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Author Topic:   Flushing of Saltwater Motors - Ship Shape TV
Wild Turkey posted 09-06-2001 12:10 PM ET (US)   Profile for Wild Turkey   Send Email to Wild Turkey  
Last night Ship Shape TV with John Greviskis had an episode on flushing of motors operated in saltwater environments. He made some eye opening statements.

He suggested outboard motors flushed with "earmuffs" should be run for at least 20 minutes. He suggested it takes 15 minutes for the t'stats to open at idle. Also, it was suggested that even that time duration would not completely remove all the salt deposits in the cooling system.

Tests were also performed recording water pressure at the powerhead of outboards. With "earmuffs" on one of his Yamaha 150's, the pressure gauge indicted only ½ psi!! The quick connection that Yamaha provides for flushing was then used and a pressure of only 1 psi was recorded.

Of course, the show was touting the Guardian flushing system.

I am just wondering if the statements and testing are true. What are some real world experiences?

I flush my outboard with earmuffs after every use…… but I don't run the motor for 20 minutes! Also, at ½ psi water pressure, am I damaging my motor?


whalertim posted 09-06-2001 12:28 PM ET (US)     Profile for whalertim  Send Email to whalertim     
Chris, This is an interesting topic! I flush w/ earmuffs everytime I take out of the water and when I get the boat home. I have been told several different ways to flush. 1- is to put the earmuffs in place, start the water, start the engin, disconnect the fuel line. When the engin stops, its flushed. I think this is the worst thing that one should do!.
2nd- Follow #1 but leave the fuel line on and the engin running for 15 min. min, put the engin in forward gear for about 30 sec. at low rpm. then put the engin in reverse for 30 sec. low rpm. Place the engin in nutural for a couple more min. and then shut it down.
#2 is the procedure that I use. It would be great to hear from others on this matter.
Bigshot posted 09-06-2001 01:24 PM ET (US)     Profile for Bigshot  Send Email to Bigshot     
I flush mine after I pull it so it is still warm and the t-stats will open quickly. Can't see the benefit of running in gear but can see the danger. Never operate over 1500 rpm due to no back pressure, etc. On my I/o I taste the water coming out of my exhausts. Once it is fresh I let her run another minute and shut her down. I do not believe the PSI bit because I have a water pressure guage and it reads normal. If it read "0" I would never run it like that. I never even flushed an o/b until probably 1988 or so, nobody did that I knew until you winterized it. If you ever doubt the toughness of an outboard go to a rental place and see how old those rental motors are. They are run WOT, who knows the accuracy on mixture, shifted at high rpms, never flushed, etc and they go 10+ years at some places. It is a definate plus but I rarely see an outboard destroyed INTERNALY by rot. I/o's will because they are steel.
lhg posted 09-06-2001 01:37 PM ET (US)     Profile for lhg    
I use the earmuffs to flush mine also, even though the engine has the hose flushing capability.

I usually run it for about 10 minutes, and often hold a rag over the exhaust to force water into the relief ports. I have both water pressure and cylinder head temp gauges, both of which have senders located on the top cylinders, and they read normal while flushing.

Sounds like ShipShape TV operates, and is funded, the same way as the boating mags.

Tom W Clark posted 09-06-2001 02:02 PM ET (US)     Profile for Tom W Clark  Send Email to Tom W Clark     
If you flush your motor on the hose after you've pulled the boat out of the water, the motor will be warm and the thermostats will be open or soon to be, so it's not really an issue.

As to asterisk water pressure, hog wash. Infomercials are pretty much worthless, give me a break...

My '90 Johnson 150 was only used in salt water and always flushed after each use. After 4 seasons of use the powerhead was replaced (for reasons unrelated to corrosion or its design) and while it was apart the mechanic showed me the insides and commented that it looked great, you couldn't tell it had been a salt water motor.

Whaler4me posted 09-06-2001 04:02 PM ET (US)     Profile for Whaler4me  Send Email to Whaler4me     
I completely agree with lhg, in that the show was basically selling the aftermarket flushing system, and therefore compensated in some way for it's time.

Just like the boat magazines. They don't write bad articles about boats because the boat manufacturer will not buy ad space any longer.

Ever notice the relationship between the number of ad pages to the depth and frequency of articles ?? = Very interesting.

daverdla posted 09-06-2001 04:22 PM ET (US)     Profile for daverdla  Send Email to daverdla     
Fell asleep during last night's show.

I think the host does some interesting things, but he totally supports every product he uses. I know I don't like every product I use.

Also, does he ever finish any of the project boats? He had an old bertram moppie that he was restoring. I never saw the finished product.

dgp posted 09-06-2001 05:45 PM ET (US)     Profile for dgp  Send Email to dgp     
With Mercury's built-in flushing device they recommend to limit the city water pressure to the engine by only opening the water tap 1/2 way. They also recommend keeping the engine at idle, in neutral and flush for at least 5 minutes.
What you want here is flow not pressure; the higher the pressure the less the flow.
gvisko posted 09-06-2001 06:48 PM ET (US)     Profile for gvisko  Send Email to gvisko     
on my 70 suzuki 4 stroke with built in
flushing device they say to flush without engine running i did this and water comes
out of all the places but this seem werd to me. what do you guys
think.?? gv
ValkariaKid posted 09-06-2001 08:12 PM ET (US)     Profile for ValkariaKid  Send Email to ValkariaKid     
I've always wondered if there was a better way to flush out my engine, and looked into the MST Guardian. I too saw it last night on Ship Shape TV, felt that the program was kind of like an infomercial for it.
I think the guardian is geared towards people who haven't flushed their engines after each use, and now need a way to remove the salt "build up" resulting from their lack of, or improper flushing. It is my belief that if you properly flush your engine using "earmuffs" after each use since it was new there shouldn't be any salt/corrosion build up at all. I can't see how the water pressure has any effect on a proper flush. As long as the thermostat is open, and you're getting a decent amount of water through your engine it should suffice.

Is this wrong?

I been doing alot of research on this subject because have an '88 Johnson 90 V4 that I believe has quite a bit of corrosion built up inside. Unfortunately I don't think that the previous owner flushed it properly after each use. I think this because even after a new impeller I still don't get a strong tell tale stream that I feel I should have. In fact it takes about 5-10 seconds after statup before I see any discharge at all. I took a piece of safety wire and poked it through the nozzle, and it seemed to help a bit, and there was quite a bit of a salty residue on the wire. While I don't have an overheating problem now I still would like to rid the engine of any corrosion to help it last for a long time.
I thought about installing a guardian system to help remove some of the corrosion, but I don't feel that it's worth $200. It looks to be nothing more than a fuel log with a garden hose attachment that I can fabricate for about $40. They claim that a spring loaded piston inside is what causes the pulsing. How does that spring overcome the water pressure from the hose once it's compressed?

Anyway... is there a better way to remove salt corrosion from my engine than the way overpriced guardian?

Thank You-

B Bear posted 09-06-2001 09:27 PM ET (US)     Profile for B Bear  Send Email to B Bear     
I have in the past opened and cleaned many heat exchangers including saltwater distilling plants.

Normally there is no salt build up found in many heat exchangers, condensers, and radiators for diesel generators, what is found there is films and growths. The normal heat rise of the cooling water through a heat exchanger is 10 to 15 degrees in a one-pass system. So even if the saltwater temperature is 86 degrees, after it passes through the engine it should leave around 100 degrees, not hot enough for the salt to precipitate out.

Distillers on the other hand have scale, salt build up, this happens when the chloride content is increased and the saltwater becomes a brine solution with high temperatures and in some cases below atmospheric pressures during the evaporation of the salt water to be condensed later as fresh water. So salt residue also shows up through evaporation.

With this in mind there is two ways there would be any salt deposit in an outboard engine.
1. If the saltwater were to be left in the engine draining off and allowing a residue to dry in the cooling passages.
2. If cooling passages become blocked and the trapped saltwater becomes a brine allowing the salt to precipitate out and become deposited on the cooling passage walls. Sorta like cholesterol in the arteries of a Heart.

Knowing this it would be important to flush the outboard as soon as possible ,with the engine idling, after taking it out of saltwater.
1. As not to allow the saltwater dry inside the engine.
2. This also helps getting all the passages flushed since the engine is still warm and the thermostats will open more quickly.
3. Helps keep all the cooling passages clear of debris. It also keeps the water pump clean.

It is also better to flush using the earmuffs so the entire engine and lower unit, and water pump will be flushed too.

What if the engine has a build up of salt deposits in it already.
There is hope!
It is possible to setup a closed cooling flush system using a de-scaler, like salt-away form West Marine, in a tub, like you have seen those Honda displays, or large trash can. Lower the engine's lower unit into the tub or can coving the intake with enough de-scaler to keep the intake covered after the solution has been picked up and is in the engine. Running the engine with this set up over a period of time should remove any scale and salt build up inside the engine.

This is very close to the same procedure I have used to clean the heat exchangers in a distiller using safe-acid.

Food for thought, I am not going to pay $200 for an alternative to common sense. Anyway that is the way I see it.

B Bear posted 09-06-2001 09:58 PM ET (US)     Profile for B Bear  Send Email to B Bear     
gvisko is right about pressure and flow. There is an inverse relationship there.
There should be some pressure since the water pump must produce some pressure in order to get the cooling water into the head.
If there is a high pressure then there is a possibility of restricted passages.

Valkarikid, I'm with you on the flush. As for the spring thing, I would be careful. What if you do not dissolve this scale or build up. What ever it is can become jammed into a smaller passage stopping all flow and causing some real cooling problems later on. At that point the de-scaler would not be able to flow by to dissolve and carry away the scale. At that point only mechanical cleaning (taking it apart and cleaning by hand) will do the job.

triblet posted 09-06-2001 10:01 PM ET (US)     Profile for triblet  Send Email to triblet     
I use the builting hose fitting on my

The manual says do not exceed 45 PSI. After
my recent adventure with water in the lower
unit, I decided to build a pressure gauge.
The water pressure at Point Lobos is a LOT
higher than at my house, and I flush there
when I dive there. I haven't measured it at
Pt. Lobos yet (Saturday, if the plankton
bloom backs off a bit), but the static
pressure at my house is 90 PSI. I suspect
that opening the hose bib half way would be
too much at home, and WAY too much at Pt.

Watch this space.


Hank posted 09-06-2001 11:06 PM ET (US)     Profile for Hank  Send Email to Hank     
With respect to clogging of the telltale, if you remove the motor cover and look down where the telltale comes through you'll see a hose connected on the inside with a little clip. Disconnect at this point and trace the hose to the the point where it connects to the engine proper. Disconnect and use your safety wire here. Then blow out the hose. I like to do this with the engine in the water. I can start the engine and see if I've cleared the passageway.
Be aware that on the OMC engines the telltale flow is split off the main flow just above the water pump and only shows that the water pump is working. It does not first flow through the engine cooling passages in the heads before showing up at the telltale.


george nagy posted 09-06-2001 11:30 PM ET (US)     Profile for george nagy  Send Email to george nagy     
I too saw the show. That system seems pretty involved. My engine is corroded after 14 yrs of SALT use. The inside is fine with not much flushing! It is the ouside that is done. The manuals use to say if you use your boat on a regular basis flushing may not be necessary I.E. commercial boats. Remember they recomend changing impeller annually to me it ment every 5 years or so.
WantaWhale posted 09-07-2001 12:12 AM ET (US)     Profile for WantaWhale  Send Email to WantaWhale     
I saw the show as well. Dumb question time: I have always been told you don't need to flush the engine every time after use in brackish water (river, bay) but only in salt water. True?. I have been out in my "new" whaler 3 times now and have not flushed it as of yet. Bad idea?


Bigshot posted 09-07-2001 10:16 AM ET (US)     Profile for Bigshot  Send Email to Bigshot     
I live on brackish water and I rarely flush. If I trailer it I flush but it is hard to do in the water9and noisy). The factory flusher on o/b's I was also told NOT to run the engine because they "backflush" it and therefore impellor will be fighting the flow.
gunnelgrabber posted 09-07-2001 10:38 AM ET (US)     Profile for gunnelgrabber  Send Email to gunnelgrabber     
way to go,guys ! ..that should about cover that subject!.."b bear ",a special thank you for your effort and obvious knowledge and all of you , i appreciate you...lm
Wild Turkey posted 09-07-2001 12:01 PM ET (US)     Profile for Wild Turkey  Send Email to Wild Turkey     
Thanks for all the responses and info....
I thought it was a bunch of BS too.

I must be doing something right, 90 HP Evinrude (13 years old).

JFM posted 09-07-2001 12:03 PM ET (US)     Profile for JFM  Send Email to JFM     
I have always used a large plastic garbage can with a hose of fresh water in the bottom. The reason is the dealers around here do it that way. They also work and test engines that way. Also it doesn't make as much noise. Regards, Jay
Bigshot posted 09-07-2001 01:23 PM ET (US)     Profile for Bigshot  Send Email to Bigshot     
Overtons sells a muffler so you can flush quietly. Goes on the prop hub. I think about $50.
Mullet posted 09-07-2001 01:50 PM ET (US)     Profile for Mullet  Send Email to Mullet     
Read on another post where they use an induction system with a small amount of soap and baking soda. I don't know what the PH of ocean water is but this may have to do with killing any acidity. Finishes with fresh water.

Thanks bigshot, I am going to order the muffler. Apparently it gives the needed back pressure but will help me a lot. We usually pull the boat mid morning on Sunday to clean it up and get ahead of the crowd. Church is right across from the house and I feel funny running my 200hp "chainsaw" during morning services.

WantaWhale posted 09-07-2001 01:51 PM ET (US)     Profile for WantaWhale  Send Email to WantaWhale     
Since we are talking about outboards and flushing, do any of you know a web or message board specific to johnson O/B's? I have maintaince questions
'96 Supersport
Mullet posted 09-07-2001 01:53 PM ET (US)     Profile for Mullet  Send Email to Mullet     
WantaWhale, ask it here. These guys are pretty smart.
FISHNFF posted 09-09-2001 01:37 PM ET (US)     Profile for FISHNFF  Send Email to FISHNFF     
Here is a question to all those with a factory installed flushing port on a berthed vessel. Do you leave the motor in the water when flushing, or do you yilt it clear? On my Merc, with the port inconveniently mounted on the back, I tilt the motor clear. The selling dealer could not give me an answer, and since the flushing port is where the telltale is, I cannot taste the water.
Mullet posted 09-09-2001 02:33 PM ET (US)     Profile for Mullet  Send Email to Mullet     
Never flushed a berthed boat but looked in Merc's manual and it doesn't address this. However, on another board there was a lot of discussion about Yahmis and they were saying that their manual specifically told them to tilt the engine.
Bigshot posted 09-10-2001 10:49 AM ET (US)     Profile for Bigshot  Send Email to Bigshot     
My 225 Ocean runner gets tilted clear when flushed. Too difficult leaning over the motor.
blackdog posted 09-10-2001 01:13 PM ET (US)     Profile for blackdog  Send Email to blackdog     
Try on the Johnson Section.
blackdog posted 09-10-2001 01:13 PM ET (US)     Profile for blackdog  Send Email to blackdog     
I mean WantaWhale

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