Engine/Outdrive flush while in the water

comsnark

comsnark

New Member
Apr 10, 2007
4,106
NJ Shore
Boat Info
SeaRay SunSport
Engines
5.7LX
So. . .yesterday I started an interesting thread on Boat Lifts.
We started to veer off the "lift" topic and onto "engine flush".

My boat has twin 5.7L Mercs with Alpha-I drives. Raw water cooled. Where I boat. . .the raw water is salt water. The boat is not trailered, and presuming that I don't put the boat on a lift, the boat will stay in the water from May-November every year.

Question 1) :smt024
Is there any practical method for performing an engine/drive flush with the boat in the water? Or am I totally committed to a riser/elbow replacement every few years?

Question 2) :smt024
Some one posted a link to the "Neutra-Salt" system. Does anyone have experience with that system?

Question 3) :smt024
Should I just bite the bullet and get a closed loop cooling system installed on both engines?

__________________

There are some good insights being posted by members on this board. I appreciate your feedback.
 
comsnark, I've never heard of flushing engines while in the water but why not. If you don't mind getting wet to put the muffs on then turn on the fresh water, run the engines till the thermostats open, wala flushed. When you pull off the muffs the outdrive will fill back up with salt water but I think the engines will hold the fresh. You seem to be worried about the risers anyway so what could it harm? I say give it a try. :huh: :thumbsup:
I just read the posts about the lift decision so, never mind. :grin:
 
You can do a search on flushing the motors and find a couple of threads. But I still think you need to pony up the boater bucks and get the boat on a lift. :thumbsup:
 
STIHLBOLTS said:
You can do a search on flushing the motors and find a couple of threads. But I still think you need to pony up the boater bucks and get the boat on a lift. :thumbsup:
Click to expand...

Oh sure. . . .I am just making sure I have thought everything through. Honestly. . I would have actually had a lift last year, but I seemed to hit a wall when I actually had the audacity to ask for *written* quotes. This year . . .I actually managed to get two written quotes in hand (but both have "issues"), with one more quote expected this week.

At this point. . .it seems clear I will spend at least part of the season in the water. If it makes sense. .and only costs a few bills, I may just go ahead and rig the boat for flushing. I like keeping my toys for a long time :wink:
 
My Merc manual says OK to flush in the water. Just tilt up, put the ear muffs on, and follow normal flushing procedure.

Thinking long term, if you're in salt water, I would invest on lift or after-market FWC kit for the block.

Esteban
 
When I bought my '96, I contacted Volvo. They informed me that most of the commercial fishermen in Virginia were running raw water cooling systems, for simplicity sake. While I realized that this did not address all concerns about an outdrive, I had a simple solution.
I had the dealer install a flushing system. It consisted of a 3/4" hose inlet at the stern, which T'd off and connected to 2 - 1/2" hoses, each of which were connected to to engine block drains.
The 3/4" inlet was capped, except for flushing.
At the end of the day, after all systems cooled down, I would unscrew the cap, connect a hose and turn it on. The water would start at the base of the engine, flushing through it and working its way up, and proceeded to flush the manifolds, risers, and part of the outdrive.
It was nothing more elaborate than a few fittings and a few hoses, for a total installed cost of $250, and my engine/outdrive was near perfect in salt water, but I replaced the risers and manifold for "safety sake" after 7 years . At 10 years, I sold her, and the engine compression check was like new.
It is interesting that newer Volvo sterndrives now come with a similar arrangement.
 
in-water engine flush

I'm getting a flush port installed by the dealer before I pick up my boat. It's a mercruiser 350-magnum B3 with raw water cooling. I have yet to see how it works, but I'll let you know in a couple of weeks.
The service guy said you just attach a hose, throw a valve open, turn on the water and start the engine for 5 minutes or so.

(it's going to be around $400 ... prices must have gone up)

-charlie
 
Sea Ray 300 said:
When I bought my '96, I contacted Volvo. They informed me that most of the commercial fishermen in Virginia were running raw water cooling systems, for simplicity sake. While I realized that this did not address all concerns about an outdrive, I had a simple solution.
I had the dealer install a flushing system. It consisted of a 3/4" hose inlet at the stern, which T'd off and connected to 2 - 1/2" hoses, each of which were connected to to engine block drains.
The 3/4" inlet was capped, except for flushing.
At the end of the day, after all systems cooled down, I would unscrew the cap, connect a hose and turn it on. The water would start at the base of the engine, flushing through it and working its way up, and proceeded to flush the manifolds, risers, and part of the outdrive.
It was nothing more elaborate than a few fittings and a few hoses, for a total installed cost of $250, and my engine/outdrive was near perfect in salt water, but I replaced the risers and manifold for "safety sake" after 7 years . At 10 years, I sold her, and the engine compression check was like new.
It is interesting that newer Volvo sterndrives now come with a similar arrangement.
Click to expand...
That's exactlly what my boat has. The guy I bought it from was from LI and installed it. If anyone is interested, I'll take some pics when it comes home Sat. :smt038
-Mike
 
I have the same thing on my boat. turn 2 valves and the engines drain, hookup fresh water and flush they do. it was a dealer install and it's pretty sweet. I believe mine is tapped in after the thermo so I don't have to start the engines, but I'll trace the setup this weekend to confirm as I haven't flushed them yet cause not water at the marina until this weekend. I'll take some pics of mine too.

mike
 
I will contact my "guy" tomorrow. . .and see if he knows what I am talking about. This sounds like a simply awesome idea. Thinking about it. . .my jetski even has quick connects on the flush connecitons. .so flushing that unit is simple-simon easy. I see no reason my 5.7L's can't be *almost* that easy . . .
 
Re: in-water engine flush

charlieft said:
I'm getting a flush port installed by the dealer before I pick up my boat. It's a mercruiser 350-magnum B3 with raw water cooling. I have yet to see how it works, but I'll let you know in a couple of weeks.
The service guy said you just attach a hose, throw a valve open, turn on the water and start the engine for 5 minutes or so.

(it's going to be around $400 ... prices must have gone up)

-charlie
Click to expand...

Charlie,
The system that I had would flush without running the engine.
When the engine is run, salt water is pumped in, which defeats the purpose of fresh water flushing.
I had no valves to turn,... Just opened a cap, connected a hose, and turned on the water...
Simple, and very effective.
 
Engine running or not?

I understand the question of running the engine or not depends on the model drive and the model of flush kit. We have a Bravo Three that requires running the engine with our model flush kit, but the same flush kit does not require engine running with an Alpha One. So that looking at the specs may help you decide.
 
I'm considering a 2005 260DA. It has the 350 MAG MPI HORIZON - 300 hp with BIII outdrive. It has 69.2 hours and has been in the water May-Oct. both years it's been alive but been pulled out of the water for regular cleaning and flushings. My only concern with this boat is that it has been in the water without flushing the outdrive everytime. Merc says online that it doesn't as yet offer an in the water flush kit for this engine, your posts triggered me to look online. This video seems to indicate a flush hose inlet for flushing?Mercs' website video outlining the Horizon

Seems like there's a air pump which removes the water in the engine.
Any experience with this system?
 
Shining said:
That's exactlly what my boat has. The guy I bought it from was from LI and installed it. If anyone is interested, I'll take some pics when it comes home Sat. :smt038
-Mike
Click to expand...
If you have them could you send me the flush pics you mentioned?
 
Sea Ray 300 said:
When I bought my '96, I contacted Volvo. They informed me that most of the commercial fishermen in Virginia were running raw water cooling systems, for simplicity sake. While I realized that this did not address all concerns about an outdrive, I had a simple solution.
I had the dealer install a flushing system. It consisted of a 3/4" hose inlet at the stern, which T'd off and connected to 2 - 1/2" hoses, each of which were connected to to engine block drains.
The 3/4" inlet was capped, except for flushing.
At the end of the day, after all systems cooled down, I would unscrew the cap, connect a hose and turn it on. The water would start at the base of the engine, flushing through it and working its way up, and proceeded to flush the manifolds, risers, and part of the outdrive.
It was nothing more elaborate than a few fittings and a few hoses, for a total installed cost of $250, and my engine/outdrive was near perfect in salt water, but I replaced the risers and manifold for "safety sake" after 7 years . At 10 years, I sold her, and the engine compression check was like new.
It is interesting that newer Volvo sterndrives now come with a similar arrangement.
Click to expand...

If you have them could you send me a diagram or photos of the freshwater flush system you mentioned
 
I know folks that had those and they worked OK. I just have something (Pun: a sinking feeling) about installing anything plastic below the water line.

My last boat, a Chaparral 2550 SX Sport 7.4 Bravo1, I cut in a S/S ball valve in the line feeding the Bravo raw water pump and added a hose feed between the valve and the pump. Also added a pressure relief valve that dumped overboard. Hose feed connection was on the transom. Close the ball valve, attach garden hose and turned on water, relief dumped pressure overboard till engine started and sucked the fresh water. When done flushing, shut off engine then opened the ball valve, back flushing salt out of raw water system before the pump, flushing the drive. That setup cost about $350 for grade 1 parts and about 4 hours to install. Installing the overboard (through hull) pressure relief valve and water fill port took longest time.

On the boat I have now, I do have Closed Cooling full system on my 7.4 B3, but trailer, so I run on muffs after every outing to flush the oil, PS fluid, raw water heat exchangers and the riser / elbows.

Keeping with the no plastic below water line theory, I even replaced the plastic raw water inlet fitting on my transom with a billet unit and the plastic raw water pump with a S/S Hardin pump body)
 
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