Exhaust Manifold clean-up

[Doug Hensley]

I have a 1976 Sea Ray with a OMC/Ford 351 V8. It appears to be a simple job to remove the exhaust manifolds, well as long as no bolts snap off. I'm curious what is the best way to clean them out. The OMC manual says to soak in Muratic acid but it doesn't say at what strength or for how long. I've heard others suggest to glass bead them, will this clean them out as well?<br /><br />Anyone have a suggestion? These are the original cast iron pieces.<br /><br />ShipRec

 

[Bob_VT]

Re: Exhaust Manifold clean-up

You can have them bead blasted as well as having the mounting surface machined "true" the biggest thing I would look for is thinning metal and or cracks. Most automotive machine shops can manage all the work.<br /><br />To prepare for the job I would spray the bolts down with PB Blaster or Kroil a few times and a few days in advance of the work....might help.<br /><br />If the bolts snap off just be prepared to drill, easy out and chase the threads for new bolts.<br /><br />Funny how the hardest bolt to deal with will always be the one to break <br /><br />Bob

 

[Trent]

Re: Exhaust Manifold clean-up

I understand where Bob is comming from. However a boat this old I personally would change the risers and the manafolds. Saltwater engines tend to last around five years and freshwater almost ten. Your OVERDUE!! My thoughts ONLY! Just a little leak can KILL your engine!

 

[Capt Ken]

Re: Exhaust Manifold clean-up

This can't be a salt water engine Trent. It would have never lasted this long. It would have bit the dust back in the 80's. Plus it said he's from Arizona. Heck, even the water is dry out there.

 

[jasonnb]

Re: Exhaust Manifold clean-up

Not to trump in on the guys above with WAAYYY more experience than I do, I just rebuilt my '76 Mercreuiser with a 302 Ford. My mans/risers still looked ok even thought they were original. I elected to replace them anyway just to be certain I didn't cook or drown my new engine. Now the exhaust is low on my worry list. Just my thoughts.

 

[Doug Hensley]

Re: Exhaust Manifold clean-up

OK My plan to clean these is for preventive maintenance. Are newer manifolds of a better design available that will fit without any modifications? If they look good I'll probably just clean them up and put them back on.

 

[Jagsare1]

Re: Exhaust Manifold clean-up

Don't waste your time with manifolds that are 26 yrs old!! Replace them and get some piece of mind. They may "look good" but if they take a dump, you may lose the engine. Even in fresh water, I can't believe they lasted that long.

 

[conimicut1]

Re: Exhaust Manifold clean-up

the guys are right, replace. I don't think people understand the concept of hyrolock particular to marine engines. In a car the mainfolds have no water in them and they last forever and even if they leak a little no big deal. In a boat they are cooled by water and rust. If even a small amount of water leaks into your engine, the engine will try to compress it. The problem is air can be compressed, fluids don't compress. So instead the piston breaks or the rod bends and bye-bye motor. Now you have to buy a new motor and the manifolds. the boat may not be worth all of this and bye bye boat.

 

[Doug Hensley]

Re: Exhaust Manifold clean-up

OK<br />Now you have me worried. Where could I find replacement manifolds for my boat and approx what would they cost?<br /><br />ShipRec

 

[snapperbait]

Re: Exhaust Manifold clean-up

Check out www.ebasicpower.com Best prices I've seen.