Diesel engine blow-by

[WillieC]

Puke bottle installed. After 2.5 hour running test...hard to tell.

IMG_2118.JPG

No drip into gray funnel and sad M&M jar. Fingers crossed.

(Edit: Looks like I should sell this thing. Now I have mismatched air filters. AND a run in the paint way down on the block. But she sure runs sweet!)

[kerrye]

Nice

[WillieC]

Update:

I installed the puke bottle, an air compressor filter available off the shelf at Home Despot, or Lose. First run looked good, but nothing collected in bottle, nothing dripped out the air cleaner after 2 hour run at normal engine loading. It was getting late so I buttoned it up.

Next day, in better light, I found all the oil I added the previous day, about half a quart, soaked into the diaper under the engine.. No oil in separator, none showing sign of having been spewed out of the engine air filter. Holy-moley! Did I blow a main seal? I couldn't pinpoint exactly where it came from, just all the usual suspects and no smoking gun. A line of oil on the diaper aligned with the visible weep check of the cam driven water pump, very odd as it is new. Obviously, the revised system provided too much back pressure to vent the blow-by so it found every other place to exit the engine. MUCH to my chagrin. I am so glad I am in the habit of checking the engine every time before running. The dipstick was close to a quart low and my original thought was to just go for a joyride.

So, natural born catastrophizer that I am, I go down the rabbit hole of regretting not buying Skol with its nice new engine and a ton of work to get it going. All my effort in the VP, down the drain, actually laying in the bilge....

Wait a minute. The oil pressure never dropped on the gauge. She ran like she always does, like a Swiss (Swedish?) watch, albeit with massive low frequency rumble. No overheat, just excess oil in the bilge. I removed the hoses from the puke bottle and blew on them to see if something clogged either and found a slight differential pressure with the filter in line. I had left the original brass filter element in the puke bottle and figured maybe that was enough to overcome, and hold back, the blow-by pressure, thus forcing it out anywhere else in the engine with less resistance. So I removed the brass filter and put it all back together, cleaned up the mess, installed a new diaper under the pan, topped up the oil, and called it a day.

Yesterday I took it for another two hour test run under normal running conditions. And what a fine day on the Canal it was. Hooked up to the anchor buoy I pulled the engine cover and everything was pristine. Diaper was spotless, no oil dripping from engine air filter, and still nothing in the puke bottle. (I did add a small wad of steel wool into the bottle as someone suggested. Oil may be caught and not made it to the bottom of the bottle yet.)

I understand that the crankcase pressure is very slight, not something to be measured in PSI. I remember as a young lad asking my dad why I couldn't make the tire pressure gauge work by blowing on it, which he let me do for a good long while before answering. I raised three of my own, so I get it, now. Not much pressure and apparently the brass filter was enough to wreak havoc on the engine. This must be why the official CCV filters have a pressure relief valve built into them.

I will do another longer run, with more loading and check again. I find it odd that no oil has yet to show up in the bottle, but I have a wacko theory:
What if...the new longer hose from the oil fill cap to the puke bottle, is large enough (diameter) and long enough and sloped just right to drain, that it will take slugs of oil sloshed up/blown up from positive crankcase pressure and not fill the hose completely so the nasty gases can pass over the layer of oil in the hose and make it back to the aircleaner and burned in the combustion cycle? The excess oil reaches some level of equilibrium in the hose and drains back to the engine fully when stopped or when throttle position is reduced or when going downhill, wait, this is a boat not a Mercedes.

More testing is in order, all this because I don't like oil mist spraying around my pretty new engine. Eventually, that mist becomes a serious fire hazard, to say nothing of what it is doing to the insides of my alternator and my own psyche. I proceed.

[Jon Fuller]

Hi. I just bought my albin 27 fc. It's consuming and spitting a lot of oil. I did not discover that what I thought was water in bilge was actually oil until I dropped my wrench into it. I have a 1984 lehman 4D61. Looking around I believe that some of the oil is coming from breather cap on valve cover. Oil filter area and below it are wet with oil. I did not notice excessive oil or surface mist when I bought it. The rest I guess is blow by. I lose about half a quart per hour. That is excessive. Technically it is okay to suck oil. Just need to closely monitor level. Hours on motor are 1355. Engine starts ok and runs fine. No excessive smoke, normal amount. Do not see clouds of black white or blue smoke. No excessive diesel exhaust smell. No smell of diesel in oil. About 45 pounds of oil pressure. Water temp About 160. Any suggestions? Love the boat, want to solve the problem. Thank you

[WillieC]

Google Closed Crankcase Ventilation. Some manufacturers catch the oil and run it back into the pan. I don't like the looks of it so I am happy just catching it. The misty vapors can go back into the combustion chamber and burn with the fuel. As I noted above, with my altered arrangement, I have yet to see any oil reach the compressor filter, nor is any dripping out of the air filter like it used to. I really do think with the longer hose, it reaches some kind of equilibrium, and the oil drains back to the engine. Not exactly what I intended, but now the boat is out of the water so may wait until spring for more fooling around. Read also that my first installment resulted in oil blowing past the seals into the engine pan. That seems to have healed, confirmed by a five hour run.

[Jon Fuller]

Hi, Thank you. I will google as you say. I also like your puke bottle idea with the upward slope to the pipe.. I will do that this weekend. Question please - what are you using for an air filter? Are you using the off the shelf compressor filter from HD? Thank you.

[RobS]

, ...and the oil drains back to the engine. Not exactly what I intended,...

Agreed Willie but Walker seems to have no problem with it.......

[WillieC]

It is from Lose. What is their brand? Kobalt? Re-read my whole thread. The path I chose, at least for now, is noted in Kerrye's comments and links and, as always, advice from Rob. Simple is good. Take a look at what they are doing with old Mercedes. The way the whole set-up appears to be working now, I could possibly eliminate the puke bottle, because nothing is showing up in it. I may rearrange things so I catch at least some of it and keep it out of the engine lubrication cycle. The original used the shortest hose to the closest cylinder to the oil fill/breather cap. Since I had no way to mount the puke bottle/compressor filter near that location without blocking access to service items, I moved it forward, mounted the bottle to the bulkhead and ran longer hoses.

One of the vendors I listed has some excellent videos showing what is going on with blow-by in these engines. Most manufacturer's include a pressure relief valve in the event of plugged filter. I am just a trial and error hack mechanic that figured I was not the first person in the world to have this problem. I hated seeing my nice clean engine compartment revert to its previous state. As they say, you mileage may vary.