Logo
FULL SITE MENU

1995 OMC COBRA 3OL SOUNDS LIKE EXHAUST LEAK

J

jimmen12

New member
"HAD IT ON THE LAKE THIS WEEKE

"HAD IT ON THE LAKE THIS WEEKEND AND THE MOTOR STARTED MAKING A PUFFING NOISE. ALMOST LIKE AN EXHAUST LEAK. I PULLED THE EXHAUST ELBOW AND FOUND THE FLAPPER JUST HANGING THERE MELTED. IT SEEMS AS THOUGH IT OVERHEATED, BUT THERE WAS NO INDICATIONS OF THE BOAT OVERHEATING ON THE LAKE. I CHANGED THE FLAPPER; NEW GASKETS FOR THE EXHAUST ELBOW; I ALSO CHANGED THE INTAKE/EXHAUST MANIFOLD GASKET. I AM STILL GETTING THE PUFFING NOISE. IT ALMOST SOUNDS AS THOUGH THERE IS AIR ESCAPING FROM SOMEWHERE ON THE PORT SIDE OF THE MOTOR. THERE WAS NO POWER LOSE. MOTOR IS RUNING FINE BESIDES THE NOISE. COULD THIS BE THE HEAD GASKET PROBLEM? OR DID SOMETHING GET WARPED?"
 
"I did a compression test, the

"I did a compression test, the highest cyclinder was 160 psi and the lowest was 95 psi. I squirted some oil into that cyclinder and re-did the test on that cyclinder. It still read 95 psi. The book is saying that is probably a valve problem. Is that the direction I should go? Or could it be a head gasket? Any other tests to comfirm?"
 
"I've seen many 3.0Ls leak

"I've seen many 3.0Ls leaking from the valves for different reasons, carbon buildup, bent valves etc. what is the comp of the one next to the 95 one? Either way it looks like the heads coming off. You can check the valve leak when the heads off, lay the head on its side with the int/exh ports pointing up, poor a little fuel in them(fill the ports) and watch around the valves for leaks."
 
"If you find that all 4 valves

"If you find that all 4 valves are holding with the leakdown test, look at the rockers, one or more pull up?

One or more rods bent ?

I myself think one piece blew off a valve. Or a tuliped valve / valves.

If thats the problem easy to fix and would mean the denotation may be off, or to hot a plug, something."
 
Just a quick update...Jim had

Just a quick update...Jim had emailed me after the compression test and he removed the the head and found a blown head gasket at cylinder # 2. I think he may be taking the head into a machine shop to check it before replacing the gasket and putting the head back on.
 
"<[img]"http://www.marineengin

"
thumbs_up.gif
Sweeeeeet!"
 
Here is the update. We took i

Here is the update. We took it to the machine shop and they found that the head was warped and one of the valves was mushroomed. They shaved the head. They removed all of the valves and boiled the head. Replaced the one bad valve.

Today I put it all back together and ran it. It runs great. Ran another compression test on the low cyclinder. 155 psi!!! Thanks for all of the help!
 
AWESOME !!! ...

ps a melte

AWESOME !!! ...

ps a melted flapper could be from someone running the engine without water
 
Back
Top