1983 O'Day 34 with a universal diesel. Having some trouble with black sooty smoke when motoring. One possible fix may be to replace an old muffler. Currently it has the original plastic wet muffler. Anyone have this issue or replaced the muffler with a correct replacement.
Replacing muffler
- Thread starter Therapyg
- Start date
I would suggest the engine is not burning all of the fuel. Dirty bottom or fouled prop?
I was pushing my Yanmar 2GM20 pretty hard one day, against a strong wind, and noticed the exhaust water was dark and I was leaving a trail of soot in the water. I thought, oh, I need to run the engine harder and blow out all the stuff in the muffler and engine.
The harder I ran the engine, the worse the soot was. Until the engine alarm (over temp) came on.
I was pushing the engine too hard and once I backed throttle down, alarm stopped, soot disappeared from the exhaust, and all is well.
I was pushing my Yanmar 2GM20 pretty hard one day, against a strong wind, and noticed the exhaust water was dark and I was leaving a trail of soot in the water. I thought, oh, I need to run the engine harder and blow out all the stuff in the muffler and engine.
The harder I ran the engine, the worse the soot was. Until the engine alarm (over temp) came on.
I was pushing the engine too hard and once I backed throttle down, alarm stopped, soot disappeared from the exhaust, and all is well.
the question is have you made any changes to the prop? black soot means unbured fuel so you are pushing more fuel than it can burn. was it like that before? like the last post your prop or your bottom is fouled if nothing has been changed can you get to full rpm or is it slugish and you are trying to push it harder.good luck with your problem maybe take to a reputable mechanic if these thing are not the cause of the problem as it will foul the exhaust elbow
I don't see a need to replace the muffler unless it is clogged or leaking exhaust gases and water into the hull. The smoke and soot is produced by the engine and needs to be corrected there.
Black soot comes from having a clean, WAXED transom and the area around the exhaust!
Get rid of the wax and the soot won't stick around. FSR does the trick.
Really.
I recently replaced a 29 year old muffler. Clean exhaust, but still the soot, until I "de-waxed" that area.
Get rid of the wax and the soot won't stick around. FSR does the trick.
Really.
I recently replaced a 29 year old muffler. Clean exhaust, but still the soot, until I "de-waxed" that area.
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If the engine is running right and the injectors have been recently serviced, then the usual culprit is the prop.
If the prop is clean (i.e. not fouled) then it is likely suffering from too much pitch.
If your early 80's engine is a Universal M25, rated at 21 hp, it should push your boat along at about 6.5 kts, maybe a little less if you are heavily loaded down. Nothing under 6 kts in any case. Check your manual, but I recall that your specified cruising rpm's are 2100 to 2600, with max revs= 3000.
We have almost the same engine, an M25XP, and cruise it at 2500 rpm all day long for deliveries.
And, having mentioned props, I would note that it is common for the original builder to install an incorrect prop sometimes, and for prior owners and misguided boatyard guys to re-prop with the wrong pitch... and sometimes even the wrong diameter.
Some research and comparing notes with owners of sister ships will help you a lot with this.
Your ODay has about a thousand # more calculated displ. than our boat but also a little more WL length. We have 23 hp, and motor at 7.0, for 24 hours straight on delivery . If pushed a bit more than our engine produces some smoke, but none to that point. And that's with the boat fully "loaded down" for a two month summer cruise.
I have sailed an ODay 34 some and it's a good-performing hull.
Regards,
Loren
If the prop is clean (i.e. not fouled) then it is likely suffering from too much pitch.
If your early 80's engine is a Universal M25, rated at 21 hp, it should push your boat along at about 6.5 kts, maybe a little less if you are heavily loaded down. Nothing under 6 kts in any case. Check your manual, but I recall that your specified cruising rpm's are 2100 to 2600, with max revs= 3000.
We have almost the same engine, an M25XP, and cruise it at 2500 rpm all day long for deliveries.
And, having mentioned props, I would note that it is common for the original builder to install an incorrect prop sometimes, and for prior owners and misguided boatyard guys to re-prop with the wrong pitch... and sometimes even the wrong diameter.
Some research and comparing notes with owners of sister ships will help you a lot with this.
Your ODay has about a thousand # more calculated displ. than our boat but also a little more WL length. We have 23 hp, and motor at 7.0, for 24 hours straight on delivery . If pushed a bit more than our engine produces some smoke, but none to that point. And that's with the boat fully "loaded down" for a two month summer cruise.
I have sailed an ODay 34 some and it's a good-performing hull.
Regards,
Loren