4JHBE Yanmar

[Lateral Hazard]

Old Yanmar. 3800 hours.
Took a 4 hour motoring trip down a river. No problems. All off a sudden we overheat. Went below and we are out of coolant in the freshwater tank. Anchored out that night and headed back to marina. We watched the temp after 2hours it started to get hotter. Put fresh water in and made it home without another issue.
Checked oil. water and glycol were present in substantial amounts.
Changed oil, refilled coolant 3 times and ran for an hour in gear and fresh water tank needed to be filled again.
BUT no white smoke, runs perfectly. Mechanic wants it hauled out and engine pulled.
Makes sense?

[wingssail]

Originally Posted by Lateral Hazard

Old Yanmar. 3800 hours.
Took a 4 hour motoring trip down a river. No problems. All off a sudden we overheat. Went below and we are out of coolant in the freshwater tank. Anchored out that night and headed back to marina. We watched the temp after 2hours it started to get hotter. Put fresh water in and made it home without another issue.
Checked oil. water and glycol were present in substantial amounts.
Changed oil, refilled coolant 3 times and ran for an hour in gear and fresh water tank needed to be filled again.
BUT no white smoke, runs perfectly. Mechanic wants it hauled out and engine pulled.
Makes sense?

You said, "Checked oil. water and glycol were present in substantial amounts".

You didn't mention if more water was found in the oil after changing it and running it for an hour, but if water disappeared from the freshwater system then that seems to me like a significant problem. First thing which comes to mind is the head gasket, but I'm not a mechanic. Depending on the accessibility of your engine probably a lot of diagnosis could occur in situ.

Secondly, if you haul the boat to remove the engine you are going to be incurring yard fees until the engine is fixed and back in. Cannot the engine be worked on while still on board the boat (I've seen rebuilds in the cockpit). Or remove the engine while boat is in the water then tow back to the slip.

But to me it's going to be one or the other, that does not sound like a "one off" problem that will just go away.

[sailormed]

"…….water and glycol were present in substantial amounts."
Does this mean that you had salt water and engine coolant in the oil or fresh water and engine coolant.
If fresh water check the water heater coil is not leaking. Mine was after ~1400 hours, 17-18 years, pressurized water was pushed in the engine coolant loop and overflowing from the expansion vase.

[Lateral Hazard]

Originally Posted by wingssail

You said, "Checked oil. water and glycol were present in substantial amounts".



You didn't mention if more water was found in the oil after changing it and running it for an hour, but if water disappeared from the freshwater system then that seems to me like a significant problem. First thing which comes to mind is the head gasket, but I'm not a mechanic. Depending on the accessibility of your engine probably a lot of diagnosis could occur in situ.



Secondly, if you haul the boat to remove the engine you are going to be incurring yard fees until the engine is fixed and back in. Cannot the engine be worked on while still on board the boat (I've seen rebuilds in the cockpit). Or remove the engine while boat is in the water then tow back to the slip.



But to me it's going to be one or the other, that does not sound like a "one off" problem that will just go away.

I thought the same thing but was told without smoke or rough running the water is not in the top of the head because I should see, (after 2 hours running time) white smoke or bad combustion.

[Lateral Hazard]

Originally Posted by sailormed

"…….water and glycol were present in substantial amounts."
Does this mean that you had salt water and engine coolant in the oil or fresh water and engine coolant.
If fresh water check the water heater coil is not leaking. Mine was after ~1400 hours, 17-18 years, pressurized water was pushed in the engine coolant loop and overflowing from the expansion vase.

Sorry, I was not really clear. Sodium was in neglible amounts so the feeling is it is not salt water
Checked hot water heater. No leakage

[skipperpete]

Originally Posted by Lateral Hazard

I thought the same thing but was told without smoke or rough running the water is not in the top of the head because I should see, (after 2 hours running time) white smoke or bad combustion.

A “blown head gasket” can create a variety of confusing events depending on where it leaks TO .
If it blows between 2 cylinders it might not even be noticeable apart from a loss of full load power and maybe light grey or whitish smoke but no overheat or coolant loss.
If the gasket blows across to the pushrod gallery there might be fuming from the oil filler and occasionally this is mis diagnosed as cylinder blow by. Again, no overheat or fluid loss
If the gasket just blows directly across to the water jacket there will be the classic bubbles in the top tank accompanied by coolant ejection and overheating.
BUT if the initial gasket failure is across to the pushrod gallery and later as the gasket erodes, the water jacket is breached and the coolant has a chance of taking the easier path to the oil pan via the pushrod gallery.
Do a cylinder leakage test to establish which mode of failure actually exists and then take off the head and carefully inspect the gasket to verify.
If you’re a reasonably handy boat owner by all means do the head gasket yourself but if you hire a mechanic he will most likely want to haul out the engine and take it to a workshop because he has no easy way of knowing how badly damaged the rest of the engine is after having been run on coolant and oil for a few hours. ( the coolant might even displace enough oil to completely cover the oil suction screen and the engine could have run totally on coolant).
Don’t suggest doing the work in the cockpit or in the saloon.
On saving money and getting a good overhaul here’s a few tips. Mechanics typically charge traveling time from workshop to the job and have to carry all the tools, plywood, oils .... everything, from the carpark to the boat and , on an in hull rebuild this goes on day after day. Even the usual washing of oil pans and engine blocks is a drawn out ordeal at a guaranteed $100 an hour. Here a Cat mechanic clocks on to the job at the workshop and off again when he gets back at $200 an hour.... and they travel as a team of 2.
There is no better place to rebuild and bench run an engine than in a proper workshop.
All the best with your engine.
Pete.

[Lateral Hazard]

Thanks Pete!!