Universal M3-20B engine zincs

[Gumdoc]

Hi. My 72 Ericson 32 has a Universal M3-20B engine. I regularly check the engine zinc and change it, mostly, yearly. It's located on the aft of the heat exchanger on the port side. In my engine manual there is a list of recommended spare parts. They list zincs as follows:ZINC 1/4NPT x 1-3/4 andZINC 3/8NPT x 1-1/4. The 1-3/4 fits the location on the heat exchanger. My tool box from the previous owner contains both size zincs. I've included a picture. I can not for the life of me find where the thicker, 3/8 x 1-1/4 zinc goes. I could find no reference to it in the engine manual except in the "spare parts list". Does anyone know if this engine has more than one zinc and where the shorter 3/8 zinc is located? Thanks

 

[kegggggggg]

I have a M3-20B on my E-29 . I have only found one zinc , in the same location that you described . The zinc I use is the thin one . Hope there are no more !! Based on the manual I think that is the only one .

 

[mherrcat]

Unless your engine is "raw water cooled" there are likely no other zincs aside from the one in your heat exchanger. Having a heat exchanger would indicate you have a "fresh water cooled" system with separate coolant and "raw water" circuits; the HX zinc is in the raw or salt water side of the circuit, which does not run through the water jacket in the engine. I don't think raw water cooled engines have heat exchangers. Any corrections in my description or terminology are welcome.

 

[clp]

Maybe it goes in your water heater?

 

[mherrcat]

If you have the typical Raritan water heater they do have a zinc; I think it is actually magnesium and integrated into the hot water out fitting and is like 10 inches long...

 

[Gumdoc]

Thanks for all of your help. I finally took a trip to Outboard Motor Supply in Alameda, CA. We looked through the Universal parts catalog for the M3-20 and identified the HE zinc. We got the part number off of the larger zinc and then looked for it in the parts list for the M3-20 engine. It did not appear as did the number for the HE zinc. So, this larger zinc is likely for some accessory, like a water heater, that I do not have. Again, thanks for your input. John

 

[Blue Chip]

Or it could be that it ended up on your boat the same way mine did...the previous owner accidently bought the wrong one..which I did... afrom The Out Board Motopr shop and just nevefr took it back.

 

[Stu Jackson]

Or it could be that it ended up on your boat the same way mine did...the previous owner accidently bought the wrong one..which I did... afrom The Out Board Motopr shop and just nevefr took it back.

Most likely the case.

On our M25, we had the OEM two inch HX. We replaced it with the larger 3 inch HX, like the M25XP engines. The smaller zinc was for the 2 inch HX, the larger for the newer 3 inch HX. I finally got rid of the old ones, since none of my friends needed my old "backups!"

It's also not an "engine" zinc, it's a HX zinc. FWIW.