Drain the block?

Chad Flaugher

Petty Officer 1st Class
Joined
Jan 2, 2015
Messages
392
Every time I go out, I drain my exhaust manifolds on my I/O engine to prevent them from rusting out... When I was draining the block of antifreeze to get it ready for our first trip out this year, I wondered, should I be draining the block after each time out? Overkill? What do you guys do?
 

Scott Danforth

Grumpy Vintage Moderator still playing with boats
Staff member
Joined
Jul 23, 2011
Messages
47,309
If I'm fresh water, leave them until winterizing. If salt water, flush after use.

No need to drain
 

Chad Flaugher

Petty Officer 1st Class
Joined
Jan 2, 2015
Messages
392
Should have mentioned that I am 100% fresh water. Colorado has very little ocean front property. :laugh:
 

VE8EV

Petty Officer 2nd Class
Joined
Sep 5, 2012
Messages
109
Might just be the marketing talking but this from a 1975 OMC Stern Drive brochure talking about fighting corrosion:

"And the engine itself is protected by OMC's wet exhaust system, which reduces corrosion and scale formation by keeping water jackets full after the engine is shut off."

It does makes sense to me, less rust if completely submerged than if drained and left wet. I don't drain mine until the end of the season.
 

bruceb58

Supreme Mariner
Joined
Mar 5, 2006
Messages
30,454
If you ever see a steel piling, the part that sits out of the water corrodes more than the one in the water. You need oxygen for rust to form.
 

Chad Flaugher

Petty Officer 1st Class
Joined
Jan 2, 2015
Messages
392
Okay, so that was my thinking as well... The manual however, does suggest draining the manifolds after every use. Why would you not drain the engine, but do drain the manifolds? Both are cast iron. I'm not questioning anybodies logic, just trying to wrap my head around the theory.
 

Scott Danforth

Grumpy Vintage Moderator still playing with boats
Staff member
Joined
Jul 23, 2011
Messages
47,309
Okay, so that was my thinking as well... The manual however, does suggest draining the manifolds after every use. Why would you not drain the engine, but do drain the manifolds? Both are cast iron. I'm not questioning anybodies logic, just trying to wrap my head around the theory.

no theory, the manual was written by an intern. dont overthink the power of unpaid interns.

your in CO, go boating. come fall, pull the plugs, poke the holes with a wire or screw to get the crud out and drain the block, heads, and mani's for winter.
 

Bondo

Moderator
Staff member
Joined
Apr 17, 2002
Messages
70,469
your in CO, go boating. come fall, pull the plugs, poke the holes with a wire or screw to get the crud out and drain the block, heads, and mani's for winter.

Ayuh,..... couldn't agree more,.....
 
Top