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On the way in the port engine overheated. Shut down and came in on one. only started to get into slip.

Checked coolant and it was basically empty. Filled back up and started.. Ran fine at idle at the dock. Seems that idling is ok, no loss after 1/2 hour in the slip. Goosed up the revs to 2500 and saw small bubbles forming in the coolant. Also the oil pressure gauge was jumping around. Assuming head gasket failure.

Looking to get through the end of the season before tearing into the engine. No long runs, fill up during the day, maybe try some head gasket snake oil.

Any suggestions?

Where did the coolant go? I had a cracked head, and the pressure at cruise would blow the top off the overflow tank and pump the coolant into the bilge. There's only four places coolant can go: into the crankcase, into a cylinder, into the bilge, or overboard through a leak in the heat exchanger. If the oil pressure is jumping check to see if there is water in the oil--might be foaming up.
I tried the snake oil--held for about a month.

Joe

If the coolant is going into the oil and you continue to use the boat you could do some damage. Check the oil for foaming and if it shows over filled that is due to coolant.

Not sure how the engine sits in the boat but a head gasket is pretty straight forward. One day to take apart and send out to make sure it is good and one to put it together. Depending on the engine layout you should be able to do it in the boat.

Just need a torque wrench when putting it back together.

Might as well have the machine shop do a valve job on it while it is there. Replace the valve seals and make sure the seats and valves are hardened.

You could keep topping off coolant and running easy.
You could try stop leak, has worked on rare occasion in my forklifts.

I would definitely make sure coolant is not going in crank...pull dipstick and if it shows milky, that is a place it's going. It can be run milky, but know your motor IS NOT getting the lubrication it requires...and a large leak will make it overfull and that is not good.


I am with Tony, get it done or do it yourself. It is a straight forward job, some heavy lifting, bit dirty and cost some if heads need to be redon. I think the term is pay now or pay later...but with later your taking a gamble.
Not sure how your luck is, but I have that 50/50-90 luck. Anytime, I am face with 50/50 odds, 90% of the time I will get it wrong.

Thanks guys. I went to the boat over the weekend. There is no contamination in the oil. Did the snake oil treatment and followed the instructions. let it sit for a day and then ran about two miles at no more than 1500 rpm. Ran a little warm but not overly hot. Did not see any drop in fluid level.

On the top of the coolant tank, the part that accepts the cap came apart. I cleaned it up and JB Welded it on. Possible that that is where all the fluid was going, seeping out of that . Obviously need a new fluid tank but if this holds at least i can test further.

I will put a new oil pressure sender on to make sure that is not the problem.

Going to use the boat on Thursday, weather permitting.

My thoughts are that its possibly the heat exchanger leaking into the raw water, or a head, or exhaust manifold gasket.

Is the engine missing? If you lost that much coolant, and it's not in the oil, it would have to effect the way the engine runs if it was getting into a cylinder or two through a head gasket or manifold. If the engine is running OK odds are the problem is in the heat exchanger.
Assuming the exchangers are the same age, when one fails the other is probably not far behind. I found something a few years back that everybody that lives up north should think about: I had an exchanger that developed pinholes in the copper tubes inside as it got older. The engine ran fine with no temperature issues and no indication of any problems. The pinholes allowed the salt water to contaminate and mix with the anti-freeze. The coolant looked and smelled just like a 50-50 mix, but when I put a tester in it the freeze point was 27 degrees--had I stored the boat like that something would have cracked for sure. I only found this because the port exchanger failed outright at the end of the season, and it made me think about the condition of the stbd side.