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SailnParadise · 06-03-2023, 06:35

Good Morning CF. I just bought a Hunter 31 with a Yanmar 2GM20F. It is pretty rusted but the flywheel turns. I haven't been able to get it started and would love some advice. I'll be putting an outboard bracket on for temporary propulsion to get out of the PO's slip and out to anchor. But I'd like to get it running before departing. The heat exchanger seems to have a lot of rust and the batteries were in a fully discharged state for at least a month I would think. There is also some pooled water below the engine but not to a level where it contacts the engine. When I try to start it the flywheel turns slowly. Might this be the batteries? I have charged them and it runs the fridge/freezer and electric toilets just fine. I am trying to avoid doing a rebuild until I can get further south and get hauled out for a bottom inspection and paint job.

SY Harmony · 06-03-2023, 06:39

A volt meter here would be very handy.
Slow cranking is typically bad batteries, corroded connections, bad grounds. With a meter you could see what the voltage is while cranking.

SailnParadise · 06-03-2023, 07:10

Quote:

Originally Posted by SY Harmony

A volt meter here would be very handy.
Slow cranking is typically bad batteries, corroded connections, bad grounds. With a meter you could see what the voltage is while cranking.

I'll go buy one right now. What would you suggest I test?

SY Harmony · 06-03-2023, 07:22

Quote:

Originally Posted by SailnParadise

I'll go buy one right now. What would you suggest I test?

You want to know what the batteries are supplying at the starter. So,
1) turn off any charging sources, shore, solar, wind.
2) key off - measure V at the batteries.
3) key on / engine off - measure the voltage at the starter. On the big cable to the block or ground cable.
4) repeat the above measurement while someone engages the starter.

Reference approx V
2) 12.5
3) 12-12.5
4) >10.5

If (4) drops below 10 (6-8 typically) the batteries likely have shorted cells.
If (4) hold 9.5 to 11 while cranking slow. I’d consider pulling the starter and having it serviced.

SailnParadise · 06-03-2023, 07:50

There was a new starter installed prior to my purchase of the boat. The mechanic stated that he used a jumpstarter (which is still on the boat and not in good condition) and installed the new starter once it wouldn't turn over. I also have a brand new battery I have just purchased but not hooked up yet

SailnParadise · 06-03-2023, 08:28

Quote:

Originally Posted by SY Harmony

You want to know what the batteries are supplying at the starter. So,
1) turn off any charging sources, shore, solar, wind.
2) key off - measure V at the batteries.
3) key on / engine off - measure the voltage at the starter. On the big cable to the block or ground cable.
4) repeat the above measurement while someone engages the starter.

Reference approx V
2) 12.5
3) 12-12.5
4) >10.5

If (4) drops below 10 (6-8 typically) the batteries likely have shorted cells.
If (4) hold 9.5 to 11 while cranking slow. I’d consider pulling the starter and having it serviced.

Getting 12.4 @ starter. Just installed new battery and still same issue. Starting motor and flywheel turns.

Cheechako · 06-03-2023, 09:06

You need the starter to turn the engine fairly fast. But first:
How long since it ran? Could the fuel be mucky and old?

-Clean all the fuel filters including the one mounted on the engine. Leave filters as full of fresh fuel as you can. (depends on how many filters you have etc)

-With the new battery installed, crank the engine over, no more than maybe 15 seconds at a time, and crack open one of the 'fuel injector nuts' on the tubing going to the injectors. (if you dont know how to bleed this way look it up on line.) You want to crank the engine allowing fuel to spray at the injector nut until fresh fuel comes out and all bubbles stop..

There's just a lot of possible problems, too much to put in a post here. But if it turns over well, I would start there. You can also spray a little diesel in the air intake while someone cranks the engine, using a spray bottle. The engine should start for a second or two doing this.

gonesail · 06-03-2023, 09:11

you might try hard wiring the battery to the starter. not sure how to do this or whether it's a good idea .. but if she turns over you would know the problem is in the old connections or ground.

SY Harmony · 06-03-2023, 09:32

Quote:

Originally Posted by SailnParadise

Getting 12.4 @ starter. Just installed new battery and still same issue. Starting motor and flywheel turns.

12.4 while cranking?

NorthCoastJoe · 06-03-2023, 09:38

On that engine there is a compression release. Open both and see if the engine spins faster it should.

Make good clean, tight connections on all wires between the battery and starter. You only need the heavy positive and ground wires. Don't forget to clean the ground side of the circuit.

Bleed the injectors as said above, you could take a gallon can of fresh fuel with the intake hose stuck into it for your fuel source. The boat's fuel tank may be full of crud this will bypass that problem.

Enough cranking speed and clean fuel it should run.

SailnParadise · 06-03-2023, 12:31

I am cleaning it now to get rid of all the rust so I can properly check the connections. The heat exchanger is very rusted. Will this effect the starting? Or will it just run hot?

SailnParadise · 06-03-2023, 12:34

Also what about checking for compression issues?

garyfdl · 06-03-2023, 13:08

Quote:

Originally Posted by SailnParadise

Also what about checking for compression issues?

Checking compression gets pretty involved and requires special equipment.

Everything else is sound advice (except hooking the battery directly to the starter IMO).

Big question is: "when did it last run"? If last season then it should run now.

You could also fill the small fuel filter on the engine half full with SeaFoam (let the screaming, wailing, and gnashing of teeth begin), bleed the system, and see if that will get it to fire and start.

And not discrediting the advice here... this is also a good source for advice:

https://www.facebook.com/groups/1616...06520846746538