Heat Exchanger Zincs Not Required ?

[kaisardog]

why not 1/ call a good big yanmar dealer, 2/ give the model and engine serial no., and 3/ ask if that engine needs zincs ?

[Wotname]

Or you could read the appropriate manual, look at your engine and work it out for yourself; quite handy skills to have for a cruising sailor.

[skipperpete]

Originally Posted by Wotname

(sigh) Another necro-thread resuscitated. The correct answers were posted on the first page but let me recap - it depends!



It depends on the materials used to fabricate the heat exchanger. If it constructed from cupronickel, it does not need zincs. Do your own research if you don't believe it.



Yanmar used cupronickel for some of their heat exchangers and these ones do not have have zincs.



Yanmar designers occasionally did a few things wrong but this isn't one of them. I am no friend on the Yanmar pricing department but mostly their designers were on the money; at least they were in the past when they designed their engines to last. I'm not sure I have faith in the newer designs but I will have to wait and see I suppose.

Wotname , your “DEPENDS” statement is profound and I agree with your observations. It pretty much applies to every engine related thread on this forum.
The Yanmar heat exchanger is a good design but its life depends totally on those 2 orings, like Kenbo I weld the damn outer housings up on a regular basis and keep a photo log of the befores but I’ve never had to replace a tubestack ( or repair one). If any Yanmar owners on salt water see a line of corrosion or moisture at the end cap joint , don’t ignore it or give it a cosmetic wire brushing , the oring is leaking and it will create a war between the bronze cap and the aluminum housing that the housing can never win.....failure of the spindly tubestack gasket has no such repercussions but is still really important. Yanmar do 3 types of tubestack waterflow. The first type is straight through , no gasket...... the second type is U flow, in and out the same end cap as in the parts diagram and the last one is 3 pass. In one end and 2 U turns and out the opposite end and if the gaskets are missing or incorrectly installed the flow path is corrupted and ya get a slow overheat, usually only on the high power models because the core is still very efficient even when the flow is messy. Here’s a pic of how bad the damage can be if the endcap oring leaks.

[Compass790]

Good post skipperpete,
I laughed at L124C having a shot at Kenbo, I know who I'd take notice of. Knew he'd have evidence but was happy to let it go.

[skipperpete]

Often people who should know better give bad advice, mechanics are no different.

[Wotname]

Originally Posted by skipperpete

Wotname , your “DEPENDS” statement is profound and I agree with your observations. It pretty much applies to every engine related thread on this forum.
The Yanmar heat exchanger is a good design but its life depends totally on those 2 orings, like Kenbo I weld the damn outer housings up on a regular basis and keep a photo log of the befores but I’ve never had to replace a tubestack ( or repair one). If any Yanmar owners on salt water see a line of corrosion or moisture at the end cap joint , don’t ignore it or give it a cosmetic wire brushing , the oring is leaking and it will create a war between the bronze cap and the aluminum housing that the housing can never win.....failure of the spindly tubestack gasket has no such repercussions but is still really important. Yanmar do 3 types of tubestack waterflow. The first type is straight through , no gasket...... the second type is U flow, in and out the same end cap as in the parts diagram and the last one is 3 pass. In one end and 2 U turns and out the opposite end and if the gaskets are missing or incorrectly installed the flow path is corrupted and ya get a slow overheat, usually only on the high power models because the core is still very efficient even when the flow is messy. Here’s a pic of how bad the damage can be if the endcap oring leaks. Attachment 242670

SP, can you confirm if the end caps on 4JH4 heat exchangers have O'rings, gaskets and a zinc as per the manual extract in post #30?

[Compass790]

Originally Posted by skipperpete

Often people who should know better give bad advice, mechanics are no different. Attachment 242685

Mea culpa....

[skipperpete]

Wottie they have Orings and gaskets but no anode. There is sometimes a plug as in your parts pic but it’s into coolant not raw water. I have no idea why Yanmar called that an anode on the parts book.

[skipperpete]

Here’s the fitting in question

[Wotname]

Originally Posted by skipperpete

Wottie they have Orings and gaskets but no anode. There is sometimes a plug as in your parts pic but it’s into coolant not raw water. I have no idea why Yanmar called that an anode on the parts book.

And not only in the parts book but also in the service manual - as shown in post #30.

I'd love to know what is the current revision of the manual and if there is any mention of the anode in any later revision.

The manual I'm using shows your recent attachment as Figure 7-25 and then calls out the anode on the next two pages.

Won't be the first time I've seen an incorrect manual though!

[kenbo]

What I never understood about the JH series heat exchanger design was why are the end caps made of bronze and not the same aluminum alloy as the manicooler body and why they used SS bolts instead of aluminum alloy. There must be a reason but it escapes me and in my mind, the entire issue of galvanic corrosion would be eliminated.

[skipperpete]

Originally Posted by kenbo

What I never understood about the JH series heat exchanger design was why are the end caps made of bronze and not the same aluminum alloy as the manicooler body and why they used SS bolts instead of aluminum alloy. There must be a reason but it escapes me and in my mind, the entire issue of galvanic corrosion would be eliminated.

Caterpillar made em out of plastic on the later 3208’s but they still had anodes same as the earlier bronze ones. The fact that after the 4JH series the next largest engine is the 4LHA..... same basic design heat exchanger but with anodes throughout the engine

[Compass790]

Originally Posted by kenbo

What I never understood about the JH series heat exchanger design was why are the end caps made of bronze and not the same aluminum alloy as the manicooler body and why they used SS bolts instead of aluminum alloy. There must be a reason but it escapes me and in my mind, the entire issue of galvanic corrosion would be eliminated.

Designers make mistakes too, limited in time & war with the accounts dept are other possibilities, maybe not in that case.
There is always a better way but it may not occur to designer till after the manufacturing has started. Works that way with my mods sometimes
Gotta bit of mileage for a dead thread, kept me amused anyway.
Don't get me wrong my only vendetta against Yanmar is the parts mafia, I'm impressed how they can copy a Pommy ( Limey ) engine & not have oil leaks in our case.
Still will call out faults in any brand engine that are obvious to my eye anyway.

[Sailor_Al]

I'm not a mechanic and I have a Yanmar 4JH4 - TE. I've been looking for a zinc on it also. The Yanmar dealer says there are none. I found a plug on the exhaust, but no Zinc in the heat exchanger.

The owner's manual does call for a coolant change annually; is it any different then a car radiator core and it's dissimilar materials.

[Lepke]

Whenever you have two dissimilar metals in a salt water circuit you need zincs. I add zincs to engines that don't have them by putting in a tee or installing where there is a plug.

Also, where you have sections of the salt water plumbing separated by hose, you should have a ground wire connecting them to zinc protected portions or their own zinc. A telltale sign of no zinc protection is white powder or crystals forming at connection points.