Merc 7.4 Gen V clicking noise
#1
Thread Starter
Registered
Joined: Jan 2014
Posts: 29
Likes: 0
From: Toronto
Hi,
I've got a 454 that performs well, no power loss with throttle at all. However; I have clicking noise that is noticeable around 2500 rpm and gets louder as you increase rpm.
Jt
I've got a 454 that performs well, no power loss with throttle at all. However; I have clicking noise that is noticeable around 2500 rpm and gets louder as you increase rpm.
Jt
#4
Registered

Joined: Dec 2009
Posts: 155
Likes: 42
From: Midland, MI
I have had blown exhaust gaskets and cracked plugs that leak around the shell make funny noises. Is there a way to run this while you listen around and try to pin point area of noise either front to back or port to strb?
#6
Thread Starter
Registered
Joined: Jan 2014
Posts: 29
Likes: 0
From: Toronto
Likely, or a loose rocker. Wouldn't a stuck lifter effect valve operation? If it's the exhaust valve would I smell un burnt fuel in the exhaust? ( cause I do)
Any way to unstick without opening up? If this is the case, would it be the cam tapping on the flat tappet?
Any way to unstick without opening up? If this is the case, would it be the cam tapping on the flat tappet?
Last edited by 77Nova; 06-09-2014 at 09:02 PM.
#8
Registered
Joined: Jul 2006
Posts: 5
Likes: 0
From: Toronto
3 years later, motor still ticking above 2500 rpm. Motor runs great, acceleration and WOT - just ticks. I've put in additives with every oil change, and changed from merc 25-40 to 15-40. The sound actually driving me crazy, but it's hard to invest in a rebuild or opening it up when the engine fires up first crank, and smooth operation. It does smoke a bit on start up, but I'm running a bravo 3 and I've read it needs to run rich at idle to shift.
Any thoughts?
Thanks,
Any thoughts?
Thanks,
#9
Registered

Joined: Mar 2013
Posts: 1,102
Likes: 11
From: Granger, Indiana
[QUOTE=hyperlite98;4557564]3 years later, motor still ticking above 2500 rpm. Motor runs great, acceleration and WOT
I'M NOT A MECHANIC
Did you check the exhaust flappers - that ones that are in or right before the Y pipe? I have been told that they will rust out or get loose and start flipping and flopping. I agree if everything else is running well don't mess with it.
3pointstar
I'M NOT A MECHANIC
Did you check the exhaust flappers - that ones that are in or right before the Y pipe? I have been told that they will rust out or get loose and start flipping and flopping. I agree if everything else is running well don't mess with it.
3pointstar
#10
Registered

Joined: Feb 2012
Posts: 4,031
Likes: 10
From: westville, NJ
The flapper are loudest at idle. The reversion pulses pulling them shut causes the noise. Once you are on the throttle, they are pinned open and shut up. Ok, I figured thread out. Hyperlite is 77 nova. Screen name change.



