raytart

iTrader: (1)

Hyfive I'll keep that in mind. Thanks. Waiting to hear from "my guy"

Dave M

I just undo the blue drain plugs after I flush and let the water drain out.

neva satisfied

I can understand that with salt water but why would you do that in fresh water?

Dave M

While not in use, I think having NO water in there is better than having ANY water in there. On another "525 header" thread this was discussed.

I'm pretty sure I'm replacing my CMI's with the SM's this winter. I have around 230 hrs. on a 2005 525. I figure I am pushing my luck by now.

HyFive578

iTrader: (3)

That is the advice I had been given as well. I flush the headers for 5-10 minutes, let things cool down and then drain the water. I installed a draining system on my headers. I removed the elbows that connect the bypass hoses from the distribution rail to the tails (this is a Merc service bulletin to allow more cooling water to stay in the jackets). One on side, I installed a 3/4" to 3/8" reducing bushing which I then connected a 3/8" to -06 AN adaptor to which I connected a 3/8" hose. That hose runs into a custom made tee that's attached to the other header, to which a ball valve (see picture) is attached. The other side of the ball valve drains out into the bilge. When I'm done flushing, I open the valve and both headers drain out in seconds. [ATTACH=CONFIG]511836[/ATTACH]

neva satisfied

You know what would be slick is an electric valve of some sort that would stay closed when the key is turned on and open to dump the water out of the drains when the key is turned off. Everything would be automatic.

HyFive578

iTrader: (3)

Sounds good in theory but I wouldn't want the headers to drain out every time I turn the motor off... and you really shouldn't drain the headers when they're hot. It's the heat cycles that ultimately causes them to break down. I wait at least 10-15 minutes before draining them and the water comes out just warm.

tpabayflyer

Yeah, I am thinking draining the water and letting the air get to the metal is a bad deal? Isn't oxygen the real killer when it comes to rust and corrosion? I would say flushing with an anti-corrosive like salt away or maybe even filling with anti-freeze?

HyFive578

iTrader: (3)

I'm sure there are differing opinions on this but here's my rationale and what I've been told by surveyors and pretty knowledgeable engine guys. If you boat in salt water, no matter how much you flush, there will still be residual salt in the system, it's virtually impossible to get it all out. If you happen to develop a leak that you have not detected and the headers are filled, that water is going to leak down and sit in the cylinder when the engine is idle. If it's salt water, that cylinder will rust in no time. Water always finds its way to the weakest point. It was strongly recommended to me to flish and drain headers after use for this reason. Another engine guy I know told me that he installs automatic drains as matter of practice on all headers when they come in with leaks to be welded. This same guy also recommends flushing with salt-away first and then running a second flush using a salt-away canister filled with WD-40 to coat the inside of the system and prevent the salt buildup.