Yanmar 3GM30 white smoke (help)

[Scubaseas]

Originally Posted by Compass790

You are not wrong but...White "smoke" can be completely unburnt atomised diesel. Watch a tired diesel on a cold morning at start up.
When the engine heats up the fuel starts to burn.
It may not be his problem but it's a possible scenario to be considered.

I agree with this. Lot of pretty drastic maybes here. It's not hydrolocked. Doubtful cracked block

The most probable that matches symptoms reported is too much fuel at cold engine.

[Compass790]

Originally Posted by Wotname

I wouldn't be so sure there wasn't water emulsified in the oil. Any hint of gray oil tends to be from small amounts of water emulsified in the oil. The more gray, the more water. It doesn't seperate out - well it might over few decades.

Yea +1 for this, the gray description raised my neck hair.
Hope ya havent got a conrod like skipperpete pictured.
Nothing that a bit of heat & a 12lb hammer cant fix or a press if you are a sophistocate

Seriously the local yammer dealer wanted about US $400 for a conrod to fit our YSM8 so I hope thats not your problem.
I'd be looking at compression or leakdown test now

[ShelleySailor]

Originally Posted by Wotname

I wouldn't be so sure there wasn't water emulsified in the oil. Any hint of gray oil tends to be from small amounts of water emulsified in the oil. The more gray, the more water. It doesn't seperate out - well it might over few decades.

Ok so lets say it is water emulsified in oil. What is that mean?
is that why it has a white smoke at start up?

[Wotname]

Originally Posted by ShelleySailor

Ok so lets say it is water emulsified in oil. What is that mean?
is that why it has a white smoke at start up?

Possibly but not necessarily.

I made mention of it as the very few reasons for the oil to go grey and none of them are good.

Water ingress in a major reason and it will emulsify very quickly.
Fast wearing bearings are another reason - the grey being caused by metal particles although these should be trapped by the filter.

Maybe the white smoke is due to water or maybe due to other causes as other have posted upthread.

Good luck in getting it sorted and I for one would like to hear of the solution when you finally track it down.

[skipperpete]

I agree with Scubaseas, the chances of a cracked block or a bent conrod are slim, I suggest that the unpleasant sound the OP heard was diesel knock maybe from too much fuel in the precom chamber and cylinder..... a sound thats very familiar to the devotees of coldstart aerosols. To establish if water is in the oil, it can be useful to take a look into the rocker box through the oil fill hole (or take off the rocker cover), if you see rust, grey mud or moisture droplets... bingo!.....and why not check the valve clearances if you do lift the cover. Is the engine showing any signs of crankcase pressure?... another helpful indicator of engine health.
Pete.

[Compass790]

Good advice from skipperpete,
If you remove rocker cover check pushrods too especially if one or more tappet clearances are way out.
They bend easy with any liquid in the combustion chamber but they are easy to straighten too.

[Dave9111]

White smoke means you are getting water into the combustion chamber/s.

White smoke doesn't come from over fueling.

Has this engine overheated? You could have a cracked block, head, or blown head gasket. If this engine has is freshwater cooled, what does your coolant look like?

If your oil is "gray" you have a problem.
Water in oil changes its color.
If bearing material was making the oil gray it would also be banging like crazy.

Oil color goes from black to gray to lighter gray to chocolate milk to light chocolate milk to cream as it picks up water.

A static compression test might spot the issue. An air compressor is hooked to an injector port via a flow measure and you pressurize the cylinder and measure leakage.

[robertmfranklin]

How do you check the mixing elbow. Do you need to take it apart?

[hpaabor]

Agree with all saying injectors. Used to have a local company that would clean / rebuild them. They stopped the service but even replacing them was money well spent for me.

[gonesail]

my white smoke resulted in replacing the mixing elbow.

[merrydolphin]

Originally Posted by ShelleySailor

I got a 1997 Yanmar 3GM30F with about 1,400 hours in my Hunter 34. Lately the engine has been hard to start. When it starts it idles rough as if it is running on 2 cyclinders, the engine just shakes and vibrates a lot, if I push it to increase RPM after about 2-3 minutes it smooths out at same time when I crank it white smoke comes out of the exaust and it is smoke and not vapor. After it starts it has a lot of white smoke until I put it in gear and get going. Under load at 2300 RPMs it runs fine and the smoke goes away. I should add there is an oily sheen in the water when its blowing white smoke. If ran for 15-20 mins it will start right up and have no smoke and run fine for the rest of the day. Next morning it will do the same thing as before.
Any ideas?
Thanks in advance!

I had a very similar problem once with a Ford/Lehman 90. Turned out to be a little seawater coming in to the cylinders from the exahaust. The live aboard load that I had on the boat was able to just bring the ant-siphon below waterline. Had to give it full throttle to start. Then the white smoke (burning the water out) and then would run fine. And re-start quite normally and quickly. (No water yet). Was a small amount that came in over time. Once I changed the Anti-Siphon no problem. But it took a lot to get to this point. Pulled the starter, had it checked, etc.

[robertmfranklin]

Mine is also a Yanmar 3GM30F.

Before launching this spring I wanted to run my engine on the hard to be sure it fired up and everything was working properly. I know from past experience, either remove the belt for the salt water pump or allow that intake hose to pull water from a sheetrock bucket. Simple and logical.

I did neither. Instead remembering the need for water cooling, I attached a hose from the municipal water supply to the intake hose. I believe City water is around 40 psi. Then I ran the engine for about 5 minutes until it stopped!

Hydrolock.

Worried, I tried very gently to hit the start button, but very quickly abandoned that approach. In stead I got down on my hands and kneed in front of the fly wheel and with an effort almost beyond my strenght I gradually moved the cranshaft little by little. It moved. I advanced slowly to about three full turns. Waited and did the same thing again. The engine started with a lot of white smoke but cleaned up and has run flawlessley for a couple 6 hour transits of Cape Cod Bay. The key, as always, is to go slow. Think think think.

But there is a questiion.

I use to crank my A-4 with a handle supplied for the purpose. The A-4 can be started this way. The 3GM30F has too much compression to start with a hand cranch. And, I've never seen a decompression lever, but maybe I haven't looked closely enought.

The effort I needed to turn the pulley was almost beyond me. I needed a crank handle. Sounds like the OP should have one, as perhaps everyone should who owns a Diesel.

Is a crank handle available?

Should I make my own?

Maybe a properly sized socket and a long handled wrench?

Anyone know the specs for the nut on the crank shaft pulley?

[Shaneesprit]

Hi
Quite simple You have AIR in the fuel
Simple as that

[Shaneesprit]

Originally Posted by SteveSadler

My Yanmar did that too. I pulled the injectors to find black goo on them. After cleaning it ran clean. The carbon buildup was from running at low rpm and low loads where exaust temps don't get hot enough to burn it off. Volvo's manual recommends running it in gear full throttle for 20 minutes each time you run it. Personally, I'll just clean the injectors.

The idea of running at full throttle is it cleans up all of the deposits not just the injectors, you need to deglaze and de carbon the inside of the engine - heat does that but heat is only made with hard load

[Shaneesprit]

Originally Posted by PaulvR

Guys, am I wrong here....I was taught that under most circumstances.....

White smoke is water
Blue smoke is oil
black smoke is fuel

Except at first Air and Water have the same colour smoke so If White check your not getting Air in the fuel