I have a 1991 Hunter 28 with a fresh water cooled Yanmar 2GM20F diesel. In reviewing the eng. manual it shows a zinc behind the cyl. head - it's not there! I'm currently taking a Pwr. Squadron eng. class, the instructor said it's probably screwed into the heat exchanger - it's not there! Does it even have one?
- Status
Not if Fresh-water cooled
If you have a closed-system, freshwater-cooled engine there will be no zincs. If it were raw-water cooled, meaning raw water circulated through the engine block for cooling, then it would have a zinc.
If you have a closed-system, freshwater-cooled engine there will be no zincs. If it were raw-water cooled, meaning raw water circulated through the engine block for cooling, then it would have a zinc.
No
The cooling system on most Yanmars is designed to not have conflicting metals in the raw water side, so, no zincs. Whoever writes their manuals has never gotten the word. But it is your job to enjoy.
The cooling system on most Yanmars is designed to not have conflicting metals in the raw water side, so, no zincs. Whoever writes their manuals has never gotten the word. But it is your job to enjoy.
From the horse's mouth
Ron, Not to pile on here but I had the same concern about my 2GM20F in my 285. When I was at the last Annapolis boat show I asked an "offical" tech guy from Yanmar and he said I wouldn't find one on a closed (fresh water) cooling system. You're bigger concern will be to flush out the fresh water loop now and then.
Ron, Not to pile on here but I had the same concern about my 2GM20F in my 285. When I was at the last Annapolis boat show I asked an "offical" tech guy from Yanmar and he said I wouldn't find one on a closed (fresh water) cooling system. You're bigger concern will be to flush out the fresh water loop now and then.
Speaking of engine zincs
The Yanmar YSM 12 (raw water cooled) on my 79 H30 is really stuck in the motor. I've tried the longest wrench I have, and beat on that with a hammer to no avail. I hate to take a torch to it, the paint still looks great. Is that zinc critical? Since some engines don't have them, I wonder? Could I just add a zinc somewhere else instead to compensate?
The Yanmar YSM 12 (raw water cooled) on my 79 H30 is really stuck in the motor. I've tried the longest wrench I have, and beat on that with a hammer to no avail. I hate to take a torch to it, the paint still looks great. Is that zinc critical? Since some engines don't have them, I wonder? Could I just add a zinc somewhere else instead to compensate?
John, there's a reason the zinc is where it is,
If yours needs one, that's probably where it should be. And paint's cheap. Get a cheater bar, as they are called.
If yours needs one, that's probably where it should be. And paint's cheap. Get a cheater bar, as they are called.
Flushing the 2GM20F
I'm new to the 2GM20F (in a Hunter 28.5 in Havre de Grace but heading south soon....). Could anyone familiar with this engine please describe the correct procedure that Bob mentions to flush and refill the fresh water cooling system? Thanks.
I'm new to the 2GM20F (in a Hunter 28.5 in Havre de Grace but heading south soon....). Could anyone familiar with this engine please describe the correct procedure that Bob mentions to flush and refill the fresh water cooling system? Thanks.
- Status