Crankcase Breather Redux

[Roger Long]

I haven't seen any hint of "old car" oil smoke in my exhaust since my arrival in Oxford. I think the heavy motion and pitching on the way up was probably the cause of what I saw a couple weeks ago.

Nevertheless, being an inveterate fiddler, especially when it ain't broke, I decided to reconnect the oil separator. First however, I took Mainesail's suggestion and unscrewed and removed the filter element. It did not seem very oil soaked and I could blow through it effortlessly. I think it's overkill though. The filter bowl now serves as simply a sump. Any liquid oil going through the line should simply fall into the bowl. This will let me assess how much oil may be going through the breather hose and keep it out of the engine.

If the separator should fill up, I shouldn't be any worse off than if the hose were simply filled with oil. I'm not concerned about the slight additional restriction of a foot of hose, and elbow and a nipple now that I have positive suction on the hose at the manifold end. If any liquid oil does get in, restriction should be less with the oil drained off into the bowl instead of needing to be pushed/sucked up the slope to the manifold connection. I'll keep a close eye on it though.

 

[kloudie1]

I dunno, Roger.. 4 oz of oil is enough to run the engine around 3 minutes.. plenty time to overspeed.. I don't think I'd put an accumulator in a line connected to the intake.. Very remote possibility of that happening for sure, but the hose on that engine, by sloping back to crankcase continuously (from the drawing) works to run the liquid back to the sump before it can get to the intake.

 

[Roger Long]

I dunno, Roger.. 4 oz of oil is enough to run the engine around 3 minutes.. .

Yes, but it can't run uphill out of the accumulator. It's set up just like a water trap in a steam or exhaust line. I can reach the hose and yank it off in a second if need be. The elbow nipple on that side is nylon so I could just break it off.

The amount of oil the hose can hold would run the engine long enough to do damage. The accumulator, if I keep it drained, should keep oil out of it.

I've never believed in running breathers to the intake but that's the way the engine was designed to work so the designers evidently didn't consider runaway a significant danger.

I was clearly pumping some oil through the engine on my rough trip up, probably due to motion splashing oil up the crankcase walls. No sign of the engine running on it though.

 

[kloudie1]

I definitely agree, Roger.. long shot and probably not an issue because the accumulator is designed to not siphon back to the intake..
Just going on my past experience with many cars and a few diesels set up to blow crankcase fumes back to intake with no accumulator/separator.. I think I remember one model of Cummings that had a separator as you are rigging (and there are probably more).. accumulated liquid oil and condensate from the crankcase and had to be drained about once a month on an engine that ran 24 hours a day. Some liquid will always condense in the lines because they are cooler than the crankcase .. the vapors are saturated in the crankcase so when they see cooler, you'll get a thin liquid film on the hose ID that will constantly run downhill in the hose. There is some atomized stuff as well that will wet out which will drain downhill too.. Not saying that what you are doing is dangerous (low probability occurrance) just saying I would not, because I have never seen a need .. I too, however, am guilty of fixing things that aren't broken.. :~)

 

[Roger Long]

accumulated liquid oil and condensate from the crankcase and had to be drained about once a month on an engine that ran 24 hours a day.

Damn! I just got to my new anchorage after about an hour and a half of running at cruise power since the reconnection and found the bowl half full of grey emulsion floating on top of about 80% pure water. I never saw a hint of water in the bowl when it had the filter element in it, the stuff that collected looked just like oil drained out of the crankcase, jet black.

I poured this stuff out into a paper towel and it's water. The engine has mostly run for short periods all week, not enough to get up to full operating temperature. Dipstick looks absolutely normal, like the oil had just been changed. Is it possible that this much water could collect?

Maybe so. I just thought to taste the paper towel I cleaned out the bowl with and there isn't a hint of salt (raw water cooled engine). Engine is running beautifully, not a hint of exhaust smoke in dry atmospheric conditions at cruise power.

I'll keep an eye on it but this new configuration should also be a good way to monitor some of what's going on inside the engine.

 

[kloudie1]

I would not have thought quite so much would condense, but the bowl and housing are the coolest part of the system and with the best heat transfer, where the water vapor would condense.. if the engine had been run a couple of times without fully coming up to temp, you might be seeing the accumulated water load from those runs as well..?? If the crankcase oil looks fine, then I'd think that you are looking at condensate from combustion blow-by. That water would probably normally be part of the white smoke seen right after start-up when it would be pulled into the intake manifold and pumped through the engine as vapor .. Interesting..

 

[Benny17441]

I also like to tinker but refrain from it when I'm miles away from home.

 

[Roger Long]

I also like to tinker but refrain from it when I'm miles away from home.

I am home

 

[Shoaldrafter]

'Roger's introduction to Diesel Engines'

Some time ago [years ago for the truth] I saw a course offered for cruisers on diesel mechanics. I think the course was in Florida and lasted a week. Anybody recall such a course and if it still around?

After all of these posts, maybe now that I am retired I need to take such a course.

Maybe I need to buy an old boat diesel and tear down and rebuild it just to get back some very old skills...

Weren't sailboats supposed to sail?

This site should be called 'Roger's introduction to Diesel Engines'.

Ed K

 

[Roger Long]

I think things are normal. I just ran 3/4 of an hour at cruise speed with a period at max continuous RPM. The inside of the liquid trap (I'm not calling it a separator or filter now that I've removed the element) is so clean that I can't even get an oil film on my finger.

I ran last week the way many people operate their diesels all the time, start, run a mile or two, and shut down to raise the sails or anchor. The amount of condensation expelled yesterday in a run up to cruise conditions was impressive. Think of what all that water is doing in a sailboat engine that is just used to get in and out of a harbor and idled to charge batteries and cool beer.

 

[Maine Sail]

I think things are normal. I just ran 3/4 of an hour at cruise speed with a period at max continuous RPM. The inside of the liquid trap (I'm not calling it a separator or filter now that I've removed the element) is so clean that I can't even get an oil film on my finger.

I ran last week the way many people operate their diesels all the time, start, run a mile or two, and shut down to raise the sails or anchor. The amount of condensation expelled yesterday in a run up to cruise conditions was impressive. Think of what all that water is doing in a sailboat engine that is just used to get in and out of a harbor and idled to charge batteries and cool beer.

This is why so many diesel mechanics and engine manufacturers suggest running the engine long enough to burn off start up condensation, which can be cumulative.... It is also why I would much prefer an engine with 2000 hours on it run correctly over one with 300 hours on it run for short bursts..... Sailors destroy engines doing short runs then letting all that water vapor sit in the engine. Hey maybe we have a new product to market...? No water vapor, or minimal, means you are running your engine correctly..

 

[kloudie1]

Relax and enjoy ! sounds like ya have it under control..

 

[Shoaldrafter]

how long

Question for Maine Sail [wrong forum?] How long does it take and where can you find directions for proper time to burn off condensation? I come from hang on your transom motors to a diesel.

Anyone else can answer.

Ed K
Addendum:
"Sailing and boats have been a great way of life, not easy and not very remunerative, but very rewarding." George O'Day

This is why so many diesel mechanics and engine manufacturers suggest running the engine long enough to burn off start up condensation, which can be cumulative.... It is also why I would much prefer an engine with 2000 hours on it run correctly over one with 300 hours on it run for short bursts..... Sailors destroy engines doing short runs then letting all that water vapor sit in the engine. Hey maybe we have a new product to market...? No water vapor, or minimal, means you are running your engine correctly..

 

[Roger Long]

How long does it take and where can you find directions for proper time to burn off condensation?

No directions on the web that I know of and it's going to vary from engine to engine. If you are just going on and off a mooring or in and out of a small harbor, you don't want to be a purist and put the sails up as soon as you can. Run at least a couple miles at the highest speed that sea conditions allow. Use the time to work your way upwind so you can have an easier and nicer sail when you do shut down the engine.

Engines like slow power changes so bring the rpm up just 100-200 and wait until the boat speed catches up and stabilizes, then bring it up some more. Slow down in similar but slightly larger stages. Cruise as fast as sea conditions allow, up to 90% max continuous RPM whenever you can.

You can't always do these things but aim for them as much as possible. The less often you are able to make cruising speed runs of over an hour, the more often you should change your oil. Going out on a calm day and exploring and sightseeing as a powerboat for several hours is very good for your engine.