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boilermaker · 04-09-2018, 10:04 AM

On my 2006 c7
After about a 4 hour drive yesterday I noticed a squeal coming from my motor during declaration.
It happens with or without the exhaust brake on but only during aggressive slowdown
Anybody have a issue like this?
I’m wondering if it’s a belt but it only does it during declaration every thing else operates normally power, gauges, no warning lights on dash.

Skip426 · 04-09-2018, 10:17 AM

Sorry to say ; but this doesn't sound good .
First place I'd say to check would be the engines turbo, remove the tubing from the turbo's pressure side ( tubing to the CAC ; Charge Air Cooler

and look for ANY indication of metal filings stuck to the inside of the tubes. That would be an indication of contact between the turbo blades and the housing.
I hope that's not the issue , but you want to check , because if the turbo is failing you don't want to be pushing metal into the engine.
There are other possible causes , but they aren't as critical.

boilermaker · 04-09-2018, 11:02 AM

Thank you for the reply
Yea I was worried about it being the turbo
Right before I heard the noise I was rerouted around an accident that put me on a very dusty dirt road and I was hoping it was a dust on the belts or pulleys issue
I will try to pull that tube off tonight and look at it

Cat · 04-09-2018, 10:31 PM

When the turbo starts to go a lot of the time you can hear it at the exhaust pipe. Have someone just rev the engine up and shut it off, while you listen at the exhaust pipe opening. You should not hear any tingling or mechanical noise at all as the turbo slows down, it should sound kinda like a ceiling fan after you turn it off.

boilermaker · 04-10-2018, 08:19 PM

I took skips advice and pulled the rubber 90 fitting off the turbo.
Other then being surprisingly dirty I didn't see any evidence of metal in it.
I took the intake boot off so I could look at the wheel.
it spins with no noise but has some up and down play in the shaft maybe almost an 1/8??
I have no idea what is acceptable. I made a video of the movement if anybody is interested in seeing it. p.m. me your email I will share.
cat, I would of liked to try your tip but I'm buy myself in a campground and don't have anybody to help me.

Skip426 · 04-10-2018, 09:43 PM

There is an allowable tolerance on the turbo shaft , for movement .
The clearance needs to be measured with a dial indicator . While the engine is running at the turbo bearings " float " on the pressurized oil.
If you have no indication of oil leaking through the seal , you might be ok .
However the dirt you've found in the tubing may be problematic.

Cat · 04-10-2018, 10:19 PM

1/8” normal as as it does not touch sides. Should have zero end to end play – pull straight out and push in to test. And it should spin easy no drag. Leading edge of fins should be smooth not erroded looking

boilermaker · 04-11-2018, 08:39 PM

Thanks for all the info skip and cat I really appreciate it.
there is no sign of oil leaking past seal
At this point I think I will drive it the 100mi home next week when this job is done.
Then I can put a dial indicator on it and see what the play is.
I also need to figure out why that tube has dust in it I really don't like that.
My filter is only two years old and there's only a couple of joints between it and the turbo I will check all bands for tightness
thank you again

Cat · 04-11-2018, 08:55 PM

Let us know what it turns out to be. If you think you've got dust getting in, you might want to pull an engine oil sample. It will give you idea of how silica is getting in and how much damage might have been done to the internals. Might be good for piece of mind. Good luck

2 Stroker · 04-11-2018, 09:06 PM

I would change out to air filter, may have a pin hole in the filter.
I like the Donaldson Blue one of the best filters made. When you get it running you could take a can of starting fluid and spray the piping and all joints while running, if you hear it pick up speed you have a outside air leak.
2 stroker

FIRE UP · 04-11-2018, 10:39 PM

Quote:

Originally Posted by boilermaker

On my 2006 c7
After about a 4 hour drive yesterday I noticed a squeal coming from my motor during declaration.
It happens with or without the exhaust brake on but only during aggressive slowdown
Anybody have a issue like this?
I’m wondering if it’s a belt but it only does it during declaration every thing else operates normally power, gauges, no warning lights on dash.

Boilermaker,
One thing you've not stated is the mileage on your coach and, whether or not the belts, fan pulley bearing, serpentine tensioner bearing(s), serpentine idler bearing(s), water pump belt, water pump tensioner bearing etc. have or have not been changed. Can any of those make noises, yep, you betcha. Just some things to think about besides the turbo.
Scott

boilermaker · 04-14-2018, 09:07 AM

The coach has 35k on it the only thing that has been changed on the motor are the belts.
A couple of months ago I loosened the serpentine belt and checked spun, rocked the fan.
A oil analysis is going to happen along with all intake hoses coming off for inspection.
Probably the turbo removed and sent out to a shop to have it rebuild.
I'm not sure where to send it I'm open to suggestions for a reputable shop.
I really appreciate all the suggestions and help I'm getting with this

Dtwallace · 04-14-2018, 10:07 AM

If you’re going to have the turbo inspected and or rebuilt, have it done by (CAT).

Don’t leave out inspection of the pressure side of system also, although a high pitch squeal will happen under load if you have a leak on that side.

I’m more inclined to a belt driven component issue from your discription. Dust in the intake pipes, it happens if you haven’t had it off in two years for inspection and cleaning.

For piece of mind, I would check the water pump, and everything else that is driven by belt, with the belts off.

Sometimes, these problems can be a bear to figure out.

DTW

boilermaker · 06-01-2018, 03:53 PM

update:
I made the 100mi drive home driving it slow and easy
when I got close I used the exhaust brake several times to see if the
noise was still there, It wasn't.
Today I pulled the air filter and all hose's going to turbo off for inspection.
I found my dust problem at the boot to the intake of the turbo to be where the leak is at, the clamp didn't feel loose.
It appears that it has been leaking quite awhile there is what looks to be corrosion, dirt or something on the mouth of the turbo where the boot clamps to that is very weird looking.
I'm kind of surprised my engine isn't dusted.
I went ahead and took the turbo off to get it inspected I'm still concerned about the shaft play, just need to find someone knowledgeable to inspect it here in sacramento or san Francisco area anybody know of any good shops?