Barnacle Buster for outboard flush?

[MattFL]

Has anyone used Barnacle Buster to descale an outboard motor, and if so did you remove the anodes and what was your result?

I've got a 99' Honda that is still running great and not (yet?) overheating, but after 20+ years in salt is starting to show signs of build-up. Chunks of free floating scale inside the motor had begun blocking the pee stream on frequent occasion, and removing the lower unit and thermostat then flushing with large quantities of water removed a small pile of rubble and temporarily resolved the concern. But now only a few months later the problem is starting to reoccur so I'm thinking there are still chunks that I didn't get out and it might be a good idea to flush with some sort of chemical to actually dissolve the calcium deposits, IF it can be done without risk to the metal in the motor. After much youtube research, I get the impression that Barnacle Buster might be the most effective of the marine specific chemicals, but I'm unsure of the safety for an outboard. Lots of videos showing people using it, but no long term follow ups. Here is perhaps the most persuasive video in regards to the effectiveness:

 

[ahicks]

Matt, nothing to share regarding any descalers.

I've seen the Honda 40's and 50's at their worst and brought them back though. Sometimes it's a LOT of work! I think for a quick peek into the condition of your motor, I would (very carefully so as not to break the bolts) remove the T-stat cover and T-stat. The condition of that area will likely give you a hint at what might be seen in other areas.

 

[GA_Boater]

I would research how phosphoric acid reacts with aluminum before using it. It may be safe and then again....

I don't know.

 

[Sea Rider]

For outboards used for years in salt water, doesn't matter for how long has been flushed after use, the best cleaning method is to remove the cylinder head(s) thermo, exhaust covers if having them and mechanically remove all salt layers and build ups on all water passages, that way motor will disipate heat fast as when the motor was new..



The issue is that won't know how stuck will find all powerhead bolts and break some when trying to remove them...If this service is done frequently as an internal preventive maintenance all bolts will be found in excellent condition...

Happy Boating

 

[ahicks]

Unfortunately, broken bolts are a real issue on saltwater Honda's.

Kinda why I suggested pulling the T-stat to get a look see. With any luck at all a 20 year old motor will have had the t-stat changed (at least once), and the bolts treated with anti seize on reassembly. If only the factories would do that when building them!

I do pull them down completely frequently for a good inspection with very little cause. Thank fully there's a good supply of used fresh water engine blocks available on e-bay.

Also noteworthy is the steering/pivot tube on this engine and several other Honda's and Merc's. They're rusting out from the INSIDE! They're no longer available from Honda for the 35-50 horse engines, and becoming more and more scarce on the used market. Point being, if you have time for some PM, this would be a darn good place to give a thorough inspection and some tender loving care. It's a pain in the butt to get to, but very likely worth the trouble on a salty! -Al

 

[Sea Rider]

Seized bolts are a big issue on any saltwater motor mainly due to salt water leaking through hardened gaskets over time. The issue is that nobody retorques said gaskets to factory specs soon after break end period finishes. On very old motors besides seized bolts will find erotion on combustion chamber and cylinder head mating surfaces that will not allow a new head gaskets to sit and seal well. Some examples..




Happy Boating

 

[MattFL]

Thanks for the replies. The thermostat (and water pump) has been changed at regular intervals and it comes in and out easily, and there is some scale in there but not a whole lot. I recently had the carburetors and intake manifold off, which opens one of the water jackets, and that's where you can really see what's building up. The anode in there was really caked with stuff. It's not overheating so I'm trying to not do any damage, but the little loose pebbles that keep clogging up the pee tube are getting aggravating, especially since we take this boat in the ocean on regular occasion and when the pee stream stops it's important to know if it's a real problem or not. I'm not taking the head off, that would do more damage than good at this point. But there are several videos on youtube where guys with overheating problems have resolved it by flushing with barnacle buster or one of the other similar chemicals (Rydlyme, Star Bright, etc..), which seems to do a good job at dissolving the scale build up. The star bright product is actually marketed for motor flushing. But I read that acids are rough on anodes (concerned about the aluminum too), and there are a couple in the motor that I'm afraid to remove because I think the bolts will break off, so I'm trying to weigh the risk vs. reward of trying this stuff.

ahicks thanks for the tip on the steering tube. I always run the fresh water hose backwards through the steering tube when flushing the motor so hopefully mine is ok. Are there any visible signs of the rust without taking things apart?

 

[ahicks]

Re: steering tube - looking up at it from the bottom (tilt the motor all the way up), you'll see it's splined and has a big E clip in place. One look there should give you what you need to know. I've seen them working just fine even when rusted so badly the E clip and the groove it fits in are gone! At that point I would suggest you start making plans to replace the tube, or the motor.

On the blocked pee tube. What a pain in the butt. I get into that all the time here. If you have an air compressor, with the motor running on muffs or in a drum, you can blow back through that pee tube in a series of 1 second puffs. It's about the water flowing backwards through that circuit - not the air. Time your air bursts to allow that passage to fill with water, then use the air pressure to blast that water backwards. The water being blown backwards through that passage will back flush that passage into the main one where the crud is much more easily dispersed. The pee tube passage is kind of a dead end where anything the enters it that won't flow through is just kinda stuck there. Once this has been done, seldom will it need to be done again. -Al