ZF 220 Transmission Replacement

[evansrr]

Buying a 2001 Monk 36 in excellent condition except transmission oil sample came back with high levels of copper, lead and sodium. Transmission works well but trouble is on the way. Owner agreed to a price adjustment so I want to solve the issue now by replacing it. I have a boatyard that will do the replacement but I want to make sure that I’m covering all the bases. Any other components related to the transmission that should be checked? Could the transmission cooler be the source of the sodium? Any words of wisdom to make sure that the boatyard is on the right track?

 

[DavidM]

I have a different take.

Sodium (Na) or maybe it’s partner, chlorine (Cl) is not a wear metal unlike the others. NaCl is salt which is corrosive to most metals. Sodium comes from a seawater leak, probably the cooler. The NaCl then attacks the metals inside and results in high metals in the oil but not due to wear.

What are your Na (sodium) and K (potassium) values? Seawater has Na and K in a ratio of 30:1. So if your analysis shows Na and K with that approximate ratio, it almost certainly came from seawater, not wear.

If so, you can change the oil a couple of times and replace the cooler and you may be ok.

I assume you did an engine oil analysis. What were those values?

David

 

[evansrr]

I have a different take.

Sodium (Na) or maybe it’s partner, chlorine (Cl) is not a wear metal unlike the others. NaCl is salt which is corrosive to most metals. Sodium comes from a seawater leak, probably the cooler. The NaCl then attacks the metals inside and results in high metals in the oil but not due to wear.

What are your Na (sodium) and K (potassium) values? Seawater has Na and K in a ratio of 30:1. So if your analysis shows Na and K with that approximate ratio, it almost certainly came from seawater, not wear.

If so, you can change the oil a couple of times and replace the cooler and you may be ok.

I assume you did an engine oil analysis. What were those values?

David

I’ll check those values. The engine was fine. As far as the transmissIon your recommendation is the consensus but it’s laid up in NC for the winter and I have a 1000 mile trip to the thousand islands in the Spring to where the labor rates are considerably higher so I am choosing to deal with it during the winter down south.
With the replacement transmission is replacing the cooler the typical way to go?

Thanks for your input.

 

[Island Cessna]

Rather than jump straight to replacement why don’t you look at overhaul. Copper and lead in your oil sample indicate bearing and disc wear, all of which would be checked and replaced in a standard overhaul. Much cheaper than replacement, and guaranteed fit when you put it back in place!
I’d start by taking the cooler to a radiator shop and having it checked, as that would clear up the question of salt water intrusion vs wear. I’d replace the cooler in any case as they are “relatively” inexpensive, and future failure can cause expensive problems.

 

[MacPhid]

If pulling the transmission I would suggest replacing the drive damper plate while it's apart. Replace the cooler for sure and then test the old one and keep as a spare.
Down the road rebuild the old transmission and keep as spare or sell. Seaboard Marine has ZF 220's in stock.

James