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Old 10-04-2016, 08:57 AM   #1
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Old Cummins V-504, blue smoke under load and smell

I hope there is still here someone experienced with this old type of engine so it can give me some light on my problem.

I have rebuilt this engine (Cummins V-504-M 195HP/3000RPM) and it serves me very well. Now I have about 135 hours of operation. Thing is that I am not driving it hard, most of time I drive it around 1500RPM. After rebuild, engine worked spotlessly in whole range of RPM with no smoke at all (everything new in engine and done by Cummins professional). Since I have not been driving it fast because of fuel consumption and my needs, I have just recently tried to go on speed again and above 2300RPM engine starts to smoke in purple/blue, has loss of power and distinctive smell. That RPM is about when my semi displacement boat is starting to transit from displacement to planning (heavy load). Above that RPM the engine can achieve maximum RPM, but lacks power. Under that RPM, engine works perfectly without any smoke or smell.

I know that blue smoke is probably oil, but I cannot confirm that since under that RPM engine does not consume any oil (level unchanged on dipstick) and I do not want to drive it above that just to check that, because I could maybe make more harm to engine. Oil pressure is fine, as always from the beginning (40psi to 80psi).

I had one failure on one summer trip, which could be the culprit, but I do not know if that is exactly when it started since I did not drive it fast until now. And on my running RPM I have not spotted any change. What happened then is that hose between engine and "distant" oil filter element was badly crimped probably and therefore bursted on the connection letting the engine to discharge all the oil in engine room. Luckily, Kysor alarm spotted low oil pressure and turned off the engine. Unluckily, although I have seen the exact alarm and what happend on pressure instrument, it was bad location for that to happen and I had to turn on the engine for 10 more seconds to stop the boat not to hit something because of big inertia before I have dropped the anchor. It was safety vs engine and it was critical, so I did what I did. Kysor has let me just about 8 seconds this time, just enough to change the outcome. Just before Kysor has turned off the engine, I had some strange sound, like grinding, but I have never had engine turning off with gear in reverse (Borg Warner 72), so it could be from engine, it could be from gearbox, could be anything really, although I have thought about the worst at that moment - engine itself.

After towing the boat to the shore, I have made a new hose and changed the oil. It was left only about 3 or 4 liters of oil in the engine out of 18 or 19 liters needed for engine operation. Actually engine needs maybe 2 or 3 liters less than that, since whenever I put all to the HIGH level on the dipstick it consumes it. Then, I have just left it to use the oil and see if it is going to stop and when it comes approximately a bit lower than the middle of HIGH and LOW mark it stops and stays there forever, so I always use that level of oil. After changed oil and hose, I have disconnected the fuel shut off valve and cranked the engine to achieve oil pressure before firing it up. Then I have reconnected the fuel shut off valve wire and fired up the engine. It worked flawlessly as nothing has ever happend, no smoke, no strange sounds, nothing. But I have continued driving it on my cruising RPM, haven't tested higher RPMs, so I do not know if that is when the problem showed up.

That problem has happend at 50 working hours (about the same as with my first oil change, recommended by rebuilder since engine is "new" and the following intervals to be at 100 hours), since then I have changed the oil again at exactly 100 hours and plan to change it every following 100 hours. Never spotted any problem until trying to reach speed recently.

Since I have instantly remembered the event with hose, I thought of blowby. I have opened the oil pouring plug with warmed up engine and at idle and there is air blowing and constant thin (I would say maybe white/gray, but more like white) smoke (not doing choo choo, just constant), but I cannot compare it to anything since I have never opened it like that before. It is not the blow that would lunch the plug in the air, it is just that I can feel it blowing on my hand and when I just put the plug on it without tightening it up, it stays there, it dances maybe a bit if I lift it with hand and release the blow around it, but that old metal plug is heavier than those plastic ones on new engines that I have seen on the youtube videos.

So can anyone tell me is there a possibility that it is just the case of maybe problem with valves and valve stems or injectors before thinking about piston rings and cylinder walls so I know what to expect before calling the rebuilder? Or you would lean more towards the rings and blowby?

Sorry for the long post, but thought I will get better answers if I describe it better.

Thank you in advance.
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Old 10-04-2016, 09:44 AM   #2
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Post your question on boatdiesel.com - a well regarded site with several engine experts for questions like yours.
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Old 10-04-2016, 10:22 AM   #3
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If you run at low power, engine and exhaust will load up with oily goo which will then cook off when you go to high power. This should clear up in a few minutes as it burns off. Completely normal.

Low power could be clogging fuel filters??

If you have run 100hrs since the oil line problem, you most likely have suffered no damage. If engine sounds smooth and runs good up to 1500, and oil pressure is same as before, good chance it is ok.

Try running it above 1500, get it to where it is smoking, no need to go to full power, and leave it there for a few min. See if smoke clears. Abort if engine sounds rough or makes unusual noises.
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Old 10-04-2016, 11:01 AM   #4
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Is it possible that the break in was too gentle?
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Old 10-04-2016, 11:37 AM   #5
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Yes, diesels need a load. Cummins are infamous for blowby, normal, so my mechanic says.

If you lost oil pressure, the worst damage would be to the main or crank bearings. It sounds like you dodged that bullet if it is still running.

Running at wot or rated power will reveal any issues but that advice got me slammed before on here so I didn't say it, don't wish to go there again. What is your rating? M1 or? Run at your rating and see what happens.
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Old 10-04-2016, 11:42 AM   #6
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To expand on the previous posts:


This is really a problem for boatdiesel. Frankly the only person I would pay much attention to on this forum in your situation is Ski as he is a mechanical engineer and a marine diesel mechanic. The rest of us are owners and shade tree mechanics. Boatdiesel has a dozen or so pros who routinely contribute.


Usually on boatdiesel one of the pros will take the lead on your problem and stick with it until resolution. Ski is one of those pros. But you will get more professional advice there(and sometimes one pro will correct another one, but in a professional way).


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Old 10-04-2016, 03:01 PM   #7
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Thank you. I would try boatdiesel.com, but for a couple of months I only get blank page after login page, from two different computers and using different browsers!? That is why I tried here.

You have at least comforted me that it is not very probable to be blowby or crank bearings.

Ski, I will try that oily goo burning procedure, thank you. I really doubt that fuel filters are the culprit, since the tank is completely new so as the fuel lines, it was not only the engine rebuilt, it was the whole boat. Older type of Separ filter/separator is used, on first 50 hours, it had original filter element with 2 microns, but there is no 2 micron replacement today, only 10 microns element is stated as 1:1 replacement, so that is what I am using now. Although filter can probably last much longer than oil change interval, I always change them together (all filters).

I have forgotten to say that I have spotted one more problem during last 90 hours, but I am not sure if that can contribute to described smoke problem. I would say that I am mostly weekend boater, except on summer vacation when I do longer tours, but I always choose the weekend tours long enough so that engine can reach operating temperature for some time. Before every ride after engine has been shut down for a day or longer (not between rides in one day), I always inspect my engine room and fluids of interest. So I have spotted belt dust. It is from the belt driving alternator and freshwater pump from the crank. The belt is "scratching" somewhere, but I can't find where exactly, and when it is doing so it becomes loose, so I must make tension again. It did not happened for about first 40 hours maybe. I did that every day when I have seen it because I was on the trip. After that I am on third belt, trying to figure if I am using the right one. The first was new industrial cogged V-belt 1/2'', then I changed for the same when spotted dust and since it is dusting again, I am now trying not cogged classical V-belt 1/2'', but still having problem, and I will try one that is a bit narrower than 1/2'' (my country uses metric system, so I do not want to bother you with measures and units). Anyway, the alternator is high up on the engine and close to the air intakes. Could that contribute to the problem if dust is "swallowed" by engine? After tightening up the belt, dust shows up after about 8 hours, and then I tighten it again and clean up.

XSbank, I prefer testing it as Ski said, rather than going on rated power immediately. As recreational boat I would say that would be M5 rating, but for that old engine there were only three ratings - pleasure, light duty and continuous duty. Mine is set as light duty (for use in applications where the average load factor does not exceed the continuous rating and where full throttle does not exceed eight hours total in any 24-hour period). Although for this engine pleasure and light duty were almost the same (5SHP difference). Continuous duty was 158BHP/2500RPM. I did test the boat at 3000RPM only at the beginning to check that it is not overloaded, to check speed and that all is well. I have put all the stuff I usually carry on the boat before the test so I could have real data. Anyway, driving mostly 2 to 4 persons. On some occasions I had 8 persons and I had same displacement speeds at same RPMs. Very satisfying and interesting hull. It is 30 foot fiberglass boat with outdrive and single engine.
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Old 10-04-2016, 05:57 PM   #8
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Nidza, if your engine is rated at full throttle for 8 hours, it should be fine at full throttle for less? Anyway, it's your engine and I'm outta here. Listen to Marchand, he is the expert.
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Old 10-04-2016, 07:44 PM   #9
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Quote:
Originally Posted by bayview View Post
Is it possible that the break in was too gentle?
That's what I was thinking as well. For at least the first 100 hours after new or rebuild they should be run in the upper 50% of the power band to bed the rings in properly or you will start to get glazing and blow by.

The easiest way to check if any damage was done by the low oil pressure would be to get an oil test done. This may also help with getting a reading on your blue smoke issue,

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Old 10-04-2016, 07:53 PM   #10
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Quote:
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Nidza, if your engine is rated at full throttle for 8 hours, it should be fine at full throttle for less? Anyway, it's your engine and I'm outta here. Listen to Marchand, he is the expert.
Well, although I appreciate your comment, I am no expert. I am a boat owner and a shade tree mechanic, just like most of us. Listen to Ski (or Tony or Paul or .... on boatdiesel), he is really an expert.

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Old 10-05-2016, 12:29 AM   #11
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I'm a V555M Cummins owner but I agree, try Boatdiesel again. There are several who know those engines well even though it may have been quite a while since they worked on them.

As another shade tree guy I suspect you may have run it too easily during the break in period. Push it harder, not abuse it, but harder to take off the glaze. 1,800-2,000 - 2,200 rpm ior so in some steps. Hopefully if you do that the glaze will give way.
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Old 10-05-2016, 01:20 AM   #12
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OK, I here you about low power break in.

Jetstream, I will do that test, good point, but if that is only due to low oil pressure then I am not sure about it because my oil pressure is as at its maximum until the oil doesn't reach its working temperature and then it varies between 40psi and 80psi, but 40-50psi is only seen from idle to about 1100RPM, in my cruising 1500RPM oil pressure is close to its maximum, from there to 3000RPM there is only around 10psi change.

C lectric, no problem driving at that RPMs, if that is going to prevent it then OK, I do that occasionally, when going up stream to get better speed, since I am on the fresh river . I have chosen the 1500RPM since the speed gain was negligible and probably only difference would probably be in fuel consumption, but that is not big price to pay if it is going to prevent bigger problems. Engine maximum torque is at 1900RPM so it likes that speed.

I will speak with network engineer at my office to try to resolve the problem with boatdiesel.com site.
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Old 10-08-2016, 07:44 AM   #13
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I'm like you or even worse I run at 900 to 1200 rpm for most of my running. When I went to put the boat away I ran it at WOT (2000 rpm as I am over propped a lot but that is another issue). The first 5 minutes it smoked a lot (blue gray smoke) but after that the smoke died away and at 8 minutes or so their was no smoke. I ran it at WOT for 15 minutes total. I am thinking that all the slow running carboned up the cylinders and I should periodically run it at a fairly high load (75% or higher) for 10 to 15 minutes to keep the engine clean. Next year I plan on checking this by running at 75% to 80% for 15 minutes every 15 to 20 hours. After doing this for 100 hours I'll take it to WOT again and see if it smokes.

Any comments or suggestions would be appreciated. The engine is a 1985 135 hp Ford Lehman in a Grand Banks 32'
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Old 10-09-2016, 05:35 AM   #14
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I waited for the weekend to do the tests, so I have results from yesterday.

It was probably the oily goo since after a few minutes at that throttle smoke has cleared up. Since it is a bit colder here I had to warm up the engine for longer period, so I did that gradually as I always do, but instead of going only up to 1500 rpm when temperature reached, I went all the way through 2200 rpm in steps for about 15 minutes at each step. After that I went to higher RPMs. I presume that is why there was even less smoke and for shorter period at 2600 rpm this time. No strange sounds and I went all the way to the WOT (and a bit above, probably prop should have a bit higher pitch, but since I drive mostly in displacement that is excellent and I have a piece of mind). No power loss. I tend to think that maybe there was no loss of power actually, but only my fear of that blue smoke and very bad smell so I always have decreased the throttle fast, but am not sure 100% now.

While inspecting around during test I have found a couple of small things that I must fix in engine room, so all in all that was very useful.

DonF, as many here said for themselves, I am also shade tree guy, but my suggestion, since you drive at that low RPM, is that you should check if your engine is reaching needed working temperature at that rpm according to manuals (checking oil temperature is even better than water temperature). If not, you should drive it at higher rpms. Since I had to calculate and build the raw water pump pulley myself, I had to do the tests at different rpms to check everything. The conclusion was, and I believe that is the case with most pumps, that the pump is giving just enough water at highest rpms to keep the engine at propper temperature, really enough water at mid rpms, and probably too much water at lowest rpms. That seems to be the nature of those two beasts - engine and pump. In my case, if I drive 1100 rpm or lower for longer period (like 10 minutes), engine temperature decreases. So I always avoid driving below that, except when I want to cool down the engine before shutting it down or as one of steps during warm-up period. Running it under load at lower temperature for prolonged periods is not recommended as you know. You are probably right that we should periodically run it at higher power to clean the engines from carbon build up and oily goo according to my newest experience and test.

Thanks everybody for your time and good suggestions!
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Old 10-09-2016, 06:49 AM   #15
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I waited for the weekend to do the tests, so I have results from yesterday.

DonF, as many here said for themselves, I am also shade tree guy, but my suggestion, since you drive at that low RPM, is that you should check if your engine is reaching needed working temperature at that rpm according to manuals (checking oil temperature is even better than water temperature).
Nidza - - I don't have a oil temp gauge (wish I did, maybe add one) but the water temp gets to operating (180F) temperature even at idle. The boat is kept on the Black River and it is about 15 to 20 minutes at idle (2 bridges) in and out. By the time I'm out of the river the water temp is around 120F. It takes about another 5 - 10 minutes at 900 rpm to get it to 180F. If I run it for 15 minutes at 1500 the water temp stays at 180F. I always run for at least 3 hours when I go out so no short tripping. And the engine spends at least 2.5 hours at 180F. But that is not to say that the combustion chamber temps are getting high enough to burn off the soot and goo. Don't think they are. I've only had the boat for a couple of months and it is my first diesel so I'm learning. My plan for next year (boat is getting pulled for the winter Tuesday Oct 11) is to go back to the the factory prop I don't like running heavy loads when over propped. Then every 10 to 15 hours run at 75% load for 15 - 30 minutes. After getting 100 hours on it I'll run it at WOT to see if there is any smoke.

Nidza thanks for your comments and info. DonF
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Old 10-09-2016, 09:14 AM   #16
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Nidza

Consider an IR gun for measuring temperatures of oil pan, various engine points etc. it is an invaluable tool that can be used routinely as you cruise along
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Old 10-09-2016, 09:39 AM   #17
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Dont know what your thermostat is but consider using a 180 degree stat. Lower load temps will be increased with no effect on high load temps.
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Old 10-09-2016, 09:42 AM   #18
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Dont know what your thermostat is but consider using a 180 degree stat. Lower load temps will be increased with no effect on high load temps.
Thanks Pretty sure mines a 180 that's what it runs at from 900 - 1500 rpm.
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Old 10-09-2016, 09:43 AM   #19
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Sunchaser - - Thanks I think I'll do that.
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Old 10-09-2016, 11:41 AM   #20
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I waited for the weekend to do the tests, so I have results from yesterday.

It was probably the oily goo since after a few minutes at that throttle smoke has cleared up. Since it is a bit colder here I had to warm up the engine for longer period, so I did that gradually as I always do, but instead of going only up to 1500 rpm when temperature reached, I went all the way through 2200 rpm in steps for about 15 minutes at each step. After that I went to higher RPMs. I presume that is why there was even less smoke and for shorter period at 2600 rpm this time. No strange sounds and I went all the way to the WOT (and a bit above, probably prop should have a bit higher pitch, but since I drive mostly in displacement that is excellent and I have a piece of mind). No power loss. I tend to think that maybe there was no loss of power actually, but only my fear of that blue smoke and very bad smell so I always have decreased the throttle fast, but am not sure 100% now.

While inspecting around during test I have found a couple of small things that I must fix in engine room, so all in all that was very useful.

DonF, as many here said for themselves, I am also shade tree guy, but my suggestion, since you drive at that low RPM, is that you should check if your engine is reaching needed working temperature at that rpm according to manuals (checking oil temperature is even better than water temperature). If not, you should drive it at higher rpms. Since I had to calculate and build the raw water pump pulley myself, I had to do the tests at different rpms to check everything. The conclusion was, and I believe that is the case with most pumps, that the pump is giving just enough water at highest rpms to keep the engine at propper temperature, really enough water at mid rpms, and probably too much water at lowest rpms. That seems to be the nature of those two beasts - engine and pump. In my case, if I drive 1100 rpm or lower for longer period (like 10 minutes), engine temperature decreases. So I always avoid driving below that, except when I want to cool down the engine before shutting it down or as one of steps during warm-up period. Running it under load at lower temperature for prolonged periods is not recommended as you know. You are probably right that we should periodically run it at higher power to clean the engines from carbon build up and oily goo according to my newest experience and test.

Thanks everybody for your time and good suggestions!
"Warm up" .... I would advise not sitting at the mooring/dock waiting for your temp gauge to move. Diesels produce very little heat when not under load. Get ready, start the engine, throw off your lines, move off at low speed. Don't sit around "warming up".
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