How to build a negative crankcase ventilation system (lose the cdr!!)

[merlot566jka]

Hey folks, This is just the beginning to a whole bunch of things I will be doing for the 6.2l burb.

The idea is not new, but the way to get there is.

Negative pressure (a vacuum) in the crank case provides better sealing for the rings and decreases oil leaks. It can also improve gas mileage by reducing pumping losses from the bottom half of the engine. OEM manufactures know this, and they have the fancy pcv (positive crankcase ventilation) which uses check valves and manifold vacuum to draw fresh air through the crankcase and plumbs it back into the intake tract. It can also decrease emissions. While that system has been shown to work wonders, we cannot have that luxury... we don't have manifold vacuum. The solution for our engines was the pesky CDR valve, which only works (well) when there is a restriction between the manifold and air filter causing a slight amount of vacuum. But that seems to me like a crappy solution to a problem. Especially in an engine with high compression, loose tolerances, and some are even faced with forced induction to add to the issue.

I come from the modern age of performance vehicles and new ideas are brewed every day by folks on forums everywhere. One thing I came across was from a buddy of mine telling me how his dipstick was blowing out and shooting oil everywhere on his Grand National's pretty engine bay. The cause was too much blow by at 22lbs of boost. Another member from the Turbobuick.com forum used an electric smog pump from an lt1 Camaro to pull a vacuum on his crankcase, providing a sufficient route for excess gas to be evacuated. The thread can be seen here.... http://www.turbobuick.com/forums/gen...-pump-how.html

With this in the back of my mind, I discovered oil leaks on my truck, pulled the oil cap and realized that there was a lot of blow by going on and my CDR valve wasn't doing its job. Ok, time to apply what I've seen else where....

First thing to tackle was the smog pump its self. Ive gone through 3 of these now. The first one was blown when I got it. I disassemble it, discovered it was full of rust, tried to rebuild it, but failed. it was just too beat up. I got another one, that worked for a few days on a prototype setup. It eventually filled with oil in the motor housing and then met its maker when it fell from its bracket. One of the leads was torn from the motor brush. Again trying to fix it, I didn't succeed. So I went on a search for a new version that is possibly more stout. I discovered that the newer LS1 Camaro's and 'Vette's had a newer pump. Then I crossed the part numbers with other makes and models, and sure enough, the newer style of smog pump comes on tons of gm vehicles. A trip to the salvage yard, $20, and 45 mins of scouring the yard lands me with one new style pump from a Chevy Malibu and an older style from a 96 Monte Carlo. The newer one is what I used here in the pics. Its completely sealed off from the impeller and a really good design. This is what you should be hunting for.


The next step was to keep oil and moisture from getting to the smog pump. An effective oil catch can was needed. I bought one on ebay for $26. It was tiny, and a huge restriction on the whole system. not to mention very cheaply made. It will become my new coolant catch can tomorrow. Money and time wasted.
I looked for something that would work, and I found many things, but it would have cost a fortune to get things that looked like they were sufficient. My solution was good ole Home Depot. Since this won't ever see high temps or extremely caustic chemicals, I chose PVC. (not to mention I am in an apt and cant really weld here, so something cheap and user friendly was in mind) I used the following
1 four inch pipe coupler $1.13
2 four inch pipe caps $2.88
2 four inch no hub rubber coupling $10.84
4 3/4in, 90 degree plastic bend combo (barb to threads) $3.84
2 3/4in PVC couplers $1.46
Black RTV $4.79
steel wool 'Brillo' pad $ FREE (from work)

I drilled the holes with a pocket multi-tool, sealed things with rtv. the pictures will really explain the whole construction.








The Brillo pad is used as a baffle/oil trap


The next step was getting it into the truck. Now the wiring for the pump should really be set up through a relay, because I believe its more than 20 amps to get it going. I used the only 12v relay I could find from Pep Boys. I think it was for a foglight setup. I used the positive from the IP shut off switch as the switching power. (later I might look into using a LM555 timer and transistor to use PWM to drive the motor....well see)
I moved the coolant reserve tank and held it in place by using one of its original bolt holes in the fender and kind of cocked it downwards...it works, but like I said earlier, Its getting replaced tomorrow anyway.
I used an exhaust hanger bracket clamped to the catch can and bolted down to where I believe the jack or something used to be held.
I then squeezed the back of the pump to fit into the cut out in the fender support. Its nice and snug, but a better mounting fixture with rubber isolation is really needed here. (this pump is a powerful sucker, it makes some real noise)
The plumbing was easy, I used a 3/4 piece of heater hose to go from the CDR outlet on the oil filler neck to the inlet of the catch can (that's the one with the 90* piece on the bottom of the catch can lid). Then I used the factory piece that was already attached to the smog pump to go from the outlet of the catch can to the inlet of the smog pump. The outlet of the smog pump was sent straight back to the intake.
Here are pictures...

[merlot566jka]

And that is it. Works like a charm, no more oil leaks , and seems to idle better.
A longer term update will be added later this week to be sure things are going as planned, but so far so good.

Good luck folks, and If you have any questions, let me know!

[merlot566jka]

sorry for the blur, I used my cell phone for the pictures, they look better in smaller scale. but they should still illustrate well.

[convert2diesel]

Good work. Always been a problem with these engines. Only concern I have is that I have the same pump on my Caddy (LT1 engine) and the pump only runs for 3 minutes until the cats are fired, then shuts down. I would be concerned about the longevity of the electric motor used. It was originally designed for intermittent use and would probably need some significant cooling to run all the time. I also thought of using this pump to supply vacuum for the heater controls and power brakes on the Buick but could only get about 5 inches of vacuum. Not enough for the brakes.

Just a thought.

Bill

[Yukon6.2]

Hi
Looks like you have come across another way to skin a cat.I was looking for a way to keep oil fumes from entering my aftercooler,i came across a crankcase filter made by racor.They are made for diesels in boats mainly.I was hoping that one would work on my engine.Has anyone here tried one on their trucks or had any experiance with one?
I might change my plans depending on this pump and catch idea,i will be watching to see how it shakes out.
Thanks for the idea and picks
Thomas

[93GMCSierra]

Nice work, I will be looking forword to your longevity as well, I do have one question though, is there a drain of some sort on your "catch can" as over time would oil start to fill it?

[merlot566jka]

Good work. Always been a problem with these engines. Only concern I have is that I have the same pump on my Caddy (LT1 engine) and the pump only runs for 3 minutes until the cats are fired, then shuts down. I would be concerned about the longevity of the electric motor used. It was originally designed for intermittent use and would probably need some significant cooling to run all the time. I also thought of using this pump to supply vacuum for the heater controls and power brakes on the Buick but could only get about 5 inches of vacuum. Not enough for the brakes.

Just a thought.

Bill

Yes, that has been a thought of mine as well. Others have said they let the pump go all the time, but I really don't know how much they drive their vehicle. That's where the thought of using pulse width modulation to control the dc motor comes into play. That way I can control voltage and duty cycle. Perhaps getting it to vary with rpms would be best. Well see what I come up with there. I don't know what I'm going to do about the load that this motor requires, I will have to research to find something to handle it.

Hi
Looks like you have come across another way to skin a cat.I was looking for a way to keep oil fumes from entering my aftercooler,i came across a crankcase filter made by racor.They are made for diesels in boats mainly.I was hoping that one would work on my engine.Has anyone here tried one on their trucks or had any experience with one?
I might change my plans depending on this pump and catch idea,i will be watching to see how it shakes out.
Thanks for the idea and picks
Thomas

Hmmm that sounds very useful, almost the same as a catch can, Ill look it up.

Nice work, I will be looking forward to your longevity as well, I do have one question though, is there a drain of some sort on your "catch can" as over time would oil start to fill it?

No drain on this one, really thought about throwing a 3/4 ball valve on the bottom but it would have been awful to try to mount it afterward. I will just loosen the top hose clamp and remove the lid to drain it. I hope it doesn't fill up fast enough for me to worry about it, that thing will probably hold about a liter and a half of liquid! Ill check it next Friday to see how its doing.

[convert2diesel]

No drain on this one, really thought about throwing a 3/4 ball valve on the bottom but it would have been awful to try to mount it afterward. I will just loosen the top hose clamp and remove the lid to drain it. I hope it doesn't fill up fast enough for me to worry about it, that thing will probably hold about a liter and a half of liquid! Ill check it next Friday to see how its doing.

You could always install a drain hose out the bottom and use the PCV valve from a gasser inserted in the line backwards. Would allow the canister to hold vacuum but when shut off would open up and drain the oil back to the engine.

Bill

[merlot566jka]

You could always install a drain hose out the bottom and use the PCV valve from a gasser inserted in the line backwards. Would allow the canister to hold vacuum but when shut off would open up and drain the oil back to the engine.

Bill

why do you always get to the good ideas before i see them! lol, that sounds awesome....Ill give it a try after the preliminary trial of the crank case.

After doing some start and go today, I really feel this needs some sort of timing to go along with it, running all the time is just not needed. Perhaps the LM555 timer is really needed.

[convert2diesel]

why do you always get to the good ideas before i see them! lol, that sounds awesome....Ill give it a try after the preliminary trial of the crank case.

After doing some start and go today, I really feel this needs some sort of timing to go along with it, running all the time is just not needed. Perhaps the LM555 timer is really needed.

Try re-incorporating a working CDR valve into the system. It is essentially a blow off valve that senses crankcase pressure. If the crankcase pressurizes then the valve opens, venting into the intake manifold. Don't know how it would react with high vacuum (may be too much differential pressure) on the output side but may be worth looking at.

Bill

[DmaxMaverick]

Try re-incorporating a working CDR valve into the system. It is essentially a blow off valve that senses crankcase pressure. If the crankcase pressurizes then the valve opens, venting into the intake manifold. Don't know how it would react with high vacuum (may be too much differential pressure) on the output side but may be worth looking at.

Bill

Backwards. The CDR is normally open, then closes with high intake vacuum. This to prevent too much crankcase negative pressure, which increases oil consumption among other things (premature seal failure, oil contamination).

The CDR gets blamed/replaced for a lot of reasons, usually excessive blowby. Actually, they rarely fail, despite how they appear (grimy/sooty), and they get replaced unnecessarily. The CDR, when operating properly in an otherwise healthy engine, will reduce the appearance of blowby. If you are seeing excessive blowby at idle and no-load RPM's (no turbo boost), it isn't the fault of the CDR unless it's frozen closed (easy to check, just blow through it).

If you don't like oil in the intake, you can incorporate an oil vapor condenser to reduce it. Otherwise, live with it. That is the nature of the 6.2/6.5 design. If you design/install a PCV (essentially what this thread about), you will be increasing oil vapor removal from the engine, and defeating the purpose of the CDR, regardless of the appearance of blowby reduction and intake oil buildup. The Diesel engine does not develop intake vacuum like a gasser, but it is present, however slight. If your blowby is defeating the vacuum present, you have other issues with the engine, and it is not the fault of the CDR. If you don't want the intake oil accumulation, address that, but trying to "suck out" the vapor with a pump is an excersise in futility, and will likely be counterproductive.

There are many options currently available (on-the-shelf products and design concepts) to capture and condense crankcase oil vapor. However, eliminating, defeating, or otherwise reengineering the CDR (or its designed functionality) will create other issues, and likely mask other engine deficiency symptoms. The engine seals (front or rear main, for example) are designed to work in a vary narrow pressure window. Exceed the pressure, and oil will be forced outward past it. Exceed the vacuum, and it will suck air and dirt (among other things, like water) inward.

[merlot566jka]

Backwards. The CDR is normally open, then closes with high intake vacuum. This to prevent too much crankcase negative pressure, which increases oil consumption among other things (premature seal failure, oil contamination).

The CDR gets blamed/replaced for a lot of reasons, usually excessive blowby. Actually, they rarely fail, despite how they appear (grimy/sooty), and they get replaced unnecessarily. The CDR, when operating properly in an otherwise healthy engine, will reduce the appearance of blowby. If you are seeing excessive blowby at idle and no-load RPM's (no turbo boost), it isn't the fault of the CDR unless it's frozen closed (easy to check, just blow through it).

If you don't like oil in the intake, you can incorporate an oil vapor condenser to reduce it. Otherwise, live with it. That is the nature of the 6.2/6.5 design. If you design/install a PCV (essentially what this thread about), you will be increasing oil vapor removal from the engine, and defeating the purpose of the CDR, regardless of the appearance of blowby reduction and intake oil buildup. The Diesel engine does not develop intake vacuum like a gasser, but it is present, however slight. If your blowby is defeating the vacuum present, you have other issues with the engine, and it is not the fault of the CDR. If you don't want the intake oil accumulation, address that, but trying to "suck out" the vapor with a pump is an exercise in futility, and will likely be counterproductive.

There are many options currently available (on-the-shelf products and design concepts) to capture and condense crankcase oil vapor. However, eliminating, defeating, or otherwise re engineering the CDR (or its designed functionality) will create other issues, and likely mask other engine deficiency symptoms. The engine seals (front or rear main, for example) are designed to work in a vary narrow pressure window. Exceed the pressure, and oil will be forced outward past it. Exceed the vacuum, and it will suck air and dirt (among other things, like water) inward.

yup, I have excessive blow by. And increased oil in the intake. Not only that, but i have oil coming out of the fill tube around the cap, even with a new filler lid. The engine is a huge grease ball. there is no oil coming from the front main or rear main seals, or any where else for that matter.
My rings are probably shot. I know this. Can I afford a rebuilt engine, or do I have the time to install another engine? nope.
My fix could be called a band-aid, cover up or a mask.
I don't think the pump is pulling enough vacuum to suck air through the seals, and to prevent that, I have purchased a valve cover for the 6.5l that has the pcv hole in it, Ill be using a pcv 'filter' to allow fresh air in. That way I know I wont be pulling excessive negative pressure, instead just changing out the bad gas for the good.

[convert2diesel]

Backwards. The CDR is normally open, then closes with high intake vacuum. This to prevent too much crankcase negative pressure, which increases oil consumption among other things (premature seal failure, oil contamination).

Your absolutely right. My bad. Just checked one I had on the floor.

Never the less, operating at slight negative pressure would do nothing to increase atomization of the oil nor would a couple of inches of H2O be sufficient to effect oil consumption or pull anything through the seals. The intent here is to merely scavange the crankcase gasses and prevent positive pressure build up. The idea of installing another fresh air source (plumb it through the air filter) is valid and would help even a new engine with little or no blow-by. Positive pressure does way more damage then a slight negative.

Bill

[DmaxMaverick]

All assuming a properly installed and operational CDR and intake-crankcase vent:

You already have a "slight negative pressure" crankcase environment. The intake will draw more than sufficient vacuum on the crankcase, even with an inline condenser. This is what the CDR is for: preventing TOO MUCH vacuum. If you have enough blowby to overcome the intake vacuum (however slight you think it is), you have a SERIOUS problem, like a holey/missing piston. Adding more air (via an inlet vent) to the crank case will, in fact, increase airborne atomized oil vapor escape. If you allow more air in, you will need to remove more than you allow, plus the current blowby, and more air movement will involve more oil vapor movement. Guaranteed.

That said, using this concept as a means of "stretching" the engine life beyond excessive blowby is not unreasonable, if it's used for only evacuation of crankcase gases (not allowing more air in). Trips to the hardware store and driveway time is much less expensive than an overhaul, no doubt. It isn't "Diesel PC", but there's absolutely nothing wrong with it. However, this is NOT an engine I would consider a candidate for a blower (or even a turbo). It will likely push it over the edge. So much for the economics approach.

[merlot566jka]

smog pump motor fried today, aprox 4 hrs run time on it. Seems a choke coil over heated, lost its solder and melted its plastic base. I re soldered it, but it heats up really fast and melts not even a second after reconnecting it.

I am going to try to find another 12v dc motor thats intended to run all the time. perhaps a blower fan for a/c systems.

the catch can certainly has oil in it, not as much as I expected, but I think there has to be another way to get the oil out of the vapor before its pulled from the engine.

an update will come later

[merlot566jka]

some good reading on vacuum pumps and crankcase evac

http://www.dragstuff.com/techarticles/vacuum-pumps.html

motor specs for the smog pumps motor....this thing is a fast mover!

http://www.igarashimotors.co.jp/prod.../037A_5066.pdf

[merlot566jka]

All assuming a properly installed and operational CDR and intake-crankcase vent:

You already have a "slight negative pressure" crankcase environment. The intake will draw more than sufficient vacuum on the crankcase, even with an inline condenser. This is what the CDR is for: preventing TOO MUCH vacuum. If you have enough blowby to overcome the intake vacuum (however slight you think it is), you have a SERIOUS problem, like a holey/missing piston. Adding more air (via an inlet vent) to the crank case will, in fact, increase airborne atomized oil vapor escape. If you allow more air in, you will need to remove more than you allow, plus the current blowby, and more air movement will involve more oil vapor movement. Guaranteed.

That said, using this concept as a means of "stretching" the engine life beyond excessive blowby is not unreasonable, if it's used for only evacuation of crankcase gases (not allowing more air in). Trips to the hardware store and driveway time is much less expensive than an overhaul, no doubt. It isn't "Diesel PC", but there's absolutely nothing wrong with it. However, this is NOT an engine I would consider a candidate for a blower (or even a turbo). It will likely push it over the edge. So much for the economics approach.

yeah, that's been tumbling around in the back of my mind too. I have pretty much come to the conclusion that this engine is going to go soon, and why not go ahead and fabricate the blower to it, get the whole set up working, and when it goes, it goes. Ill bite the bullet, get a new long-block ordered and take a couple days off work to take care of it all.

Economic....ehh, I sold my trailblazer for exactly what I owed on it and used 2 weeks paycheck and a beer (1 budlite, part of the purchase price...yeah, odd) to get the Burb. Ive saved about $600 in fuel costs, $390 in insurance, and $250 a month in payments. (for 5 months) and Ive put $800 into the truck for repair/maint/resto. I think I am still in the economic area as far as the truck as a whole. Not economic for using the charger on the engine....

And I got outta 'Vettes because of the PC bs. Then I went into Fieros...no politics there.... so I know what your saying. Im sure my old Engineman Chief would knock me sideways if he had seen what I've been thinking about to do with this engine! There are somethings you just don't do...but 15 years ago, who would have thought that people would be racing 4 door diesel trucks at the drag strip pulling better times than some of the 'muscle cars'?? That would have been something you didn't do...
Maybe a couple of years from now my idea wont sound as, well, pointless.

[More Power]

Just my 2-bits..... This engine works best when operated at a slight negative pressure, like that provided by the stock Crankcase Depression Regulator and related plumbing arrangement. More negative crankcase pressure (vacuum) than this will allow some amount of dirt to be pulled past the various oil seals and into the engine.

Jim

[convert2diesel]

Just my 2-bits..... This engine works best when operated at a slight negative pressure, like that provided by the stock Crankcase Depression Regulator and related plumbing arrangement. More negative crankcase pressure (vacuum) than this will allow some amount of dirt to be pulled past the various oil seals and into the engine.

Jim

A number of years ago I read an article done by the people at Caterpillar on the topic of crankcase ventilation and oil rejection temperature. Somewhere in all this mess I have a hard copy of the report but for the life of me, can't find it.

The jist of the conclusions was that the oil rejected from the bearing surfaces were close enough to vapour point that elevated crankcase temperatures would allow some of the aromatics in the oil to essentially vaporize, causing increased fogging and fractionalizing of the atomized droplets. In the report they suggested increasing the air flow through the crankcase and even suggested using a small blower to scavange the sump to lower the crankcase temperatures especially in their stationary engines. Apparently the on-road engines get enough pan cooling when in motion. They did some testing and were able to maintain about 4 inches of vacuum on the engines with no apparent seal draw. Maybe Cat seals are better suited for this application.

Subsequent to reading this article, I have noticed Cat and others on some of their stationary engines are now using forced scavanging, at least on their larger installations. Perhaps it has something to do with the new pollution regs, but it is possible they acted on their own testing.

I have always felt the CDRs on our engines were barely functional for the purpose intended, at least on the NA engines. The difference in oil consumption between city driving and highway would bear this out. Even brand new, the 89 6.2 used about a quart every 1,200 miles in the city but required no oil between changes when operated on the highway. Granted the numbers got worse as the engine aged, but that is to be accepted as a given.

Just some thoughts.

Bill