EXHAUST MANIFOLD FAILURE, FYI

[Water Sports]

OK I need educating, why are SS better than cast?  The SS eventually fail.  I personally have never heard of cast manifolds failing.  Any help would be great. Thanks

[Water Sports]

Some more info on manifolds.  With the help of a professional fabricator, we tested and dismantled  4 sets of manifolds.  All manifolds failed in the same area;  cylinders 5 &6 respective to right and left.  The crack was mended on one set,  pressure tested, and installed on engine.  That boat will be in the water in a week.  Going to run for about 25 hrs.  If all is well, I'll have two more sets repaired and installed.  We average about 350 hrs on a engine per year.  Will keep the forum informed of the progress.

I been in contact with Harris Marine, they make the manifolds out of cast and say they'll last thousands of hrs., still trying to get some measurements to see if they will fit under hood.  Has anybody tried these manifolds?  Any further ideas?

There still is hope to keep these engines running.  I 'hope' the repaired to last 1000hrs

[toyotafreak]

Awesome!!!! Please continue to post. There are a bunch of us out here even if the traffic doesn't look like it. First sign of problems...we're back in a minute. Some of us can't spring for $800 a piece for just in case...

[Supraman]

Thanks for the update. Have you seen any other trends that indicate failure is going to happen soon? Have there been any warning signs?

How often do you replace the plugs?

[elgringo-inaz]

Hey water sports!  So I sprung for the $750 USD port side manifold from Capt R.  Do you need old one?  It Leaked and where manifold meets block, very corroded, but you might need it....just sitting here...

[Water Sports]

Just fired up the boat with the repaired manifolds.  We only repaired the cracks on 5&6, there could be additional cracks form in the future in other cylinders.  This is definitely a test.  The repaired manifolds had approx. 1500 hrs @ before they failed.  This should at least tell me if additional cracks form and where. 
One test is to check spark plugs for moisture the day after a day of use.
The only sure test that I know of is to remove manifolds and check for water in air chamber.
If anybody knows a better test let us know.

[tryme]

do these failures seem to be occuring by age of the boat or hours?  i still only have 240 hours on mine

[Water Sports]

The hours and type of use.  Well maintained engine will make manifolds last longer.  I've had some last over 1500 hrs.