Oil film on stern 38-200

[FrankJ]

Hi,
During this past season 2010 I notice a black film on the stern of the boat. The engine does not smoke. Would getting the injectors cleaned help? Is it a big job to remove them in the winter? Or can an additive be added to the fuel to correct this? The Universal manuel for the #5432/m40 engine calls for 8-8.5 quarts of oil. I've been putting 10 quarts in-filling to the mark on the dipstick. I've also notice a slight oil leak to the right of the water pump by a long narrow pan.

I would appreciate suggestions.

Frank/Dragonfly

 

[rwthomas1]

I have a 5432 and recently had to replace it. I tore into a spare engine, almost completely apart, reassembling, and installing it myself. I'm pretty familiar with that engine now. The old engine would soot the transom as you describe. The new engine does not. Many things were changed in the engine swap but what I think made the difference is the new exhaust. The old exhaust was very restrictive.

Going by recommendations from waterlift mufflers suppliers, the old system was woefully undersized. A 32hp diesel should have a 2 1/2" ID system, right to the transom. Mine was 1 1/4" ID internally at a few spots with a 1" thru-hull on the transom! I uprated to 2" throughout, as that is the size of the outlet on the exhaust elbow. 2" hose to the new 2" in/out waterlift muffler to a new 2" thru-hull on the transom. The engine sounds very different now at high RPM. Virtually no transom soot. I would have used 2 1/2" hose but I don't have the room.

A restrictive exhaust, especially in a naturally aspirated diesel will restrict engine breathing. The result is the engine acts like its over-fueled. Not enough air to burn the fuel completely and the soot ends up as smoke and crud on the transom. Not really good for power or the engine either.

I would take a very close look at the exhaust particularly if it is original.

Do a search on my 5432 project, I documented it pretty well.

RT

 

[u079721]

Hi,
During this past season 2010 I notice a black film on the stern of the boat. The engine does not smoke. Would getting the injectors cleaned help? Is it a big job to remove them in the winter? Or can an additive be added to the fuel to correct this? The Universal manuel for the #5432/m40 engine calls for 8-8.5 quarts of oil. I've been putting 10 quarts in-filling to the mark on the dipstick. I've also notice a slight oil leak to the right of the water pump by a long narrow pan.

I would appreciate suggestions.

Frank/Dragonfly

As for the oil, I'm pretty sure the question of oil capacity on the 5432 (M40) has come up here before, with the suggestion that if you fill all the way to the mark on the dipstick, with the engine at the 15° or so angle at which it is mounted, then you may be overfilling the crankcase slightly. The recommendation I remember was to fill it with the suggested amount, even if it reads a half quart or so low. (Anybody else remember this? Class? Class?)

As for the soot, we had a 1989 E38 with (I think?) a better exhaust system than the older 38s, but we still had that soot on the transom. We had the injectors cleaned and the valves adjusted, and it still didn't help. What did seem to help some was a diesel additive to reduce soot (something from West Marine - forget the name) but even then we still had plenty of soot.

I always felt it was just because the exhaust fumes traveled up the underside of the transom before escaping, and that the soot on the transom underside was sort of inherent in this design. Other boats mostly have the exhaust in the upper part of the transom so that the exhaust is free to dissipate without touching the boat surface, and some boats even have 3" long exhaust pipes to help the fumes dissipate. So I just lived with it and washed the transom every 50 hours of engine time.

Rob's experience with a new engine is certainly interesting, BUT I'm not sure whether his new set up is clean because of a better exhaust, because it isn't a 5432 (?), or because his engine is now new and naturally puts out less soot.

 

[Frank Langer]

I had quite alot of soot on the transom of our E30+, even though the engine has less than 1,000 hours on it. I started using Stanadyne fuel additive, and it noticeably reduced the soot on the transom. I still get some, but not nearly as much. I recently bought some Startron to see if it will be bettery yet, but haven't had a chance to try it yet.

If I push the engine hard (which I try to avoid), it creates a bit more soot. I don't have a tachometre, but generally try to run at about 80% throttle.

Frank

 

[rwthomas1]

To clarify: I replaced a 5432 that was damaged due to a fuel dilution problem with a "new" used 5432. The "new" 5432 was disassembled to a short block, all clearances that could be checked at this point were, the engine was found to be in good condition so I simply reassembled it, painted everything, etc. etc. and installed it.

The injectors on the "new" engine were never tested. To remove them you need a Kubota socket I couldn't easily find so I left them alone.

Could the new engine just run cleaner than the old? Sure, I don't really have a perfect comparison here. The exhaust is still the most significant change in the whole project of simply swapping one 5432 for another 5432.

Either way, if the exhaust is woefully undersized and original it is certainly due for replacement either way.

Hope that helps, RT

 

[rwthomas1]

A pic of the new 2" hose running from the exhaust elbow to the waterlift. Its 2" up and out as well, just visible in the right side.

RT

 

[mherrcat]

Everything in that picture is just way too clean...

That's disgusting!

 

[Stu Jackson]

Frank, oil at your pump? Check the seals, may be going and need to be replaced.

 

[FrankJ]

Oil film followup

I'd to thank everyone for your reply and hope you enjoyed your Thanksgiving.

I like the idea of adding a fuel additive and will lower the oil level in the spring. Is the oil pump (the Universal manuel calls it a F.W. circulating pump) one in the same? And Rob your engine compartment looks so clean.

Frank