Befor I open up all the hoses....Where am I suppose to be looking for the pencil zinc? Little slow here so explain exactly. Thanks, Dennis Stone 77 SRFK #764
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Zincs!!!
Dennis It's in the HX (heat exchanger) the rolling pin sized piece of steel at the aft end of your engine. Port side, lower on a Catalina M25 and later engine. Stu
Dennis It's in the HX (heat exchanger) the rolling pin sized piece of steel at the aft end of your engine. Port side, lower on a Catalina M25 and later engine. Stu
If it helps any...
The attached link is to a picture I posted of the zinc that I replaced. It might give you an idea of what you are looking for. Really it just looks like a bolt head - probably painted engine color if it's never been replaced - and it sticks out the bottom of your heat exchanger as Stu noted. Mine (M35B) was very close to a pettcock for draining antifreeze on the bottom of the exchanger as well. Close your raw water intake. Upon removal, a small amount of seawater will run out. Don't forget to reopen your intake before running your engine. Tim "April IV" C350 #68 Seattle
The attached link is to a picture I posted of the zinc that I replaced. It might give you an idea of what you are looking for. Really it just looks like a bolt head - probably painted engine color if it's never been replaced - and it sticks out the bottom of your heat exchanger as Stu noted. Mine (M35B) was very close to a pettcock for draining antifreeze on the bottom of the exchanger as well. Close your raw water intake. Upon removal, a small amount of seawater will run out. Don't forget to reopen your intake before running your engine. Tim "April IV" C350 #68 Seattle
Use Caution
I had a mechanic come out and give me 'diesel 101' the other day and we replaced the zinc in the heat exchanger. The old one was completely gone. Why do I bring this up? Because a few days later, I (luckily) noticed the engine overheating and zero water coming out of the exhaust port. Managed to stop the engine before any damage was done. The old zinc was floating around in the heat exchanger and had jammed up against the new one, thereby blocking the water flow and causing the overheating problem. Check your zinc periodically to make sure it slowly corrodes. If it breaks off, you need to remove the big chunk from the heat exchanger to avoid blockages. Same thing for the water pump rubber impellers. If you have to replace the impeller, make sure you track down the missing impeller parts or else they'll jam up your cooling system and that's not good. FWIW, the mechanic told me that on my '87 Cat 30 (M25 engine) that the only zinc to check was the one on the heat exchanger. The other ones are on the skag and shaft under the water and my bottom guy checks those each month....if anyone knows something different, I'm all ears!! Fair Winds!!! Jim
I had a mechanic come out and give me 'diesel 101' the other day and we replaced the zinc in the heat exchanger. The old one was completely gone. Why do I bring this up? Because a few days later, I (luckily) noticed the engine overheating and zero water coming out of the exhaust port. Managed to stop the engine before any damage was done. The old zinc was floating around in the heat exchanger and had jammed up against the new one, thereby blocking the water flow and causing the overheating problem. Check your zinc periodically to make sure it slowly corrodes. If it breaks off, you need to remove the big chunk from the heat exchanger to avoid blockages. Same thing for the water pump rubber impellers. If you have to replace the impeller, make sure you track down the missing impeller parts or else they'll jam up your cooling system and that's not good. FWIW, the mechanic told me that on my '87 Cat 30 (M25 engine) that the only zinc to check was the one on the heat exchanger. The other ones are on the skag and shaft under the water and my bottom guy checks those each month....if anyone knows something different, I'm all ears!! Fair Winds!!! Jim
M25 Zincs - Engine, that is...
Jim wrote: "the mechanic told me that on my '87 Cat 30 (M25 engine) that the only zinc to check was the one on the heat exchanger. The other ones are on the skag and shaft under the water and my bottom guy checks those each month....if anyone knows something different, I'm all ears!!" Jim: Sure, the INSIDE one (that's ONE) is on the HX. Sure glad your mechanik done told ya dat. You need to know yourself, and look and see it. Dem skag's are purty sure goners when the sun comes up. Sure hope yur bottum guy done get alla dem critters frum down unda. The REST of them critters are on the outside of your boat and it's up to you as to how many ya wanna stuick on dere. Try a manual, two.
Jim wrote: "the mechanic told me that on my '87 Cat 30 (M25 engine) that the only zinc to check was the one on the heat exchanger. The other ones are on the skag and shaft under the water and my bottom guy checks those each month....if anyone knows something different, I'm all ears!!" Jim: Sure, the INSIDE one (that's ONE) is on the HX. Sure glad your mechanik done told ya dat. You need to know yourself, and look and see it. Dem skag's are purty sure goners when the sun comes up. Sure hope yur bottum guy done get alla dem critters frum down unda. The REST of them critters are on the outside of your boat and it's up to you as to how many ya wanna stuick on dere. Try a manual, two.
HX, Thank you for sharing
your attempt at humor. Or were you being serious? I was trying to help someone with some info...what exactly was it that you were trying to do? Jim
your attempt at humor. Or were you being serious? I was trying to help someone with some info...what exactly was it that you were trying to do? Jim
How long?
After reading this posting and various other ones related to the issue, I ventured into checking/changing the zinc anode on our M25XP locatd on the HX this week-end. The one in place although not completely gone was rather short and corroded. The replacement one I purchased from a local Universal parts dealer had a zinc portion of app 1 1/2" long. Which would not fit in the HX so I decided to cut it down to what I established was the adequate lenght. Through my various search on these fine forum postings I could not find anything about the matter of the proper anode lenght. Can anyone confirm the recommended/required lenght of the anode? Was I wrong in cutting it? Should the whole 1 1/2" of zinc fit in the HX? Thanks, Ghislain Gaumond "Emilie-Jolie" C30 #4708
After reading this posting and various other ones related to the issue, I ventured into checking/changing the zinc anode on our M25XP locatd on the HX this week-end. The one in place although not completely gone was rather short and corroded. The replacement one I purchased from a local Universal parts dealer had a zinc portion of app 1 1/2" long. Which would not fit in the HX so I decided to cut it down to what I established was the adequate lenght. Through my various search on these fine forum postings I could not find anything about the matter of the proper anode lenght. Can anyone confirm the recommended/required lenght of the anode? Was I wrong in cutting it? Should the whole 1 1/2" of zinc fit in the HX? Thanks, Ghislain Gaumond "Emilie-Jolie" C30 #4708
Cutting is correct
Ghislain, You were correct in cutting the zinc. I was told by a Universal/Westerbeke dealer that zinc manufacturers often make zincs in one longer size rather than multiple smaller sizes. If I remember correctly, you need to cut off about 1/2" to make it fit into the heat exchanger.
Ghislain, You were correct in cutting the zinc. I was told by a Universal/Westerbeke dealer that zinc manufacturers often make zincs in one longer size rather than multiple smaller sizes. If I remember correctly, you need to cut off about 1/2" to make it fit into the heat exchanger.
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