Repetative Burning of Exhaust Flapper and Hoses


B

BeechBoy

New member
Greeting and Thanks in advance for your help.

I have a 2008 Formula 37PC equipped with 496 HO's with Bravo III drives.

I am on my 3rd set of exhaust flapper valves, on both motors, and now had to replace every rubber exhaust hose (8 on 2 motors) due to overheat and burn damage.

This is not a water pump, water pump scoring, or water pump impeller problem. It is not a clogging problem do to mud/silt. The motors run 1.7# PSI at idle and near 25+ underway.

This is a lift-kept boat, which allows the drive to drain when placed on the lift.

I have heard there may be a problem with air getting into the freshwater pump side causing intermittent issues with the sea water pumps getting a constant supply of sea water. There is little, if any head pressure from the drive to the water pumps. There is also scuttle on that the supply hose to the fresh water pump is 1.25" yet the Bravo III drive only allows for a 3/4" inlet. Combine this with the draining of the drive and part of the freshwater system while placed on the lift (or trailer) presents a challenge for the pumps to get moving water.

I have also read (but not verified) that Merc understands this problem and has a conversion kit that installs thru-hull pickups and sea strainer that work in conjunction with the Bravo III pickup. It also is standard equipment on Horizon motors(?).

Hoping someone can help me with this challenge.

Thanks!
 
Hello
Have a 2006 31 PC with 496 mags 227 hours , just took off my port pump for maintenance and its wore badly , impeller intact will have to replace both with brand new Mercury pumps
But have read somewhere about the 37 PC with over heat problems , and yes sea cocks where added ( will find it and post for you )
I would also call Formula or e mail them
 
Did you check risers above the exhaust manifolds ? The holes that lets the water out to exhaust are about 3/16 wide and an inch or so long , Rust up easily . If clogged or rusted clean with a saws all blade then glass bead the inside, as glass beads are non abrasive, compared to sand. also check the plastic balls at thermostat housing, they add water to exhaust at high rpm. Dale
 
As noted your not getting enough water through the exhaust. Have you owned the boat since new or more recent? Has the boat ever been in salt?

Has your exhaust risers and elbows been inspected and cleaned?
 
yep, that exhaust is going on 6 years old and if it has ever been in salt or never been inspected or any combination of those two, its time for a look see. those risers are bad to corrode and clog up. and they corrode from the inside out so you can't tell until they are taken apart.
 
Boat is fresh water only. Never seen salt water. It is also left kept. Corrosion in the exhaust, or anywhere is not an issue.

Thanks for the help guys!
 
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