Mercruiser Knocking

[fischstix6]

The Boat 1997 Crownline 225 BR
Engine: 97' 7.4L with a bravo three out drive.
Recent Repairs: Replaced the yoke assemble, gimble bearing, and drive house bearing that attaches to the yoke assembly.
Problem: After completing the repairs and taking her out for the day. The boat ran fine for the most part. However, when I first applied power to the boat she seemed to lack some power. Later the engine alarm sounded and the engine shutdown. The oil pressure seemed to drop and the engine shutdown. I checked for oil levels, gear Lube, and overheating no problems there. Restarted engine and oil pressure became normal. Ran the boat the rest of the day with no problems. Once out of the water I flushed the engine and now I have a new noise. It sounds like a medium knock that sounds two to three times the rhythm of the RPM?s and sounds like it is coming from inside the exhaust pipes. Also there seems to be valve clatter that started recently as well.
Do I need to be concerned is this normal or do I need to check something?
Also the drive housing on the outdrive is always warm is that normal?
Any help would be appreciated,
Thanks
Fischstix6

 

[JustJason]

Re: Mercruiser Knocking

Later the engine alarm sounded and the engine shutdown. The oil pressure seemed to drop and the engine shutdown. I checked for oil levels, gear Lube, and overheating no problems there

check and recheck to make sure your not overfilled on oil. not even overfilled by a little bit is acceptable.

Once out of the water I flushed the engine and now I have a new noise. It sounds like a medium knock that sounds two to three times the rhythm of the RPM’s and sounds like it is coming from inside the exhaust pipes

the knock... or it should be closer to a tick, is probably coming from the shutters inside of the collecter (exhaust pipe).

check and recheck to make sure your not overfilled on oil.

 

[fischstix6]

Re: Mercruiser Knocking

Thanks for the reply. Yeah I checked the oil and that was at the proper levels "not over filled". The noise is heard through the exhaust pipes. I am pretty sure it's not the shutters in the collectors the noise sounds to heavy to be that. The noise sounds like it's coming from deeper in the engine.
fischstix6

 

[180shabah]

Re: Mercruiser Knocking

Break out the mechanics stethiscope and start listenin'

You said it sounds like it is 2-3 times per revolution, so it is either in the exhaust or you have multiple valve issues. The ear will tell.

 

[JustJason]

Re: Mercruiser Knocking

i agree.... really no place else to go but with a stethoscope... or screwdriver.

 

[mikey.himself]

Re: Mercruiser Knocking

Is it possible that it could be a valve or a timing chain ?

 

[fischstix6]

Re: Mercruiser Knocking

Thanks fellas
I'll break it out and get back to ya.
fisch