Antifreeze leaking out of exhaust bellows(Tube)

[Rich Hargis]

I have a custom built 28' Skipjack fishing boat with a Marine Power 454 mated to a Borg Warner transmission and a TR outdrive. Today while doing some work on the boat I noticed some antifreeze on the ground behind the boat. At first I thought it was dripping out of the drain plug, but when I looked closer there was some in the exhaust tube on the transom plate. I then checked the heat exchanger and confrmed that the fluid level was low. Does this sound like a manifold problem or something worse?

 

[achris]

Re: Antifreeze leaking out of exhaust bellows(Tube)

If the engine is fresh-water cooled, then it would indicate a leak between the manifold and (probably) the elbow. The best way to be sure would be to drain the heat exchanger and pressure test it....

Chris....

 

[04fxdwgi]

Re: Antifreeze leaking out of exhaust bellows(Tube)

I have a custom built 28' Skipjack fishing boat with a Marine Power 454 mated to a Borg Warner transmission and a TR outdrive. Today while doing some work on the boat I noticed some antifreeze on the ground behind the boat. At first I thought it was dripping out of the drain plug, but when I looked closer there was some in the exhaust tube on the transom plate. I then checked the heat exchanger and confrmed that the fluid level was low. Does this sound like a manifold problem or something worse?

If it's a "half system", cooling only the block, then I would be looking at the heat exchanger. But, as achris stated, if closed cooling system cools the manifolds too (full system cooling), then it could just be a gasket problem between the manifold and riser.

 

[Rich Hargis]

Re: Antifreeze leaking out of exhaust bellows(Tube)

Thanks guys, I will replace the riser gaskets first.

 

[achris]

Re: Antifreeze leaking out of exhaust bellows(Tube)

That looks like a full system. I'd start by draining the system and pressure testing it. Where you hear the air leaking, that's where you leak is.

 

[04fxdwgi]

Re: Antifreeze leaking out of exhaust bellows(Tube)

Thanks guys, I will replace the riser gaskets first.

Be sure to use the S/S blockoff plates w/ a gasket on each side of it between the manifold and riser. Have seen some use just the heavy gasket (no plate) and get results you are seeing.

PS: Used to live in Chula Vista (Hilltop Drv) during my Navy days. Nice area, back then.
Looking for a heat exchanger for my 454, too. New one / kit is wayyyy too much money.

 

[achris]

Re: Antifreeze leaking out of exhaust bellows(Tube)

Be sure to use the S/S blockoff plates w/ a gasket on each side of it between the manifold and riser. Have seen some use just the heavy gasket (no plate) and get results you are seeing.

PS: Used to live in Chula Vista (Hilltop Drv) during my Navy days. Nice area, back then.
Looking for a heat exchanger for my 454, too. New one / kit is wayyyy too much money.

That is standard issue for the Merc genuine system. No plate, just the gasket. My '94 4.3LX with closed cooling has that, and nay a problem with the gaskets in 19 years. Same with my mate's '95 engine. Just a gasket, no problems from his system either....

Chris...

 

[04fxdwgi]

Re: Antifreeze leaking out of exhaust bellows(Tube)

Guess I should have said "You could use the optional", instead of "Be sure to".

Yup.... Most have used just the gasket with good results, but others have seen the leak, also, since the positive pressure of the closed cooling system can blow through the gasket, if the gasket turns mushy, which I have seen first hand. I would go for the insurance of the plate sandwiched between 2 gaskets. There must be a reason why they make it available.

Only need to buy them one time and reuse them forever.

 

[Rich Hargis]

Re: Antifreeze leaking out of exhaust bellows(Tube)

Be sure to use the S/S blockoff plates w/ a gasket on each side of it between the manifold and riser. Have seen some use just the heavy gasket (no plate) and get results you are seeing.

PS: Used to live in Chula Vista (Hilltop Drv) during my Navy days. Nice area, back then.
Looking for a heat exchanger for my 454, too. New one / kit is wayyyy too much money.

I think I will go with the optional plates just for piece of mind.
I live east of Hilltop drive off of Jst, just up the road from the marina.