Loud ticking noise

mvn

2008 5.0L Mercruiser coupled to an Alpha One drive.   Towards the end of the last boating season, I detected a loud ticking noise coming from right cylinder bank.   Increased ticking rate with RPM.  Also detected an abnormal odor in the engine compartment.   Felt hot gas pulsations coming from the vicinity of the #1 spark plug.   A mirror placed under the exhaust manifold showed a protruding manifold gasket.   I removed the exhaust manifold and checked the exhaust shutter.   Then I looked at the gasket (see attached).   This engine was never worked on... factory original.   Turns out there's a service bulletin out there claiming improper exhaust manifold bolt torques from the factory.   After replacing the gasket,  all is well again. 

Mark

 

mvn

 

Alswagg said:

yes, this is very common.  We started retorquing all exhaust manifolds mountings at the 20 hr or first oil changes.  I have changed many of these gaskets.  Luckily not too bad to do.  Al

Well, on a 226 the starboard side is easy.  The port side, that's a different story especially when you're trying to do it yourself!!  I figured out a way to rig a beam across the engine compartment opening and support the manifold with ratchet straps.  Worked out quite well.

Mark

Glassguy54

Is it just 2008 5.0, or are other years & displacements also affected?

mvn

Alswagg can comment better than I; however, reading on other forums shows that it is primarily a GM small block issue on all years.  Some have used Volvo or Fel-Pro gaskets with better success than Merc.  Failures seem to readily occur between 20 and 60 hours.

Mark

212rowboat

If and when you guys encounter issues with failed exhaust gaskets, there is one solution that works every single time without fail, and will last until you unseat them...

The mighty "Remflex" gasket is the answer.. it will seal even warped manifolds.. they are pricey, but worth every bit of the cost.. if you couple the remflex gaskets with stage eight (not grade eight, but stage eight) bolts, that problem is forever solved..

Dream_Inn

A neat trick to holding the exhaust manifolds on is buy a couple extra bolts 2 inches longer.  Cut the head off, finger them in on the ends.  Now you can put the gasket on and then the manifold without having to worry about the gasket moving or trying to put a bolt in at the same time.  Then you can, by hand, walk out the bolts when you have the other bolts finger tight.

mvn

drewactual said:

If and when you guys encounter issues with failed exhaust gaskets, there is one solution that works every single time without fail, and will last until you unseat them... The mighty "Remflex" gasket is the answer.. it will seal even warped manifolds.. they are pricey, but worth every bit of the cost.. if you couple the remflex gaskets with stage eight (not grade eight, but stage eight) bolts, that problem is forever solved..

Here's a link to Stage 8 Fasteners.  Very interesting..........

http://www.stage8.com/

Mark

 

212rowboat

I swear by them, Mark.

I've also used these, which I don't recommend.. :