Antifreeze Leak


New member
Hello all,

I have been dealing with an issue on my port motor that may or may not be catastrophic and looking for advice from some more experienced mechanics. I have Chrysler FWC 360's.

Right before I winterized (Nov 2022), I started getting a bit of white smoke out of my port engine. I previously changed manifolds/ risers/ elbows in the spring. Per the manufacturers (incorrect) instruction, I did not deck the surfaces so I knew at some point I was going to have to remove the risers, clean the surfaces and re-install. Long story short, I cleaned the gaskets and re-installed only to find out my mechanic had given me the incorrect gaskets. While bleeding the cooling system roughly two quarts of antifreeze went into the engine. I called the manufacturer and got the correct gaskets and installed. Flushed the motor with four oil changes and got the oil looking pretty good.

The engine runs and sounds just as good as before, and starts right up. I have NOT run the boat other than at idle at the dock during this whole ordeal. However I now have very subtle sound in the engine (similiar to two marbles in your hand) and low oil pressure roughly about 15-20 lbs less than normal. My mechanic came down, looked at it and said the main bearing is shot, gotta pull the motor.

I recently gave this scenario to a different slightly more experienced mechanic, and immediatly he said that a lifter had crud in it, suggested I change the oil to 20-50 (I use straight 30), thicken it up with an additive he recomends and run it under load and the sound should work its way out and the oil pressure might rise. He believes the engine was not run long or hard enough to do catastrophic damage and I caught it early enough.

I am going to de-winterize and give this a shot, however before I do so I am going to cut the oil filter open and look for bearing debris and do a compression test. If those two are good, I will run the engine.

Looking for input on the second mechanics suggestion.
I think you would find an used oil analysis (like Blackstone) much more definitive than opening up the filter...
you didn't provide a lot of details...big question to me is how old (how many hours) is the engine? I'd trust the coolant level has stabilized?
a lifter making noise should be fairly easy to segregate from a main bearing knock...if the main bearing is noisy, adding an additive to the oil likely wont make much difference...and running the engine with a bad bearing will only increase the liklihood of needing machine work...