Replace the exhaust flapper valve or not ?

[erie_guy]

Last august, I seriously overheated an engine when the raw water pump failed. I replaced the defective impeller and it performed well for the remaining 2 months of the season. Upon noting that the overheat had discolored (darkened) the oil in the drive, I was advised to change the oil and check the front seal.

Well this week I pulled the drive off and sure enough there was a quantity of drive oil inside the boot. Additionally I found two melted exaust flappers in the exhaust passage partially blocking the outlet to the drive. I put the drive in the trunk and took it to a marine repair facility in Port Clinton, OH for a look-over, oil replacement, and pressure check.

The mechanic that looked over the drive commented that he belived that the exhaust flapper valve has been discontinued on several VP engine systems and that I may not have to dig into the exhaust system to replace them. He also mentioned that the sound of the exhaust would probably have a higher pitch since the flapper valves are not in the engine exhaust.

I have a 1997 Volvo Penta 5.7 GI engine with a SX VP drive. Can anyone confirm that VP does not offer or reccomend a replacement exhaust flapper valve for this system ?

It did run fine for the two last months of the season and I did not notice any difference in the exhaust sound - but it was always pretty quiet.

Thanks for any help !!
erie_guy
Port Clinton, OH

 

[havasuboatman]

Re: Replace the exhaust flapper valve or not ?

That flapper is there to help keep water from flowing backward thru the drive and exhaust and then into the engine from a sudden slow down, Or say, some A-hole has to run his skier right next to the beach your boat is beached on, and the wave that slams into your transom. Keeps that water from washing up the exhaust and into your cylinders.

 

[a70eliminator]

Re: Replace the exhaust flapper valve or not ?

Most people just leave them out, I don't think they are even factory installed anymore.

 

[dubs283]

Re: Replace the exhaust flapper valve or not ?

it is to your advantage to install new flappers

it takes an experienced mechanic about a half hour to do it so a novice could have it done in an hour or so

the flappers are there for a reason, a hydrolocked motor can cause some real headaches, especially if you are a ways from home

 

[a70eliminator]

Re: Replace the exhaust flapper valve or not ?

Ther is a Volvo Penta service bullitin reguarding the exhaust shutter delete . I can't link it but someone will be able to, you can google the service bullitin.

 

[83Evinrude]

Re: Replace the exhaust flapper valve or not ?

Here is where Don S shares the bulletin, looks like they quit using the flapper in 1999.

http://www.4shared.com/file/51149475/c49b77de/Volvo_Exhaust_Flapper_valves.html?cau2=403tNull

 

[erie_guy]

Re: Replace the exhaust flapper valve or not ?

Thanks Evinrude -

I appreciate the link. It appears that VPs really do not have to use an exhaust flapper valve anymore and repair parts are not available. I do have twins so if I experience a hydrolock, I can still get home.

Thanks for all your help.

erie_guy
Port Clinton, OH