1994 horizon 180 omc cobra 5.0

[Boats&hoes]

So I just bought the boat and it was discovered it was poorly maintained. I ordered new exhaust manifolds and risers. While removing the parts I noticed rust flakes falling into the exhaust pipes where the bellows attach. Should i try to flush, or vacuum the stuff out or should it be fine? Also the flappers were both gone lol i have no clue where they would be. Just trying to make sure i have no issues with plugged exhaust down past the turn pipe.

 

[Lou C]

that's a sign of an overheat, did you see the pins that the flappers mount to? If so that means there were flappers so I'd think about removing the drive to find them. Could be in the bottom of the exhaust housing, that will be visible when you pull the drive. Rust flakes, from old exhaust, could be a clogged exhaust related overheat.

 

[Boats&hoes]

that's a sign of an overheat, did you see the pins that the flappers mount to? If so that means there were flappers so I'd think about removing the drive to find them. Could be in the bottom of the exhaust housing, that will be visible when you pull the drive. Rust flakes, from old exhaust, could be a clogged exhaust related overheat.

Yeah it overheated. Mainly because the thermostat didn’t function. I ordered the new parts but yeah I was affraid of having to pull the drive. I know those flappers wont just disappear lol. It did blow water out of the bellows like it was clogged

 

[Lou C]

depending on how bad the overheat was, there are other things to be aware of:
exhaust hoses may be burned on the inside
if a shift cable was laying against the exhaust down pipe it can be melted
the water tube grommets inside the outdrive can be melted and not seal properly (this requires pulling the drive and splitting the drive)
if a really bad overheat, start looking for water in the oil, or in the cyls, a sign of a blown head gasket.
Reason why I know, is because it happened to me, wound up replacing:
exhaust flappers and hoses, water tube grommets
engine ran fine 2 more seasons, then at end of the third season after the overheat it blew both head gaskets, had water in the oil and a cyl
I caught it in time and got the water out, and installed reman heads and new gaskets. Still running well 5 years later.

 

[Horigan]

It's possible the flappers were removed per a service bulletin. They were removed on my boat. Look down each pipe and pull the drive and look into the exhaust port to see if they're lodged in the pipe, if they were installed. How did the water flow out of the bellows look "clogged"? Did the Y-pipes start filling up?

I agree to look at the other potential overheat issues listed above.

 

[Boats&hoes]

It's possible the flappers were removed per a service bulletin. They were removed on my boat. Look down each pipe and pull the drive and look into the exhaust port to see if they're lodged in the pipe, if they were installed. How did the water flow out of the bellows look "clogged"? Did the Y-pipes start filling up?

I agree to look at the other potential overheat issues listed above.

 

[Boats&hoes]

Found them lol. They was in the drive.

 

[Boats&hoes]

depending on how bad the overheat was, there are other things to be aware of:
exhaust hoses may be burned on the inside
if a shift cable was laying against the exhaust down pipe it can be melted
the water tube grommets inside the outdrive can be melted and not seal properly (this requires pulling the drive and splitting the drive)
if a really bad overheat, start looking for water in the oil, or in the cyls, a sign of a blown head gasket.
Reason why I know, is because it happened to me, wound up replacing:
exhaust flappers and hoses, water tube grommets
engine ran fine 2 more seasons, then at end of the third season after the overheat it blew both head gaskets, had water in the oil and a cyl
I caught it in time and got the water out, and installed reman heads and new gaskets. Still running well 5 years later.

I found clogged exhaust ports when i pulled rhe drive. The flaps made there way to the deive. I looked for water in the oul. No problem. I did shut it down quick when it over heated. I ordered new everything for the exhaust.

 

[dubs283]

Yeah it overheated. Mainly because the thermostat didn’t function......It did blow water out of the bellows like it was clogged

Thermostat rarely causes an overheat issue, at least not nearly as often as a weak/failed sea water pump impeller which should be replaced as part of routine maintenance.

OMC did use a "vented" exhaust bellows for idle relief and it's possible that style of bellows made it to the crossover Volvo/OMC package.