Crankcase Vent, to separate or not.....

[hollywood8118]

While servicing the great beast in the middle of the engine room I noticed the breather line that goes directly from the top of the valve cover to a barb tapped in the intake manifold was weeping a oil film. The heater hose I installed a few years back ( red because it was pretty cool looking) was shot and needed replacement.* So I started to do a search on diesel crankcase venting and found a lot of info, mainly dedicated to trucks. One of the issues is that it is possible to actually pull enough vacuum to pull oil from the crankcase which can cause a runaway diesel.* So the question is how do you deal with your crankcase vent. My engine is a non turbo John Deere, so that removes the issue of the turbo scavaging oil and causing things that spin way too fast to go into lots of little pieces.

 

[Codger2]

hollywood:

This is how I deal with your problem. I've been using "Walker's" products for 15 years and love them!*** Walker Engineering - Home

 

[Nomad Willy]

I'm not saying it is but it sounds like a classical case of blow-by. The rings could be either worn out or stuck to some degree. The blow-by enters the crankcase under pressure, passes through the push rod holes to the area just above the cyl head and the valve cover. The air gets recirculated through your red hose to the intake (manifold). If your engine is worn out you may know what to do. If the rings are stuck high ring and piston temperatures usually cause more ring sticking and failure. If you can get "Sea Foam", a product designed to dissolve carbon, and get it to the rings for a few hours to a day the rings may free up and restore your engine. If you pour the Sea Foam into the cylinders through the glow plug holes or the injector holes (a) the fluid may not reach the rings as most diesels have a dished piston crown and you may just half fill the depression on the piston crown. Then when you crank the engine you may have a 60-1 compression ratio. (b) the Sea Foam may (probably) act like fuel and produce a few seconds of full throttle operation (complete w pre ignition) that could cause more damage than stuck rings. The foregoing is strictly opinion and I suggest you ask your mechanic how to apply the Sea Foam to your rings. Also I think it's possible (assuming your rings are to some degree stuck) that your situation could have come about through running underloaded over a long period of time. We kicked the underloading issue at least half to death and everybody on the thread seemed to go away w the same opinion they started with. So if it were my boat I'd start w a compression and/or a leak down test. Or (much cheaper) try the Sea Foam as directed by a good mechanic.

Eric Henning

 

[hollywood8118]

nomadwilly wrote:

I'm not saying it is but it sounds like a classical case of blow-by. The rings could be either worn out or stuck to some degree. The blow-by enters the crankcase under pressure, passes through the push rod holes to the area just above the cyl head and the valve cover. The air gets recirculated through your red hose to the intake (manifold). If your engine is worn out you may know what to do. If the rings are stuck high ring and piston temperatures usually cause more ring sticking and failure. If you can get "Sea Foam", a product designed to dissolve carbon, and get it to the rings for a few hours to a day the rings may free up and restore your engine. If you pour the Sea Foam into the cylinders through the glow plug holes or the injector holes (a) the fluid may not reach the rings as most diesels have a dished piston crown and you may just half fill the depression on the piston crown. Then when you crank the engine you may have a 60-1 compression ratio. (b) the Sea Foam may (probably) act like fuel and produce a few seconds of full throttle operation (complete w pre ignition) that could cause more damage than stuck rings. The foregoing is strictly opinion and I suggest you ask your mechanic how to apply the Sea Foam to your rings. Also I think it's possible (assuming your rings are to some degree stuck) that your situation could have come about through running underloaded over a long period of time. We kicked the underloading issue at least half to death and everybody on the thread seemed to go away w the same opinion they started with. So if it were my boat I'd start w a compression and/or a leak down test. Or (much cheaper) try the Sea Foam as directed by a good mechanic.


Eric Henning

*

Eric,
Thanks for the reply but what I am referring to is inherent to ALL diesel engines, new or old. I am 1900 hrs into what is usually a 30,000+ hr. motor. In over the road (non tier2/3) the crankcase usually vents to atmosphere. With the exception of a pollution issue and an occasional drip of oil its not really a problem. On our boats no one wants a smelly/oily engine room. What I was trying to ask has anyone added a aftermarket oil/air separator to their crankcase vent system??* All the new Diesels have a separator that removes oil mist from the blow by and dumps it back in the oil pan

*

 

[Forkliftt]

HW,
Why not first replace the cool hose with an uncool hose that is designed to be exposed to oil. Fuel line would work if is a small diameter. A larger diameter hose might need to be sourced from an Industrial hose supplier.

 

[hollywood8118]

I guess I was on the never ending journey to find the better mouse trap.....

1. less buildup/gunk in the intake....

2. no chance of ( very slim anyway ) of a runaway diesel

3. more cool stuff to hang off the engine ( Joke! )

My actual point was that I was not sure the engine was actually designed with the current hose to intake as a stock item, the previous owner/builder is unavailable (may he sail in peace) and the original manual for the engine was destroyed prior to my ownership. I have a replacement manual but the setup is a little different that shown.
I know walker makes a nice setup ( must be for the $$$) and Racor has recently started making aftermarket separators.

my engine runs great, is a shiny brilliant white, doesn't use any appreciable oil... this all started because of the mushy hose

 

[Nomad Willy]

HW,Sounds like you just need a hose suitable for oil.
Nice boat * *..assume it's yours.


Eric Henning

 

[Delfin]

Hollywood, on my boat I vented both the CAT and genset to the outside by plumbing a combined aluminum vent line up the raceway that contains the dry stack exhaust.* I put a condensate drain on the bottom of the vent, and a 180 at the top of the vent to keep the rain out.* The exit is on top of the stackhouse, and there is oil residue that has to be cleaned up every 100 hours or so, but it's no big deal.

 

[hollywood8118]

nomadwilly wrote:

HW,
Sounds like you just need a hose suitable for oil.
Nice boat * *..assume it's yours.


Eric Henning

*

Yep, 7 years and counting. We purchased her with the plan to escape again when the kids walk out the door to college. 3000 mile range, we are up to 1900 hrs. on the repower, rigged with paravanes that we use quite a lot. I am in the middle of rewiring all the ac side of the electrical.* She was launched in 1970 and looks like a converted fish boat, but she was only designed to look like one.... never was. The P.O. detested the "gin palace" motor yachts and drew the lines himself..... who knew that the converted fishboat thing would become so popular. I must be a little like him, I love squeezing her on the dock in a row of plastic fast dock queens.* But as much as I love her I still have bouts of boat envy... I saw Delfin's boat a couple years ago and almost slipped in my drool puddle on the deck!

*

 

[hollywood8118]

Delfin wrote:

Hollywood, on my boat I vented both the CAT and genset to the outside by plumbing a combined aluminum vent line up the raceway that contains the dry stack exhaust.* I put a condensate drain on the bottom of the vent, and a 180 at the top of the vent to keep the rain out.* The exit is on top of the stackhouse, and there is oil residue that has to be cleaned up every 100 hours or so, but it's no big deal.

I have a bud that runs a passenger ferry, his does the same thing except vents through above water thru hull in the side of the hull. Thanks for the reply. By the way I did install a bypass oil filter, I have not made the final connection of* the return line as I am timing that with the next oil change.

*

 

[Delfin]

Hollywood, I have found that the oil seems to be getting cleaner as engine hours increase on the bypass filter, so I assume it's cleaning the suspended soot built up over prior hours.* The Puradyn I have has a heated condensate line (is that what you installed?) and I am finally sending off a sample of this condensate to see what's in it.* I suspect not much, but we'll see.

 

[sunchaser]

CCV venting overboard is illegal. Not that you'd get caught mind you, but it is no different under the eyes of the law than pouring your used oil into the water. With the correct hose and a vent bottle, you'll be just fine - check out this setup on boatdiesel.com and under "articles" for year 2007. Very simple and a great explanantion of marine*CCV. No big $$ airsep required. Racor makes a marine CCV*system too.*My CCV vents go right back into the air intake (similar*to over the road diesels), very little*fluid appears*- a few drops per hour - but engines only have 600 hours so far.

-- Edited by sunchaser on Monday 3rd of May 2010 11:18:24 AM

 

[Phil Fill]

I made an air sep by attaching a hose to the vent then into a gallon milk jug filled with paper towels.* Every year I replace the old jug with a new milk jug filled with paper towels.* Seem to absorb most of the oil and keeps the engine room clean.* That is basically what the expensive air sep is?* I*am cheap?

 

[Sailor of Fortune]

On Many of the Detroit powered Work boats I have been around, The hose is run into a 5
gallon (empty) oil bucket. The top is left on. The hose is run through the spicket. Oil absorbent pads are placed in the bottom of the bucket and help remove the oil from the air.
Needless to say,the top is cut for removal (to place pads and clean now and then.

 

[RickB]

sunchaser wrote:
CCV venting overboard is illegal.

No it's not, putting oil in the water is though.

Most dry stack installations that don't use an "air sep" or vent to the turbocharger air intake will pipe the crank case vent to the top of the stack and use a condensate trap to catch the moisture.

 

[hollywood8118]

Delfin wrote:

Hollywood, I have found that the oil seems to be getting cleaner as engine hours increase on the bypass filter, so I assume it's cleaning the suspended soot built up over prior hours.* The Puradyn I have has a heated condensate line (is that what you installed?) and I am finally sending off a sample of this condensate to see what's in it.* I suspect not much, but we'll see.

I also installed a Puradyn, I am excited to see the results as the hours rack up. do you have a picture that shows the bypass setup?. I have not seen anything negative regarding these units. How much liquid do you get from the condensate line in 4 hours?, I have not figured what size of container I need for this.

*

 

[Delfin]

Hollywood, I'll take some and post them.* I mounted it on the ass end of the engine, over the gear.* For the condensate, I settled on a small o.j. container that slips in behind one of the hoses on the gear.* I think it takes about 12 hours to produce a 1/2 pint of condensate.* I will be interested in the test results to see if there is any more H2O in this oil than should be, or if it shows elevated levels of volatiles.* It looks like just oil to me, but I'll post the results once I get them back from the lab.

 

[sunchaser]

RickB, excuse my lack of proper wording. I should have said "CCV direct venting overboard into the water is illegal" In the old days, DDs being some of the worst, operators dropped their CCVs into the bilge and then it was discharged overboard. The USCG inspections have the CCV venting issue on their checklist.