head gasket preventive maintenance ?

[amahaork]

after 10 years in salt water, what may be the consensus here: to open motor to replace head gaskets or wait until it started to leak or overheat ? and exhaust chamber gasket? Thank you.

[99yam40]

removing bolts may break bolts, so I would never remove them until absolutely necessary.

[mjm-1957]

Don't fix what aint broke. Plenty of time for misery later on.

[DennisG01]

Different camp here... I wouldn't be opposed (have done it, too) to some PM. The longer you wait to pull bolts out, the more likely it is to break one. Besides, if you're careful, you can usually feel if it's not turning right... and then soak it and go backwards/forwards. It would give you a chance to check and clean out the cooling passages.

Removing the t-stats is often a good tell-tale to what the rest of the cooling passages are like, as well.

On the other hand, you can set up a flushing system with something Rydlyme and that should clean things out, as well. A bilge pump to pump the solution in and a back/bucket to catch the exiting solution and recirculate.

[amahaork]

removing bolts may break bolts, so I would never remove them until absolutely necessary.

To exercise caution, I will remove thermostat and pump-flash it with vinegar. Thank you

[99yam40]

In my opinion, blown head gaskets happen when a motor overheats and head warps.
Preventing that overheat is a good idea.
Rydlyme marine descaler works well to remove deposits.

but it has to get to the deposits to remove them.
so blocked passages may keep it from getting to everything.

recommendation is to circulate it for hours.
we just did my brothers C60, and plan to put it into the water tomorrow to see if it did any good.
it was overheating at WOT and we were finding crusty stuff plugging up the stat when we pulled it after the alarm was set .

[amahaork]

well, 4 hours in vinegar brought some result, but close examination revealed possible leaked base gasket. thinking about removing power head. I used everywhere Mercruiser Perfect Seal 10 years ago restoring this motor. had number of broken bolts. helicoil them. will hope for the best.

[panasonic]

So the engine was overhauled 10 years ago? How old is the engine and what is it exactly?

[amahaork]

1995 200 TXRT carb. someone was cranking weak battery until relay got fried. relay was replaced, but from different motor, and relay protruded more and jammed one cylinder oil line behind. cylinder was scorned.
I found absolutely terrific guy - owner of repair shop, who bored that cylinder to next Yamaha size. I used all OEM parts.

[panasonic]

She looks pretty crusty..I hope you have good luck with your bolts.

[amahaork]

Well, bolts were OK - thanks to Mercruiser Perfect Seal. 10 years ago snapped two head bolts and 8 small bolts on covers and use helicoil. Anyone use that lifting eye on flywheel?
It looks crusty I agree, not so terrible inside, never overheated. what my concern is accumulation of carbon inside exhaust chamber in upper are next to cylinders #1 & #2.
my theory that: when I shot off hot engine, coolant stop flowing and immediately drop level, hence leaving upper part of exhaust chamber hot. carbon accumulating and gets loose. those loose particles of carbon
at certain position of piston, return to combustion chamber and scratch cylinder walls. not much, yet, but I see them.

[amahaork]

lifting eye

[99yam40]

lifting eye is made to be used for that.

may need to decarbon using ring free or seafoam

[amahaork]

this season I had not use Ring free

[amahaork]

research conclusion that carbon accumulation on top (in areas of thermostat) due to good cooling, once cold water rush in thermostat opening, cools this area (ref: Dangar marine)