Oil Analysis - High Sodium

[Phil JC]

First oil analysis on my VW Marine 150-5 TDI engine. (5cyl, 2.5L, Turbo intercooled) 3300 hours. Oil was 10hours old, sampling was an insurance requirement after the engine ingested some fresh (rain) water while stopped (another story in itself) Lab test result came back with a warning about high sodium levels (31ppm). Checked the coolant and its VW spec which uses OAT so (apparently no Potassium or Sodium). So the 31ppm appears to be from seawater (or contamination during sampling). At a bit of a loss as to how saltwater might be getting into the oil, the engin is in a yacht and the 10hours motoring prior to sampling was in calm conditions ie no salt spray. Wondering about injesting from intercooler leak? Is 31ppm actually that high?

TIA
Phil

 

[louc]

Before panicking I’d do a virgin oil analysis on the motor oil you’re using to see what the base reading of potassium is for that oil. Also on these engines is the exhaust closed cooled? If not a leaky exhaust can let seawater into the cylinders & motor oil.

 

[jimn]

First oil analysis on my VW Marine 150-5 TDI engine. (5cyl, 2.5L, Turbo intercooled) 3300 hours. Oil was 10hours old, sampling was an insurance requirement after the engine ingested some fresh (rain) water while stopped (another story in itself) Lab test result came back with a warning about high sodium levels (31ppm). Checked the coolant and its VW spec which uses OAT so (apparently no Potassium or Sodium). So the 31ppm appears to be from seawater (or contamination during sampling). At a bit of a loss as to how saltwater might be getting into the oil, the engin is in a yacht and the 10hours motoring prior to sampling was in calm conditions ie no salt spray. Wondering about injesting from intercooler leak? Is 31ppm actually that high?

TIA
Phil

How would the engine ingest rainwater?

 

[louc]

Edit, I should have said, when you do a virgin oil analysis check for sodium in the oil sample.

 

[Phil JC]

How would the engine ingest rainwater?

The rainwater filled a cockpit drain that was closed, backflooding the exhaust through the siphon breaker.

 

[Phil JC]

Edit, I should have said, when you do a virgin oil analysis check for sodium in the oil sample.

Thanks for your comment. I'm hoping to avoid that by looking at the manufacturers published datasheet, but nothing useful so far.

 

[Phil JC]

 

[Phil JC]

Oil: https://penriteoil.com.au/products/enviro-c3-5w-30-full-syn
Coolant: https://penriteoil.com.au/products/red-oem-coolant-concentrate

 

[jimn]

The rainwater filled a cockpit drain that was closed, backflooding the exhaust through the siphon breaker.

How are the drain & exhaust connected? Can you show this siphon breaker?

 

[Phil JC]

How are the drain & exhaust connected? Can you show this siphon breaker?

The siphon breaker in question is on the exhaust water seperator. The siphon breaker is an inverted 'U' with a 1/4" hose from the top lead off to discharge into a cockpit drain. The cockpit drain through hull vlave was closed allowing rain falling into the cockpit to fill the drain until it backflowed through the 1/4" hose and the siphon breaker backflooding the exhaust water seperator, then flooding the exhaust, this then flooded one cylinder until it flowed through the crankcase breather and into the crankcase (we think).