I have had a problem with my Yanmar 3JH2-TE (turbo) running hotter than I like. I have to run at 2600 RPM instead of my normal 2800 RPM to keep the temp gauge at normal. I believe that this problems harkens back to one time when I accidentally used undiluted coolant (should have been 1:1 with water). I've been told that this can coat the outside of the heat exchanger tubes which impedes cooling.
I have checked all of the normal things: strainers, impeller, exhaust elbow, etc and all are fine. The raw water flow through the system is right on spec based upon a rough calculation I did using a bucket and timing how long it took to fill it at some RPM.
So today I pulled the heat exchanger. The interior of the tubes are absolutely clean. I rodded it to make sure and a very minimal amount of stuff came out. However, the outsides of the tubes are coated with maybe a 1/32" (or less) brown film that scraps off with my fingernail. However, I can only access a few tubes and the rest are wrapped by the large tube containing all of the smaller tubes.
So, how do I clean this? Find a radiator shop to acid boil it? Will acid even dissolve this?
Note that I'm as far south in Mexico as you can go (Puerto Madero - Marina Chiapas) without being in Guatemala. I'm getting ready to store the boat for hurricane season and thus I've pulled apart the engine.
-- Geoff
I have checked all of the normal things: strainers, impeller, exhaust elbow, etc and all are fine. The raw water flow through the system is right on spec based upon a rough calculation I did using a bucket and timing how long it took to fill it at some RPM.
So today I pulled the heat exchanger. The interior of the tubes are absolutely clean. I rodded it to make sure and a very minimal amount of stuff came out. However, the outsides of the tubes are coated with maybe a 1/32" (or less) brown film that scraps off with my fingernail. However, I can only access a few tubes and the rest are wrapped by the large tube containing all of the smaller tubes.
So, how do I clean this? Find a radiator shop to acid boil it? Will acid even dissolve this?
Note that I'm as far south in Mexico as you can go (Puerto Madero - Marina Chiapas) without being in Guatemala. I'm getting ready to store the boat for hurricane season and thus I've pulled apart the engine.
-- Geoff
