Misadventures of a new diesel owner

[Nick J]

Hey, did you know these boats actually sail too? You wouldn’t know it watching me over my first 4 months of ownership, but we were finally able to take Segue (soon to be renamed) out for the day.

I had a small scare when I went below to find the new exhaust riser smoking a bit when I was running around 2400 RPM and 5 knots (according to Yanmar, I should be able to cruise at 2800 with a WOT at 3600). I throttled down and tried my best to hide my anxiety from the rest of the family as they were enjoying the day. After 30 minutes at 2000 RPM, I checked again and found no smoke so I bumped it back up to 2400. The smoke was gone so I’m chocking it up to residue and other contaminants on the new riser burning off. It also wasn’t in time with the motor which I was thinking would indicate an exhaust leak at one of the joints.

Another thing I noticed was the shaft vibrating in the log above 2400 rpm. It wasn’t anything compared to the vibration we felt during the sea trial when the prop was encrusted with barnacles, but It concerned me enough to keep the engine below 2400 for the rest of the day. I’m planning on replacing the engine mounts, shaft seal, cutlass bearing, and probably the prop in September, but I was hoping to get a few months of use out of the boat before then.

I’ve been on many boats with diesel engines, but it’s different when it’s your boat. When it comes down to it, I’m a new diesel owner with very little actual experience. Every little vibration and rattle has me concerned. Is shaft vibration normal? Am I on the right track with the smoking exhaust riser? It goes against my DIY nature, but I’m thinking it might be time to invite a mechanic on board to take a look, ease my mind, and help me prioritize my projects.

 

[Frank Langer]

Hi,
Regarding the vibration, I would get in the water and check to ensure the strut is solid and secure and the cutless bearing is ok. Both can be readily checked by wiggling them somewhat vigorously, but don't break them! If they are solid, the most likely issue in my experience is poor engine alignment. The correct way to check is to undo the tranny coupler bolts from the tranny and insert a feeler gauge (like for spark plugs). Ideally there should be no gap at the four quadrants, Ericson manual says no more than .002 gap. An easier, somewhat reliable check is to put the transmission in neutral, then try to turn the prop shaft. If you can turn it fairly easily with one hand, it's ok, but if it feels stiff and hard to turn, it needs alignment. An engine out of alignment with the prop shaft and strut will almost always cause vibration.
I'm not a mechanic, but have owned boats for 27 years.
Frank

 

[JSM]

After thirty years of Atomic 4 ownership switching to a Universal M25XP made me a bit crazy to say the least. I also had vibration issues over 2500 rpm. New motor mounts helped but I found that alignment was the biggest factor in reducing my vibration issues.

 

[Kenneth K]

I had some exhaust leakage/smoking/odors from my new riser when I installed it too. In hindsight, I probably didn't torque down the stainless steel pipe fittings enough, but it seemed like a lot of force at the time. I do remember reading that minor leaks will self-seal with soot after a short time, and I haven't noticed smoking or odors since after that first season. I think you'll be fine.

 

[Rocinante33]

A new exhaust riser should be re-torqued now after the first good use and heat up, IMHO. The smoking may have indeed, been residue.

As far as the alignment, if you don’t have a feeler gauge, you can use a thick (not excessively thick) Piece of paper. That is about .002” thick. Should slide in and out in each quadrant, as described.by Frank.