White Smoke at over 2,000 RPM - Westerbeke 38B - Four

[jviss]

Summary: Never overheated, ran at 180º F, but got white smoke at over 2k RPM. Smoke goes away when speed is lowered.

The Westerbeke 38B - Four is a traditional four cylinder diesel, naturally aspirated, a marinized Misubishi tractor or industrial engine ( I don't know the Mitsubishi model).

All seems pretty good with the engine and systems, as far as my inexpert eye can tell. But who knows? It's new to me, as is this boat, and while it was supposedly cared for by a full service yard, I've found some items that should have been taken care of that were not.

It ran beautifully at the sea trial last September.

So, this cool Sunday (yesterday) while leaving the harbor I noticed white smoke once I pushed it past about 2k RPM. When I backed off, back down to 2k or less, the smoke went away.

I assumed it was steam, but I can't be sure it wasn't unburned fuel. The smoke did not fall to the water, it seemed to go straight out about a foot with some rising, before dissipating. But I'm not sure. There was no blue color that I could see.

Peter Compton's book, Troubleshooting Marine Diesels, is my Bible on this topic. Therein he says steam can be from:

• water vapor from condensing exhaust gases is normal in colder climates
• Insufficient raw water flow
• Excessive exhaust gass temperatures

He says white smoke that is unburned fuel can be from:

• Poor atomization
  • injector nozzle stuck open
  • injector nozzle seat worn
  • injector pressure low
  • low ambient temp.
  • low grade fuel
  • injector timing retarded
• Poor compression
  • leaking inlet or exhaust valves
  • worn piston rings and cylinders
  • piston rings stuck in grooves
• Water in fuel - Small quantities of water in the fuel will show as white exhaust smoke.
  • contaminated fuel
  • defective cylinder head gasket

He also notes that "excessive periods at idle cause a buildup of unburned fuel within the exhaust system that burns off in the first few minutes the next time the engine is operated under normal power. This condition is normal for diesel engines and common in sailboats that idle for lengthy periods charging batteries or running freezers."

Well, we do charge batteries on the mooring, about 1.5 hours at 1500 RPM.

But I'm thinking, of all the possible causes, I might have a raw water flow inadequacy, only because this comes and goes so closely related to engine speed and load.

Could it still be steam from inadequate raw water flow even though I didn't overheat?

Also, it was unseasonably cool out, maybe 70 to 75º on the water Sunday (Massachusetts South Coast).

I would think any of the unburnt fuel issues would result in symptoms at all engine speeds. That's why I'm thinking it's steam.

My plan is to next go through the raw water system, from through hull to strainer, heat exchanger, transmission (raw water cooled JS marine gear), hoses, etc.

Thoughts?

 

[Rick486]

I once owned a 4-107, which was replaced with a 4-108 in my Pearson 39 yawl. These are traditional, low speed diesels. My cruising speed was 1800 RPM flat out. The literature said it could run much faster but I never dared, and they both seemed happy at 1800. I did often see white smoke depending on weather, and how I had been running. After a period of slow running, there would be some white smoke upon speeding up to cruise, which then dissipated, sometimes. The mechanic who installed the 4-108 for me said that the white smoke (brand new engine) was unburned fuel, which resulted from the slow running. However, the exhaust system on that boat was strange in that the injection elbow went to a hydro hush, and then up a lift to a long exhaust hose to the stern. All of that was 1-1/2 hose. The mechanic said at the time that the entire exhaust system should have been at least 2", in his opinion. FWIW

 

[berner73]

How long did you run it above 2K to see if a rise in engine temp would result? Were you able to put your hand in the path of the smoke for about 15-20 seconds and smell it after? Should be able to pick up the smell of diesel that way if it's unburned fuel. Do you see the same behavior when in neutral (no load) - i.e. could it be a pitch issue with the prop? Can you talk to the PO to see if they experienced the same thing?

 

[jviss]

However, the exhaust system on that boat was strange in that the injection elbow went to a hydro hush, and then up a lift to a long exhaust hose to the stern.

Thanks for your comment. Mine's similar, a cylindrical, fiberglass(?) muffler near the elbow, and then a lot of hose to the transom pipe. Maybe it gets loaded with unburnt fuel from slow or low-load running?

 

[jviss]

How long did you run it above 2K to see if a rise in engine temp would result? Were you able to put your hand in the path of the smoke for about 15-20 seconds and smell it after? Should be able to pick up the smell of diesel that way if it's unburned fuel. Do you see the same behavior when in neutral (no load) - i.e. could it be a pitch issue with the prop? Can you talk to the PO to see if they experienced the same thing?

I ran it for about 30 minutes at 2500, maybe longer, with no water temp increase. Solid regulating at 180º.
We were short handed and still shaking-down, so no opportunity to get onto the swim platform and get a hand over the exhaust. I didn't think to check if I get smoke with no load.

I had forgotten, I abruptly sped up last week and saw white smoke, too, and come to think of it, too quickly for it to be 'sudden steam,' so that must have been fuel. Don't know it they're related.

 

[jviss]

By the way, the worst of these symptoms I can imagine is the last one I listed, a head gasket. Ugh!
Could be fuel, but I just added 1/2 a tank of new fuel last week. I don't know how old the existing fuel was. Also, don't see any water in the Racor.
During sea trial it ran up to good speed and power, at "book specs." Panel tach (off alternator) and digital tack on flywheel agree.

 

[jviss]

Follow-up: solved. It was a seawater strainer clogged with grass. Actually, there's a sharp elbow from the hose to the Groco ARG-750-P strainer, and the elbow was clogged, the basket wasn't full. All good now.

 

[Panera]

I just had a similar experience with my Yanmar only black smoke. It turns out that one of the fuel bleed valves was loose allowing air into the system when operating at higher speed. Closing the bleed valves tight fixed the problem.

 

[odaydokay]

Follow-up: solved. It was a seawater strainer clogged with grass. Actually, there's a sharp elbow from the hose to the Groco ARG-750-P strainer, and the elbow was clogged, the basket wasn't full. All good now.

To me, allowing anything like that inside the boat is a risk I don't want to take. My boat came with a so called Great South Bay Strainer (see Buck Algonquin 00RSS1000P as example). With one of those, it is very unlikely anything will get as far as the inside strainer, ever.... Just a thought. Has worked for me for 23 years on my O'Day 28.

 

[jviss]

To me, allowing anything like that inside the boat is a risk I don't want to take. My boat came with a so called Great South Bay Strainer (see Buck Algonquin 00RSS1000P as example). With one of those, it is very unlikely anything will get as far as the inside strainer, ever.... Just a thought. Has worked for me for 23 years on my O'Day 28.

Thanks, I will look into that.

 

[Rick486]

To me, allowing anything like that inside the boat is a risk I don't want to take. My boat came with a so called Great South Bay Strainer (see Buck Algonquin 00RSS1000P as example). With one of those, it is very unlikely anything will get as far as the inside strainer, ever.... Just a thought. Has worked for me for 23 years on my O'Day 28.

If you search around this web page you will see that the use of an exterior strainer has been debated extensively. Some say that the exterior strainer is difficult to maintain clean and it is a simple matter to clean out an inboard strainer, in the absence of an outboard strainer, when it clogs with flotsam, eel grass, or some such. Personally I have used external strainers on the 3 inboard boats I have owned over 37 years and never had either an outboard or inboard strainer clog.

 

[odaydokay]

Rick, you did remind me of one thing: The holes in some of these strainers are in fact quite small and when applying your bottom paint (if one chooses to paint them), it will be necessary to bore those holes out after the paint dries, not every year but maybe every 2-3, before launching.

 

[Rick486]

Rick, you did remind me of one thing: The holes in some of these strainers are in fact quite small and when applying your bottom paint (if one chooses to paint them), it will be necessary to bore those holes out after the paint dries, not every year but maybe every 2-3, before launching.

Right on oday!
My routine is to inspect the inside of the strainers from outside with a bright flashlight (mine have slots rather than holes on this boat) in the spring, then spray the inside with the same anti fouling paint I use on the prop, then, as you suggested, be sure to inspect the slots after bottom painting to be certain there is no blockage.

 

[odaydokay]

Sounds right for your situation There are many stories about intake fouling and this is pretty cheap insurance in the scheme of things. I think you would have to be deep into some mud to clog one.

 

[jssailem]

You might want to take a look a full flow pipe elbow for your raw water strainer.

http://www.discountmarinesupplies.c...hVsgbMQdFx1OjbwQBG2RMw0vwDQtahPxoCk50QAvD_BwE

 

[jviss]

Thanks, John, yes, I've been thinking about that! I'm putting it on the list for the Fall, will just keep checking the strainer during this sailing season.

I wish I could check the oil and the strainer from the same location! I confess, with some embarrassment, that I had to consult the manual to find the dipstick! (Starboard, towards the rear of the engine, accessible through a removable panel in the aft cabin.) I wish the transmission dip stick was at least as easy, that one requires removing a "box" in the aft cabin bunk. Oh, well. Gotta check it, as parts are no longer available for the JS transmission.

 

[jssailem]

I agree with that idea. I relocated my raw water strainer so it was serviceable on the side of my engine with access. Also made sense to change to a Groco ARG750. Easy to open and clean. Love it.

 

[jviss]

Also made sense to change to a Groco ARG750. Easy to open and clean. Love it.

Yes, but my "sight glass," the clear part, is stained brown and you can't see through it. The new part is like $40.

 

[jssailem]

You can remove the glass from the bronze frame. Then you might be able to clean the glass with something like CLR or FRS. Or even Barkeeper’s friend.

 

[jviss]

You can remove the glass from the bronze frame. Then you might be able to clean the glass with something like CLR or FRS. Or even Barkeeper’s friend.

Yes, I did, and tried cleaning it. It seems like the vegetative matter dyed it.