Mercruiser 3.0 Head and Manifold Help

Hey Boaters,

Just took off my exhaust manifold to replace gasket. Riser had a leak and wanted to just go ahead and replace both. Also had a funny squealing suction noise was coming from front of manifold best I can tell. After removing manifold, the manifold looks to be in great shape. I do see rust water stains around the head gasket. See Pics. I did have a minor overheating problem that went away after replacing my impeller which DID NOT make sense because the impeller looked and felt brand new. There is some kind of pressurized leak indicated by the sound. video: http://www.youtube.com/watch?v=mxJi3w2b4G0. I dont want to ask leading questions, but could this be a head gaskey issue. There is rust stains around the head bolts. I just have zero experience with boats and wanted some input. Thanks for any thoughts.

Nick

Re: Mercruiser 3.0 Head and Manifold Help

Block looks cracked. The noise is your alternator bearings or water pump going out. Run without belts for a minute or so.

Re: Mercruiser 3.0 Head and Manifold Help

Does appear the head gasket might have an issue,inexpensive to check and repair.

Re: Mercruiser 3.0 Head and Manifold Help

888 said:

Block looks cracked. The noise is your alternator bearings or water pump going out. Run without belts for a minute or so.

Click to expand...

Thanks, but I am not sure how you can see a cracked block. I can't see a crack and I am right next to it. I understand hairline cracks can occurr, but that is a separate issue. I would like to clarify on the "minor overheating" I first quoted. The details are it was running 10-20 degrees hotter than normal for only a few mins while hooked up to hose in my driveway. Hardly a true overheating. I am leaning towards head gasket, the question is why. Gasket issues are usually caused by other issues. The boat/engine is 9.5 years old. I have had it since new, and it has been used a few times each season. Its kept indoors in houston, tx, no freezing issues. Used in salt water 3-4 times total, and flushed immediately. I am just wondering if the block is just toast on the inside due to corrosion. Having said that, one can see from the pics, the exhaust manifold and head show very little signs of corrosion in the water jacket area, so why would the block be so much more corroded. Who knows. Just not enough experience to know anything. Thanks for any more thoughts.

Nick

Re: Mercruiser 3.0 Head and Manifold Help

Hi Guys:

Having never re-built an inline 4 but many inline sixes and having looked carefully at your pics, in my opinion you may have a head gasket problem due to lots of corrosion internally. See the water pump outlet in pic #1.

I listened to your YouTube video carefully but sadly I don't have the expertise to diagnose that sound. I bet Bondo or Don will come up with the answer though!

Good luck:

kilowatts

Re: Mercruiser 3.0 Head and Manifold Help

Ayuh,.... Welcome Aboard,... That is an odd spot for rust,.... ain't comin' from above, runnin' down is it,..??

I don't boat in Saltwater, so, I'll go with BD's thoughts on it... there Is water behind it..

I agree, the sound, sounds like a bearin', or belt, probably bearin'...

Re: Mercruiser 3.0 Head and Manifold Help

After replacing the head gasket make sure you use thread sealer on the head bolts some of the hole on the 3.0's aren't blnd and go through to the water jacket also after torquen em down bring the engine up to operating temp and let it cool back down to amiant and re-torque the head bolts. Also I would go with the a bad bearing makin the odd noise you speak of. Good luck and post back with your results.

Re: Mercruiser 3.0 Head and Manifold Help

hou1nxb said:

Thanks, but I am not sure how you can see a cracked block. I can't see a crack and I am right next to it.

Click to expand...

Why is that spot rusty?

Re: Mercruiser 3.0 Head and Manifold Help

Hope the op didn't go into shock after seeing the crack right in from of his face.

Re: Mercruiser 3.0 Head and Manifold Help

I'm going to say you have a bad head gasket. Can't see what kind it is, but the older automotive ones will rust, then leak. Could also leak into the cylinder when you shut down and the engine cools, but mostly will be pushed out when you are running. It also is showing rust the full length of the engine, so I'd be surprised if it was a crack rather than an overall failure of the gasket.

Replace it with a good Felpro Marine gasket, and seal the bolts when they go back in. Also take a look at the freeze plugs on the head (5/8" diameter). Easy to check now, hard to check later.

There are more pieces to the waterpump than the impeller. Should also be a plastic tube, copper tube, rubber grommet at the top, and a gasket below the lower pump housing. I've had all of those fail at one time or another.

--Jim

Re: Mercruiser 3.0 Head and Manifold Help

888 that small circled area is a ledge for registaring for machining the oil pan mating surface my 3.0 LX has the same ledge and so does my buddies 2007 3.o volvo some are left bare and some are painted over just so happens his was left un painted. The forward area in question leached water along the top of the head and followed the path of least resistance thus the sut trail.

Re: Mercruiser 3.0 Head and Manifold Help

Ok thanks for clearing that up. I just seen it looked differant and knew that was a hot spot for cracks so I put two and two together.