Question Humming Sound from Turbo

[JRJ04]

Anywhere between 6-10 lbs of boost, regardless of load, im starting to hear a new sound coming from the turbo. I still hear it singing away when it gets spooled up, but theres a "humming" sound in that boost range now. the second I let off it (whether it be sudden or slowly), it goes away.

Could this be a boot leaking? Wastegate? Turbo going south? No oil leaks, and still runs great.

Your thoughts?

 

[DaveBen]

Start with the easy stuff (and cheap). Check all of your boots for cracks or loose clamps. I really doubt it is your turbo. The wastegate won't come into operation at 6-10 pounds.

Dave

 

[JRJ04]

yea its just weird that it would be the boots...you would think it would get louder as i get into it more, but it goes away. maybe just the tone changes and i cant hear it? nonetheless...ill check it out today.

 

[BIG JOE]

Sure it's from the Turbo.. and not the PS pump JR ?

 

[rammertide07]

Mine did the same thing....about 400 (driving from LA to AL) mi before it started pooring oil through the turbo. I had to replace it for about 1500. If you start noticing more smoke from the exhuast then I would say you're heading in the same direction as mine did. My diesel mechanic seen he has seen trucks in the same shape, and when they tried to turn them off they would keep running due to the oil still being pumped into the engine just by the centrifical force. And the only way to shut them off then is to rip off the air intake and stuff a shirt or something down it to choke it out.

Also another sound I heard that lead me to the conclusion that was the turbo is that I had my dad to test drive it and get his opinion. When he pulled back up I was standing on the passenger side...close to the exhaust. When he turned it off I heard a scrubbing/grinding noise instead of that nice whistle.

 

[JRJ04]

Mine did the same thing....about 400 (driving from LA to AL) mi before it started pooring oil through the turbo. I had to replace it for about 1500. If you start noticing more smoke from the exhuast then I would say you're heading in the same direction as mine did. My diesel mechanic seen he has seen trucks in the same shape, and when they tried to turn them off they would keep running due to the oil still being pumped into the engine just by the centrifical force. And the only way to shut them off then is to rip off the air intake and stuff a shirt or something down it to choke it out.

Also another sound I heard that lead me to the conclusion that was the turbo is that I had my dad to test drive it and get his opinion. When he pulled back up I was standing on the passenger side...close to the exhaust. When he turned it off I heard a scrubbing/grinding noise instead of that nice whistle.

No oil in the turbo, all the seals are good. Have not heard a grinding from it at all.

Joe, I'm pretty sure its the turbo...ps pump is making a differnt noise, but who knows

 

[JRJ04]

Update

After driving it more...I'm almost certain its not the PS/pump because engine RPM makes no difference. I can really hear the noise between 4-8 lbs of boost. load makes no difference...it just in that range.

 

[rammertide07]

Pop the air intake off the turbo and see if the wheel is loose.

I'm not sure if you're saying "all the seals are good, so there is no oil in it" but the seals don't have to be bad for oil to get into the trubo. But I'm sure if oil was running through the turbo you would notice it. But still wouldn't hurt to see if there is any play in the turbo wheel.

 

[JRJ04]

yep couldnt agree with you more...

hopefully ill have some time to look at it today. ive been told if theres a little play in it...thats ok...but if theres a lot, youre in bad shape. is that true?

 

[rammertide07]

yep couldnt agree with you more...

hopefully ill have some time to look at it today. ive been told if theres a little play in it...thats ok...but if theres a lot, youre in bad shape. is that true?

"Up and down shaft movement should be no more than 0.003 to 0.006 inches. End play should be 0.001 to 0.003 inches. This test may not reveal excessive clearances, however, if the turbocharger has varnished or coked bearings."

Found it off a site. It will explain everything about problem checking the turbo: Turbo Repair and Turbocharger Repair - Turbo Repair Kits and Turbo Diesel Repair