# FLUSHING OUTBOARD WITH ACID



## TOOEXTREME (Jun 23, 2004)

Has any one flushed their outboard motor with white vinegar or muratic acid to take the deposits out of the water jackets in your outboard?


----------



## marlin021797 (Jun 1, 2008)

one time my grandfathers boat was overheating so we took a 75G drum and bent it and squeezed it around the motor. we then filled it with clorox one time and CLR (calcium lime and rust) another time. that worked for us.


----------



## texedd (Mar 25, 2008)

yes, here is what you need: bilge/livewell pump with a hose on each end, some acid (i jsut used hull cleaner), a small stock tank & baking soda

remove your lower unit, then also remove the thermostats, but put the covers back on and tighten the bolts.

fill the tank with 1/3 ration of acid to water....u dont need alot. take the pump and attach a hose on the outflow side (use an old piece of garden hose) and attach it to the water tube. 

connect the pump to a battery. the water will fall into the tank and just be reused. flush for about 30 minues, you do not need the engine turned on. throw the t-stats in the tank and let them soak or just replace them

repeat the process after cleaning the stock tank with baking soda and fresh water, then again with jsut water. the baking soda will neutralize the acid. 

let me check the ratio just to be sure, i will pm you. this is a good method, but to really get it, you have to remove the heads and i am not that mechanically inclined. anyway, i have done the above at least once a year when we had brown tide real bad down here....that ***** will start growing in your motor..lol


----------



## Sonnysmarine (Mar 18, 2007)

Do not use Mauratic acid unless you have the heads off to make sure you flush good to keep from eating out the inside alum. I have used it with the heads off mixed at 1/3 acid to 2/3 water. and squirted around the cly walls after oiling them down good, but need to get the engine up adn running that day and add extra oil if two stoke. but will ruin the paint job and more if not careful, and breathing it can be really bad. Be carefull if using acid on a engine


----------



## Propwash (Jul 29, 2005)

Is there any harm in pouring straight muradic acid into the thermostat housing and letting it drain out?


----------



## marty benge (Aug 20, 2008)

mix it mild pull thermostats put a test amount in houseing it should barelly bubble you dont want to remove or soften the paint on a yamaha I hook up one pump to water tube that stabs in w.p. houseing and another to the flush adaptor let it work for about 1 hour stopping and check inside periiodically I have been useing this method 5 years now I like better than pulling heads and scraping like I did all the previous years.good luck marty


----------



## TOOEXTREME (Jun 23, 2004)

*FLUSHING MOTOR*

I flushed with vinegar instead of acid. Flushed for about 4 hours with vinegar and flushed the motor with water. I have not ran the boat in the water though. If this does not work then I will have to take it to the dealer and have the alarm codes read.


----------



## Capt Black (May 21, 2004)

If the motor is still under warranty, don't do it. You can PM Chris Coulter from Chris' Marine in Aransas Pass and he can tell you what Mercury recommended in order to keep the warranty intact when they flushed out my motor. I am pretty certain it was diluted osphoric acid and run a couple of days. Motor works like a charm and no more overheat alarms. Later, Aubrey


----------



## Pocketfisherman (May 30, 2005)

Osphoric acid is what is used in products designed to remove rust stains from porcelain, boats, etc.


----------



## Capt Black (May 21, 2004)

Pocketfisherman said:


> Osphoric acid is what is used in products designed to remove rust stains from porcelain, boats, etc.


Yes, I have been using it for years to help maintain my trailer axles. I knew of this application a long time ago. Just had never heard about it being used to clean out the engine block. But don't take my word for it, give Chris or Mac a call at Chris' Marine.


----------



## Propwash (Jul 29, 2005)

Last summer I was getting an occasional alarm on my 200 Mercury. As a precaution, I bought new thermostats, water pump impeller and gaskets. Before I installed the new parts, I poured a bottle of undeluted muratic acid into the thermostat housing, then flushed with fresh water. Just wondering if I made a costly mistake? I have ran the boat once since then and all seemed fine.


----------

