My Yanmar, White Smoke, and a Knock

[LittleFlower]

Hello everyone. I left Daphne, my NorSea, on a mooring for about three weeks while I traveled. Prior to that, the engine was running smoothly. It has 730 hours. When I returned, first it wouldn't start. Now it starts, but there is a knock, which is a sound it hasn't had before. I can tell she isn't as powerful as before. Also, out comes white smoke for the first minute, then it goes away. Fuel and oil levels are good, and the filters were just changed. Any tips? I have some ideas, but before I dive into this I thought I would ask for some help.
Teresa

[Ram]

hI Teresa I just read "Follow the wind " Very nice, What kind of engine do you have?

[LittleFlower]

Thank you Ram. I have a Yanmar 2GM.
Teresa

[DaveC]

I would suspect a blown or otherwise leaking head gasket, or leaking water jacket on the exhaust.

Either way I think you're getting water into a cylinder or the exhaust somehow. I wouldn't run it until you found out the cause because if too much water gets in you can bend a connecting rod (or worse) since water doesn't compress very easily. A gasket is cheap, a new bottom end isn't.

Due to the fact it goes away when the engine warms up a bit means the leak is very small at this point and perhaps the metal expansion when the engine warms up seals it up well enough. When it sits there a while the seeping water accumulates, and when the engine runs it blows out and doesn't come in fast enough to be visible as smoke.

[Artful Dodger]

Wondering does this engine have a close coolant system, if so then you would test the coolant system for leaks, if it does not then you could also check the exhaust system for leaks, by jery rigging a pressure system with the injectors removed and see if water gets into the clinders. One other thing the noice is a deep noice or sound like a chirping.

[klem]

White smoke is a sign that you have water in the cylinders. The possible sources are through the exhaust system, the head gasket, or through the actual cylinder wall(pretty rare). Some more info on both your exhaust and cooling system would be helpful. Depending on the type of exhaust, it can rust through and introduce water which is relatively common. If it is a headgasket, your oil is likely to be contaminated as well but not necessarily.

Since you say that the engine is down on power, chances are that you are having a problem directly related to what is going on in your cylinder and not in the exhaust system. Start by looking at your oil and seeing whether it is milky at all. Also, a compression and leakdown test will help a lot with diagnosis.

[Ram]

Originally Posted by DaveC

I would suspect a blown or otherwise leaking head gasket, or leaking water jacket on the exhaust.

Either way I think you're getting water into a cylinder or the exhaust somehow. I wouldn't run it until you found out the cause because if too much water gets in you can bend a connecting rod (or worse) since water doesn't compress very easily. A gasket is cheap, a new bottom end isn't.

Due to the fact it goes away when the engine warms up a bit means the leak is very small at this point and perhaps the metal expansion when the engine warms up seals it up well enough. When it sits there a while the seeping water accumulates, and when the engine runs it blows out and doesn't come in fast enough to be visible as smoke.

I have to agree , this sounds like it could be it

[Gene :^)]

1. White steam that dissipates quickly and doesn't really go more than 10 ft from the boat?

This is steam from water in the cylinders. Head gasket or internal water/coolant leak. Use BlokCheck...

Test Tools Inc. - Block Chek

2. White smoke that lingers and wofts across the water into the distance, remaining thick?

This is atomized but not combusted diesel.

Q. When the white smoke stops, does the knocking stop also?

When a cylinder is not firing along with the rest, the engine will make a knocking sound (like a rod knock). The thick cloud of lingering white smoke is the atomized, unburnt diesel coming out. Once it warms up enough to fire, it should stop knocking. It could be "not firing" due to low compression, leaking injector line, bad injector, or maybe bad injection pump.

Does your engine use glow plugs? Do you need to use them to start normally? Is this recent problem occurring in very cold weather start up? Could also be as simple as a bad glow plug.

[Gnitfar]

Originally Posted by Gene :^)

1.

Does your engine use glow plugs? Do you need to use them to start normally? Is this recent problem occurring in very cold weather start up? Could also be as simple as a bad glow plug.

Gene, it's been a few years, but I don't believe the Yanmar GM series, 1,2 and 3, the poster indicates a 2GM, they do not have glow plugs.

[Gene :^)]

Great, one less thing to check and narrows our search.

I would do the BlockChek next. Was only $30 at my local auto parts store (not chain autoparts) and it can be used over and over. Test your friends engines when out cruising.

[Gene :^)]

Any new information on this? Did you find the problem?

[LittleFlower]

I did some work yesterday and ended up replacing a fuel injector. One was bad, so I put in a new one. I'll take the old one in to get fixed. But I think I also need to check the compression and head gasket.
Thats where I'm at with this! A lot of research and reading to understand the basics of my engine, and only a little time in the engine room!!
Teresa

[Chief Engineer]

A bad injector is the #1 thing to look for....Keep us posted

Make sure you get new sealing gaskets for the injector....You have to get those from a yanmar dealer

[Artful Dodger]

I'm wondering if you should right now stop and seek the help of a well recommended mechanic to be sure of the problem. You seem to be capable of doing the repairs but knowing what to repair I think is the secret. I have been following another thread where the chap and you were and are in the same boat of looking for what to repair. It cost him thousands before he found the cause of his real problem. For all it took was a mechanic to take a quick look using his basic observation skills to determine it was a compression related problem. There comes a time when spending just a little becomes an investment and I think this is your time for such a case.

[LittleFlower]

Thanks everyone for the tips on what to look for and the steps to take.

So far, I've replaced on fuel injector. I determined which one wasn't working properly by disengaging one at a time. When the engine stopped, I could tell which one was the working one! Now the boat sounds MUCH better. The knock is gone. However, before I use my engine too much I want to check the compression as well. Thats the next step. I still need to get new gaskets for the fuel injector. I'm afraid I did make one mistake. Apparently, fuel injectors are supposed to be stored in oil, and my new one was not. I wonder if perhaps I need to remove it again, put it in oil for a while, and replace it again. Also, I need to take the old one to a mechanic to have reworked so it can be a spare. I'm working slowly.I must have water leaking in somewhere. That would explain the white smoke. I want to find it, but am still trying to figure out the next step.

To answer your questions:
My Yanmar has a closed cooling system. Its "fresh water" cooled. I think its silly that they still call it "fresh water" cooled even though the engine uses coolant rather than water!

there are no glow plugs

the sound was a knock, not a chirp. It was an irregular knock. Its no longer there. I would like to listen for it again, but I want to check the head gasket before I run the engine too much more.

I checked the oil. It looks normal and at normal levels.

What is a leakdown test?

Gene, I tried to contact Blok Check but they didn't email back. I can't find a local dealer.

Artful Dodger, about your concern, I strongly feel that the journey toward self sufficiency is worth the extra time (and possibly money) spent. It needs to be my own hands in the engine room! This is important to me.

On the other hand...I don't want to screw things up.

Teresa