Diesel advice needed

I have an M40 in my 38-200 which has some white smoke in the exhaust. This spring when commissioning I replaced the fuel injectors. Unfortunately, did not check compression while it was apart. The engine runs much smoother with the new injectors but still have white smoke. I am not sure I trust the gages but my temp gage shows 160-165F even if I run hard for several hours.
1. What things should I check next to see if I can eliminate the smoke?
2. How concerned should I be? As I said, it seems to run great.

The real experts will probably give you good advice shortly, but in the meantime I can mention a couple of things to check or think about. Firstly, you mention white smoke--is it like steam/vapour or real thick white smoke? Is there any smell to it at all that would give a clue as to it's origin? Is it a bit blue and does it have a burnt oil smell like out of the exhaust of an old car on the road? If there is no blue/burnt oil smell, then I'm thinking your compression is not the problem. Is your engine oil clean, with no milky look to it (which might indicate coolant or water in the oil)? Does the engine smoke as much when it is warmed up or does it only do this on start up and while warming up? Does it do this regardless of the outdoor temperature (mine will show steam/vapour in very cool or damp conditions). Does it do it the same at all speeds/rpms or only at full throttle? You mention that the engine temp is about 165 which sounds ok, but do you have any indication that the engine is overheating (in case the gauge is faulty), like a burnt coolant smell, overly hot hoses? Is there any sign of smoke in the engine compartment or only out of the exhaust? How many hours are on this engine (ie. it's age/useage) and since when has it produced the white smoke?

Hopefully as you think about the answers to my questions, it may help you to develop some ideas about the cause of the smoke, and if you can provide more detail, others may be able to pinpoint it more effectively.

The fact that your engine runs smoothly is a very good sign, and it may not actually be anything to worry about--let's see what the experts on this site suggest.

Frank

Frank
it is pretty light, no smell. Next time it happens I will put a paper towel over the exhaust and see what I collect. I think it only happens when I run at higher rpm for a while. We ran over to fill with diesel today and ran for about an hour and no smoke. But we were at lower rpm most of that time. Oil is black. It probably goes through a quart in 50 hours or so. I added a quart today. Will probably change the oil before it goes down another quart. The smoke does not happen all the time. I need to keep a dairy and see if I can detect a pattern. We are in New England so it is usually cool with moderate humidity.

Hi,

I'm not a mechanic, so I'm not really sure. But it seems to me that if you had a real engine problem it would smoke consistently, or at least consistently under higher load. Adding a quart of oil after 50 hours does show some engine wear in my opinion, and maybe the engine burning some oil is contributing to the smoke; but if this was excessive it would be more like blue smoke with an oil smell rather than white.

I think keeping a diary for a while may be a good way to sort out under what conditions it smokes. My current guess is that it may be water vapour, especially if it dissipates quickly rather than lingering in the air.

Maybe the experts will chime in soon to give a professional opinion.

Good luck and let us know what you find as you do the diary.

Frank

Hi,

white smoke is typically water vapor. It's possible that you have a minor head gasket leak if only noticeable at higher RPM. However, check your oil before you worry. If it is nice and black with no sign of mocha, then if that is it, it's not leaking into the crankcase, and I would still be hesitant to assume that was the issue, and more investigation is needed. I've seen some white from happy engines over the years in what seems to be certain combinations of water temperature and air temperature etc. - I would generically say that when I've had an engine with a blown head gasket, it's very obvious - smoke, over heating, contaminated oil, doesn't run well and so on. An engine that seems just fine running at normal temperatures with a what looks like a little white "smoke" may be just some inherent water vapor/self made fog and nothing to worry about.

If the engine is over loaded e.g. has a fouled prop or doesn't have the correct prop and isn't able to get up to max RPM properly, you will belch black smoke.

And remember, this take is worth what you paid for it

Update. We cruised 30 miles today. Motored out of Provincetown with no smoke. About 15 miles out got fogged in so motored the rest. Heavy smoke (and fog). When we got into harbor I checked exhaust. No smell or noticeable residue. Based on what you guys have said, sounds like steam. Not sure how it is happening but engine seems happy and no evidence of water in the oil. Fingers crossed.

Is it smoke or is it steam?

Dear friend, A number of years ago I went through three iterations of prop pitch attached to my Yanmar 3GMF engine before dialing it in on the nail head. Of the many suggestions and observations I made, I was able to rule out being overly propped by virtue of the soot going away aft of the exhaust fitting after the first blade tweaking. I was then able to eliminate excessive oil or fuel consumption as being the culprit by closely noting whether the cloud was more or less remaining horizontal (heavier than steam vapor) after exiting the exhaust flange or if it was rising and dissipating quickly. So I went from lots of soot to whitish exhaust smoke to steam vapor and finally pretty much nothing once the prop was in tune. Next time you have the chance, observe to see if the exhaust tends to rise more than you remember before, that might tell you that it's steam vapor. Even at that, I wasn't happy knowing that it was just that much steam, so I pressed on to the point of acheiving virtually no steam. Oh, I imagine on a cold day it might be visible a bit but not to the extent that I feel the engine is working too hard. Cheers, Glyn Judson, E31 hull #55, Marina del Rey CA

I generally don't have any smoke or steam when underway with normal operation. But I do notice when it's very damp or foggy that I get a bit of steam which dissipates quickly--not a cloud of smoke, just a bit of steam if I look down at the exhaust over the transom. I'm guessing that's what yours is, especially given that it operated fine on the earlier portion of the trip.

Frank

Glyn Judson said:

Dear friend, A number of years ago I went through three iterations of prop pitch attached to my Yanmar 3GMF engine before dialing it in on the nail head. Of the many suggestions and observations I made, I was able to rule out being overly propped by virtue of the soot going away aft of the exhaust fitting after the first blade tweaking. I was then able to eliminate excessive oil or fuel consumption as being the culprit by closely noting whether the cloud was more or less remaining horizontal (heavier than steam vapor) after exiting the exhaust flange or if it was rising and dissipating quickly. So I went from lots of soot to whitish exhaust smoke to steam vapor and finally pretty much nothing once the prop was in tune. Next time you have the chance, observe to see if the exhaust tends to rise more than you remember before, that might tell you that it's steam vapor. Even at that, I wasn't happy knowing that it was just that much steam, so I pressed on to the point of acheiving virtually no steam. Oh, I imagine on a cold day it might be visible a bit but not to the extent that I feel the engine is working too hard. Cheers, Glyn Judson, E31 hull #55, Marina del Rey CA

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Ok, so that is interesting. I have a 16" Max prop two blade. I have had the boat for three years and never touched it (did have the yard redo cutlass bearing etc but don't think they changed anything on the prop). Looking at the instruction book it looks like the PO set it to 20 degrees blade angle and 11 degrees pitch. Max RPM is about 2800. What did you finally settle on? I do get a minor amount of soot after several hours of motoring. As I mentioned yesterday I think it is steam now, not smoke because it does tend to swirl upwards and dissipates and there is no noticeable smell. I need a dry day to be able to confirm. I would still like to make it go away.

May just be steam

lnill said:

Ok, so that is interesting. I have a 16" Max prop two blade. I have had the boat for three years and never touched it (did have the yard redo cutlass bearing etc but don't think they changed anything on the prop). Looking at the instruction book it looks like the PO set it to 20 degrees blade angle and 11 degrees pitch. Max RPM is about 2800. What did you finally settle on? I do get a minor amount of soot after several hours of motoring. As I mentioned yesterday I think it is steam now, not smoke because it does tend to swirl upwards and dissipates and there is no noticeable smell. I need a dry day to be able to confirm. I would still like to make it go away.

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I notice steam from the exhaust during winter months here in Galveston Bay. The water temp usually averages 50-60 degrees. I concluded the steam was caused by hot water spilling in to the colder water creating vapor. Temperature differential would be about 100 degrees. I figure your water temperature has risen enough to fix the problem. If no steam is detected for the rest of the summer, you may be good until the water temp starts to drop again. Good luck.

Proper prop pitch.

Inill, Our prop setups are vastly different, I have a 3-blade fixed prop that had to be removed, re-pitched and replaced throughout the testing phase. Now, what I'm about to share applies to my installation and may not be what you should ultimately end up with, so with that said, the way it is currently pitched, I can sometimes get some steam with the correct weather conditions but on a warm summer day, there is no steam whatsoever. Early on at the #2 stage of redoing pitch, my concern over excessive steam was that I was overtaxing the engine, thereby causing it to run too hot. The question you have to ask yourself is to what degree do you have steam and is it an indicator of an overheating problem. My first impulse is to say that it probably is not an issue but you are the one who could answer that better. FYI, here are the numbers for my installation. Yanmar 3GMF, a Kanzaki KM3P transmission, 2.61:1 ratio driving a 3-blade fixed prop, 13 X 12 1/2 RH All that results in my being able to achieve 3,700 RPM on flat water with a maximum sustained engine speed of 3,400 RPM. To run at full throttle (3,700 RPM) would result in overheating after one hour operation, guaranteed because it's happened to my wife several times when single handing without the knowledge that the engine could only safely run at 3,400 RPM. Can you say two blown head gaskets before I figured out what she was doing???? Mind you, ultimately it was my fault and not hers, I should have told her not to run the engine at that higher speed. Confused more now? Glyn Judson, E31 hull #55 Marina del Rey CA

Glyn Judson said:

Inill, Our prop setups are vastly different, I have a 3-blade fixed prop that had to be removed, re-pitched and replaced throughout the testing phase. Now, what I'm about to share applies to my installation and may not be what you should ultimately end up with, so with that said, the way it is currently pitched, I can sometimes get some steam with the correct weather conditions but on a warm summer day, there is no steam whatsoever. Early on at the #2 stage of redoing pitch, my concern over excessive steam was that I was overtaxing the engine, thereby causing it to run too hot. The question you have to ask yourself is to what degree do you have steam and is it an indicator of an overheating problem. My first impulse is to say that it probably is not an issue but you are the one who could answer that better. FYI, here are the numbers for my installation. Yanmar 3GMF, a Kanzaki KM3P transmission, 2.61:1 ratio driving a 3-blade fixed prop, 13 X 12 1/2 RH All that results in my being able to achieve 3,700 RPM on flat water with a maximum sustained engine speed of 3,400 RPM. To run at full throttle (3,700 RPM) would result in overheating after one hour operation, guaranteed because it's happened to my wife several times when single handing without the knowledge that the engine could only safely run at 3,400 RPM. Can you say two blown head gaskets before I figured out what she was doing???? Mind you, ultimately it was my fault and not hers, I should have told her not to run the engine at that higher speed. Confused more now? Glyn Judson, E31 hull #55 Marina del Rey CA

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Today winds were behind us at 5 knots or less. We motored with the jib out for about 25 miles. Water 67, RH 55%. This is what it looked like.

Update

Decided to resurrect this one and see if I can get any more good advice before I start paying the yard mechanic. The engine has had the white smoke as in the picture I posted off and on all season. For the past couple of months it has been hard to start when cold. I have to crank for as much as 30-40 seconds before it will finally fire. Also there seems to be raw diesel coming out the exhaust when it first fires (based on the sheen I see on the water and smell). Once started, runs great and able to restart instantly the rest of the day. Things I think I need to check include:
compression
valve timing?
engine temp (my temp indicator never gets above 165)
Decompression lever working properly
anything else? Replaced injectors last spring. Is there any adjustment that might be putting too much fuel into the cylinders?

thanks for any advice.
Lee

There might be unrelated problems here. The hard starting gets my attention first. IMHO you should never have to glow plug the engine over 15 to 20 seconds in the summer, and usually less.
I would check that circuit. Follow connections from ground back, plug by plug, to the switch and to the hot. After decades of time and xx hours on the engine, it's possible that new glow plugs are needed. IIRC you can source them quite inexpensively thru a Kubota tractor parts source. You have a Universal diesel engine, right?

With 12 volts, it's easy for a bit of corrosion in any single connection to reduce the current flow.

The vapor or smoke: alas - if it's a problem, it's above my pay grade!
We get a little bit of vapor under load when the humidity is high, like when motoring under load in our cold water. Not much, tho.

Regards,
Loren

Try this..

We've had our 1987 32-3 for 14 years. I never saw the white steam until we started racing in January here on Galveston Bay. The water temp is 67 and your engine temp 165. The hot water from the exhaust is hitting the water and turning to steam. I hold the glow plugs for 40-60 secs in the winter. It starts right up. The fuel you see may be because you are cranking the engine too long and the fuel pump is pushing in fuel and not burning it. The steam will continue till the water warms up. The engine isn't overheating because you stated the temp is 165. Try holding the glow plugs down for a count of 50 secs. This may start the engine in 5 secs. Good luck! Let us know.

hard starting

Have somebody energize the glow plugs while you hold a finger on their bases. Or jump a wire from the battery. Do they get hot? If not it's probably a simple wiring issue.

Christian Williams said:

hard starting

Have somebody energize the glow plugs while you hold a finger on their bases. Or jump a wire from the battery. Do they get hot? If not it's probably a simple wiring issue.

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Good idea. I am going to make a list and meet up with my mechanic next week. I had wiring issues that affected the start switch and re wired that part. Need to re wire all the engine compartment. Won't fix the white smoke but might help the starting.
Could the smoke relate to the low running temp?

I only noticed white steam or smoke once when the raw water became slowly blocked; in my case by weed in the intake. The temp per the gauge didn't change but the steam started early in the scenario. Could be anything that reduces the raw flow to the muffler.

Another thing to look at... A diesel will also belch white smoke if running lean. the injection pump is usually gear driven and precisely aligned with a dial gauge that reads in the thousandths of an inch. there Is a procedure of rotating the engine from TDC back to the lobe bottom in the pump drive, then rotating it back to TDC. at that point a specific measurement value must be achieved (example: .0085+/- .0002) If the lift is too low, you will be lean and have white smoke, too high and you go rich and get black smoke. Also diesel has been re formulated several times in the last few years to remove sulfur and other things, which can change what the optimum pump adjustment is. While on the re formulating subject, recently the nickel and other stuff has been removed from oil and this WILL eat solid lifter cams in older engines. Next time you are in the auto parts store to get oil, ask them for the additive to replace it and use it religiously. You will probably need a diesel mechanic to check your injector timing, as the tools are hard to round up. Edd

All good input. Next week I am going to just rewire the glo plugs. I rewired most of the boat two years ago including the starter circuit but I didn't do the rest of the engine, so will clean that up. If that doesn't fix it then will have the yard mechanic check timing of injectors and compression. That will suck up some $. But a repower would suck a lot more.