Originally Posted by nestorph
Thanks for the advice. Replacing the impeller has jumped to the top of the list along with changing the oil and filter. Followed by fogging oil...
I have the shop manual so I'll find the fuel stop lever...
It may not be in the manual. follow the fuel line from the tank to the engine. The shut-off could be anywhere, but is usually located near the filter, so you can shut off the fuel to change the filter. There could also be one between the filter and the engine. it that's the case, shut off the one closest to the engine.
I think the fogging oil idea is over kill.
FWIW - I am in pretty much the same situation. I just bought a boat that has sat on a trailer
for two seasons. Previous owner had it for 22 years. I did my own evaluations/survey. My engine is a 2GM
, so the older version of the 2GM20
. Opening the compression
release, I can turn the engine over, by hand. I cannot do that with the compression release closed, regardless of the handcrank position. That tells me I have compression in both cylinders.
I am going to change the water pump
, because the engine has been sitting 2 (well, almost 2 1/2) seasons, and sometimes the impellers will take a 'set'.
I have also pulled the injectors, but not so I could 'fog' the pistons. I did it because the engine is 40+ years old, they have (probably) never been serviced, and, there is some diesel exhaust soot on the transom. The injector shop said they do need to be rebuilt (@ $117 each, including new nozzles). Btw to pull the injectors disconnect the fuel lines and get them out of the way. Loosen the retaining nuts but leave about 1/2 the thread engaged. Then, with the compression release open, rotate the engine by hand, build up some momentum, and then shut the compression release; the injectors will literally 'pop' free. Remove the retaining nuts the rest of the way and you can remove them by hand.
I rotated the engine by hand so that both pistons are mid-stroke and poured about 3 oz of Sea-Foam into each cylinder to soak. This will (hopefully) serve two purposes: first - if there is any still in there when I get back to the boat this weekend, the rings should be sealing - but Sea-Foam is as thin as water (maybe thinner) so if there isn't any, I'm not going to panic/worry about it. Second - the Sea-Foam will get in and around the rings, dissolving the carbon and free them up (if by chance they were stuck) and help with compression.
I also pulled my exhaust elbow
and inspected it, again because there was no indication of it ever being done. It was fine.
I also checked the air cleaner - which is actually a silencer. The foam around the perforated inner metal cone was almost gone. The engine has a PCV system, and apparently, the oil vapors from the crank case dissolved the foam which was then 'digested' by the engine. From what I've been able to determine on-line, this is not unusual, the Yanmar 'filter/silencers are junk, and a lot of people run without them. (The old single
cylinder Yanmar I had in a Hunter
27 didn't even come equipped with a filter, just an intake tube.)
All of this was a couple hours worth of work
, most of which was trying to get the exhaust hose off the exhaust elbow
When my injectors are ready and my other parts
come in, I will go back up (the boat's 2 hrs away) and:
- remove any Sea-Foam that might be in the cylinders and install the injectors.
- check and adjust the valves - again because there is no record of it ever being done and the engine is 40+ years old.
- install the exhaust elbow
- install a new water pump impeller
- install new zincs
- install new belts
At that point, because the boat is on a trailer
, I will rig up a cooling
water system using a bucket and hose and test the engine.
BTW there is a "Yanmar Marine
Engine Owners Group" on Facebook that is a wealth of info (not that CF isn't