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Old 21-10-2011, 23:48   #1
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Buying Used Yanmar 2GM20

I have had my Atomic 4 for the last 10+ years since I bought the boat in 2000. The Atomic 4 is a fine engine and is easy to work on and keep it running and is running great. But from time to time I think about other repower options and this time I actually think I may go through with it. I am looking at a used Yanmar 2GM20. The engine appears (sorry I forgot to bring my camera with me) to be in a great condition. However it has a couple of things that need to be attended to:

1. The engine sputes black smoke when it is accelerated quickly (i.e. throttled hard). But once it reaches a stable speed the smoke disappears. It also does not smoke if the acceleration is done gradually and smoothly. What could cause the engine to do that? I confirmed that the black smoke is diesel (not engine oil - no sheen in the exhaust water.) Is it something to worry about?

2. The engine instrument panel probably needs to be replaced. The oil pressure alarm and other lights are working sporadically. The start button does not work. Is it easy to source a used panel? The new ones are too expensive.

3. The engine mounts are too high for the boat. I probably need to find smaller mounts that have a lower profile (about 1" shorter than the standard Yanmar mounts).

4. It's raw water cool. I would like to convert it to FWC. What should I expect to pay for a conversion kit?

Thanks in advance for your insights!

Ray
WC Pearson Triton106
Alameda, California
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Old 22-10-2011, 00:29   #2
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Re: Buying Used Yanmar 2GM20

Re the sporadic lights etc, it may well be the wiring loom connector which sits down next to the engine. On mine, wiggling the connector makes the intermittent lights work (just another item on the long list of jobs....). Yanmar sell new looms complete with connector, which would be worth doing anyway for a new installation. Then if the panel is bad, it can be changed out later.

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Old 22-10-2011, 06:36   #3
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Re: Buying Used Yanmar 2GM20

Upgrading the 2gm can potentially cost thousands of dollars. Look at a new Beta Marine. They can supply engine mounts that will match your Atomic installation.

David
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Old 22-10-2011, 07:17   #4
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Re: Buying Used Yanmar 2GM20

If it smokes under hard acceleation and then clears up, think of a bus or a truck moving from a dead stop. There is a lot of fuel being dumped into the cylinders and not being burned.

I may have an old panel for a 2GM but then again, building a new one is not difficult

Regarding engine mounts.....the footprint for a Yanmar is diffent that an A4....this may require modification of the engine bed.

You may also need to change the size of the exhaust hose.

Keep in mind that fuel tank will need to be changed out.

Diesel fuel tanks are different (fitting wise) than gasoline tanks.
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Old 22-10-2011, 07:19   #5
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Re: Buying Used Yanmar 2GM20

Turning a 2GM into a 2GM20F is not cheap.......
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Old 22-10-2011, 07:37   #6
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Re: Buying Used Yanmar 2GM20

The black smoke is most likely due to an oversized prop. Converting to fresh water after the engine has been used in salt is a bad idea. The damage has been done. If the price is right, just use it as it is, otherwise the conversion is not only expensive but the engine won't last anyway. You might as well buy a new diesel.
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Old 22-10-2011, 22:21   #7
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Re: Buying Used Yanmar 2GM20

Thanks everyone for your insights. They are very helpful. I have been reading quite a bit about repowering and am prepared to address all of the challenges that come with it.

Quote:
If it smokes under hard acceleation and then clears up, think of a bus or a truck moving from a dead stop. There is a lot of fuel being dumped into the cylinders and not being burned.

I may have an old panel for a 2GM but then again, building a new one is not difficult

Regarding engine mounts.....the footprint for a Yanmar is diffent that an A4....this may require modification of the engine bed.

You may also need to change the size of the exhaust hose.

Keep in mind that fuel tank will need to be changed out.

Diesel fuel tanks are different (fitting wise) than gasoline tanks.
I take it then that it is not unusual for diesel engines to blow black smoke under hard acceleraion. That's good to hear. I am also aware that the engine foot prints are different and I will modify the existing engine foundation to accomodate the wider 2GM20 engine stance. I calculated the differene in footprints (11.5" vs. 14.5") and figured that by sistering a 1.5" wide plank to the existing foundation they should fit the 2GM20 foot print just fine. This is probably an over simplification. The actual modification work will be far more involved but not beyond my skills.

The exhaust elbow can be adapted to 1-5/8" exhaust hose I was told. Is there any reason why it can't be adapted to 1-1/2" exhaust which is what I have currently? The fuel tank I have now is only one year old Moeller tank. I understand that I need to add a return hose. Could I just tee off the existing pick-up fitting?

Quote:
Re the sporadic lights etc, it may well be the wiring loom connector which sits down next to the engine. On mine, wiggling the connector makes the intermittent lights work (just another item on the long list of jobs....). Yanmar sell new looms complete with connector, which would be worth doing anyway for a new installation. Then if the panel is bad, it can be changed out later.

lockie
Yeah, I may have to replace the wiring loom and the instrument panel. It looks pretty corroded already. I will give it a thorough cleaning. If it still does not work I guess I will have to replace them. The dealers are charging $1000 for the panel alone which seems very steep. I suppose I can use my existing Atomic 4 panel which is complete. But I understand that the diesel tachs are different from gas tachs, right?

Quote:
Upgrading the 2gm can potentially cost thousands of dollars. Look at a new Beta Marine. They can supply engine mounts that will match your Atomic installation.

David
I have looked at the new Betas. They are very niuce, just not in my price range. Even with all of the new things I have to add (panel and mounts) the 2GM20 will still be far less expensive.


Quote:
The black smoke is most likely due to an oversized prop. Converting to fresh water after the engine has been used in salt is a bad idea. The damage has been done. If the price is right, just use it as it is, otherwise the conversion is not only expensive but the engine won't last anyway. You might as well buy a new diesel.
The engine has been sitting in a garage for the last four years. So, there is no prop issue here. But I am rethinking conversion to fresh water cooling. I have reading other people's RWC 2GM20 and they don't seem to have any systematic complaints. I suppose if I flush it with fresh water and muriatic acid once a while it might be fine.
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Old 23-10-2011, 07:15   #8
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Re: Buying Used Yanmar 2GM20

You can get a fitting for the tank that converts it. It is actually a fitting that is tapped into the fuel tank sender plate.

I would not reduce the exhaust hose size. This can lead to excessive back pressure, poor performance and smoking....in some cases.
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Old 23-10-2011, 09:06   #9
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Re: Buying Used Yanmar 2GM20

If there.s no load on the engine and it blows black smoke, run, don't walk, away and find another engine on craig's list !
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Old 23-10-2011, 09:31   #10
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Re: Buying Used Yanmar 2GM20

I want to go back to your first post. If it runs fine, why change? Yes, Gasoline is not nice fuel from a safety standpoint but - a gas engine stands up to the occational light use most of us sailors use our engines for. If all you are doing is using it to get you in and out of the Marina and now and then to get you home when the wind dies - diesels really don't like that light use. But even if you use it more, you really are going to find the conversion will result in a lot of headackes. Even putting a beta in (which is by far the easiest) still demands a lot of fitting that is expensive. I really would like you get some bids for the job. Of the bids that are interesting, go back a second time if need be and ask to separate labor out. Believe me, it is a big enough labor job to give you a little to think about.

I would keep the trusty old Atomic 4.

Re black smoke, the way you describe it is probably not a problem. It is not a gs engine. MIght get a diesel mechanic to run it. What is it's history?

Re conversion to fresh water , figure $300-400 for new parts. $150 - 200 each for a heat exchanger and a DC pump. Generally the damage is salt build up in the cooling walls. I have had pretty good luck using vinegar to remove it.
Cheers
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Old 23-10-2011, 11:16   #11
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Re: Buying Used Yanmar 2GM20

For a diesel that has sat idle for a long time....you probably need to get the injectors serviced. Parts and Labor....around $300.00
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Old 24-10-2011, 20:44   #12
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Re: Buying Used Yanmar 2GM20

Thanks again everyone for your input! I do appreciate them very much. I left out some background information that may have made my dilema more understandable.

Quote:
Originally Posted by jannpage View Post
I want to go back to your first post. If it runs fine, why change? Yes, Gasoline is not nice fuel from a safety standpoint but - a gas engine stands up to the occational light use most of us sailors use our engines for. If all you are doing is using it to get you in and out of the Marina and now and then to get you home when the wind dies - diesels really don't like that light use. But even if you use it more, you really are going to find the conversion will result in a lot of headackes. Even putting a beta in (which is by far the easiest) still demands a lot of fitting that is expensive. I really would like you get some bids for the job. Of the bids that are interesting, go back a second time if need be and ask to separate labor out. Believe me, it is a big enough labor job to give you a little to think about.

I would keep the trusty old Atomic 4.

Re black smoke, the way you describe it is probably not a problem. It is not a gs engine. MIght get a diesel mechanic to run it. What is it's history?

Re conversion to fresh water , figure $300-400 for new parts. $150 - 200 each for a heat exchanger and a DC pump. Generally the damage is salt build up in the cooling walls. I have had pretty good luck using vinegar to remove it.
Cheers
I have plans beyond just sailing the SF Bay or coastal cruising. If that were the case I would not repower. I would either continue to use my A4 or go with an outboard or even sail engineless. For blue water cruising an diesel engine has several uses - (1) charging battery, (2) get through calm, (3) get off a lee shore, (4) a source of hot water.


Quote:
If there.s no load on the engine and it blows black smoke, run, don't walk, away and find another engine on craig's list !
Only when it is under hard acceleration. Under (artificial) load actually it does not smoke.

Quote:
You can get a fitting for the tank that converts it. It is actually a fitting that is tapped into the fuel tank sender plate.

I would not reduce the exhaust hose size. This can lead to excessive back pressure, poor performance and smoking....in some cases.
Thanks Chief, that's good to know.

It seems from this discussion I need to take care of the following:

1. Lower profile mounts ($200?)
2. New panel or panel components (including loom connector) (How much should I budget for a used one?)
3. Exhaust hose and maybe new waterlift muffler ($200-400?)
4. Shaft coupling ($50)
5. New (or used) prop ($100-$300)
6. Engine mount modification (DIY)
7. Add return hose
8. Tap into fuel tank sender

In addition, I may need to:

1. Injector service ($300)
2. FWC conversion ($300-400)

Wow, definitely not cheap even if I do all of the work myself. I hope to control the total out pocket cost to less than $1000. Looks challenging.
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