I am in the process of purchasing a boat that has a Cummins 330 engine - 2001 - with 170 hrs. The Oil analysis came back with Na (sodium)count of 253, Al (Aluminum) is 37, Cu (Copper) is 4, and Pb (Lead) is 0 The mechanic that checked the engine suppects leaking head gasket, cracked head etc. which the seller has no problem repairing. My question is how can I know what (if any) damage to bearings pistons etc. might have occurred? Any advice would be appreciated.

Thanks, Jack

Hi Jack,
Simple answer is you can't......
The analysis is like a fingerprint...it won't tell you the health of the individual who made it. The oil could have been changed 2 hours before the sample was taken or the wear particles could be settled out. Cummins normally recomends a max of 60 ppm NA before they get really excited. You can get the mechanic to perform a coolent pressure test with the base pan off and try to determine how bad the leak is. If the leak isn't bad then prhaps the engine is worth a rebuild. The problem is you just don't know. You can consider making a deal with the seller. Change the oil run the engine for 30 minutes and then take a sample run for another 10 hours and resample again. If the NA has increassed by ~ >15 PPM run......

regards.....

Hi Alan,

Thanks for your timely answer! We found a leak or some malfunction in the intercooler, and the high sodium was acutally salt water and not coolant. Owner is installing a remanfactured engine rebuilt by Cummins and with a new engine warranty.

Once again thanks,

Jack

Just a tip , some newer oils are using a performance additive"s" that is picked up in analysis as sodium . I have forgotten the names of these additives but some oils are using rather large amounts of this .

These days it might be a good idea to send in a new oil sample for a baseline . That's how I found out about the additives .

Some oils (usually older type oils) use Na as a detergency dispersancy additive in place of some Ca. You should recognise this, as Ca will decrease in the same ratio as Na is increasing. We see this a lot with bus companies where the driver tops up with any oil along the road while on a trip. It makes it that much more difficult to detect an internal coolant leak.

I read your questions and answers and I,m traying to detect internal problems in marine engines analising the metals contents in the oils by atomic absorption. Do you know something of this theme? or about the metals contents in oils?
Thanks a lot.