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Yanmar 2GM20F: please criticize my plan!

Jun 25, 2004
283
Hunter 306 Pasadena MD
Despite doing 10 or 20 boat projects over the past 5 weeks, I'm running short of time to do everything before I launch on the 27th. I've done thru-hulls, running rigging, blahblahblah, new batteries, overhauled the entire sanitary system, and I'm in the middle of rub-rail leak fixing. The next week needs to be devoted to finishing the rubrail and painting the bottom. Our H306 has been on jack stands since November 2016, so I need to do several engine projects too.

Engine projects (2GM20F) done so far:
1) new batteries
2) new Groco sea strainer, thru-hull, and related hoses
3) installed new impeller, checked the raw water pump, smoothed the interior surface
4) added a very small amount of water (4 oz?) to top up the coolant
5) started and ran the engine on land for a minute or two. Started on the second try, despite 3.5 years of idleness!!! Ran flawlessly.

Want to do:
6) change primary fuel filter
7) change secondary fuel filter
8) flush and fill with new coolant
9) maybe new belts
10) maybe hire fuel polisher. Or maybe buy a cheap borescope to check the fuel tank.
11) remove and inspect the mixing elbow
12) change oil(s)

My conservative instincts tell me that since it started and ran flawlessly, I should launch first and drive it around the corner to the slip before doing the rest of the work. In particular, I want to change the coolant, but I don't feel comfortable running the engine very long on jack stands, so it makes sense to me to do this once I'm in the water. Please confirm or criticize!

Jay
 
  • Like
Likes: kloudie1
Jun 21, 2004
1,858
Beneteau 343 Slidell, LA
Go for it! Looks like a good plan. All of the remaining engine work can be done in your slip.
 
  • Like
Likes: ggrizzard
May 24, 2004
6,769
CC 30 South Florida
Hope you had a raw water pickup while running the engine as that impeller can burn up if ran dry in under a minute. Fill a 5 gallon bucket with water and run a hose to the intake side of the raw water pump and run the engine again and watch the exhaust discharge port for an adequate amount of water coming out. (Disregard if the replacement of the impeller took place after the engine was first ran.)
 
May 17, 2004
3,434
Beneteau Oceanis 37 LE Havre de Grace
If it’s sat for 4 years already I think you’re ok taking it for one short ride around the marina before you do the other jobs. Run it under load for a minute while tied up in the launch slip, to make sure it handles the load alright before untying.
 
Jun 25, 2004
283
Hunter 306 Pasadena MD
Go for it! Looks like a good plan. All of the remaining engine work can be done in your slip.
Thanks. I'm always nervous about messing something up when I can't run the engine for a good long while to test it. Like overheating b/c there's an airlock in the coolant. Or stalling out b/c of air in the fuel line.
 
Jun 25, 2004
283
Hunter 306 Pasadena MD
Hope you had a raw water pickup while running the engine as that impeller can burn up if ran dry in under a minute. Fill a 5 gallon bucket with water and run a hose to the intake side of the raw water pump and run the engine again and watch the exhaust discharge port for an adequate amount of water coming out. (Disregard if the replacement of the impeller took place after the engine was first ran.)
Yep: I always test it on land using cooling water from a bucket, and I did watch for water discharge. What I haven't done is to continually fill the bucket with a hose so it can run longer than 1 bucket full.
 
Jun 25, 2004
283
Hunter 306 Pasadena MD
If it’s sat for 4 years already I think you’re ok taking it for one short ride around the marina before you do the other jobs. Run it under load for a minute while tied up in the launch slip, to make sure it handles the load alright before untying.
Good idea: thanks.
 

Sailm8

.
Feb 21, 2008
1,712
Hunter 29.5 Punta Gorda
I would add shifting from forward to reverse to see what happens. Don't want any surprises when cruising the marina.
 
Jan 4, 2006
3,830
Hunter 310 West Vancouver, B.C.
I've done thru-hulls, running rigging, blahblahblah,
I don't think you did the "blahblahblah" in the correct order but, looks close enough for government work.

Your list looks good so far. Maybe, as time allows, add:

- I know you're doing the shaft zincs but mention anyway
- check the oil pressure alarm
- check the hi temp. alarm
- check the re-breather oil drop out
- check the Xmission - shaft alignment
- gap the valve lifters

As far as fuel polishing, way too expensive "if you don't need it". Install a small inspection port on the top of the tank and pull a sample with your vacuum oil pumper:

Fuel Tank Pump Out Fitting.JPG


Also, send down the borescope for a further look.
 
Last edited:
Jul 19, 2013
310
Pearson 31-2 Boston
I'm sure you meant item 12 to be

12) change oil(s) and oil filter

This is a lovely little engine!
 
Jun 25, 2004
283
Hunter 306 Pasadena MD
I don't think you did the "blahblahblah" in the correct order but, looks close enough for government work.

Your list looks good so far. Maybe, as time allows, add:

- I know you're doing the shaft zincs but mention anyway
- check the oil pressure alarm
- check the hi temp. alarm
- check the re-breather oil drop out
- check the Xmission - shaft alignment
- gap the valve lifters

As far as fuel polishing, way too expensive "if you don't need it". Install a small inspection port on the top of the tank and pull a sample with your vacuum oil pumper:

View attachment 179305

Also, send down the borescope for a further look.
New zincs are sitting on the chart table at the moment: I think of that as going with paint, mainly b/c they're down there on the outside...

Most of the other things, I don't know how to test. I have the book which came with the engine, but I assume that's different from the service manual. Where can I read about testing these alarms etc., please? I'm a reasonable auto mechanic, but haven't worked much on diesel engines. Mine has just worked fine for many years, with routine (minimal) maintenance. Mainly oil and impellers.

My fuel tank is in a horrible place: really totally inaccessible unless I remove it. (I can see 1/2 of the side of the tank, and can barely get at the top at all.) So I think the borescope is probably my best bet for seeing what's going on in there.

Thanks for the suggestions.

Jay