In Boat Head Gasket Replacement

[R&B]

After much denial we have come to the realization that we must replace the head gasket on our Yanmar 3gm30. I have been told by a mechanic that the engine MUST be removed to do the job. I planned to do the job myself in the boat, since we are liveaboards and didnt plan to take the boat out of the water this winter, so removing the engine is not an option at this point. and having them do it will break what is left of the bank. My question is has anyone done this without removing the engine, if so how difficult was it. I have read up on the proceedure and I cant see any reason to Have to remove the engine..Any opinions will be greatly appreciated.

Richie

[Chief Engineer]

As long as you have reasonable room to swing a torque wrench it shouldn't be a problem.....

From my experience with some Cats...you are working on your knees the whole time
and it gets VERY tiresome working in those "coffin like engine rooms"

[S/V Antares]

If you can see the engine (No joke on some boats) you can likely get it done. Borrow a good sized breaker bar to get the head bolts undone. Clean everything before reinstalling.

Question? Who said it needs a headgasket and why? What tests were done?

[Chief Engineer]

Oh yeah....I forgot that question....what was the engine doing that led you to beLIEve that you needed a headgasket?

[Lancerbye]

I have done this in the boat on a much larger engine. Had the head redone etc. If you have the swing room as has previously been mentioned it is actually a not bad place to do it. Main thing is keep everything clean and organized.

[never monday]

it;s an easy job for me.

Again,
what were that symptoms that lead to this diagnosis. GM's generally don't blow head gaskets.

[R&B]

Thanks for the replies, The reasoning for the head gasket is the loss of engine coolant. everything was checked and it seems as if we are lossing into the engine. The loss has been steadly increasing.. I have an ok amount of room I am sure that I will need long message but I should survive (I hope)....I greatly appreciate any advice thanks

[delmarrey]

Coolant can go out thru a heat exchanger. Has the core and seals been checked?

How many hours on the motor?

and

Has it ever over heated?

[never monday]

Originally Posted by R&B

Thanks for the replies, The reasoning for the head gasket is the loss of engine coolant. everything was checked and it seems as if we are lossing into the engine. The loss has been steadly increasing.. I have an ok amount of room I am sure that I will need long message but I should survive (I hope)....I greatly appreciate any advice thanks

have you pressure tested the cooling system yet?

Is the expansion tank connected to the fill cap?
are you seeing coolant anywhere in the bilge?
sheen on the water behind the boat?

[Chief Engineer]

One other symptom will be a "steamy" exhaust with a sickly sweet smell.

Don't be so quick with the headgasket.

BTW I have seen a couple of boats in my career that had the engines pulled to "replace the headgasket" all they got was a cleaned engine and an emptier wallet.

[senormechanico]

Check the heat exchanger first. Much easier and cheaper!

Steve B.

[Chief Engineer]

Just curious...how are you coming along?

[R&B]

Ok here is how we got to this..I have been loosing coolant from the fresh water side since I got the boat..I have change all hoses and gaskets over time and we still lost coolant. We never overheated but cant find any leaks..So I called in the "Mechanic" for his expert opionion. He pressure tested the coolant system and came to the conclusion that it must be the head gasket. I still not totally convinced but I seem to be running out of options...The engine has between 2500 to 3500 hrs on her. She runns great and other than this very annoying problem we have not had any other problems..I have not started to do this yet since I feel I need to read up more on the process and dont have lots of time yet.and I am not 100% convinced yet. eventhough I dont really have many other options. This is why I put this out there because I have never been let down by the opionions of this group. Thanks for the help

[never monday]

what was the result of the pressure test? id the engine hold pressure?

do you have the plastic Yanmar overflow tank installed? does it have the hose going to the bottom? Is there a crack in the hose from the radiator cap to the overflow?

Is the coolant just disappearing? or are you getting it in the bilge or engine pan?

[hellosailor]

I'd also suggest making Real Damn Sure first. Among other things, you can probably dump some UV oil dye into the fresh water section. this is plain mineral oil with a bright green (typically) UV dye used to check for leaks in oil systems and AC leaks. IF if is getting sucked into the engine it will also show up (under blacklight) inside the cylinders, inside the engine oil, and on a clean handkerchief held against the exhaust for a while. There are also water-based dyes of the same type. In any case--the UV dye will show up where the fresh water is going. Similarly, an engine oil analysis (about $25) should show excess water or other contaminants in the engine oil if the coolant is getting into the engine and past the rings.

Could be the mechanic is right, and sure, and simply very conservative because he wants to have the engine out so the head AND block can both be machined perfectly flat before re-assembly. Could be. But maybe not.

Might be worth getting a second expert (ahem) mechanic down there to get a second opinion, and estimate.