Should I replace the exhaust manifold?

[Tmakaro]

I have a mercruiser 3.0 liter 1992 motor in my Bayliner. The motor has 400 hours on it and is used 75% in salt water. After every use I flush the motor with fresh water and a product called salt away. I do not have a frsh water cooling system installed.

Anyways, today I notice a leak with some rust between the exhaust manifold and the elbow(exhaust riser?). I pull off the elbow and notice the gasket is pretty nasty. My thought is to just buy another elbow so I clean and file down the area on the manifold only. I notice there are intended holes around the main exhaust hole. I assume water flows through those holes.

My question is what if some of the water leaks into the main exhaust hole? Does it matter?it looks kind of rusted in there already. Should I be considering a new manifold too?

 

[tpenfield]

Re: Should I replace the exhaust manifold?

When water leaks into the main chamber of the manifold it can go into the valves & cylinders and then you get to rebuild your engine

With salt water use, it is a good idea to check them on 4-5 year intervals and then replace when the mating surface area becomes too thin.

You want to make sure that you have about 1/4" of good mating surface for both manifold and elbow. You would replace both, if they both were bad. Use OEM style gaskets (gray/metallic), not the paper (green) ones.

 

[Tmakaro]

Re: Should I replace the exhaust manifold?

When water leaks into the main chamber of the manifold it can go into the valves & cylinders and then you get to rebuild your engine

With salt water use, it is a good idea to check them on 4-5 year intervals and then replace when the mating surface area becomes too thin.

You want to make sure that you have about 1/4" of good mating surface for both manifold and elbow. You would replace both, if they both were bad. Use OEM style gaskets (gray/metallic), not the paper (green) ones.

Thanks for the info. My boat is actually a '02 not a '92 lol. I'm a decade off.

So I pulled the manifold today and I've got a new one and a new riser on order. I went with oem to be safe.

I'm going to put on a fresh water kit while I am at it. Should have been done a long time ago but I figure since I only have 400 hours and I flushed with Salt away every time then it is probably still worth it. That way the engine block gets bathed in rust inhibiting coolant.

 

[Bondo]

Re: Should I replace the exhaust manifold?

Thanks for the info. My boat is actually a '02 not a '92 lol. I'm a decade off.

So I pulled the manifold today and I've got a new one and a new riser on order. I went with oem to be safe.

I'm going to put on a fresh water kit while I am at it. Should have been done a long time ago but I figure since I only have 400 hours and I flushed with Salt away every time then it is probably still worth it. That way the engine block gets bathed in rust inhibiting coolant.

Ayuh,.... Yer 'bout 300 hours too late,.... Read this,...

 

[Tmakaro]

Re: Should I replace the exhaust manifold?

Ayuh,.... Yer 'bout 300 hours too late,.... Read this,...

I notice you say ayuh a lot. What does it mean? Is it short for something? A marine term or navy term?

 

[mark1905]

Re: Should I replace the exhaust manifold?

I notice you say ayuh a lot. What does it mean? Is it short for something? A marine term or navy term?

http://m.urbandictionary.com/#define?term=ayuh