2GM Yanmar Oil in Exhaust

[Blue Crab]

The 9 kts has a simple explanation: he sails in upsidedownland. It's 6 on the correct side of the equator.

[Cadence]

I think you have been pushing it to hard. I think you eluded to that in the OP. I'm am afraid you have engine problems. Clear prop or bottom probably has nothing to do with it. I agree with the follow that said 9k on a 25 ft. sail boat is not realistic. Check the oil level. Bet it is sump oil you are seeing not fuel as an exhaust oil slick.


I hope I am wrong.


Best of luck.

[Wotname]

Originally Posted by 01kiwijohn

Slow up there. Could be only the result of prolonged, previous running at less than designed loads. I run my 3GM30 at WOT for about 5 mins every time I take it out. It blows some blue smoke for a minute or so, then settles down.
9 knots? Contessa 25?? Probably not happening. Check with GPS.
For correct pitch, Yanmar usually suggest (taken from their Installation Manual) 1) Run at max idle, record that speed. 2GM 20 spec. is 3800 to 3850. 2)run boat at max throttle and engine speed should be between no load max RPM and Rated output speed; ie; 3600 and 3800 for the 2GM.
Most engines run at about 95% of max output if pitched correctly.
Let me know if that helps

I concur- most likely the "oil in the water" is carbon and diesel.

If the OP's engine instrumentation is working, the engine isvprotected from the only two things that will quickly kill it - over temp or low oil pressure.

If it starts easily when cold, compression is will be good enough.

I think you are out on the specs by 200 RPM. The 2GM20 max continous is 3400 and 3600 for two hours.

[miabellabrian]

Thanks all for your replies, some very helpful and some just discussing the hull and my speed. ( measured with the GPS in knts). The issue is really serious, and it isn't a little build up carbon/smoke, I'm talking about great amounts of blue smoke and oil getting pumped out the exhaust.! It was running fine previously and this all happened within an hour !!!
I'm starting to think head gasket or rings or valve guides. Just wanted info on how to check these 3 things, no good replacing the head gasket only if the rings are stuffed !!
I'm kicking myself for pushing the engine so hard yesterday.

Sent from my XT1033 using Cruisers Sailing Forum mobile app

[Cheechako]

Are you gaining oil level in the sump? If so it’s diesel.
You could have a frozen injector streaming diesel and it is exiting unburned out the exhaust.
The GM series have a habit of breaking a piston land sometimes. Not sure about if a 2 cylinder would still start readily though. On my 3 cyl I couldnt tell anything was wrong at times. Hopefully that’s not it.
Are there any oil coolers on it? Maybe a leak there going out

[Wotname]

Get a compression check done before pulling the head. Even better get a leak down check done, this will tell you where the problem lies!

[boeing1]

have you checked your exhaust mixing elbow, suspect clogged,

[hamburking]

Originally Posted by 01kiwijohn

Slow up there. Could be only the result of prolonged, previous running at less than designed loads.

The 2gm is a 20hp diesel. That's enough power for a 30'-32' sailboat. So I would expect that pushing your little 25' takes no effort at all for the 2gm. This would agree with the above quote...prolonged running at less than design load. In fact, I would think you would be at hull speed at barely above idle.

Now, I doubt you want to pull the engine and put in a 1gm, which would be more appropriate. So, you might want to run a can of SEAFOAM through instead. Also, give it some load every hour of running...maybe tow a small barge around for a while?

So, I agree...carbon buildup. No need to panic.

[Cadence]

Originally Posted by hamburking

The 2gm is a 20hp diesel. That's enough power for a 30'-32' sailboat. So I would expect that pushing your little 25' takes no effort at all for the 2gm. This would agree with the above quote...prolonged running at less than design load. In fact, I would think you would be at hull speed at barely above idle.

Now, I doubt you want to pull the engine and put in a 1gm, which would be more appropriate. So, you might want to run a can of SEAFOAM through instead. Also, give it some load every hour of running...maybe tow a small barge around for a while?

So, I agree...carbon buildup. No need to panic.

I think he has just run it to hard. Just taking the LOA as the assumed waterline length, the displacement speed is only in the vicinity of 6.5K max.
9 would be plowing. JMHO

[Celestialsailor]

Originally Posted by Blue Crab

The 9 kts has a simple explanation: he sails in upsidedownland. It's 6 on the correct side of the equator.

Could be the knot meter read-out was installed upside-down.

[Celestialsailor]

Again... I'd like to ask 1) How many hours a go was the oil changed?
2) Are you loosing oil in the crank (dip stick)?
3) Do your gauges work? What do they say (Temp and oil pressure)?

[Cadence]

Originally Posted by Blue Crab

The 9 kts has a simple explanation: he sails in upsidedownland. It's 6 on the correct side of the equator.

I never thought about that, that way.

I wish him well. Doubt he ever got close to 9k.

[Cheechako]

Originally Posted by hamburking

The 2gm is a 20hp diesel. That's enough power for a 30'-32' sailboat. So I would expect that pushing your little 25' takes no effort at all for the 2gm. This would agree with the above quote...prolonged running at less than design load. In fact, I would think you would be at hull speed at barely above idle.

Now, I doubt you want to pull the engine and put in a 1gm, which would be more appropriate. So, you might want to run a can of SEAFOAM through instead. Also, give it some load every hour of running...maybe tow a small barge around for a while?

So, I agree...carbon buildup. No need to panic.

Many Yanmars are not what people think they are.
"Released in the late 70s, the Yanmar 2GM was the forerunner of the 2GM20 and developed 13hp (based on 1.0hp equaling 746W) at 3300rpm with a maximum continuous rating of 11.8hp at 3200rpm."

[four winds]

Correct Cheechako.

2GM.............13hp max
2GM20.........16hp max
3GM30.........24hp max

According to the pfd. manual posted earlier. Always thought my 3GM30F was 27hp. Need to check my old printed manual.

[Cadence]

Originally Posted by svthreecheers

Hello Brian
Blue smoke means oil being burned in your combustion, would indicate problem
with pistol rings or valves/valve guides / head gasket.
Take a Compression Test, if too low, injected some oil through the hole and
test again.If the pressure stays the same you will have problems with the head
( gasket, valves or guides ) If the pressure increases you can expect trouble
with the oil and compression rings on your piston.
I have a 42 ft displacement hull, 85 hp engine, top speed 7 know.
Wish I could get 9 kn!
Good luck
Cheers
Siggi