Quote:
Originally Posted by Beneteau32
I don't think anything has frozen, the boat is in Southern California. I am going to have a mechanic take a look at it next week, but I am trying to get a handle on things before then.
We ran salt away through the engine because it had been overheating previously. When we did this the salt away did not come back out, which is why I am not sure it worked. After this it ran well for about 20 minutes, no overheating, before we noticed the oil leaks and shut the engine off.
Besides a compression test, should I do anything else to determine if the engine can be rebuilt, or if it needs to be replaced?
What is a fair ballpark estimate to have the engine rebuilt?
Is it possible to retrofit freshwater cooling?
Thank you for the replies/advice/help!
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Several points:
Regarding the oil in the water and water in the crankcase, it is most likely sea water has entered the engine probably due to a failed exhaust
elbow allowing water back though an exhaust valve into the cylinder. Also much sitting without starting is hard on the rings and cylinder. The bore gets a light coating of rust and this is removed at the next start thus increasing wear.
Regarding your
flushing, unless you used a custom made fitting to replace the thermostat housing OR removed the thermostat
and blocked the short hose from the block to thermostat housing before
flushing, your flushing solution probably went out the exhaust. The correct way is to remove thermostat, block the hose mentioned above, remove the engine zincs (I think the
2GM has two, the
2GM20 does), remove the
raw water discharge hose at the exhaust
elbow and the raw water inlet hose after the
water pump. Then circulate the flushing solution thought the block and
head using an external
pump (like a small
bilge pump in a 2 gallon bucket). Depending on what flushing solution you use, this could be anywhere form 30 minutes to 24 hours. I can provide more detail if you wish.
Regarding converting the engine to using
coolant and an
heat exchanger; this possible but more difficult then many think. If you use
Yanmar parts and if they are still available, it will be very costly. If you try it using after market components, there are several hard to solve issues - the thermostat aspects are not convertible and you have to fit a another
water pump.
However, it is unlikely you have any serious issues with the raw water cooling even though it may look seriously compromised. These engines are designed for a long life using raw water cooling. I have had 5 raw water cooled engines (3 Yanmars, 1 Buhk and 1 Arona). I am currently rebuilding a 1976 Yanmar and after a good descaling using Muriatic acid, the internal water jacket and galleries are almost as good as new. If you keep replacing the engine zincs and carry out a good flush (vinegar is as good as any) say every 5 years or so, the lifetime of the cooling aspects is almost indefinite. The main downside of raw water cooling is that the engine is designed to run cooler (to prevent salt precipitation) and thus is more inefficient. IMO, this is a small
price to pay for a KISS cooling system.
The principle reason larger engines were initially
coolant cooled was that they were never designed for raw water, they were auto or industrial engines by design. Now of course, the efficiency aspects prevents raw water cooling for new engine designs.
I think you will find your 2GM is rebuildable and IIRC, they used wet sleeves so at the worst, you will new new sleeves, pistons, rings, valves, and bearings.
It can be
DIY job and there is no end of support on CF if you are unsure of your ability to do the
work. Really you just need a suitable venue to carry out the
work - garage, shed, basement etc.