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roadnsky 08-03-2016 08:38 AM

1 Attachment(s)
Attached is the procedure

Booniac 06-14-2022 08:53 PM

Flush Help Please
Hello everyone.
I have been reading and enjoying all the posts and information posted.
I am looking for some help if anyone has any advice.
I read through the whole Flushing thread a couple times but I am still a bit timid. Im a sailor not a mechanic.

I want to do a flush of my engine. I run it in the Sf Bay and have not flushed it once in the past year.
I thought a flushing meant connecting a fresh water hose, forward of the raw water intake and behind the water pump. I have a Tee connection with two ball joints.
I would turn on the engine with the raw water open and then open the valve for the fresh water. I would want to close the raw water valve after a few minutes and have only the fresh water pumping through. I would keep this configuration for a few minutes and then open the raw water again, close the fresh water and then shut off the engine.
This is what I thought a flush was. Was I incorrect?
It sounds like a good way to help prevent corrosion if i can do it after every couple of sailing trips.
But after reading all the threads I have not seen one mention about my concept of flushing my engine.
The threads all mention an Acid flush with Muriatic acid. I am not against this idea at all and it sounds good. The pressure flush, I'm not to keen on. Again im not a mechanic and I don't want to do the wrong thing or strip something.

Here are my actual questions for anyone with knowledge or experience.

1.Can I do the Acid flush and then the Fresh water flush that I mentioned earlier?

2.Is the Freshwater flush I mentioned even a thing? if so; Is the process i mentioned earlier acceptable?

3. For the acid flush; if I put a hose from the Tee to the mixture bucket, forward the Raw water inlet, with the raw water valve shut. Can I just turn the engine on? Will that draw the Acid mix from the bucket? Or will the mixture need to be forced in to the block? or the raw water open the whole time? Im worried that any running of the engine without water could be detrimental.

The Fresh water flushing I mentioned seems like a good concept and it can be done as often as desired because it seems so simple (hook up a hose, close one ball valve and open another). As opposed to a Forced Flush or Acid flush which take tools and a better confidence than I have.

Sorry for this being so long and my lack of experience (im sure ive used the wrong terms somewhere).
But thank you to everyone that was able to read all the way through and contribute.
I really appreciate it.
looking forward to your feedback

Fair winds!

Dave Neptune 06-14-2022 09:59 PM

I see you posted twice and in both posts I did not see a reason for an "acid flush". An acid flush is usually only done if you are having a heating or over heating issue.

What you are doing with the hose is good for rinsing the saltwater out of the block but does little to dissolve or clean out deposits that are not allowing the engine to cool properly. Again I see no complaints in that regard.

If you just want to flush the engine out for "good house keeping" I would use vinegar and let it sit for a couple of days. The vinegar is far less aggressive and still does a good job unless the block is really plugged up and over heating.

I did one acid flush in 34 years pretty much just after I bought the boat and had over heating problems. From that time on I did a vinegar soak about every 3~4 years and never over heated.

Are you experiencing heating problems?

Dave Neptune :cool:

Booniac 06-15-2022 11:53 AM

Very cool. Thanks Dave.
Yeah. I did post twice. This is my fist time posting on any type of forum and I wanted to be sure I was posting to the correct place.

I think i understand a bit better.
The acid flush is usually to correct a problem, as opposed to it being for maintenance.

I will do the Fresh water flush since you stated that it helps to de-salt.

Yeah. I'm just trying to be proactive and keep my engine happy.
For the Vinegar flush; if i put a solution in a bucket and an intake into the bucket. How do I "let it sit in the engine for a few hours"?
Start the engine and then stop it, half way through the bucket?
Now the vinegar solution is in the system until I run fresh or Salt water again?
Or is there some way to close the system and trap the solution in there? and then open again to discharge?

I will do the fresh water flush today. Im looking forward to it. (small victories).

What ratio of vinegar to water should I use?

Thanks again everybody

Dave Neptune 06-15-2022 12:29 PM

You can disconnect the hose from the pressure side of the pump and drain the block into a bucket or the bilge. Then disconnect the hose from the "high side" of the manifold which should be the highest point of the engine. Once drained plug the hose disconnected from the water pump and then fill the block with vinegar (no mixing with water) at the manifold once full just let it sit for a day or two. Then hook the hoses back up and start the engine.

The vinegar does not stink like an acid wash does. So the boat will smell like a salad for a day or so not like a sewer ;).

After running be sure the water is flowing good. After running check the fitting on the manifold that feeds to the exhaust as it is the place most likely to gather debris that can restrict water flow and thus the cooling capacity.

Dave Neptune :cool:

jcwright 06-15-2022 12:34 PM

Hello Booniac.

You asked if fresh water flushing is ‘a thing’. It is. You may find this thread on flushing helpful:

To make things easier for myself, I have a 3-way valve so I can switch from raw to fresh water from the onboard tank.


joe_db 06-15-2022 12:46 PM

FYI - Salt water will eventually kill your engine. If you plan on keeping the boat a long time I would look into switching to fresh water cooling.
One big reason for acid flushing is overheating, which is a vicious cycle. The hotter the engine, the more salt and minerals form deposits, which makes it run hotter. My old engine would start the year at about 160 in a few months be past 180 going for 200 :eek: I would then give it a good flush and it would go back to 160.
My current engine runs in the 120-140 range and does not seem to suffer from salt deposits. I have FWC gear to add to it when I get a chance.

jcwright 06-15-2022 02:37 PM

+1 on Joes’s advice.

My flushing setup is this poor man’s workaround, not the FWC system I’d like to have. But, I also run around 140 and the last acid job I did about 3 years ago produced very little junk.


Booniac 06-15-2022 10:46 PM

Thanks for all the feedback!
Very helpful.
I think i will run the fresh water through from a 5gal bucket.
In the past, i read somewhere that the hose pressure can damage the impeller, or gaskets or something can get damaged. After hearing that mentioned again here I will use a bucket process
The suction from the engine should draw it right through. Im hoping. I may even try to keep the Raw water open initially just to make sure she doesnt run dry.
And the vinegar does sound like another good idea.
But should I be worried about dislodged particles getting caught in the block, or something? wouldn't that be a bad thing?

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