Coolant leak, scared to disassemble the cylinder head

[CFS Klopas]

There was a milky water coning out of my air intake muffler when I tried to start it. Not realizing how big of a problem that was, I tried a few more times before I figured out it was raw water coolant. I'm hoping it just needs a gasket, but my best guess is I didn't properly winterize by adding an inadequate amount of antifreeze to the coolant system and the Yanmar 2gm is toast.

The reason I'm afraid to get to work is it seems my efforts aren't working. I've only had it out twice, ince under power and onve under sail. Sailing is also out of the question because I need a new topping lift among other mast work. I managed to get the engine running a month ago, but I figure another month is optimistic to figure out what's wrong and get it going again.

The air intake is marked in pen on the cooling system diagram, the muffler mount is still attached in the picture.

[jamhass]

It is common for raw water to enter the cylinder from the exhaust side. This can happen if the anti-siphon system is plugged, stuck or otherwise inoperable, or if one attempts to start too long. Without exhaust flow, raw water can build up in the exhaust and flow in to the cylinder.

I would look to the exhaust side first.

You can also do a compression test. If you hear or see blow by into the cooling channels then you need to pull the head and inspect further.

From your post, it sounds like it is time to bring in an experienced mechanic. Could save you money in the long run.

Good luck.

[CarlF]

Yes. The likely case is that you cranked your engine so long that cooling water filled the exhaust, backed up into the cylinders, and is coming out the intake. You are not the first (nor the thousandth) to have this happen.

Most people would get a mechanic at this point, but if one isn't handy it's important to quickly get the water out of the engine (at least it's not salt water). First, close the raw water intake. You are in no danger of overheating. Then remove the injectors, crank the engine to eject most of the water from the cylinders. Replace the injectors and start the engine. Don't open the raw water input again until it is running.

[deblen]

You should be able to purge the cooling water from the cylinders by opening the decompression lever.


Yanmar 2QM15 Decompression Lever? - SailNet Community


Len

[CFS Klopas]

I had already been playing with the decompression levers, didn't notice any extra purging. One of the many things broken is a control cable used to engage the second cylinder from the helm using the decompression lever, that job is halfway done.

I did notice purging when I disconnected the raw water hose and cranked it by hand. Used a hand oil transfer pump to suck water out of the exhaust, that was full too. Starter motor was unable to start combustion, but the water is out.

[Boatyarddog]

Originally Posted by CarlF

Yes. The likely case is that you cranked your engine so long that cooling water filled the exhaust, backed up into the cylinders, and is coming out the intake. You are not the first (nor the thousandth) to have this happen.

Most people would get a mechanic at this point, but if one isn't handy it's important to quickly get the water out of the engine (at least it's not salt water). First, close the raw water intake. You are in no danger of overheating. Then remove the injectors, crank the engine to eject most of the water from the cylinders. Replace the injectors and start the engine. Don't open the raw water input again until it is running.

I'd have to disagree that Exaust water backed up into the cylinders.
This condition would cause the engine to Hydrolock.
If that occurred the engine will not crank.
If the engine needs a head gasket it can be done easily if the engine isn't to corroded.
Your not gonna know till you look it over.
Wonder if the lubricating oil in the crank case is milky too???

[buzzstar]

What is the question? You need to pull the head. If it is a gasket, the fix is not terrible. If it is a cracked block, it is a bummer. The topping lift also needs repair. You have choices: Fix, sell as is, keep at dock/mooring/anchor as an ornament, or abandon. No matter what, based on your description, pulling the head is the start.

[CFS Klopas]

The people who said call a mechanic were proven correct. After 15 hours of trying to disassemble the head, 4-5 trips for basic tools, leaking the diesel tank into the bilge and destroying a battery, I surrendered today after 4 hours of work on a stuck bolt.

[CFS Klopas]

Just got it back from 10 weeks at the shop, the first half figuring out they needed to rebuild it and the second half shipping the engine elsewhere to do it.

The two main problems were faulty injectors that they replaced and a valve that had broken off and had damaged the pistons. If the symptoms above don't match that, the engine has had a variety of problems in the year I have owned it.