Here is another possibility - you inadvertently added diesel with low cetane. You could try a cetane additive to determine if it makes any difference. Did you buy the fuel from a different source than you normally do?
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Universal M25 Knock?
OK Diesel engine gurus, I have a puzzle...
I have a 1987 Universal M25 with unknown hours, but the hour meter was installed about 395 hours ago. When I bought the boat, four years ago, it showed 175 hrs. The engine has a tendency to drop oil pressure when warm (drops from 45 to 10 PSI after several hours of running), but never overheats, and oil pressure never goes low enough to set off the alarm.
I recently installed three new injectors, and all seemed well until yesterday.
Yesterday, there was little wind on Narragansett Bay, so we motored for about 4 hours down the West Passage to Wickford. We had a nice lunch, then motored out, and raised the sails, as the wind had piped up... After making our way back up the East Passage, and passing Bristol Harbor inlet, the wind died again, so I fired up the engine again.
We ran the engine for about an hour at 2700 RPM, when suddenly it started knocking. I quickly throttled down, and the knock changed frequency. All the gauges looked normal (Oil @20 PSI, Water temp @180, Voltage @14+) I popped it into neutral, and the knock persisted. I looked over the transom, and noticed smoke (white - possibly grey) out the exhaust. I went below, and opened the engine compartment, but could not locate the source of the knock, so I shut it down.
I checked the oil - warm but the level was OK, looked for leaks - none, looked at the coolant overflow - OK. There was some oil that had escaped from the breather tube, but not a lot, and it really isn't that unusual. Because I could find nothing amiss, I started the engine again, and the knock was gone! We safely motored back to the pumpout, and then the slip (about another hour) without a problem.
What happened? What should I look out for?
I have a 1987 Universal M25 with unknown hours, but the hour meter was installed about 395 hours ago. When I bought the boat, four years ago, it showed 175 hrs. The engine has a tendency to drop oil pressure when warm (drops from 45 to 10 PSI after several hours of running), but never overheats, and oil pressure never goes low enough to set off the alarm.
I recently installed three new injectors, and all seemed well until yesterday.
Yesterday, there was little wind on Narragansett Bay, so we motored for about 4 hours down the West Passage to Wickford. We had a nice lunch, then motored out, and raised the sails, as the wind had piped up... After making our way back up the East Passage, and passing Bristol Harbor inlet, the wind died again, so I fired up the engine again.
We ran the engine for about an hour at 2700 RPM, when suddenly it started knocking. I quickly throttled down, and the knock changed frequency. All the gauges looked normal (Oil @20 PSI, Water temp @180, Voltage @14+) I popped it into neutral, and the knock persisted. I looked over the transom, and noticed smoke (white - possibly grey) out the exhaust. I went below, and opened the engine compartment, but could not locate the source of the knock, so I shut it down.
I checked the oil - warm but the level was OK, looked for leaks - none, looked at the coolant overflow - OK. There was some oil that had escaped from the breather tube, but not a lot, and it really isn't that unusual. Because I could find nothing amiss, I started the engine again, and the knock was gone! We safely motored back to the pumpout, and then the slip (about another hour) without a problem.
What happened?
What should I look out for? 21 - 40 of 53 Posts
The more I think about the intermittent nature of the problem the more I think it may be an injector problem. When knocking and putting out excess smoke one of the injectors may not be producing a proper spray pattern, due to debris or water?
If it was fuel starvation I think you would just lose power. Kind of sounds like fuel may be puddling up? Are there any indications that excessive blow by vapors can be collecting in or near the intake tract?
Having the injectors checked by a shop would be easier than pulling the head?
James' comment about cetane additives would be an easy try. Or maybe a heavy duty "cleaner" additive? I used to use this in my VW diesels & never had any fuel related problems:
DIESEL KLEEN® +Cetane Boost®: Max HP Formula ? use during non-winter months for the ultimate in performance.
I am sure there are lots of different additives that may be as good or better?
Paul T.
Edit: Just saw your picture, the tanlk has been around for a while.
I did some tests with the Power Service additive a long time ago. Put some diesel in a coffee can, added a little water to it, then added the additive & the water was no longer visible. A tank that old may very well have some water in it. However, a good filter/separator should catch it. Some units have a clear bowl on the unit allowing you to see water or debris.
Paul T
Thought maybe you might have missed the edit.The more I think about the intermittent nature of the problem the more I think it may be an injector problem. When knocking and putting out excess smoke one of the injectors may not be producing a proper spray pattern, due to debris or water?
If it was fuel starvation I think you would just lose power. Kind of sounds like fuel may be puddling up? Are there any indications that excessive blow by vapors can be collecting in or near the intake tract?
Having the injectors checked by a shop would be easier than pulling the head?
James' comment about cetane additives would be an easy try. Or maybe a heavy duty "cleaner" additive? I used to use this in my VW diesels & never had any fuel related problems:
DIESEL KLEEN® +Cetane Boost®: Max HP Formula ? use during non-winter months for the ultimate in performance.
I am sure there are lots of different additives that may be as good or better?
Paul T.
Edit: Just saw your picture, the tanlk has been around for a while.
I did some tests with the Power Service additive a long time ago. Put some diesel in a coffee can, added a little water to it, then added the additive & the water was no longer visible. A tank that old may very well have some water in it. However, a good filter/separator should catch it. Some units have a clear bowl on the unit allowing you to see water or debris.
Paul T
Paul T
I have read about but never had the water/injector problem, that I know of. If there is water in the tank It would be good to get it out before it goes into/thru your filter/separator. From the picture it looks like there is a port cover/cap that may be able to remove on the left side. If so, maybe put a piece of hose into the forward left corner & use a pump to pull it out. Suggest you not try to siphon it by mouth. I swallowed a LARGE mouthful of gasoline doing that.
Perhaps you could weight the boat so that the forward left corner of the tank the lowest. I think most pick up tubes are not right on the bottom of the tank. So if you are picking up water, there may be a fair amount of water in the tank. After removing the tank cap, you may be able to see any water rolling around in there?
A good filter/separator should catch any water or debris? "Should" is the key word.
Paul T
This O'day 35 has the original 1986 Florida Marine Tanks 35 gallon tank;
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E! isn't that steering cable a bit on the loose side of tight?
Me's dunno nutin bout no molly cues meself
That pic was taken 4 years ago; before I removed the steering quadrant and dropped the rudder so that I could replace the cutlass bearing and prop shaft. Upon re-installation, everything was tightened appropriately.
If you were to see this view today, you wouldn't recognize the place, except for the original, oxidized, fuel tank.
Ah, understood, space. One thing always seems to lead to another, turning into a big project.
Paul T
I actually think that the solution on my boat is better. There is a hydraulic high pressure hose screwed into where the oil pressure switch would normally go, and this is run to a bulkhead in the engine room. There is a "T" fitting on the other end of the hose, on the bulkhead, and an oil pressure switch, and oil pressure sender on the T. This reduces the mass connected to the vibrating engine by a pressurized T fitting, and isolates the switches from the effect of vibration.
Here is an OLD picture, in which you can see the hose, pressure switch, "T", and sender to the right of the OLD Sea Ranger battery charger (now gone);
21 - 40 of 53 Posts
