Moan 75-80 mph???

I have a Chevy Suburban R2500, 2WD, 454.
When I am traveling on the freeway, at approximately 75-80 mph, the engine begins to give off a pulsating moaning sound. If I reduce the RPM's, the
noise disappears. There is no vibration felt. Could this be the harmonic balancer? If not, any ideas?
Thanks, Andrew
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It is moaning while trying to warn you to slow down before you become a ghost.
john

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You didn't give the year. Exhaust resonance is my guess. Maybe resonance accentuated by rusting thin exhaust pipes. Tires are a maybe as is a wheel bearing or u-joint, but those aren't usually specific to that speed and have other signs as well.
| I have a Chevy Suburban R2500, 2WD, 454. | | When I am traveling on the freeway, at approximately 75-80 mph, the engine | begins to give off a pulsating moaning sound. If I reduce the RPM's, the | noise disappears. There is no vibration felt. Could this be the harmonic | balancer? If not, any ideas? | | Thanks, | Andrew | | |
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I would add the possibility of noise from the A.I.R. pump. If it didn't pulsate I would check the tranny filter. The air cleaner intake could also cause some moaning as they are very restrictive.
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Mad Dog

"Shades" <shades snipped-for-privacy@netins.net> wrote in message
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It's a 1990 Suburban without A.I.R.
There is as newly rebuilt trans and engine installed and a K&N filter. The exhaust is also new with a Flowmaster Big Block II muffler and new cat. Does this help?
Thanks, Andrew
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not really bro, sorry
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Mad Dog
"msr971" < snipped-for-privacy@cox.net> wrote in message
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I still stick with exhaust resonance. That's allot of engine and if its like mine, the tailpipe is a fairly long one. Try installing a resonator tip to the exhaust, see if it helps.
| It's a 1990 Suburban without A.I.R. | | There is as newly rebuilt trans and engine installed and a K&N filter. The | exhaust is also new with a Flowmaster Big Block II muffler and new cat. Does | this help? | | Thanks, | Andrew | |
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