Yanmar 2GM20 - Zinc Anode

[SteveIOW]

Can someone please confirm that the threaded plug that holds the zinc anode on the starboard side of the block relies on a tapered thread to make a sea water seal. If so what sealant, if any, should I put on the thread? The engine is a sea water cooled Yanmar 2GM20.

 

[Mataji]

I had this engine in a Centaur for 6 years and never used any sealant. I used to get my engine spares from George Hulley in Dumbarton. George was very knowledgeable and free with his advice. He stressed that both the anodes in the engine be checked regularly. I'm sure that if any sealant was necessary George would have mentioned it.

 

[vyv_cox]

Sealant would be an electrical isolator if it worked perfectly, so not appropriate for an anode. Don't know yours but a Bukh one is sealed by a fibre or copper washer between the bolt head and the block.

 

[VicS]

Sealant would be an electrical isolator if it worked perfectly, so not appropriate for an anode. Don't know yours but a Bukh one is sealed by a fibre or copper washer between the bolt head and the block.

I belive the Yanmar anodes have similar washers: http://www.keypart.com/stock/123210-09310-r

 

[MagicalArmchair]

From the workshop book for the 2GM20

The next page is quite useful too:

 

[RichardS]

From the workshop book for the 2GM20

The next page is quite useful too:

I didn't post about my YM series engine anode as the GM might be different but that cylinder head anode looks similar to my YM series which has a rubber gasket. The cylinder block anode doesn't appear to have the large gasket so that leaves me a trifle confused!

Richard

 

[SteveIOW]

I didn't post about my YM series engine anode as the GM might be different but that cylinder head anode looks similar to my YM series which has a rubber gasket. The cylinder block anode doesn't appear to have the large gasket so that leaves me a trifle confused!

Richard

Thanks for all the advice to my original post but I too am confused as to why the block anode mounting plug on the starboard side of the engine does not have a gasket but the one on the aft side of the cylinder head does.

I do not know what purpose the small rubber washer (gasket) under each anode serves. I find it is usually damaged when replacing anodes. I suppose it would be too much to expect Yanmar to supply a new rubber washer with each anode.

 

[RichardS]

Thanks for all the advice to my original post but I too am confused as to why the block anode mounting plug on the starboard side of the engine does not have a gasket but the one on the aft side of the cylinder head does.

I do not know what purpose the small rubber washer (gasket) under each anode serves. I find it is usually damaged when replacing anodes. I suppose it would be too much to expect Yanmar to supply a new rubber washer with each anode.

My 3YM anodes do not have the small gasket. I can only think of two reasons for its inclusion and that is 1) to make if easier to unscrew the anode when it's bady eroded and there is less the grab hold of, although I grip it with a pair of pliers and it always unscrews, or 2) it's supposed to keep the stainless steel thread on the anode and the nut from corroding together because you can't cover the threads with grease in case this breaks the electical connection, although that seems unlikely.

I cannot see that those small washers are necessary which is presumably why they were dropped from the YM series.

Richard

 

[vyv_cox]

My 3YM anodes do not have the small gasket. I can only think of two reasons for its inclusion and that is 1) to make if easier to unscrew the anode when it's bady eroded and there is less the grab hold of, although I grip it with a pair of pliers and it always unscrews, or 2) it's supposed to keep the stainless steel thread on the anode and the nut from corroding together because you can't cover the threads with grease in case this breaks the electical connection, although that seems unlikely.

I cannot see that those small washers are necessary which is presumably why they were dropped from the YM series.

Richard

My thought was as your No.2). Presumably some corrosion has occurred in there, which disrupts the electrical connection.