View Full Version : Replace manifold and risers?

01-25-2011, 11:13 PM
My boat is a 99 PS205. 1300 hours. I bought the boat 5 years ago with 900 hours. The previous owner ussed the boat in a brackish enviornment, altough i have seen no signs of salt damage. The boat was faithfully flushed. Don't know if the manifolds and risers are original.

In the past few seasons, I've noticed signs of leakage around the riser gaskets and drain plugs. Decided to pull manifolds and risers to see what needs to be replaced. Manifold gasket is in good shape. No leaks there. Riser gasket is shot. My question is how can I tell if I need to replace the manifolds and risers or can I get away with new gaskets? Can they be cleaned and resurfaced. There is corrosion in both, but a dealer told me today that it was normal wear and tear. Any advice?

01-26-2011, 01:50 AM
Swing by an automotive machine shop and have them take a peek at what ya got. I have exhaust manifolds resurfaced all the time that are warped and it works out fine. The process used is just like a big belt sander so it will also remove minor surface erosion just fine.

01-26-2011, 10:24 AM

02-05-2011, 02:18 PM
I was interested in when do you replace them too. How do you tell when they are shot?

02-05-2011, 06:14 PM
At this point, remove the risers and inspect. If ok, sand down both surfaces using a flat block, and shop vac as you go. Buy new gaskets, and use Permatex #2. This should take care of your leaks. If it looks really bad on inspection , consider riser replacement. To take it to the next level, remove manifolds and risers, clean and sand all surfaces, and respray with hi temp paint. Consider adding manifold drains, it makes it easier to winterize.

02-05-2011, 07:08 PM

02-21-2011, 03:20 PM
Been working on the boat lately and decided it was time to remove the manifolds and risers to inspect and refresh.
I've noticed after removing the manifold's that there were no gasket's between the motor and the exhaust manifold's.
The boat is a 91 Prostar with the Indmar 351.
My question, should I buy the PCM gasket's as per SKIDIM sells or should I just re-silicone them around the port's?


02-21-2011, 04:09 PM
Suggest gaskets, sealants make parts hare to take off/clean in the future and in my experience have a increased chance for failure.

02-21-2011, 06:25 PM
Gasket all the way!! You wanna have a boat full of People waiting on you while you scramble to fix what a couple bucks would have took care of for years?

02-22-2011, 12:21 AM
Thanks for the input guys.
I thought since Indmar doesn't sell the gaskets they must have came out the factory without them.
So I'll just buy the PCM gasket's install them without silicone and torque? Do I have it right?
Does anyone know the torque?

Interesting site I found while searching:

02-23-2011, 10:01 AM
Just called my local Mastercraft dealer regarding the manifold gasket's.
I was told by the parts advisor that these boats come out the factory without exhaust manifold gasket's.
When asked what I should use to mate them back to the block he suggested using high heat NAPA sealant.

I hope this helps others!