When my port motor is running at idle I have a "tick-tick-tick..." that is in unison with the speed of the motor. If I bring up the RPMs a little, it quiets then goes away. I have completely gone thru the valvetrain (valves/springs/lifters/etc.) and everything is kosher. Oil pressure is fine. I have used a stethescope, but still can't pin point where it is coming from.

I spoke with someone today who mentioned that the exhaust flappers located at the transom (that prevents water inversion) mounted inside the rubber tubes that the exhaust pipes insert into, can sometimes when they get older develop a ticking. They are the flappers that are hinged in the center, located just before the exhaust gasses pass into the Silent Thunder box. Has anyone ever heard of this, or experienced it to confirm that this may be what I have going on? I would love it to be something as simple as this!

My exhaust manifolds are off and I didn't have time today to get them on to run it and listen to see if it was coming from there.


Thanks for any help!

When I had this problem, I locked them open, by shoving a broom handle up the tailpipe to keep them open and prove it was the flappers, not the valves etc. and it was the flappers. If you have some sort of access to lock them open, and run the motor then do that.

Thanks man. Unfortunately I don't have any access to them once the exhaust manifolds are bolted on. If that is where it is coming from I will just live with it........and have peace of mind knowing it isn't something criticle.

Oh yeah, and rchevelle71, when yours started doing that, did they look any different.....was any rubber missing, etc.....???

It is probably the rubber gone around the flapper, happened to mine. It only takes about 20 min to remove the silent thunder box to inspect the flappers. One of mine even broke the metal. I run the clamp on flappers now, and no silent thunder. Hope this helps.

Sam

I had something like that and it cost me $$$

Care to elaborate..........??

I had an 88 242 630 HP, it had the flappers. you remove the rubber hose and they are atteched to the metal tips that go thriugh the transom to your silent thunder. not a big job but very important to have.

What kind of speed did you see with 630 HP in a 242?
Did that 242 come with a 7.4/454 2 bolt main and Bravo drive?

It was kind of a clink, tick. You could hear it at idle in neutral......it was something in the drive or coupler. I don't remember.....and usually say FIX IT. Sorry!