Why do we flush motors?

[charleville]

I used to flush my outboard motor immediately after every day's use.

Now that I use it several times each week, I only flush it maybe once per week.

However, I am getting lazier and I sometimes will let it go 3 - 4 days before flushing or alternatively just rely on using it again in that time. When I do that I still see a strong tell-tale so I am assuming that no salt will build up as it will be all flushed out with the new saltwater pumped through when out on the Bay.

So, I am now wondering if I am not doing myself a favour by not flushing more regularly, which would be the case if corrosion were the main problem that I should be avoiding.

So the question is, why do we flush motors? Is it to avoid a build up of salt or to avoid immediate corosion? All advice gratefully received.

[Owen]

If you were to open your thermostat housing you will probably see a coating of salt that looks like jelly in the smaller galleries.
I believe this will start to form immediately that the water drains from the engine. If left long enough it will harden. I guess the telling part is how much is flushed away (by either flushing or salt water) on the next startup.
I flush my engine every time, but being 2nd hand I can't know what happened prior. If I assume the jelly I found was from the previous owner(s), then I can also assume that subsequent flushing and/or use doesn't get it out
I had to scrape it out. I don't think the larger galleries would be such an issue.

cheers,
Owen

[finga]

'cause my dad would kick me in the posteria if I didn't

Occassionally a short interlude (say a day between runs) maybe OK but I still like to flush at least everyday after running (if I'm using everyday for awhile) just to get rid of the salt that may/maynot build up in the galleries etc.
And it annoys the bejees out of the not so nice neighbours :cheesy:

[charleville]

And it annoys the bejees out of the not so nice neighbours :cheesy:

Ah well, mine is a fourstroke and pretty quiet even with just the earmuffs so I cannot claim neighbour peace (or otherwise ) as an excuse.

[disorderly]

Just wondering if there is some wonder product you can add to a body of water( ie cut off wheely bin,barrel etc) to remove this salt build up in the water galleries or do you just have to wait for the inevitable overheated motor.
cheers Scott

[charleville]

'cause my dad would kick me in the posteria if I didn't

Notice the elapsed time since my last post on this topic. I went straight out and flushed the motor!

[richieboy]

Before I got into my current line of work, I used to work as an engine reconditioner.
We'd always get motors in that were cracked through the water jackets allowing saltwater to peirce the cylinders and eventually seize motors. Not only this but the heads as well. Although the cases are alloy, corrosion will still build upin between the cylinders and cause the cast sleeves to crack. Very expensive when you have to rebore out to the biggest oversize piston, only to find the crack is straight thru to the jackets and you have to re-sleeve a cylinder.
Jetski's are notorious for it if you own one.

Rich

[bootyinblue]

There is a myriad of additives that claim various benefits from flushing motors. Most seem to be a reservior type set up you click on the muffs and then click the hose to it, similar to a hose on lawn applicator.

A good 5 minute flush to bring the motor up to operating temp and thus running warm water through the system is all that is required. But I occasionally put a little shot of silicone spray in the water just to add a bit of a lubricating film

[disorderly]

b.i.b,Its one thing for companies to make these claims but do you think these products actually work?How could you actually tell if they had any effect?

[PinHead]

I have heard on these posts and elsewhere that the preferred method of flushing is in a drum or flush bag as opposed top muffs. My question is: if using a drum then isn't the salt being removed and into the drum to be recirculated...granted it is diluted but still salt nonetheless.

[FNQCairns]

If you were to open your thermostat housing you will probably see a coating of salt that looks like jelly in the smaller galleries.
I believe this will start to form immediately that the water drains from the engine. If left long enough it will harden. I guess the telling part is how much is flushed away (by either flushing or salt water) on the next startup.
I flush my engine every time, but being 2nd hand I can't know what happened prior. If I assume the jelly I found was from the previous owner(s), then I can also assume that subsequent flushing and/or use doesn't get it out
I had to scrape it out. I don't think the larger galleries would be such an issue.

cheers,
Owen

Owen does this stuff have the consistancy of Jelly and do you use any of the flushing additives? I have never seen this Jelly and am shy of the flushes due to reports I have heard.

cheers fnq

[charleville]

if using a drum then isn't the salt being removed and into the drum to be recirculated...granted it is diluted but still salt nonetheless.

That would depend on whether the tell-tale was squirting back into the drum or outside.

When I was using a drum at home, the tell tale would squirt out onto the grass but I did have to top up the water in the drum after a while.

[charleville]

corrosion will still build upin between the cylinders and cause the cast sleeves to crack.

Thanks for this reply.

I think that you are saying that it is important to flush after each trip to get rid of the risk of corrosion.

I was hoping that someone who has done your line of work might offer a perspective. Many thanks.

[tigermullet]

I used to be fanatical on flushing outboard motors until my brother and I had a large aluminium boat built. It is powered by an outboard and has been on the water for just on nine years. The first motor which was used for about 5 years was never flushed. Because we had the chance to upgrade for minimum cost we replaced the motor and the new one has never been flushed either. No problems have been encountered. I do flush the dinghy motor but that is just because I can bring it home at the end of each trip.

I have to question my reasons for flushing the little outboard because it is generally on the water for two weeks at a time and, like the mother ship's motor, is not flushed.

Before we launched the bigger boat for the first time I was concerned about not being able to flush the motor and asked a lot of questions. One person that I came across had a motor more than ten years old which had never been flushed. No problems there either.

Over all I think that I would prefer to flush the motor with fresh water and for convenience would prefer the ear muffs. The best idea that I have heard for putting a 'coating' on the water jackets etc., was to flush the motor in a drum to which one cup of diesel was added. That sounded good to me but I have never tried it.

Having said all of that I do not really know - we might have been just lucky.

I think that knocking the centre out of the thermostat and just leaving the housing in place is a very good idea. Many years ago and old outboard mechanic recommended that and told me that he had seen more motors under 50hp wrecked by improperly functioning thermostats than anything else.

When you think about it, it does make sense. Outboards are sold all over the world and are operated in some very cold water. Our water is temperate and the difference in time for a motor to warm in the absence of a thermostat would be only a few seconds. Leaving just the body of the thermostat restricts the flow and aids warming but is never prone to partial opening and consequent over heating situations

Please do your own research. I feel happy with the non flushing and non working thermostat ideas but would not like to feel responsible for someone else adopting the idea and then having problems with their motor.

[Reel Nauti]

It's not an easy question to answer and even more difficult to determine whether we are in fact doing our motors any good by flushing. When you consider that small outboards on yachts would never see fresh water, and there are millions of them the world over, you have to wonder.
An old mate of mine had a 40hp Mariner which he had bought new. He is meticulous in his care of any machinery, and the motor was flushed every single time he got home from the ramp, regardless of the time of day or night! 12 years went by with no probs, and then on one trip the motor stopped. He took it home and pulled it down and the corrosion throughout the head was well advanced. In fact the head was buggered.
So I'm blowed if I know. I flush in a drum, and have never had an engine fail on me, and I also remove the thermostat and just leave the brass ring in tact. However, now with the brand new motor I won't do that as I'm sure it would void the warranty.

Cheers

Dave