Possible bad cam
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Joined: Apr 2011
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From: Iowa
Possible bad cam
Posted this over in the touring section, but mkguitar suggested I repost this over here so I'll copy my post from that thread.
I tore the 91 ultra apart looking for the cause behind an excessive sucking sound through the intake digging in deeper I found this.
Intake lobe on the front cylinder has the finish wore off. Could this be the cause behind the noise.. not letting the valve open far enough? Factory 80" with approx 35k on rebuild and its an andrews ev27 and new hd lifters with right at 10k miles on everything.
At first I thought it was an intake gasket leak had then intake off probably 6-7 times. Swapped carb off of my sportster (both s&s) compression test but no leak down test and never put air in the cylinders.
Thanks for any insight you guys might have.
I tore the 91 ultra apart looking for the cause behind an excessive sucking sound through the intake digging in deeper I found this.
Intake lobe on the front cylinder has the finish wore off. Could this be the cause behind the noise.. not letting the valve open far enough? Factory 80" with approx 35k on rebuild and its an andrews ev27 and new hd lifters with right at 10k miles on everything.
At first I thought it was an intake gasket leak had then intake off probably 6-7 times. Swapped carb off of my sportster (both s&s) compression test but no leak down test and never put air in the cylinders.
Thanks for any insight you guys might have.
Last edited by Nick_R; Jun 15, 2014 at 08:48 PM.
Road Captain
Joined: Aug 2012
Posts: 625
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From: New Albany, Ms.
I had this happen , last year. Thought it was intake leak. Replaced seals & didn't fix sucking sound. Finally figured out rear rocker box cover gasket was blown. Right in the center, blew out a piece of gasket. Replaced & hasn't "sucked" yet. Something to look at.
Ride Safe,
Harold
Ride Safe,
Harold
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Joined: Apr 2011
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From: Iowa
I had this happen , last year. Thought it was intake leak. Replaced seals & didn't fix sucking sound. Finally figured out rear rocker box cover gasket was blown. Right in the center, blew out a piece of gasket. Replaced & hasn't "sucked" yet. Something to look at.
Ride Safe,
Harold
Ride Safe,
Harold
Seasoned HDF Member
Joined: Dec 2010
Posts: 7,736
Likes: 1,524
From: Coromandel Peninsula New Zealand
Its gone matt on one of the lobes....this is usually a sign that the hardening has gone south.
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Thread Starter
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Joined: Apr 2011
Posts: 67
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From: Iowa
I had this happen , last year. Thought it was intake leak. Replaced seals & didn't fix sucking sound. Finally figured out rear rocker box cover gasket was blown. Right in the center, blew out a piece of gasket. Replaced & hasn't "sucked" yet. Something to look at.
Ride Safe,
Harold
Ride Safe,
Harold
Resealed the rocker box put the lifter block back in, adjusted pushrods and wa-la no noise. Still should look into the cam but it wasn't the cause for any noise.
Thanks for all the help
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Joined: Jul 2013
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From: Houston, TX
I have a sucking noise too... sounds like it's at the intake, but only on acceleration. No intake leaks... I'm assuming it's just the sound of the motor sucking in air through the free flowing A/C.
