Yanmar Advice: Coolant In Oil

[Saltyluke]

Hello good people!
I’m kindly seeking advice, we’re in contract for a yanmar 3GM30F (plus a whole lot of fiberglass and sails etc) and the engine oil analysis came back with antifreeze detected and elevated sodium :/ Advice welcome!

Should we suspect a corroded/leaking heat exchanger? What does replacement of the heat exchanger entail?

Here’s the read: ‘SODIUM HIGHER THAN NORMAL WITH A POSITIVE ANTIFREEZE REACTION NOTED. OTHER SAMPLE ANALYSIS RESULTS APPEAR NORMAL. MONITOR ANY COOLANT LOSS. CHECK COOLING SYSTEM FOR OIL. SILICON & ALUMINUM (TYPICALLY DIRT) APPEAR ELEVATED. IRON APPEARS SLIGHTLY ELEVATED.
OTHER ANALYSIS READINGS APPEAR TO BE ACCEPTABLE. RESAMPLE AT HALF THE REGULAR SAMPLING INTERVAL TO MONITOR COMPARTMENT AND WEAR METAL TRENDS.’

We’ll likely be looking to bring in a mechanic to help assess but the due diligence costs are adding up!

Thanks for any assistance out there!

[sailingabe41ds]

hi..
not a mechanic but the first thing that comes to mind is a head gasket issue.
abe

[AA3JY]

Re-torq the head bolts and readjust the valves. Then compression test and eye on the fluid level

[Jammer]

You should assume that the head gasket is blown meaning that the engine will need a valve job.


If it is just the heat exchanger you will have a pleasant surprise

[Saltyluke]

Thanks for the responses!



We ran a sea trial yesterday (beautiful day by the way). There was a little +/- 5 seconds of white smoke on startup then it seemed to run pretty smoothly. Both the surveyor and boat maintenance/repair person on site agreed that it would be important to figure out how coolant is getting into the oil before completing the purchase.


Sounds like close attention to possible head gasket issues is in order. AA3JY, "Re-torq the head bolts and readjust the valves. Then compression test." Would this help either stop a small leak in the gasket or help determine if there is a bigger problem with the head gasket?


They're going to flush and add new oil, but I understand that it may take many hours of operation before a measurable quantity of coolant gets back in the oil?


Appreciation for any additional info.



cheers!
LUKE

[Jammer]

It has been my experience that when head gaskets start to fail, they gradually get worse. Gasoline engine/diesel engine. Might last a while, who knows, 10 hours, 100 hours. Might get better but I wouldn't count on it.



It is also possible to look for combustion products and oil in the coolant which is another sign of trouble. When the problem is advanced enough there will be visible combustion gas exiting the coolant reservoir at which point you're hoping to make it to the dock.


The question to you will be whether you think it will be worthwhile to proceed with the purchase at this point given that there are known problems that could lead to an engine overhaul within the first year. In most cases the answer will be "no" but if you're getting a fantastic deal on the vessel and have $20k in the bank for a repower then perhaps it's worth it.


You could also try to start putting some of these costs on the seller i.e. ask them to pay for an engine survey or repairs before proceeding with the sale.

[sailingabe41ds]

How much would it cost to replace a head gasket....can they do it on site without removing the engine?

Abe....take that off the selling price.

[AA3JY]

Originally Posted by Saltyluke

Thanks for the responses!



We ran a sea trial yesterday (beautiful day by the way). There was a little +/- 5 seconds of white smoke on startup then it seemed to run pretty smoothly. Both the surveyor and boat maintenance/repair person on site agreed that it would be important to figure out how coolant is getting into the oil before completing the purchase.


Sounds like close attention to possible head gasket issues is in order. AA3JY, "Re-torq the head bolts and readjust the valves. Then compression test." Would this help either stop a small leak in the gasket or help determine if there is a bigger problem with the head gasket?


They're going to flush and add new oil, but I understand that it may take many hours of operation before a measurable quantity of coolant gets back in the oil?


Appreciation for any additional info.



cheers!
LUKE

Your report didn’t specify the quantity of possible coolant incursion thus the response: “re-torque the head bolts..”, etc. as a possible ‘KISS’ first step responce.

A Head gasket replacement can be done with the engine in place…