oil-cooler white powder build-up

[mainship 34]

Hi Every one, My boat is 2005 Mainship 34 with two Yanmar LHA-STP diesel. I am the second owner and bought her in 2017. I just hired a marine mechanic to do a complete cooling system service including both fresh water and seawater two month ago. I drive the boat once every two week. Yesterday, I suddenly found out there are big white powder build-up at oil cooler of port engine. It had never happen before the service. I told the mechanic who has done the service and he told me there may be some clogging at mixing elbow which should be changed every eight years.

Please see the attached photos

My question is 1) why there was no the white powder before the service?
2) how ofter Yanmar mixing elbow need to be replaced?

Thanks you so much.

Wang

[Flying Monkey]

It could be many things. One thing it could be is very small leaks that allow a small amount of heated water under pressure to come out.
That water is loaded with minerals. The water evaporates and leaves the minerals behind as 'fluff'.
Does the 'fluff' taste salty?
The first thing I would do is disassemble, clean, and reseal.

[mainship 34]

Hi Fly Monkey, thank you so much. I will taste it tomorrow and report back to you.

[skipperpete]

Replace the zincs pronto, that corrosion is a bad sign.

[mainship 34]

Hi Skipperpete,

I will do it tomorrow and report back to you. Thank you so much. Best regards

[mainship 34]

Hi Skipperpete, I checked the two anodes of oil cooler. One is 50% worn out and the other is 10% worn out. The two anodes have been changed three months ago.

[mainship 34]

Hi Flying Monkey, the powder at oil cooler isn’t salty at all and isn’t dissolved in water but in vinegar. The powder at the inter cooler is tasted salty and can be dissolved by water. I also checked the anodes. One of the 50% worn out and the other 10% worn out. Both anodes have been changed three months ago.

[skipperpete]

Ok, that makes it more difficult. Is any of the white white powder appearing on the raw water pump or engine seacock? That corrosion is from within the raw water circuit,not from external leaks. has any electrical work been done on the boat or engines, is it possible that the anodes are insulated with the threads over wrapped with teflon tape?
This is concerning because the oil cooler is a soldered unit, no gasket , so the leak from within is coming through the joint. With an oring sealed endcap this is a heads up to immediately reseal or repair the weep but a soldered joint is more difficult to resolve. I see you’re in Australia, message me if you want any advice, hopefully a corrosion analist will weigh in with some informed and current knowledge of how this might happen

[mainship 34]

Hi Skipperpete, Thank you so much for your advices. There is no white powder on seacock and raw water pump. I taste the powder and it isn’t salty at all.

[mainship 34]

Hi Skipperpete and Flyingmonkey,

I just had a conversation with Yanmar parts dealer about the white powder and was suggested to change the mixing elbow first since I haven't change it for 6 years. I decide to change the elbow and see how it going since it is difficult to find a corrosion analyst right now ,Is it also called bond galvanic corrosion tester? Sorry my English is no good. I also have a question about the air filter of Yanmar 4LHA-stp, how often do I need the change it? How come the service manul of yanmar doesn't mention it at all ? Thank you!

[skipperpete]

Originally Posted by mainship 34

Hi Skipperpete and Flyingmonkey,

I just had a conversation with Yanmar parts dealer about the white powder and was suggested to change the mixing elbow first since I haven't change it for 6 years. I decide to change the elbow and see how it going since it is difficult to find a corrosion analyst right now ,Is it also called bond galvanic corrosion tester? Sorry my English is no good. I also have a question about the air filter of Yanmar 4LHA-stp, how often do I need the change it? How come the service manul of yanmar doesn't mention it at all ? Thank you!

Most of em don’t have an air cleaner, just a wire mesh strainer at the turbo intake but when they do have an actual air filter it’s just a “ waistband” of porous black foam. If you have this fairly expensive belt of filter foam, just give it a wash in soapy water every time you do an oil change but let it dry before putting it back on. Make sure it’s in good condition, it’s bad when the foam starts to disintegrate and gets inhaled by the turbo ( despite the presence of the wire mesh strainer).

[mainship 34]

Thank you so much!