Can I use barnacle buster to flush an outboard?

[Insequent]

First up the mea culpa: I have not been very diligent in flushing the outboard with fresh water after operating it in the ocean. So the tell-tale is down to a dribble. The over heat alarm has gone off.

So, i changed the impeller even though the old one looked perfectly fine. I changed the thermostat, which was not fine at all. Quite gunked up and clearly not working. With new impeller and thermostat the tell-tale remains a dribble. I've tried some salt-away, and plan on continuing that for few days, starting the motor and running it for a short time using the salt-away as a flushing fluid.

But I also have some partially spent and diluted barnacle buster at home from when my John Deere heat exchangers were flushed. Would there be any issues in flushing the outboard with this for a few minutes at a time, and then flushing with water afterwards? I'm thinking the gunk that needs to be cleaned out (see old thermostat in pic below) will need something more aggressive than the salt-away. Is there something else I could do instead?

 

[Don L]

yes you can use that

 

[Comodave]

I don’t see any problem using that. Also maybe get a fine wire and run it up into the pee hole and see if you can break the buildup loose???

 

[Insequent]

I don’t see any problem using that. Also maybe get a fine wire and run it up into the pee hole and see if you can break the buildup loose???

For the last few years I've used either a zip tie or a piece of weed wacker line in the pee hole when it had poor flow. Usually a bit of salt or whatever came out and then it worked fine. But now that trick is no longer having any effect.....

The motor is an 11 year old Honda BF40D. Service by the dealer a couple of years ago, new impeller as part of that and good flow until last six months. The guy did say there was one part that he could not remove . Bolts were going to need heat etc to try and loosen and we ran out of time to do it. Not sure what the part was, but chances are it was part of the cooling system

 

[Comodave]

I don’t know what the inside of the pee hole is like, but maybe a small drill bit to cut away the buildup?

 

[DavidM]

Outboard blocks and their cooling passages are aluminum. Hydrochloric acid, the main component in BB eats up aluminum fairly quickly. But from the looks of things that OB is on its last legs anyway, so what have you got to lose.

I would set up a recirculating path using the earmuffs and letting the outflow dump in a bucket. Use an old bilge pump to pick up from the bucket and recirculate the BB solution,.

Just as a guess, the BB will dissolve the calcium carbonate scale ten times faster than the aluminum, but you have heavy scale built up. So circulate the acid for a minimum of ten minutes. Then shut down and pull the thermostat to see how much scale is gone, or just monitor the pee hole and stop circulating when it flows strongly. It may take as much as 30 minutes to dissolve all of the scale.

You might lose a hundredth of an inch of aluminum to dissolve a tenth of an inch of scale. I suspect you can afford to lose a hundredth of an inch from your sea water passages, but if not, so what.

David

 

[Insequent]

Thanks David. That was basically my plan. Circulate for 5 minutes, let it sit for a few minutes then circulate again. But first I'll put the old thermostat in a cup and agitate in the old BB solution for a bit to get a feel for how effective it is at removing the gunk.

Comodave - the pee hole and the first few inches of the thin hose at least are clean, no buildup at all. The blockage(s) are further upstream. Even with the new thermostat and impeller I got an overheat alarm after running for a few minutes at 1000 rpm with the earmuffs on. Internal arteries are quite clogged it appears.....

 

[Insequent]

It will take me a little while to sort out hose fittings and wiring to set up a bilge pump to do the re-circulation. I'll update when done, likely a few days time due to other stuff I have going on.

 

[RT Firefly]

Greetings,
Mr. I Can you put the motor in a "bucket" and add barnacle buster in with the coolant water rather than setting up a, what sounds to be, a complicated system (bilge pumps etc). Let it run at idle for as long as it takes...

 

[Insequent]

RTF - I don't think I have enough BB to cover the intakes on the outboard. The "bucket" has to be largish for the lower unit to fit inside it. But I'm going to see what I can find at home that might work for that approach. The BB might not have much "kick" left in it based on trying to clean the old thermostat. But I can add some HCl to it....

 

[RT Firefly]

Greetings,
Mr. I. Active ingredient in BB appears to be phosphoric acid. Don't have any idea of concentration. Not sure about adding HCL. I'd stick with phosphoric. Perhaps top up your existing BB with vinegar?
Do a test dissolution of various mixtures on the smeg on your thermostat.

I DO know that there are some pretty exotic alloys in outboards. Last thing you want to do is dissolve the corrosion along with the base metal.

My University Chemistry is woefully lacking. (50+ years ago).

 

[tego]

NEVER USE HYDROCHLORIC ACID ON ALUMINUM! It starts a chem reaction that continues long after you've flushed with water afterwards. Use Phosphoric acid to bump up your "Barnacle Buster" solution. The BB also has some inhibitors in it that will help protect the aluminum. I used to clean alum. heat exchangers for Eli Lilly, Dow Chemical and Nabisco Brands for 16 years before I went cruising back in "93. Ben

 

[Insequent]

Thanks for the timely clarification on acids.

Whilst I did see one claim that BB has both hydrochloric and phosphoric, the MSDS I read only indicated phosphoric. I'll try the stuff I have, but rather that topping it up I'll get more BB (or local equivalent) and dilute etc if I need to.

 

[Insequent]

I managed to get setup earlier than expected. The BB worked a treat. The dribble turned into a stream after 3 or 4 minutes. There were some sputters at one point, and I'm not sure I'm getting full stream/pressure as yet. Pic is with about 1000rpm on engine. I think I got lucky!

I'll get some more BB tomorrow and then run a few times over the weekend. I only have a small quantity of old BB at present and it gets warm quite quickly. I want to have about 25 litres in the "bucket" to get a longer run-time.

 

[Comodave]

It’s always nice when you get a good solid stream out of your pee hole…

 

[RT Firefly]

 

[tego]

If the solution is warmer, it speeds up the reaction and does a better job of cleaning. Ben

 

[BruceK]

The BB worked a treat. The dribble turned into a stream after 3 or 4 minutes. There were some sputters at one point.. .

Can it be used orally?

 

[RickyD]

That pee water is looking very black. Could your impeller have been wearing and pieces getting stuck in the channels? I have the same engine, maybe newer. When I first bought my dinghy used, they said don't worry about the indicator stream being weak, it is cooling fine. Well several sessions with Salt Away and the stream was back. I later traded that dinghy for a newer one with the fuel injected Honda 49 and had a friend "help" me with doing the service. He was experienced so I pretty much let him do it all. Well we left out a cover plate and I ground up the impeller a bit with tiny pieces clogging the indicator and cooling chambers. After changing all parts and running without much change I called in professional help. First he said to use compressed air or anything like carb cleaner or WD40 and spray up deeply into the indicator hole while running. This did dislodge some black chunks. It took three weeks of normal use before it all passed like a kidney stone and I got max spray at higher RPMs.

 

[Tom Daly]

Don't forget to check/replace the zincs inside once you're done with the acid cleaning. (at least on Yamaha there are zincs inside the cooling jacket in the powerhead)


-tom

 

[Insequent]

That pee water is looking very black. Could your impeller have been wearing and pieces getting stuck in the channels? I have the same engine, maybe newer. When I first bought my dinghy used, they said don't worry about the indicator stream being weak, it is cooling fine. Well several sessions with Salt Away and the stream was back. I later traded that dinghy for a newer one with the fuel injected Honda 49 and had a friend "help" me with doing the service. He was experienced so I pretty much let him do it all. Well we left out a cover plate and I ground up the impeller a bit with tiny pieces clogging the indicator and cooling chambers. After changing all parts and running without much change I called in professional help. First he said to use compressed air or anything like carb cleaner or WD40 and spray up deeply into the indicator hole while running. This did dislodge some black chunks. It took three weeks of normal use before it all passed like a kidney stone and I got max spray at higher RPMs.

Well noted Rick! Yes, there were tiny pieces of ?rubber coming out. The original impeller was replaced at a service a couple of years ago. It may well have left bits behind in the cooling system, as it was probably 8 or 9 years old when removed and may have been in poor condition when removed. I did not see it. After they replaced the impeller they flushed with something, but never got a strong stream from the pee-hole and I suspect that flushing was nowhere near sufficient to fully clean the cooling system properly.

When I replaced the impeller a few days ago the one I took out was in basically perfect condition. I'm confident it wasn't shedding into the cooling system. With the new impeller I started off flushing using SaltAway. But it took the Barnacle Buster to get the flow in the pic. Now, both the SaltAway and the BB could have contributed to loosening up bit of the original impeller, and scale, for it to be "pee-d" out.

Curiously enough, the day after the pic was taken I needed another period of BB flushing to get a similar stream. I flushed with fresh water for 7 minutes, all good. Next morning same story - I needed BB to get a stream again. Third day, repeat. So despite fresh water flushing at the end of the day, overnight something was loosening or swelling and blocking the cooling passages.

At this point I became impatient, and added some HCl (at 10:1) to the diluted BB mixture. So then I got some serious cleaning! I ran the engine for about 10 minutes, good stream from the pee-hole. Then I turned the engine off and continued the re-circulation for a time and noticed bubbles from the prop exhaust. Clearly I was now getting corrosion of the internal zinc anodes, so I quickly ran fresh water flushing for 15 minutes.

Next day good stream immediately (fresh water at start up) and a 10 minute water flush. The pee-hole stream is now much stronger than in the pic above, even at idle. It would seem the cooling system has now been quite thoroughly de-scaled! No more black bit either. Tomorrow I'm going out into Moreton Bay for a few days and will make an effort to get the RIB onto the plane for a bit of time. Some heat into the engine and high water flow from the impeller is the goal. Normally I'm just running the engine at 2000rpm, or a bit over, as I'm going between anchored boats or in a designated go-slow zone. Going forward I'll likely run SaltAway through the system each time I return to the marina as I now have the set-up needed to do it. This includes some blocking to get the RIB hig enough, temporarily, on the boat deck to have the Honda trimmed down and vertical, something some of the Honda material says to do.
Then a 60 litre "bucket" and bilge pump with ear muffs to recirculate it easily. I'm storing 40 litres of the SaltAway solution and will re-use it a few times before replenishing.

 

[koliver]

For the last few years I've used either a zip tie or a piece of weed wacker line in the pee hole when it had poor flow. Usually a bit of salt or whatever came out and then it worked fine. But now that trick is no longer having any effect.....

The motor is an 11 year old Honda BF40D. Service by the dealer a couple of years ago, new impeller as part of that and good flow until last six months. The guy did say there was one part that he could not remove . Bolts were going to need heat etc to try and loosen and we ran out of time to do it. Not sure what the part was, but chances are it was part of the cooling system

Been there, recently, also on a Honda 40.
For the last several years, I rod out the pee hole, starting at the side of the block. The 5 or 6" plastic hose and the external fitting occasionally get plugged, but rarely. The rest gets plugged in the top few inches internally. I have a thin zip tie that works well. It needs to be flexible to go around some corners, starting within an inch of the top, so a coat hanger wire is too stiff and a downrigger wire is not stiff enough. some small zip ties are too wide, some are too weak, so you need to find the sweet spot.
Once I realized that no pee didn't mean the impeller was shot, I have become used to clearing the channel regularly in order to continue to keep a flow.
The first time I had this problem I spent the $ to get the impeller changed and heard from the mechanic that it was actually looking OK and they had clear a salt blockage to get the flow running.
Not a serious problem, though we are all used to seeing a proper stream and the lack thereof suggests a more serious problem than almost always is the case.

 

[Insequent]

Initially I was hesitant to do an impeller change myself. Then I found the attached guide and decided to try it. It is actually quite easy to do. If your mechanic did not check or change your thermostat then I suggest you do that. It is an even easier task. Only 6 bolts to take off with a 10mm socket, then pop it out.

Over the years with the motor either being in the water or on the boat deck flushing seemed too big a hassle. Now that I have what I need to do it easily I will be flushing every time I am back in the marina, maybe not the same day but the next day would be fine. More often than not I'll be using SaltAway given that I bought a gallon and its used quite diluted.

A new 40HP here runs to about A$8k, before installation. I'm happy to now flush regularly to delay that for as long as possible. The Honda always starts instantly, and runs well. There are a couple of painted steel components that suffer corrosion, but I clean, use rust convereter and re-paint with spray engine enamel to manage that.