I have a 2005 420 Sedan Bridge with Cummins 480CE diesels. The Port engine has a history of overheating under load but much $$ later, that has been resolved. However, now my Port engine smokes excessively on start up but cleans up considerably when cruised at 2200. At idle, after run, still smokes more than starboard, but “acceptable” - barely. Thoughts? If I want to rebuild, can I rebuild in the boat or do I have to remove? If so, how difficult in this boat to R&R?
Excessive smoking 480CE
- Thread starter Navapoto
- Start date
- Jun 5, 2016
- 5,590
- Boat Info
- 410 Sundancer
2001
12" Axiom and 9" Axiom+ MFD
- Engines
- Cat 3126 V-Drives
What color is the smoke? White, blue or black?
Blueish. I have a video
Oil analysis and consumption monitoring?
Excessive blowby?
Excessive blowby?
Blowby is always tested at engine operating temperature. Did it get tested to the Cummins specification?
No, and problem with oil samples I sent is there was only 10 hours on oil.
I know I have a significant problem, I just hope it’s head related, like valve guides. If not, and it’s lower end, I need to know how much work it is to pull those engines out of the boat if I can’t rebuild them in the boat.
saopm
Active Member
If it needs a full rebuild, the engine will need to come out. I can’t see how you would remove the oil pan while in the boat. As you can imagine, the salon sliding door assembly will need to come out and I’m guessing the transom wall/assembly.
Both engines get to 2650 WOT and stay within operating temps and oil pressure so with only 1200 hours and the fact that valves do not like high EGT’s I’m hoping new heads will suffice. Wish me luck.
- Sep 25, 2016
- 1,257
- Boat Info
- 300 Sundancer 1994, trailered tri-axle LoadRite roller
- Engines
- Mercruiser 5.7 260HP Alpha One Gen II, twin
Slow down before you go to full rebuild mode...
You had a chronic overheating issue recently that you resolved.
Worst case would be you scored the cylinder walls, but it could be much simpler as well.
You noted it is worst when cold and gets better when warmed up and run.
You may have cooked the valve stem seals which can be changed without removing the head.
But valve stems are not going to get better when warmed up.
You very likely have some stuck rings. From coking the oil and carbon buildup when it was running hot. Cold the aluminum pistons contract and will pull the rings as they do. As the pistons expand they make better, but not normal, contact with the cylinder walls.
As @ttmott said start with blow by check. Cold it will be likely bad, warmed up better, but not normal.
Pull the valve cover and injectors, do a compression check and a leak down check.
A bore scope would also be advisable.
If no significant scoring, again likely stuck rings.
Get a gallon of top end cylinder lubricant like Marvel mystery oil. Take a quart and mix with a quart of diesel fuel. Pour about a cup into each cylinder and let soak 48 hours. Use the starter to blow out any remaining oil (so you don't hydro lock). Add the remainder of the Marvel oil to the crank case about one quart for each 5 quarts of engine oil, don't over full. Reinstall the injectors and run the engine.
It will smoke like hell at first but that will clear in about 15 minutes. Then take it out and run it up on plane. Back off to minimum planing speed. Run like that for a few hours. Use full throttle for a few minutes per hour.
Bring back to idle and see how much improvement.
If this frees the rings you can do the valve seals if you want to.
And then do an oil change after no more than 5-10 hours.
It has worked for me on both diesels and recently a Dodge V8.
You had a chronic overheating issue recently that you resolved.
Worst case would be you scored the cylinder walls, but it could be much simpler as well.
You noted it is worst when cold and gets better when warmed up and run.
You may have cooked the valve stem seals which can be changed without removing the head.
But valve stems are not going to get better when warmed up.
You very likely have some stuck rings. From coking the oil and carbon buildup when it was running hot. Cold the aluminum pistons contract and will pull the rings as they do. As the pistons expand they make better, but not normal, contact with the cylinder walls.
As @ttmott said start with blow by check. Cold it will be likely bad, warmed up better, but not normal.
Pull the valve cover and injectors, do a compression check and a leak down check.
A bore scope would also be advisable.
If no significant scoring, again likely stuck rings.
Get a gallon of top end cylinder lubricant like Marvel mystery oil. Take a quart and mix with a quart of diesel fuel. Pour about a cup into each cylinder and let soak 48 hours. Use the starter to blow out any remaining oil (so you don't hydro lock). Add the remainder of the Marvel oil to the crank case about one quart for each 5 quarts of engine oil, don't over full. Reinstall the injectors and run the engine.
It will smoke like hell at first but that will clear in about 15 minutes. Then take it out and run it up on plane. Back off to minimum planing speed. Run like that for a few hours. Use full throttle for a few minutes per hour.
Bring back to idle and see how much improvement.
If this frees the rings you can do the valve seals if you want to.
And then do an oil change after no more than 5-10 hours.
It has worked for me on both diesels and recently a Dodge V8.
I love Marvel Mystery Oil.
Hope springs eternal. Thank you.