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Discussion Starter #1 (Edited)
2012 Chevy Express, LGH motor, L6/90E transmission, 162,000 miles. All factory.

I purchased this van with 142,000 miles on it. We've pulled an 8,500-pound travel trailer with it for almost 10 months. We scale regularly and run around 17,700 lbs gross. The van pulls nicely, does not lack power ( I know that's a relative statement ), and gets pretty good mileage. The van has excellent service records up through about 110,000 miles when it was sold and the service from 110k to 142k was not able to be determined. Upon purchase of the van, I had the trans fluid exchanged with Amzoil, two oil changes with Amsoil, and just recently installed the Amsoil by-pass filter system with the 20-micron full flow and 2 micron low filters. The rear diff also has fresh Amsoil.
Recently I am getting a mild whirring sound or whine out of the motor. The sound is intermittent, coming on usually at a standstill, in gear or out of gear, and diminishes with driving. I recently had the engine cooling fan assembly replaced, and can definitely hear it coming off and on when the engine is heated up, but the whirring sound sounds different? I have no check engine light and all the gauges are showing normal. I don't think it's a power steering pump, there is no shutter in the steering wheel or brake pedal, and the fluid level is correct and clean. All fluid levels are correct. It does not sound like an alternator and the Amp meter has not fluctuated. Of course, I'm panicked that it is the fuel pump but have no performance changes, and almost all the driving we do is on the highway. I've rolled under to try to determine a location of the noise, it's not apparent.

Looking for some direction here. Thanks for your input.
 

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Welcome to DieselPlace

Have you removed the Serp belt and briefly ran the motor to see if the noise still occurs?
 

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Discussion Starter #3
I have not. I did turn the AC on and off to see if that affected the sound, no change. I'm only familiar with the alt., pwr. steering pump, AC, and water pump. I'm guessing in the diesel application there may be other pump driven components.
I'll look up S-belt removal and see if I need a special tool. I need to have an extra onboard anyway.

Thanks for the input.
 

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If it started after the install of the bypass filter system I would look at that first.
 

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Try to record it and post a video
 
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I had an intermittent whine end of last summer when my fan clutch went out and it acted like you describe. Seems like it would make sense to look in that direction considering the work that was just done.
 

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Welcome to DieselPlace

Have you removed the Serp belt and briefly ran the motor to see if the noise still occurs?
Welcome to DieselPlace

Have you removed the Serp belt and briefly ran the motor to see if the noise still occurs?
Well, I started to get ready to do that, but the noise is intermittent. I'm ordering a belt to have on hand, if the noise comes and stays I'll definitely pull the serpentine belt.
 

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I had an intermittent whine end of last summer when my fan clutch went out and it acted like you describe. Seems like it would make sense to look in that direction considering the work that was just done.

The sound is intermittent, and it comes on immediately upon start-up or when the engine coolant gets to about 110 degrees, fairly cool. I can hear the engine cooling fan when it kicks in, and it usually only kicks in hard when it's hot enough to have the AC running. Thanks for your input.
 

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If it started after the install of the bypass filter system I would look at that first.

Check, done. It was the first thing I looked at. My Amsoil guy ( it's an Amsoil bypass system ) took a look at it too, the van wasn't making the noise when he looked, but he couldn't find any pinched hoses, or apparent mistakes in my install. Both filters come up warm along with the engine, so I don't suspect any kind of flow restriction. The Amsoil guy said to watch for resonance in the system, maybe when the AC compressor kicks on....

Thanks for your reply.
 

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Check, done. It was the first thing I looked at. My Amsoil guy ( it's an Amsoil bypass system ) took a look at it too, the van wasn't making the noise when he looked, but he couldn't find any pinched hoses, or apparent mistakes in my install. Both filters come up warm along with the engine, so I don't suspect any kind of flow restriction. The Amsoil guy said to watch for resonance in the system, maybe when the AC compressor kicks on....

Thanks for your reply.
I know some people who have added aftermarket oil coolers and sandwich plates, etc experience a hydraulic whine type noise. Personally I am not big on these bypass filter setups for the Duramax. They are great wearing engines with normal oil/filters and oil related failures are extremely rare.
 

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I know some people who have added aftermarket oil coolers and sandwich plates, etc experience a hydraulic whine type noise. Personally I am not big on these bypass filter setups for the Duramax. They are great wearing engines with normal oil/filters and oil related failures are extremely rare.
No aftermarket oil coolers anywhere, the van is stock through and through.

Thanks for the input!
 

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No aftermarket oil coolers anywhere, the van is stock through and through.

Thanks for the input!
I mentioned that because it seems any changes made in the oil filter area has resulted in some new noises for some people.

Sent from my XT1710-02 using Tapatalk
 

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I mentioned that because it seems any changes made in the oil filter area has resulted in some new noises for some people.

Sent from my XT1710-02 using Tapatalk
Ok, I can go with that. The day I put the bypass filter on, I heard the noise. I can't say that was the first time I heard the noise, and you know how it's easy to get freaked out at every little noise after working on a car...I didn't want to blame something as simple as a bypass filter, but I do have to say, the noise seemed to start then...

If it is the filter system, what do you think is making the noise? It seems like the oil pump would be a pretty solid unit, the bypass hoses are only about 22" long, the filters and manifold are hanging right next to the fuel filter. Everything is put in with a torque wrench where instructed. Do you think the bypass system can resonate to point of hearing it?
 

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Ok, I can go with that. The day I put the bypass filter on, I heard the noise. I can't say that was the first time I heard the noise, and you know how it's easy to get freaked out at every little noise after working on a car...I didn't want to blame something as simple as a bypass filter, but I do have to say, the noise seemed to start then...

If it is the filter system, what do you think is making the noise? It seems like the oil pump would be a pretty solid unit, the bypass hoses are only about 22" long, the filters and manifold are hanging right next to the fuel filter. Everything is put in with a torque wrench where instructed. Do you think the bypass system can resonate to point of hearing it?
I have done same thing after installing a new part and start thinking to much. It could just simply be a hydraulic noise when oil is cold from traveling through all the extra stuff. It is right under your seat and if you have the window open it makes it easy to hear. Like I said earlier I would not run one on a duramax. When it comes to the oil system I very much prefer to take the KISS approach if there are no issues with the stock setup.
 

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I mentioned that because it seems any changes made in the oil filter area has resulted in some new noises for some people.

Sent from my XT1710-02 using Tapatalk
I have done same thing after installing a new part and start thinking too much. It could just simply be a hydraulic noise when oil is cold from traveling through all the extra stuff. It is right under your seat and if you have the window open it makes it easy to hear. Like I said earlier I would not run one on a duramax. When it comes to the oil system I very much prefer to take the KISS approach if there are no issues with the stock setup.

So my wife and I ran an errand yesterday, 1 hour out at 75 mph, parked a couple of spots then back to our place at 70mph for about an hour. Everything on the van works perfectly. I'm always impressed at how quiet this thing is at cruising speed (other than wind noise at the windows). All gauges were in their "normal" position. The noise came and went, intermittently, mostly right after startup and in traffic. Not a peep on the highway.
Thanks for your input, I'm going to really focus on this and see if I can jump under there and observe the oil bypass system. I have to admit, the sound does not sound like an idler pulley or anything else I've ever heard, and my reflection on a few years of farm tractor operation reminded my of the sound I hear when operating a front end loader and all the valves and hoses are right there. In fact, the day I installed the system, upon initial start-up, I thought to myself, hmmm, sounds like there is some air in the system ( I did fill both filters before start-up ). I'll keep you posted.
 

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Found it!

The noise came up a little, pulled over on a road, crawled under, the braided hoses are against the broad side of an aluminum shield, just barely touching. I pulled the hoses back a little and poof, no sound. Resonance from the hose in the shield. I'll make the needed adjustments.
Thanks, everyone!

Haha, I also have a question about my fuel filter, I'll post it soon, now that I've got the weirdo figured out.
 

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Found it!

The noise came up a little, pulled over on a road, crawled under, the braided hoses are against the broad side of an aluminum shield, just barely touching. I pulled the hoses back a little and poof, no sound. Resonance from the hose in the shield. I'll make the needed adjustments.
Thanks, everyone!

Haha, I also have a question about my fuel filter, I'll post it soon, now that I've got the weirdo figured out.
Glad you found the issue.
Thanks for keeping us updated
(y)
 
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