Mercruiser Exhasut manifold set

I have a 2001 Mercruiser 5.0. Last week the exhaust bellows melted (burned internally). The marina replaced the bellows for a pretty penny and told me the problem is that there is restricted water flow and the starboard side exhasut was overheating. The engine is running well at 170 degrees and a large amount of water was running out of the port side idle port but trickling out of the starboard side. The remedy to the problem being recomended is replacing the exhaust manifold, riser and elbows ($2k).

The questiona I have are:
Is this a fairly straightforward replacement? Can a person of average skill complete this job or are there special skills/tools required?
I run in saltwater. Is there a better brand than another for replacement parts?

Thanks for your input and considerations!

Re: Mercruiser Exhasut manifold set

2K, thats a lot.check the iboats store.I`m sure you will find it a lot better. replacing then is not that big of a chore and you save the labor.

Re: Mercruiser Exhasut manifold set

I just bought a full set of Barr manifolds and risers/elbows for $659.

Since your engine is not that old, it should be a fairly easy replacement.

Somewhere, I recall seeing some porcelain coated manifolds, but I cannot recall where. Those would be good in salt water.

I got the plain cast iron ones. I should get at least 10 years out of them.

Re: Mercruiser Exhasut manifold set

As BT Doctor said, it's not a difficult job. Get a service manual; you can download one free from 4shared.com. Two tricks: 1) Get an extra pair of mounting bolts from any home center. Cut the heads off with a hacksaw. You can even use some threaded rods. After you remove the outer 2 mounting bolts, replace them with the headless threaded bolts/rods. These will support the manifold as you remove and later install the center 2 mounting bolts. This saves sore arms and broken sparkplugs. 2) Before mounting anything, use a flat file to clean off the mating surfaces of each part. That will eliminate later leaks. There have been numerous postings on doing the job. Do a search, or PM me if you have any questions. Two grand for that job is a great deal of money; but , unfortunately, probably what any marina would charge. You can do it yourself for half that cost. Hy

Re: Mercruiser Exhasut manifold set

Merc genuine manifolds and elbows seem to outlast most of the after-market ones, and they are all now ceramic coated, so should last longer. It's a simple job and shouldn't cause you too much grief... Just one thing, DO NOT use a file on the gasket surfaces. A very sharp wood chisel will remove the old gasket without risk of damaging the gasket face on the cylinder head. If you feel you must 'polish' the surface, use a brickies' wooden float with a strip of fine emery on it.

Chris........

Re: Mercruiser Exhasut manifold set

Thanks for the great information.

I was able to pull off the old equipment fairly easily. It was Barr and in pretty bad shape.

Is OEM the best (and longest lasting) option out there? Any recomendations on suppliers for parts?

Thanks again!

Re: Mercruiser Exhasut manifold set

1flcheesehead said:

Thanks for the great information.

I was able to pull off the old equipment fairly easily. It was Barr and in pretty bad shape.

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That's what happens to after-market gear...

1flcheesehead said:

Is OEM the best (and longest lasting) option out there?

Click to expand...

In my 20+ years of experience, yes.

1flcheesehead said:

Any recomendations on suppliers for parts?

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Just hunt around on the interweb and see what prices you find.... Also get a quote from your local Merc dealer. Let him know you're searching the web too and see if he can better it. Ya won't get if ya don't ask....

Re: Mercruiser Exhasut manifold set

Achris: I guess my description wasn't as clear as it should have been. I agree, never use a file on the gasket surface of the block. I was referring to drawing a flat file across the mating surfaces of the exhaust manifolds and the risers. There have been numerous postings on various forums of the leaking problems caused by some slight residual slag left, particularly on the outer edges, of the manifolds and risers. A light draw with a file will clear that without damaging the surfaces. Hy

Re: Mercruiser Exhasut manifold set

littlebookworm said:

Achris: I guess my description wasn't as clear as it should have been. I agree, never use a file on the gasket surface of the block. I was referring to drawing a flat file across the mating surfaces of the exhaust manifolds and the risers. There have been numerous postings on various forums of the leaking problems caused by some slight residual slag left, particularly on the outer edges, of the manifolds and risers. A light draw with a file will clear that without damaging the surfaces. Hy

Click to expand...

Yep, fair enough, but I still prefer a brickie's float (a wooden one) with a strip of fine emery on it. That way you see any high or low spots in the polish pattern. Particularly on elbow surfaces were you can see warping really quickly. It works well regardless of material, steel, ali etc... Great for checking flatness on ali outboard heads.

Chris.....

Re: Mercruiser Exhasut manifold set

Thanks for all the suggestions. With the words of encouragement, and a few helpful tricks I picked up a set of quicksilver/mercruiser manifolds, spacers and elbows from a local business (they priced matched ebay - yeah!). All told it took about 8-9 hours to tear down and replace. It was fairly straightforward with the hardest part being the weight of the manifold itself.

So...I patted myself on the back, grabbed a cup of coffee, put on the muffs, and started her up. Purrs like a kitten, BUT, the starboard side still has considerably less water coming out (idle relief port). I ran it until it hit 170, then shut her down. My intention was to run it, then inspect and snug any bolts that may be loose. I found the starboard manifold and elbow to be hot to the touch and the port manifolds cool to the touch. I could keep my hand on the port side indefinitely, starboard only until about the count of 4. So now I am troubled.

I pulled off the water/cooling hose (both ends) that feed the starboard side and it is clear with no restrictions.

Any thoughts on this? I do not want to put it through a sea trial until I am sure I am not going to burn another set of bellows and flapper valves.

Thanks for all your help!

:facepalm:

Re: Mercruiser Exhasut manifold set

Ayuh,.... Water takes the path of least resistance 'n flows Downhill,...

That said, it could be a simple as how level the hull sits...
Or, it's possible the T-stat housing has Issues....

Re: Mercruiser Exhasut manifold set

Just curious............were those the original manifolds and risers? 10 yrs old?

Re: Mercruiser Exhasut manifold set

They were not the originals manifolds. I had these installed about 4-5 years ago. We run strictly in salt water.

I am mostly concerned with the fact that one side is hot, and one side is cool.

Any thoughts would be appreciated.
Thanks!

Re: Mercruiser Exhasut manifold set

Reason asked is because I just replaced my risers after 4 seasons in salt water and they looked pretty good........going to wait 5 yrs next time.