Alternator Bearing Question **Noise Solved**

[nick0789]

Update:

I used a stethoscope and swear the noise is coming from up top.

I replaced the intake manifold gasket (Fel-Pro), knock sensors (OEM), harness (Dorman), and oil pressure sensor (OEM) and the noise persists.

And on top of it, I’m now getting the P0327 code for the front knock sensor. To say that I’m pissed about the sensor is an understatement. Everything was torqued as it was reassembled and now I’m telling myself I should have just said screw it and left the knock sensors alone.
I’ve read online of people having OEM duds out of the box, but I guess my question is if I can pull the front knock sensor without having to fully tear down again. I’ll take it to the shop before I go through that hassle again.

I’d even be okay with just pulling the manifold bolts and lifting enough to get under there if I can.

 

[afpj]

For the latest issue, my first thought is the dormant harness. Yes, there are OEM duds out there, but I have a very distinctive dislike for dorman products nowadays. I've been burned twice by Dorman products (used them twice in the past 10 years, so 100% failure rate), there will not be a third.

 

[Doubeleive]

Update:

I used a stethoscope and swear the noise is coming from up top.

I replaced the intake manifold gasket (Fel-Pro), knock sensors (OEM), harness (Dorman), and oil pressure sensor (OEM) and the noise persists.

And on top of it, I’m now getting the P0327 code for the front knock sensor. To say that I’m pissed about the sensor is an understatement. Everything was torqued as it was reassembled and now I’m telling myself I should have just said screw it and left the knock sensors alone.
I’ve read online of people having OEM duds out of the box, but I guess my question is if I can pull the front knock sensor without having to fully tear down again. I’ll take it to the shop before I go through that hassle again.

I’d even be okay with just pulling the manifold bolts and lifting enough to get under there if I can.

it's common for non oem knock sensors to do that a couple days after install, just replace it, cheaper to do it yourself, there is no cheat to it

 

[nick0789]

For the latest issue, my first thought is the dormant harness. Yes, there are OEM duds out there, but I have a very distinctive dislike for dorman products nowadays. I've been burned twice by Dorman products (used them twice in the past 10 years, so 100% failure rate), there will not be a third.

Yea, I'm not generally a big fan of Dorman products, but the GM harness was not in stock on RA and no store around had it. I researched around online and most people on the forum went with Dorman or OEM so I bit the bullet and picked one up.
Last night I went back out and was able to wedge my hand between the intake and valley cover and popped the front harness connector out. Stuck a multimeter in the pigtail and the associated color pin at the other end (dark blue for the front) and the resistance looked good i.e. it didn't stay at "1 " on the multimeter. I want to say it was 0.2 ohms so I just said screw it and lifted the intake again and replaced the front knock sensor with another OEM sensor. The first one came from RA so who knows if it was packaging/shipping or potentially even someone dropping it at the warehouse at some point.

I did notice it was SUPER easy to remove with the wrench, even for 15 ft-lbs of torque during the original install. I swore I torqued it right after the rear but I may have just snugged it instead. Getting the side eye from the wife probably threw my concentration off lol.

Either way, I got a new one in and torqued, hooked up, and tested out. My drive to work is ~ 8 miles and nothing popped up then. I took it for a spin down the highway during lunch (~ 75 mph and 2,200 rpm) for about 20 miles total and no codes popped up. Fingers crossed I don't have to deal with it again.

I'll be taking the tahoe into the shop on Thursday to see if they can locate the sound of the whine/whistle, and I'll report back with what they find (if anything).

 

[corvette744]

Yea, I'm not generally a big fan of Dorman products, but the GM harness was not in stock on RA and no store around had it. I researched around online and most people on the forum went with Dorman or OEM so I bit the bullet and picked one up.
Last night I went back out and was able to wedge my hand between the intake and valley cover and popped the front harness connector out. Stuck a multimeter in the pigtail and the associated color pin at the other end (dark blue for the front) and the resistance looked good i.e. it didn't stay at "1 " on the multimeter. I want to say it was 0.2 ohms so I just said screw it and lifted the intake again and replaced the front knock sensor with another OEM sensor. The first one came from RA so who knows if it was packaging/shipping or potentially even someone dropping it at the warehouse at some point.

I did notice it was SUPER easy to remove with the wrench, even for 15 ft-lbs of torque during the original install. I swore I torqued it right after the rear but I may have just snugged it instead. Getting the side eye from the wife probably threw my concentration off lol.

Either way, I got a new one in and torqued, hooked up, and tested out. My drive to work is ~ 8 miles and nothing popped up then. I took it for a spin down the highway during lunch (~ 75 mph and 2,200 rpm) for about 20 miles total and no codes popped up. Fingers crossed I don't have to deal with it again.

I'll be taking the tahoe into the shop on Thursday to see if they can locate the sound of the whine/whistle, and I'll report back with what they find (if anything).

Good job on testing before replacing im a big fan of seeing what is bad before replacing.The side eye is always bad lol

 

[nick0789]

The tahoe seems to be the prized pig at the state fair: they have 4 people looking at it at the same time at the shop lol
They swear they can hear it up top around the throttle body / purge valve solenoid, and will be doing a vacuum test and smoke test after lunch.

With me having a bad vapor canister a while back and the original purge valve solenoid getting clogged with charcoal, is there any way for charcoal to make its way through the solenoid itself and get jammed somewhere in the top end of the intake? I can't find a diagram for the internals of our solenoids.

If not, then based on what I was told I won't be surprised if they find smoke around the solenoid port.

 

[nick0789]

I'm going to go ahead and put an end to this thread: I finally got the noise to go away.

The shop completed the smoke test and vacuum test and no issues came up from either test. I took it home and messed around with it some more since I had the original parts from the EVAP system left over from doing the fuel pump replacement a few months back.

I cleaned the throttle body and replaced the throttle body gasket, swapped the purge valve solenoid back and pulled the EVAP line running along the fuel rail. There was one leftover pellet of charcoal in the line that I blew out, and the solenoid seemed to seal better on the top of the intake.
No whistling noise after that. My guess was the o-ring on the replacement purge valve solenoid wasn't sealing well enough while cold and that the smoke test / vacuum test were done while the engine was still slightly warm so it sealed just fine for the shop.

I also went ahead and replaced the throttle body itself last night because there was a lot of build-up that I couldn't clear without risking any damage to the butterfly valve. Acceleration and shifting seems to be faster too now with the new throttle body and buildup should be better controlled now that I have installed a catch can.

Thanks again to everyone that gave their input with this noise!

 

[Joseph Garcia]

Thank you for posting the solution to your issue. Much appreciated.

Those pesky charcoal pellets. Just another confirmation that you should remove the gas filler nozzle just as soon as it clicks off the first time. That extra pint of gas in the tank is simply not worth the H-e-l-l that you will cause yourself, if those pesky charcoal pellets get loose.

 

[SnowDrifter]

I'm going to go ahead and put an end to this thread: I finally got the noise to go away.

The shop completed the smoke test and vacuum test and no issues came up from either test. I took it home and messed around with it some more since I had the original parts from the EVAP system left over from doing the fuel pump replacement a few months back.

I cleaned the throttle body and replaced the throttle body gasket, swapped the purge valve solenoid back and pulled the EVAP line running along the fuel rail. There was one leftover pellet of charcoal in the line that I blew out, and the solenoid seemed to seal better on the top of the intake.
No whistling noise after that. My guess was the o-ring on the replacement purge valve solenoid wasn't sealing well enough while cold and that the smoke test / vacuum test were done while the engine was still slightly warm so it sealed just fine for the shop.

I also went ahead and replaced the throttle body itself last night because there was a lot of build-up that I couldn't clear without risking any damage to the butterfly valve. Acceleration and shifting seems to be faster too now with the new throttle body and buildup should be better controlled now that I have installed a catch can.

Thanks again to everyone that gave their input with this noise!

You think it was from a charcoal pellet? Or issue with the evap valve sealing?

 

[nick0789]

I think that 16 years was a good run for the OEM canister. While I never top off the fuel, I can’t say that the PO also did the same.

As far as the “actual” cause of the noise, without knowing how the solenoid functions (when it opens/closes the vent), I’d lean towards the o ring being the true cause. When my canister originally failed and I got the “tighten fuel cap” message the valve and the upper EVAP line were stuffed with pellets so I would figure that the noise would have been noticeable before I did all the EVAP/fuel tank work.
I’m done caring about it at this point (lol), though I do have the other valve in the garage. It would be easy enough to swap back and listen for the noise.