VP MD17c gray smoke

[sailcruiser]

I have a Volvo MD17c that has light gray smoke that stinks of diesel. The injectors have been pulled and professionally serviced and that improved but not solved the issue for a short while but it is back. Is there anything else to look at besides the mechanical injector pump and air filters?

If the injector pump is serviced does the shop also need the injectors for timing purposes?

Is it possibly this is a fuel issue?

I'm open to any and all suggestions. Cleaning the air filter on this engine is difficult because you can't see it inside a horn type thing. I soak it in diesel then blow it out with compressed air. Is there a better method?


I done the following so far:

Changed both fuel filters
Injectors removed calibrated and cleaned by a professional shop
Cleaned air filters as described above

Engine starts on first try doesn't sound like its missing
Does not appear to burn oil. Same quantity out s put in last fall. (Monitored all season none added)
Engine oil is only a shade or 2 darker
Smokes as much cold as when warm
I believe I see fuel in the exhaust water

Thanks for any suggestions,
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[a64pilot]

Since you can't really inspect the air filter and don't have a way of determining manifold pressure, I'd remove it and see if it makes any difference, obviously make sure nothing if loose and could be sucked in, or if that overly concerns you, go to the auto parts store and buy a K&N or look alike cone filter and install it.
Once you determine it's not the air filter, I'd move onto testing compression, looking for leaking valves, how long has it been since they were adjusted? Valves wear tight and eventually they could get so tight that they leak. Another easy check.
Somewhere in this checking bypass your fuel tank and pull good clean fuel from an external tank to verify its not that. Then verify injector pump timing is good.
Finally after all the easy and cheap stuff has been checked, pull both the injectors and pump. injector testing is cheap, rebuilds not so, but if they are good then you'll only pay for testing

[Shawn67]

How much smoke, smoking like crazy or a smaller amount? Lots of smoke is likely an injector that is sticking slightly open. I had this happen on my MD7A. It smoked more as more throttle was given. Pulling the injector, opening it and polishing the inside of the nozzle with a bamboo skewer fixed this. There was some deposits inside that was keeping it from closing all the way. Using an IR thermometer I could tell which injector was sticking open as that cylinder was running hotter.

If it is just a smaller constant amount of smoke it could be due to injector timing. I also had this when replacing my fuel injector pump. Mark your injector pump and the block so you have a reference point for your current timing. Loosen the bolts on the pump and spin it slightly to one side or the other. Start the engine and see if you have more or less smoke. Through trial and error I was able to dial out all light gray smoke on my MD7A.

Shawn

[sailcruiser]

Originally Posted by a64pilot

Since you can't really inspect the air filter and don't have a way of determining manifold pressure, I'd remove it and see if it makes any difference, obviously make sure nothing if loose and could be sucked in, or if that overly concerns you, go to the auto parts store and buy a K&N or look alike cone filter and install it.
Once you determine it's not the air filter, I'd move onto testing compression, looking for leaking valves, how long has it been since they were adjusted? Valves wear tight and eventually they could get so tight that they leak. Another easy check.
Somewhere in this checking bypass your fuel tank and pull good clean fuel from an external tank to verify its not that. Then verify injector pump timing is good.
Finally after all the easy and cheap stuff has been checked, pull both the injectors and pump. injector testing is cheap, rebuilds not so, but if they are good then you'll only pay for testing

Thanks a64pilot. I had a similar plan but I like the idea of removing the air filters and using a cone. That may help eliminate the worry of something I can't see. I appreciate the ideas. This has been bugging me for quite a while. 2 mechanics and it's still there. That's why I figure I'll give it a shot and see how it goes.
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[sailcruiser]

Originally Posted by Shawn67

How much smoke, smoking like crazy or a smaller amount? Lots of smoke is likely an injector that is sticking slightly open. I had this happen on my MD7A. It smoked more as more throttle was given. Pulling the injector, opening it and polishing the inside of the nozzle with a bamboo skewer fixed this. There was some deposits inside that was keeping it from closing all the way. Using an IR thermometer I could tell which injector was sticking open as that cylinder was running hotter.

If it is just a smaller constant amount of smoke it could be due to injector timing. I also had this when replacing my fuel injector pump. Mark your injector pump and the block so you have a reference point for your current timing. Loosen the bolts on the pump and spin it slightly to one side or the other. Start the engine and see if you have more or less smoke. Through trial and error I was able to dial out all light gray smoke on my MD7A.

Shawn

Thanks Shawn! To me it's a lot of smoke but that's subjective. If I can figure out how to upload a short clip I'll do so. Otherwise here is a photo. The smoke in the shadow looks much darker than it is. In the sun it's light gray.

Interesting idea on the injector pump. It's worth a try. We will be on the hard until Spring here soon and I'd really like to knock this out.

Thanks again!
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[a64pilot]

From the picture it looks like oil, if it is, it will have a very different smell than if it's fuel.
Your nose should be able to tell you what it is.
If it's fuel, and smoking like that, it will be eye burning strong, as in you hate to be running direct down wind strong.

[sailcruiser]

Originally Posted by a64pilot

From the picture it looks like oil, if it is, it will have a very different smell than if it's fuel.
Your nose should be able to tell you what it is.
If it's fuel, and smoking like that, it will be eye burning strong, as in you hate to be running direct down wind strong.

It does look like oil in the shadow I don't think it is based on close observation. The smoke is eye burning strong and makes me nauseous.
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[a64pilot]

Originally Posted by sailcruiser

It does look like oil in the shadow I don't think it is based on close observation. The smoke is eye burning strong and makes me nauseous.
SC


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It's fuel then, and once you prove the air filter isn't it, I'd be real suspicious of the injectors, timing etc.

[Shawn67]

When my injector was sticking slightly open it was like a smoke screen. Really bad smoke. I actually had off/on problems with one injector sticking open/closed for about a year that I had initially misdiagnosed as an air leak to that injector.

Sometimes it stuck completely closed and I would run on one cylinder (with about 1500 rpm max) or later on sometimes it stuck open a little and smoked like crazy. That is after the injectors had just been rebuilt a year earlier. Opening the injector up (they are very simple inside) and physically cleaning it out solved that problem. I also added Opti llube XPD to the tank.



The video below was taken right after I cleaned out my exhaust manifolds water passages to see if it was going to flow water well before I converted to fresh water cooling. Pretty sure I am running on only one cylinder in this video, it is actually insane how well the Volvo idles on 1 cylinder. It certainly was only on 1 a week or two later when I had it launched and was able to apply a load to the engine. That is when I finally figured out the injector sticking and pulled it and cleaned it up. In this video I hadn't really adjusted the timing yet which is why it was somewhat smokey. Next time I'm on the boat I'll try and get a video of the exhaust now that I have the timing dialed in. Much less smoke. A little when cold then just about none when it warms up.

IMG_3633

If you do try adjusting your timing make sure you mark your starting point. After that *small* adjustments make a pretty big difference to smoke as well as how quickly the engine starts. I timed mine based on smoke and starting.

Good luck,

Shawn

[sailcruiser]

Thank you both for your suggestions. I'll work in this when weather permits. Without a glow plug the old diesel doesn't want to start when it's cold.
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