Lehman 225 moderate black smoke...

Hey guys. Had the boat for about a year now. We’ve noticed the starboard engine has started to smoke quite a bit. While underway at 1600 it had a moderate amount of black smoke. Never used to. Port engine doesn’t smoke. If it wasn’t for the smoke, I’d never know anything was wrong.

We had friends following us to an anchorage and they said it was pretty much smoking the entire time, even in no wake zones.

I did have an overheat issue with that engine when we had a split coolant hose. It alarmed a couple of times at 200 degrees before I shut it down. I can’t imagine it ever got hot enough to hurt anything, although it is in the back of my mind.

Any thoughts?

I have a Cummins 5.9 in my F350 with bigger injectors and turbo. Black smoke is a sign of too much fuel and not enough air. So maybe this Lehman is having a turbo or intercooler issue?

I am not much of an engine mechanic and I have the same engines so I will be watching this thread to see what is recommended. I don’t have any current issues with mine but I always want to learn more about them.

Likely an injector issue if the air intakes/filters are relatively clean...

Have you ran them at a heavy load for a long enough period of time recently to clear up any carbon deposits that may have an affect on valves?

Flybull said:

Likely an injector issue if the air intakes/filters are relatively clean...

Have you ran them at a heavy load for a long enough period of time recently to clear up any carbon deposits that may have an affect on valves?

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I haven’t. I know I’m supposed to but we’ve had that cooling issue that I’ve been chasing for a while.

Black smoke is from soot in the exhaust from unburnt fuel.

That can be caused by too much fuel, or not enough fresh air.
It could be as simple as a plugged air filter, or as complex as a fuel injector pump.

I would start with the simple things, "the air filter", then look at the turbo. It should have CLEAN veins, and spin very easily. If the turbo has a oil seal leaking it will mix with the intake air, and cause a rich condition of unburnt fuel. If you pull the air filter off you can look into the turbo, and start the engine. Then have someone watch the exhaust for black soot. With the engine running at 1000 RPM hit the kill switch, and watch the turbo spin down. It should it should take about 15" to stop turning. KEEP your fingers clear while doing this! If the turbo stops spinning with the kill switch the shaft bearing is out. Have the bearing and seals replaced. Check the oil supply and return lines at the same time.

If that all checks out it is time to check the injectors, and injector pump.

The injector side of things is difficult and should be done by a diesel tech.

Thanks guys. I think I’m going to try some Lucas fuel injector cleaner for diesels.

No air filter, just a screen. Turbos are fine, I can hear them spooling. But I’ll pull the screens and spin the shaft and check for play. They also smoke at idle and especially while maneuvering for docking (1000 rpm usually).

Actually since the engines are warm right now I’ll start them and run them up at the slip and take a video.

So I just did a test, engines already warm. In neutral, right engine hit the stop at 2900 rpm, left was 3100. Both smoked about the same at idle. But here was the result of running the right engine to 2700 rpm. That’s a lot of smoke for no load. I’d be willing to bet it’s an injector issue. Had a similar issue with my Cummins in my truck.


https://youtu.be/TfaoSEGXeuw

Many high output turbo engines will smoke like that at no load hi rev. Turbo is not making boost without load. No boost, not good combustion.

The 225 has an aftercooler, pretty sure of that. Could be plugged. I'd look for a tap on the intake manifold and get a 0-30psi or 0-20psi gauge and plumb it to the intake mani and take it for a run and read it. Swap to do the other side.

Could be an air issue, could also be an injector issue. I have been around many engines where injectors were swapped, serviced, rebuilt, whatever and 95% of them the problem persisted and actually caused by something else.

The boost gauge check is cheaper than messing with injectors!

Also go in engine room and start one engine at a time. Rev it from idle to like 1500 quickly and listen. A sick injector (usually) causes a rough accel. You can hear it and feel engine shake on its way up. Compare to good engine. Another cheap test.

Also check blowby flow at idle, look for puffing. Compare to other engine.

No tech needed to do the above stuff.

Yes, it has an aftercooler.

I do not know how the timing is set on your engine but retarded timing might not give the fuel the time to burn, so black smoke?

Many injector shops will test injectors for almost nothing , if they get the rebuild job $60-$85 or so , each .

I've a friend with the L225s. A few years ago he removed his after coolers and had them ultrasonic cleaned and pressure tested. ACs do need a servicing every few years as a normal maintenance item.

As suggested by others, ACs, injectors and fuel delivery pump could be culprits. Possibly prop size needs checking, overloaded maybe.

Steve91T said:

So I just did a test, engines already warm. In neutral, right engine hit the stop at 2900 rpm, left was 3100. Both smoked about the same at idle. But here was the result of running the right engine to 2700 rpm. That’s a lot of smoke for no load. I’d be willing to bet it’s an injector issue. Had a similar issue with my Cummins in my truck.

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I have exactly the same engines on my boat. Before I would touch or do anything I would suggest you call Bryan @ American Diesel. Please check your Tachometers for accuracy. SP 225 is factory limited to 2800 rpm neutral and 2500 rpm under load. It is not recommended adjusting upper rpm. The other thing in most cases this engines are way too powerful for our boats. It is recommended to throttle up them once in a trip to 2000 + rpm for some time to let them blow the carbon and other build up's out. I normally run my boat @ 1500 rpm / 9 knots once engines reach the normal operation temperature and surrounding waters permits me to do so I get my boat to 2000 rpm / 10.5 knots and a massive wake for 20 min to 1 hour all depends on surrounding and the length of the trip. Good luck.