MCM 170 Exhaust Manifold

[pparvin]

Could some one please explain what seperates the closed cooling system from the exhaust. I have an 86 MCM 170 with the alpa one stern drive. I took off the expansion tank to check what appeared to be a leaking gasket and have antifreeze sitting in front of all the exhaust ports.

 

[Don S]

Re: MCM 170 Exhaust Manifold

If you didn't drain the antifreeze out of the manifold before pulling the expansion tank, the AF will fill go into the exhaust when you pull the tank. The gasket seals the exhaust from the water passages. This drawing should explain.

 

[Bondo]

Re: MCM 170 Exhaust Manifold

Could some one please explain what seperates the closed cooling system from the exhaust.

Ayuh,... Welcome Aboard,... The gasket separates the water from the exhaust side,...

I took off the expansion tank to check what appeared to be a leaking gasket and have antifreeze sitting in front of all the exhaust ports.

If that gasket appeared to be leaking to the Outside,...
Why would you think it wasn't also leaking to the Inside,..??
It's the same gasket,....

 

[pparvin]

Re: MCM 170 Exhaust Manifold

Thanks for responding, I drained both cooling systems prior to removing the tank. The last time we had it on the water it overheated and over pressurized the freshwater side and was concidering the possibility of exhaust leaking through the gasket, as a 20 year Navy marine mechanic I learned th start at the easiest point and working to the hardest which is the possibility of a blown head gasket.

 

[Bondo]

Re: MCM 170 Exhaust Manifold

I learned th start at the easiest point and working to the hardest which is the possibility of a blown head gasket.

Ayuh,... The Headgasket is extremely Likely, as 470s Don't like to be overheated...

 

[gettin'even]

Re: MCM 170 Exhaust Manifold

I had anti-freeze leaking into the exhaust ports due to a leaking gasket at the coolant tank/exhaust manifold connection. Turns out the exhaust manifold was warped.

And...as Bondo said, these engines do not like to be overheated. The headgasket usually doesn't survive.

Let us know what you find.

 

[pparvin]

Re: MCM 170 Exhaust Manifold

OK, I pulled the head off, the gasket "looked" good, but you know what that means, nothing. I will go ahead and replace it and check the manifold to make sure it isnt warped. I also pulled the heat exchanger off opened it and cleaned it. I will replace both the water pumps going back together. As an after thought, It seems kinda wierd to see cadet next to my name, considering I'm a retired Navy Senior Chief.

 

[Bondo]

Re: MCM 170 Exhaust Manifold

It seems kinda wierd to see cadet next to my name, considering I'm a retired Navy Senior Chief.

Ayuh,... Keep posting,.. Your rank will go Up fairly quickly...

The factory Manual for your motor is up in the Adults Only section of this forum,...
Download it, save it,+ Follow it,...
Your motor is very particular about How it goes back together...

 

[pparvin]

Re: MCM 170 Exhaust Manifold

I have the Clymers manual, I dont know if it is as good as I need or not. It may take a few weeks or so to post any progress I have a lot of travel for my job coming up.

 

[Bondo]

Re: MCM 170 Exhaust Manifold

Ayuh,... The Clymers will make a good kneepad when you're workin' on the boat,...
Go up to the Adults Only section,+ grab a copy of the Factory Manual....

 

[pparvin]

Re: MCM 170 Exhaust Manifold

Will do, Thanks.