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post #1 of (permalink) Old 08-27-2003, 08:16 AM
Matt S.
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Tapping and Sucking - Exhaust Leak???

Here's the situation...97 K1500 5.7L with ~80k miles on it. Tapping/ticking sound coming from engine compartment only when under load (it does not occur while idling or revving in Park). When gas is left off, tapping/ticking stops and whistling/sucking sound briefly heard. There's no loss of power. Figuring this is an exhaust leak somewhere because of the sucking air sound. Didn't see anything obvious on the manifolds. Anyone had a similar experience?

Thanks!
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post #2 of (permalink) Old 08-27-2003, 11:12 AM
ratlover
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Re: Tapping and Sucking - Exhaust Leak???

Look for obvious signs of escaping exhust(probably wont be visible unless its been going on awhile) or feel around while its running for escaping gas. I havent ever heard of a sucking sound??? Listen around with a steshescope or a peice of tubing and also a solid rod to try to narrow down the sound....it might not be very noticable without load but still there. If you need any more explination of how to listen for sounds let us know....

diagnosing sounds is kinda a PITA without hearing it...

It follows rpm I assume? Check at the mani/head and the mani/y pipe conection.
post #3 of (permalink) Old 08-27-2003, 11:13 AM
ratlover
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Re: Tapping and Sucking - Exhaust Leak???

obvious signs would be black streaks or burnt gasket ect....think of hot gas blowing out and what it might do
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post #4 of (permalink) Old 08-27-2003, 01:07 PM
 
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Re: Tapping and Sucking - Exhaust Leak???

You might want to check your donut gasket. I had to replace one on mine. You should be able to get under the truck and here that leak if that is what it is.
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post #5 of (permalink) Old 08-27-2003, 01:07 PM
Matt S.
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Re: Tapping and Sucking - Exhaust Leak???

Thanks for the info. Sound does vary with RPM. I think the "sucking" when going off throttle is just pressure equalization when exhaust pressure drops.
post #6 of (permalink) Old 08-29-2003, 08:05 AM
Matt S.
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Re: Tapping and Sucking - Exhaust Leak???

So my local garage found nothing, though the mechanic noted he's not too good for hearing stuff anymore. Any other ideas? May have to take it to the dealer and bend over...
post #7 of (permalink) Old 08-29-2003, 04:05 PM
ratlover
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Re: Tapping and Sucking - Exhaust Leak???

Listen to the motor and possibly have a buddy so they can raise the rpms while you poke around.

Get a mechanics stethescope or make one. A lenght of vacume line or similar tubing stuck in your ear can help you pin point were a sound is coming from.

The next way to pinpoint a sound(ussually for sounds from a motor like to see what valve seems to be ticking and such) get a solid rod of metal. A long screwdriver or a long prybar, or a long extension placed were you think the sound is coming from and moved around to pin point it and the other end placed up to and touching your ear will let you listen to whats happening in the motor. Wount really let you hear for an exhaust leak though. Sometimes things can sound like they are coming from one side of the motor but are actually coming from the other by ear but these ways will really help you narrow it down. It also amplifys things.....might not be noticable by ear.

all kinds of things can make ticking noises like valves to fuel pumps to really bad stuff. listen all over the place

they have those little remote microphone deals for this while road testing....might be able to rig something up for a test drive or latch onto one.

same noise on a hot or cold motor?
post #8 of (permalink) Old 08-29-2003, 04:35 PM
Matt S.
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Re: Tapping and Sucking - Exhaust Leak???

I'll try to dig deeper this weekend. Sound is only there once motor is warmed up.
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