[bristol299bob]

. It is a common fail point when a hole will develop and allow oil to drop directly into the exhaust manifold passage of the head, bypassing the cylinder, which would explain why you don't have significant smoke.

This is interesting, I'd not heard of this issue before. Is the fix for this a new/used head? Or can the head be repaired if this were to happen? Is there any way to diagnose this short of pulling the head and taking it to a machine shop?

 

[AhoyhoyMarine]

If the failure is in that passage, no machine shop will even bother to attempt to repair it because the cause of the failure renders the surrounding material too poor to weld to and the cost of attempting puts you in the replacement head range. Replacement is the simplest and most reasonable step, provided this is the fail point. remember, not being able to see the engine means I really don't know what your problem is. I'm just giving you things to look at and to think about when you are "getting into it". I've seen people attempt to use liquid steel to patch the holes but always to just sell the boat and rid themselves if the problem. The patches don't last, obviously.

 

[Rek]

Oh that's a good lead. I'll pull the valve cover first then. Splashing back on the 14th, and will be checking the engine that same week. The mechanic I'm speaking to may have a spare head for me.

Cheers, will report back.

 

[Rek]

I pulled the head off today, and my mechanic friend was right. I have a hole in the head, visible through the hole where the exhaust elbow and the head meet. I did not have to remove the head to see this, but it had to be done anyway... could not see a hole while the head was mounted.

My engine was fine before I serviced the elbow, but that was only because layers of carbon were keeping the hole shut. I cleaned them off... and immediately after I started to have oil mixed in with the water. So yea, I've found my problem.

 

[Minnewaska]

Glad you at least figured it out, if not glad to hear how significant it is. What’s the next move? New head? Is the engine worth rebuilding? Why do you think this occurred and could there be other failures looming?

 

[PhilCarlson]

I pulled the head off today, and my mechanic friend was right. I have a hole in the head, visible through the hole where the exhaust elbow and the head meet. I did not have to remove the head to see this, but it had to be done anyway... could not see a hole while the head was mounted. View attachment 139625
My engine was fine before I serviced the elbow, but that was only because layers of carbon were keeping the hole shut. I cleaned them off... and immediately after I started to have oil mixed in with the water. So yea, I've found my problem.

Oofda! Well, they're good engines if you can find a new head....

 

[Rek]

Glad you at least figured it out, if not glad to hear how significant it is. What's the next move? New head? Is the engine worth rebuilding? Why do you think this occurred and could there be other failures looming?

It's a bittersweet discovery yes. In all, am glad I've found the issue.

I may have found a replacement head, a mechanic I know was re-building a Yanmar and may be willing to part with the head. Anyway, last time we met up he made the suggestion.

Some of my more hardcore DIY friends suggested getting bronze brazing rods, heating the whole thing up 500 degrees in a bbq and brazing the area (!!!). More reasonably, he mentioned pinning the hole, but I am not sure if that's really a good idea either .

 

[Minnewaska]

I look at it as too much work not to do a good job.

 

[PhilCarlson]

Some of my more hardcore DIY friends suggested getting bronze brazing rods, heating the whole thing up 500 degrees in a bbq and brazing the area (!!!). More reasonably, he mentioned pinning the hole, but I am not sure if that's really a good idea either .

I'm all about heroic DIY saves, but patching that is another hidden problem waiting to happen. You'll never be able to monitor the fix but at least you won't have to guess when it fails. New head saves you time and worry.

 

[AhoyhoyMarine]

There is a guy in Oak Bay selling a 2GM with a busted crank. You might be able to get the whole thing for 1/3rd the cost of a new head, and a back up gear. If it were on the mainland, I'd go buy it just for the gear and head.

Yanmar 2GM Marine Diesel Engine for parts or rebuild - boat parts -...

Yanmar 2GM Marine Diesel Engine for parts or rebuild. I recently removed this 2 cylinder 13HP Diesel from my sailboat. I tore it down and discovered a crack in the crankshaft. The head is relatively...

victoria.craigslist.org

 

[Rek]

For now, I've got two options: mechanic friend has a used head, and a 2GM20 that is currently being re-built that I can swap to. I am considering doing a swap, since the alternate has fresh water cooling. Price isn't bad either, would be able to swap parts from my current engine too.

 

[Linebyline]

I removed the head today and also found a large hole. I imagine far to large to repair- will look for a replacement.

 

[Rek]

I removed the head today and also found a large hole. I imagine far to large to repair- will look for a replacement.

Well well well, that sucks eh? I sympathize. Not glad that you have a hole, but am glad that you too found the culprit.

 

[Linebyline]

Well well well, that sucks eh? I sympathize. Not glad that you have a hole, but am glad that you too found the culprit.

Doubt anyone will recommend prepping the surface and JB weld DIY job, or even have a machine shop repair for the cost of just replacing with a used top end for $500-700? Thoughts?

 

[Minnewaska]

I would not jerry-rig a repair, unless I considered the engine disposable. In High School, that's exactly how I viewed some things, as the right repairs cost more than the car. The cost of the jerry-rigged repair was just rent for a year. Of course, I'll I needed to do was coast to the side of the road, when I lost that bet. Aboard, I find Murphy asks me to pay up at the worst time.

In this case, I'd sure like to get my head around why such catastropic damage and whether that cause was likely to have impacted other major components as well.

 

[PhilCarlson]

Doubt anyone will recommend prepping the surface and JB weld DIY job, or even have a machine shop repair for the cost of just replacing with a used top end for $500-700? Thoughts?

Do it right, do it once.

 

[Linebyline]

Scraping some carbon away today I found 2 holes & signs of a old JB weld job. On the hunt for a used head now.

 

[Minnewaska]

Does this engine have a heat exchanger or does sea water directly cool the engine. I believe the 2GM came both ways. Suspect the latter. Obviously a prior owner knew of this problem and put tape on it.

 

[PhilCarlson]

Does this engine have a heat exchanger or does sea water directly cool the engine. I believe the 2GM came both ways. Suspect the latter. Obviously a prior owner knew of this problem and put tape on it.

2GM is raw water cooled. 2gmf and 2GM20(f) has the heat exchanger.