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wsvoboda · 16-07-2009, 20:45

I have about 175 hours on my 3GM30F Yanmar engine and I get blue smoke from the exhaust at 2500 plus RPM's. No over temp warnings, and engine oil has been changed every 50 hours. New coolant added and previous owner claims he started it every week for three years??? Hmmmm, did he ever put the engine in gear while at the docks, don't know, will never know. OK the boat is 34 feet and weighs in at 13 tons with an 18 inch three bladed prop. Any sugestions are welcome, please and thankyou, Respecfully, Bill

**neilpride** · 16-07-2009, 21:20

Hi wsoboda , blue smoke is burning oil, and 175 hours is a new engine , if the last owner just start the engine in the dock and let the engine idle in low rpm for the past of 3 years maybe the pistons rings are stuck in the grooves, i know yanmars like fly in hig revs , you sure is blue smoke?? how is the oil level?? to much oil and the engine burn oil , you notice to much diference in the oil stick after change the oil?
Another cause for blue smoke is a valve guide , is the seal for the inlet or exaust valve in the cilinder head, if one of this seal is not sealing properly , the oil in the cilinder head pass this seal and burn in the combustion chamber, blue smoke.
What kind of oil are you using? 15w40 , 15w50 SAE ?
A good compresion test maybe necesary, and some engines burn some oil and everything is fine, if the drop in the level betwen changes is just a litle.
Cheers.

wsvoboda · 16-07-2009, 21:47

Neilpride, no loss of oil, I check it each time before I start my engine. The diesel I buy is ag diesel and has a red die. I notice that the exhaust smells like unburned fuel when I get the RPM's up. It is a steamy blue exhaust color.

**neilpride** · 16-07-2009, 22:31

Well if you dont notice oil drop, good news, in hig revolutions the oil from the cranckase climb to the cilinder head at a good rate , and the cilinder head is overflow with oil to keep the lubrication at a good level, more oil in the cilinder head is more work for the valve guide, my opinion is to change the oil and filter and put the yanmar recomended oil, measure the oil , and when is time for a oil change measure again to see the oil quantity, no big drop, no big deal.
Engines burn some oil in their life , i dont know how the previous owner break up this engine , a break up new engine like Pull the pedal to the metal is the worst thing you can do in a new engine, pistons dont adjust well to the liners etc...
Lets see , good luck.

svquest2 · 16-07-2009, 23:23

Is that as fast as the engine will turn? If it is, perhaps it's overloaded. That smoke may be unburned fuel and you may be creating a carbon build up. Is any black soot floating on the water? !8" is a good sized prop for that boat of 13 tons so what is the pitch?

Joe S

Badsanta · 17-07-2009, 09:39

What is the WOT wide open throttle rpm in neutral? Do this simple test, start the engine then one at a time open the decompression levers, there should be a change in sound each time, it should run a little rough because that piston is not firing. If no change on one, it could mean a stuck valve, causing lack of compression. That would pass the unburned fuel causing whitish smoke.

wsvoboda · 17-07-2009, 19:31

Thanks to all who have replied. I have done the compresion release with the cylinders before with change in each one as it should be. The engine oil I used is from chevron and is Delo 400LE 15W40 that I was told is for deisel engines and is also recommended by Yanmar manual, The max WOT is 3600 but I don't want to do this in neautral, I have done this in gear, I had to remove my starter because it gave up the goast and I removed my breather cover and back plate, I notice in the intake area of the number 3 cylinder there was allot of white foam, milky oil as us Harley riders used to call it when we ran muliti grade oils in our Bikes. I am new to diesels so I don't understand why the valve cover breather attaches to the intake manifold next to the number 3 cylinder??? any more Ideas are greatly appreiated, Just tell me I'm loosing my mind and not my diesel, Respectfully , Bill

Chief Engineer · 17-07-2009, 20:10

Sounds like it might be over filled with oil.

With the engine running, remove the breather hose from the intake.....obsereve what comes out of the breather hose and get back to us.

Will comment on the white foam tomorrow

Badsanta · 17-07-2009, 20:12

If you over crank with out shutting off the water intake you could back fill the exhaust with sea water and the watter will back up into the engine starting with the #3. Maybe it took in some water. I would run it and change the oil a couple of times. or maybe a head gasket leak. My book calls for 30 weight oil same as the transmission. I can get 3600 rpm in neutral but never in gear.

Badsanta · 17-07-2009, 20:14

Follow what ever the chief says.

wsvoboda · 17-07-2009, 21:04

Badsanta, sounds like you have the same diesel as mine? To all, The cranking might come into play because my starter resently died. There was allot of cranking in small intervals, it was almost like my batteries were not supplying enough cranking amps but that is not the case. I disconnected to raw water line that goes to the the exhaust gooseneck but I never had any drain from the raw water system. That tells me that the syphen break is working properly. The cranking and raw water breathing problem could have come into play but my motor was smoking before this episode, Respectfully, Bill

Badsanta · 17-07-2009, 21:26

Yes I have the same motor. The only smoke I ever got was when my prop was fowled. If you are in the water, when was the last time you had your prop cleaned?

wsvoboda · 17-07-2009, 22:32

Quote:

Originally Posted by Badsanta

Yes I have the same motor. The only smoke I ever got was when my prop was fowled. If you are in the water, when was the last time you had your prop cleaned?

Everything is fine with the prop and shaft, I wonder if all the oil foam from the vent is causing the problem also, on the newer Yanmar engines, does the manufacture route the vent tube the same way asy my 3GM30F??

**neilpride** · 17-07-2009, 22:59

Is the oil level correct?? i agree with chief, see what is coming from the breather hose with the engine runing, you have a oil presure gauge in the panel? or just a alarm? hig cranckpresure blow oil from the breather to the intake .