Replace Exhaust Manifold or Not

[mdiggs]

Hey Everyone,
Just got the carb rebuilt on my 67 Donzi 16'. It's running great, but the mechanic suggested that I replace the original exhaust manifold on the Interceptor engine because it leaks and, under full power, allow water into the 4th cylinder.

This was my dads boat, and it looks like my dad had messed with this area before, trying to keep water from leaking out of the manifold at the 4th cylinder, so I'm debating whether to change it (1000 bucks parts and labor) or live with it as my father did.

I hear that replacing the exhaust manifold has been associated with a loss of power.

So: Questions: Should I replace the exhaust manifolds? What happens if I don't? Should I expect a loss of power?

Thanks for any advice you can give.

[VetteLT193]

if it is allowing water into the engine it could pretty easily ruin the engine.

I say replace.

$1000 seems high but I'm not familiar with that engine.

[MOP]

Osco makes a nice set of center rise manifold for the Fords I had them On my 16, they are a little more free flowing then most. Unless the engine is modified you will see no decrease in fact you may see a tiny bit of improvement over the old style logs.

Phil

[Cuda]

Leaking exhaust is the number one reason for catastrophic engine failure. Change it now, or change it after you rebuild your engine.

[mrfixxall]

Change them their only going to get worse..this is what will happen,you will park the boat at your favorite place of eating then when you go to start the boat (if the manifols=ds get worse)and it will hydro lock or worse case it will go past the hydro locking stage and possibly bend a connceting rod or brake it and then you will have a new boat ancor:)

[Tidbart]

What kind of engine is it? Merc?? Volvo? I see Phil referenced Ford.

GLM makes some affordable aftermarkets. I don't if they would apply to something of that vintage.

http://www.glmmarine.com/catalogs.html

Bob

[mdiggs]

Thanks, guys. It's a Ford Interceptor 350. The mechanic didn't explain the gravity of the situation (he probably figured I understood it, and of course, I did not). I'll make an appointment pronto.

[Morgan's Cloud]

Ya spends a little now , or a LOT later :doh:
Not taking into account the tight space you have to work in there , exhaust manifolds are a DIY kind of project .

[zimm17]

My dad put osco center risers on the twin 302's in the old 1969 7 meter. Good quality and didn't loose any performance.

[MOP]

Every OEM went to center rise manifolds for the added power, they flow much better then logs. I do like the look of logs and they do keep the original look.

[BigGrizzly]

I like the Osco, and the price is right.

[Greg]

A friend of mine is a very good welder He said he has fixed many of these by cutting a plate out of the side fixing the inside and then rewelding the plate back in place. Don't know how bad yours is but you might want to let a welder take a look at it. Just my $.02. Hope this helps Greg

[yeller]

A friend of mine is a very good welder He said he has fixed many of these by cutting a plate out of the side fixing the inside and then rewelding the plate back in place. Don't know how bad yours is but you might want to let a welder take a look at it. Just my $.02. Hope this helps GregThat's what I did with my old logs when I forgot to drain them one winter and cracked them on the inside. :bonk: I cut a section of the outside off with a dremel and had someone weld the inside, then weld the cut section back on. Never did leak again on the inside but did leak on the outside....ten years later. Less than $100 for the repair.