Oil in expansion tank

[ciscokid69]

Picked up debris on intake for raw water and cooked the impeller. Engine temp got to 218 degrees before shutting down. Fixed raw water side. Discovered engine oil in expansion tank. Engine oil is clean. Down a quart from previous day check. QSB 6.7 Called for help but would welcome input. I am not very knowledgeable but current assumption is an engine oil cooler is pushing oil into coolant. Thanks

Topic

[Tony Athens]

I’d be washing out the coolant system and do a 1st class pressure check at 25-30 PSI with the system empty.

I have not seen a failed engine OC on either a QSB 5.9 or 6.7.. How much oil was in the coolant.. A quart would be super obvious.. Some “scum” is normal on old coolant.

Tony

[ciscokid69]

Over temp alarm.

Barry, My previous answer was incomplete. Yes the alarm did sound in the last minutes. We were at the marina entrance at the time and able to dock. Scott

[ciscokid69]

Fortunately the pressure test revealed the head gasket was ok. Appears the lubricating oil cooler failed perhaps secondary to the raw water issue and overheating. We have owned the boat for 2 years and earlier discovered the coolant (antifreeze) was not adequately maintained. While we did not test when changing I wonder if the corrosive quality eroded the integrity of the lubricating oil cooler. I was able to clear the alarms.

[Barry]

+1 on the compromised head gasket. BTW, what did you pick up? Did you get an over temperature alarm?

[Philip]

Or you have a compromised head gasket.

[Author]

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