?

 

oldfordnstone- No, definitely not a whistle. It sounds like something between a bird chirping or a bell ringing. At first I thought it was symbols or something in the song on the radio. It'll be like 2-7 chirps, varies, and then nothing for a bit, then it'll do it again unless the load is off.

87crewdually- I checked the belt last night and to my eyes, it looks in really good shape, almost new.

I also tried spinning the fan. It moved fairly easily, a bit of resistance but definitely not binding or anything. I also didn't feel any play in it.

 

Hmm, maybe a weak belt tensioner, causing a little slip in the belt when the fan is commanded to engage?

 

Out of what I read, your fan clutch might be slipping the belt.

 

Ok, the noise has gotten worse. It's much more repeatable now, like all the time. Any time I'm on the gas it's there. If I let off, sit idling or get on the gas in the driveway it doesn't do it. Any time I'm driving and on the gas, it does it. Don't need to be towing any more either. It's also continuous now, not intermittent at all.

oldfordnstone-You mentioned a tea kettle whistle before. Now it sounds more tea kettle-ish rather than the birds chirping. I'm now thinking that was just a precursor noise. But it still sounds more mechanical, like bearings, rather than air/exhaust/coolant leaking. The degas isn't puking or anything either.

How can I check if the fan clutch is bad? Can I just unplug it and if the noise goes away that it's it? How can I verify if the belt tensioner is good or is the culprit?

 

can you post up a video for us to listen to?
seems like it might be boost related since its only under load.
reving the engine in the driveway wont make much boost if any.
watch boost numbers, and see if there is a common number where the tea kettle sound starts.

i would think a fan clutch noise would be more RPM related. would probably be able to make it happen in the driveway.

 

NP, I will post up a video as soon as I can. May not be till tomorrow or the next day though.

 

also check all of your CAC boots.
some may be ripped on the bottom or underneath the clamps so you will have to remove them to inspect fully.

 

I just did the oil cooler upgrade/replacement about a month before all this started. I thought I torqued everything down to spec on the boots and pipes to the turbo, but I coulda missed one. I know for a fact I didn't torque down the whatchamacallit pipe on the top front of the intake to the 50ish?(memory sucks) ft-lbs stamped on it. I kept tightening and tightening but I was afraid of bending the intake so I quit before hitting the ft-lbs stamped on it. Could be that

 

yeah you can tighten the crap out of it if you want.