Engine Noise Mercruiser 3.0 L. See video; sounds like exhaust or vacuum leak?

[Yngvar]

Hello from Oslofjord,

we have a Scand 24 with an inboard 2003 Mercruiser 3.0 and Alpha One Sterndrive.

We changed the oil pan gasket last summer (where leacking oil).

We noticed a small sound this summer, like leaking in the exhaust manifold or something...

We can not seem to place the sound. It seems like it is coming from rear part of the engine, low down...

We tigthened the bolts on the exhaust part believing it was a leak there...no change in sound.

The sound is like a hissing in tune with the engine rev going "psst", "psst" and when engine is turned of it sound like its letting out air while stopping "psssssssst".

The video of the enige running is uploaded to YouTube, anyone have an educated listen/guess?

We would be very happy for any clues

http://www.youtube.com/watch?v=h0nd0nQiatA

Thanks and br,

Captain Yngvar
and Jonas, the cabin boy.

 

[mariner1900]

Re: Engine Noise Mercruiser 3.0 L. See video; sounds like exhaust or vacuum leak?

Hi, It sounds the same as my engine did when the manifold gasket failed. Run the engine and feel all around the joint between the manifold and cylinder head, top and bottom and also around the riser. You should be able to feel the leak blowing on your hand.

 

[Yngvar]

Re: Engine Noise Mercruiser 3.0 L. See video; sounds like exhaust or vacuum leak?

Thanks for the replies, they helped us.

We felt some wind under the exhaust manifold so we concluded it was the manifold gasket....

After getting the exhaust manifold off we saw a part of the head gasket sticking out under it

So, we had a leack in the second cylinder, blown head gasket on one cylinder....that is what we are hearing in the video!

Thanks to mariner1900 for insipring us to take of the Exhaust manifold. We continued while we had the momentum and got it all off. Is now taking the top-block to a workshop to see if we need to sand it flat or not before re-assembly.

-->Getting the top-block out was less work than we antissipated! I guess putting it togehter again is the tricky part he he, novice both of us fixing this...

Thanks to Bubba1235 ....spot on with your video-diagnostics, guess you is Admiral for a reason ;-)

Br,
Yngvar and Jonas

 

[Yngvar]

Re: Engine Noise Mercruiser 3.0 L. See video; sounds like exhaust or vacuum leak?

Heres the boat for spesially interested, looking forward to get it back in use.

(Pickure is taken on way home after buying the boat last year. The oil-pan gasket burst on the way home....learning curve at sea is very fast ;-)

 

[Ora]

Re: Engine Noise Mercruiser 3.0 L. See video; sounds like exhaust or vacuum leak?

Incredible...I developed the exact same noise this past weekend with my 3.0 Mercruiser engine. How did the repair go for your head gasket? Did it resolve the issue? How long did it take to complete the repair? I am deciding whether I (as a novice) am going to take this on myself or have it repaired for me. Thanks for any advice you have!

 

[Ora]

Re: Engine Noise Mercruiser 3.0 L. See video; sounds like exhaust or vacuum leak?

It turns out it was my head gasket...your diagnosis was perfect! Cylinder 1 in particular. I had it repaired and took it out on the lake for 6 hours. We had a normal day at the lake tubing, etc. We decided to head back to the marina and on the way the noise that we heard before resumed. Today the mechanic said it was the same cylinder on the head gasket that blew again. What could be wrong that causes a new head gasket to blow? I even kept the original blown head gasket so I know that there was a replacement. Please help.