Possible Blown Head Gasket?!?!?

[int76]

99 Glastron 5.0Gl Volvo Penta / SX Outdrive only 100hrs on it!!!

Well Ive tried to track down this damne rattle noise from the back side of the engine and havent been able to figure anything out. The u-joints are good, the gimble bearing is good and outdrive is smooth. So I think maybe the coupler and do a search and find this thread:

http://forums.iboats.com/showthread.php?t=314470&highlight=penta+coupler

IDENTICAL symptoms as mine to a T so I figure I may have a head gasket issue. There is NO water in the oil but the last time I pulled it out of the lake I noticed when pulling the plug the water had a "rainbow tint" to it which I thought was odd. So im checking things out running it in the driveway on the muffs and loosen one side of the y clamps for the exhaust and notice water is flowing through there!?!?!? how can water be coming out the exhaust but not getting in the oil??? Could this possible be my problem?

little more info from my last outing...While trying to troubleshoot the rattle noise I came to a pretty abrupt stop after going about 35mph, after which the boat would not start and barely turned over leaving me stranded for about 20 mins. Smoke was coming from the carb?!?!? and after 20 mins of cranking occaisonally the boat started and I limped it back on the trailer, after which I started it on the trailer in the water and it ran perfect. After reading about exhaust flappers and mine being gone (found both and hinge pins when I pulled outdrive to check things out / grease things) I think the water may have got pushed back into the exhaust and maybe cranking it over blew the gasket?!?!? Got it home ran it on the muffs and again ran perfrect, idled perfect and run good through the gears in the drive....

 

[cr2k]

Re: Possible Blown Head Gasket?!?!?

The "smoke" coming out the carb could be fuel vapor from flooding from either improper float level or the super tiny bleed holes on top of the main jet venturi being plugged allowing fuel to siphon into the carb.

Just a possibility. You could do a compression check to determine if you have a head gasket issue.

 

[TilliamWe]

Re: Possible Blown Head Gasket?!?!?

... So im checking things out running it in the driveway on the muffs and loosen one side of the y clamps for the exhaust and notice water is flowing through there!?!?!? how can water be coming out the exhaust but not getting in the oil??? Could this possible be my problem?....

Do you really not understand how I/O exhaust sytems work? Water is introduced to the exhaust in the riser. It's introduced there, so it doesn't get into the cylinders, it goes out with the exhaust.

 

[TilliamWe]

Re: Possible Blown Head Gasket?!?!?

... I think the water may have got pushed back into the exhaust and maybe cranking it over blew the gasket?!?!? Got it home ran it on the muffs and again ran perfrect....

Water probably did get into the cyliders, but you obviously got it out, cause you got the boat started. I doubt it "blew" a headgasket. When water gets in a cylinder, it hydrolocks the motor, and can bend stuff, it doesn't blow headgaskets. BTW, the original noise you heard was probably your flappers rattling, as they were getting ready to fall off. They might be down in the bottom of your exhaust y-pipe, now. If you pull the outdrive off, they might be right there, too.

 

[ENSIGN]

Re: Possible Blown Head Gasket?!?!?

Did you get the old water shutters out? There in the Y pipe or drive and will affect performance and make a noise

 

[int76]

Re: Possible Blown Head Gasket?!?!?

I was unaware water was pushed/exited through an i/o exhaust system, thanks for that info.

Yes I originally trouble shot the noise as being the flappers so I took off the exhaust couplers and outdrive and found both flappers and hinge pins there. That was prior to my last outing in which the noise was still present so it wasn't coming from the flappers.

The only reason I even considered the blown head gasket was because of the other thread in which the guy had absolutely identical symptoms as me and that's what his ended up being. I'm just really confused on how a head gasket coukd generate such a noise....

 

[littlebookworm]

Re: Possible Blown Head Gasket?!?!?

The rattling noise could be pre-ignition, which could be coming from a partially blown head gasket between two adjacent cylinders. The quickest was to check is with a compression test. I'd also recommend a leak-down test. I seem to remember a thread on this site on how to make and use a leak-down tester. I suggest you do, or have done, both tests and see what they show. Good luck. Hy