Diesel Engine Smoking

[Russt1950]

I am looking to buy a 36 Catalina boat. Everything on the boat is ok except, I went back today to run the motor and notice black smoke coming from the exhaust. The owner has not used the boat in awhile. I ran it at 2200rpms and at first the smoke was really thick. After a while it started to ease up. Also, the temp started to rise a little over 180 and then there was white smoke or steam coming from the exhaust. The motor only has 650 hrs on it and I would to get this boat, but don't know if this is a serious problem or not. Any advice appreciated.
The motor is a Universal M35B.

Thanks, Russell

[Chief Engineer]

Get an engine survey done.

[Orrjames]

Sounds like it needs an oil change, and is prob low on coolant in the closed system. Perhaps check the sea strainer as well. Also look for any kinks in the exhaust hose leading out to the overboard discharge . Additives to the fuel can cause strange smoking problems too. It is difficult to get on board with a motor that is not running right and a good inspection from a mechanic would be a good idea. In reality though diesel motors are quite simple in design, and people tend to over look the importance of regular oil changes and coolant checks. I own a 79' Pearson 365 powered by a westerbeke 42B four , it runs awesome but did smoke bad when I bought it. The fuel was old with lots of additives for slime removal and I gave it an oil change. No smoke now. Hope this helps a bit.

[Russt1950]

Thanks for that info. I'm really mostly concerned with the steam coming from the exhaust. The black smoke only came out at first, but then started to ease up.

[DeepFrz]

Follow the Chief's advice.

[jannpage]

First, You are right to be concerned. Of course. And of course, it is perhaps only a symptom. What does the owner/broker say? I would assume you have a serious engine problem and drop the offer accordingly until I knew for sure. I agree it may ony need some fresh fuel and an oil change. It is not unusual for the oil to be diluted with unburned fuel. But the overheating is even more worrysome. NEVER TRUST AN OWNER SUPPLED SURVEY. The Chief is right as far as he goes. Never buy a boat without a professional survey.

[Russt1950]

I don't think the owner knows about diesel engines becaused he pays someone to change the oil. When running at 2200 the temp climbs to 180, but when you ease throttle back it will come down. The owner said he hasn't used the boat in 9 months. I'll looked at it again and run it and if its the same, I'll look for another boat. Thanks

[Chief Engineer]

Don't run away just yet.......what was the air temperature when you started the boat....180 is normal operating temperature....when was the bottom/prop last cleaned?

[Russt1950]

The air temp was about 72 and there is a lot of bottom growth on it.

[bstreep]

Have the prop cleaned, then try the boat out. That being said, do NOT buy the boat without a survey - a surveyor of YOUR choice. Tell us where the boat is, and you'll get some recommendations.

[markpierce]

Originally Posted by Russt1950

I don't think the owner knows about diesel engines becaused he pays someone to change the oil. When running at 2200 the temp climbs to 180, but when you ease throttle back it will come down

What temperature are you expecting and how low does the temperature drop to? On my JD 4045D, 180 degrees is spot-on.

[mbianka]

I agree a good engine survey is in order. Specifically ask for a compression check. The black and white smoke could be an indication of a head gasket failure. First the oil combusts then the water heats up and turns to steam (white smoke). Happened on my boat with 1800 hours on it. Went from great engine to dead engine in 6 hours.

[Chief Engineer]

Black-Fuel
Blue-Oil
White-Water

[Sandero]

Shiva has a Volvo MD17D - original installed new in 1986. The engine has over 4000 hrs. It has one major rebuild of the head, new injectors and so forth... did not have rings done.

In cold weather... the engine will start right up and put out dark grayish blue smoke. As the engone temp comes up to normal operating temp... 10 minutes or maybe 15... the smoke clears. When the engine is warn there is only a touch of smoke.

I believe the engine needs rings, but the oil tests fine... will do another test in a few weeks. Power seems fine, but fouled bottom and prop slows the boat a knot or more.

The smoke freaked me out when it first appeared... I think it's from the rings and when it heats up they seal better... Just a guess as I am not a mechanic. It's not worth it to me to undergo the expense.

When the engine gets old it may be time to repower. For now... she's fine.

[delmarrey]

IMHO - Black smoke would be sticky injectors, and steam would be a bad setup on exhaust system or plugged exhaust elbow.