Lehman 80 - soot problem

Keep finding black soot on the transom after a run.
Engine runs fine with no overheating, no fuel in the oil or coolant. Prop is correctly sized, but do not usually run over 1800 rpm.

Ideas welcome.

Greetings,
Welcome aboard. Bejasus? Irish?

I used seafoam and it cleaned the injectors and no more soot

Scots actually but I can see why you would think Irish. It is the name of the boat but actually an anagram of our kids names. BEn,JAde,SUmmer,Sasha. It seemed an appropriate name.

Leamens /Perkins I have a Perkins 6 that has about the same finesse engineering standards as a Leamen . Both share 50 yo technology they both smoke learn to love it

Greetings,
Mr. B. Sorry. No insult intended. I have an Irish friend and that's one of his more common expletives. As in..."She came around da corner and scared the bejasus out of me"...Again, apologies...

No apologies required. We found it an apt name since the boat frequently scared the bejasus out of us. ��

Welcome Bejasus, lots of old diesels smoke a bit and produce some transom soot. Mine does, but not excessively. It is really not a sign of any issues unless it is excessive, so just learn what takes it off without too much work and enjoy!

I get it too. Even with two 6.3l Volvos only 17 years old. I haven't explored if there is a solution to it just yet. I hope an oil change might do it, I thought new air and vent filters would do it, but TBH, I believe it is just the location of the exhaust outlets in our case. But hey, they run hard and true... and nothing a couple of magic erasers won't fix

Have you ever had the injectors rebuilt?

Nope, but intend doing so soon.

Most times visible smoke or a dirty transom is simply caused by the time period in which the engine was built.

They used the best tech at the time , rebuilding an old problem free injector will not solve the problem.

For most cruisers age is a blessing , no need to super filter "clean " from the pump fuel as the new engines require , no need to check SCA in the antifreez.

Like a mustache on the bow , a sooty transom just shows you use the boat.

Scrub it before you sell it.

FF,
Spot on but many a good thread has come about from over kill of some problem that may not be a problem at all. Over the years we've had probably hundreds of posts about swivels. Never heard of one breaking.

Never had the soot problem prion to going to the Bahamas last year. A little blue smoke on start up was normal. The black soot is not, so we will see what an injector service will do.

Is the air filter clean? If so, injectors would seem the next likeliest place to look. But as others have said, older diesels do tend to emit a bit of exhaust soot.

Look at tailpipe while at cruise speed. Is water spilling out having a grey-ish color? Any visible black smoke? If yes to either, you are operating the engine beyond its "smoke limit". If no to both, engine is operating at an ok point and whatever soot sticking to transom is normal.

Don't know if its good, bad or indifferent, but I have twin Lehman 135's of 80's vintage and have never found any soot anywhere on the boat even after 3 years of cruising with it.

Ken

I'm not so sure "modern" engine design and materials will guarantee a clean stern. I've seen many Volkswagon diesels w a considerably modern engine including turbocharger going down the road w a sooty butt.
Maybe there's a sensor that senses one cylinder is lean and enrichens all four cylinders to compensate. ??

Nomad Willy said:

I'm not so sure "modern" engine design and materials will guarantee a clean stern. I've seen many Volkswagon diesels w a considerably modern engine including turbocharger going down the road w a sooty butt.
Maybe there's a sensor that senses one cylinder is lean and enrichens all four cylinders to compensate. ??

Click to expand...

Over time & miles, my TDi increasingly left visible smoke under acceleration. The diagnostics showed no code that would explain it. But, during each timing belt service, I spent a lot of time cleaning black gunk out of the intake tract downstream from the EGR (exhaust gas recirculator). After breathing in enough exhaust gas, the butterfly plate that closes the intake on shutdown became so caked that it was reducing intake air. Apparently the electronic control module couldn't compensate enough to maintain clean combustion, ergo - black smoke.

After I installed a deadplate over the EGR port, problem solved. In doing that I admittedly negated part of the engine's so-called "clean-exhaust" technology, but OTOH reducing the visible smoke (unburned hydrocarbon particulates) in my exhaust is a good thing.

Enough TDi owners who pay attention to their diesels seem to have been adopting the same tactic, so much so that EGR "deadplate" kits are available on-line.

Diesels produce soot. Excessive soot when an engine is in spec can be insufficient air getting to the engine. Caused by restrictive vents, dirty air filter or sound dampener.
Often, yacht owners, complaining of engine noise, restrict the vents with baffles or other sound proofing materials. Some boats are built without enough vent area. Diesels require much more air than gas engines.

From an expert on diesels and soot.....has patents on how to reduce it.

"That engine probably produces close to one pound of particulates every 24 hours of run time even if there is no smoke visible.

Soot is the largest part of diesel particulate emissions. Even if there is no black smoke visible then the soot on the transom is a result of air flow stagnation in the area keeping exhaust there long enough for soot particles to coalesce on salt spray mist that sticks to the paint. Even the smoothest looking paint has pits and valleys that under a microscope look like the surface of the moon. Soot collects in those areas.

Trust me, I know soot. "

Greetings,
Mr. ps. Pass my regards on to the "diesel expert"...

Enough TDi owners who pay attention to their diesels seem to have been adopting the same tactic, so much so that EGR "deadplate" kits are available on-line.

Click to expand...

I have a similar "mod" on our 99 Jetta TDI. After cleaning the intake twice I said no more.

How do you operate your engine? Idle warm-up? Ever run WOT?

Maybe read the "smoking Cummins" thread?

RT Firefly said:

Greetings,
Mr. ps. Pass my regards on to the "diesel expert"...

Click to expand...

Hope to have dinner next week....

Never seen soot on the transom from my Lehman 120s exhaust.Something is amiss with the OP`s engines or their operation, or both.
VW is an unfortunate example for soot and particulates. My Peugeot 2.2L diesel car is painted black. Does it produce soot, hard to say, but I don`t think so.
I`ve seen diesel cars hit the freeway going out of town, first hard acceleration producing a big burst of blackish smoke, clearing the muck built up idling around town I`d say. My run to/from the marina involves highway speeds, car diesels like that.

I really never notice any soot on my transom...but just replaced my national ensign because it was so dirty looking.

There's soot back there whether you see it or not or whether it sticks or not....it is a by product no matter how well your engine runs. Of course it's much less if everything is running correctly.

"I really never notice any soot on my transom..."

Nor me , but at 12 ft off the water it would be a task for the dry stack.