Electric crankcase evacuation pump

[A.J.]

Before I started this I put a vacuum gauge on my dipstick tube to check to see how bad my blow-by was if I had any at all. The needle fluttered back and forth at idle but under boost it steadied out but didn’t show pressure. And before anybody suggests a valve job the needle doesn’t fluter when hooked up to the intake. I’m guessing the PCV valve opening and closing or the turbulence of the crank and pistons moving is what’s causing it.

I installed a G.M. electric smog pump to use as a crankcase evacuation pump. I had to do a modification to my PCV system. I had to build a check valve so my PCV system would pull the crankcase into a vacuum. The way I have my oil catch can set up is basically an extension of my valve cover. I have the PCV pulling vapor out of the valve cover via the catch can. During boost any blow-by would then got to the airbox. In order to pull a vacuum in the crankcase I had to put a check valve between the oil catch can and the airbox. The check valve had to be big enough to flow blow-by into the airbox without creating back pressure in the crankcase. With the airbox vent hose being 5/8” I made the check valve with 5/8” barb fittings. I hooked the evac pump to pull a vacuum on the catch can.



You need to do some modifications to the electric smog pump before you use it. Go here for the mods:

http://www.turbobuick.com/forums/gen...-pump-how.html

I don’t want my evac pump running all the time and when the intake has vacuum there is no need for it to run. So I have the pump hooked up to a relay and a Hobbs switch. The switch is set for 2 p.s.i.



Now at idle my crankcase is at 6-10” HG. Under boost the evac pump pulls about 3” HG.





A.J.

[Ondonti]

Mmm that looks good. I think I would enjoy that in addition to what I already have. How heavy is that thing?

[A.J.]

Do you mean the evacuation pump? It's not that heavy it's just finding a place to put it. The bracket that bolts to the block from the Buick Roadmaster I swiped it from is pretty thin and light.

I've also made a few changes to the original design. I didn't bother posting them because it seemed nobody was interested.

First I had to relocate the 5/8" barb check valve I made. Because I had it between the pump and the air box I couldn't pull more than 3" HG after awhile in the crankcase. I moved it to between the pump and the catch can. Now it pulls 10" to 13" HG.



Second I set the Hobbs switch to 5 p.s.i. instead of 2 p.s.i. because vacuum holds from 13" HG longer than when I first set this up, so there is no need for the pump to come on so soon.

A.J.

[Ondonti]

So the pump didnt like pushing through the check valve but it pulles okay?
What wire are you running it off of. I dont know how much current that thing will pull and every device I add to my harness (like alky pump) makes me paranoid.


Im guessing it wont want to push through the check valve I have on my exhaust

[A.J.]

So the pump didnt like pushing through the check valve but it pulles okay?

The pump didn't have a problem pushing or pulling, the PCV couldn't pull the crankcase into deep enough vacuum. There might be some air leaks in the pump housing. Or the pump plus the slight leak in the check valve was too much to pull a deep enough vacuum. I plan on getting a smoke machine ($600) for locating vacuum leaks. When I get it I'm going to smoke the pump to see if it leaks. That might be why It won't pull more than 3" HG. But then again I am using an "air" pump as a "vacuum" pump. Not what GM intended.

What wire are you running it off of. I dont know how much current that thing will pull and every device I add to my harness (like alky pump) makes me paranoid.

I have the pump hooked up to a relay. The Hobbs switch supplies the ground to the relay to complete the circuit. I also have the relay on a 20 amp fuse and it's been fine. Every time I add a new accessory I give it it's own fuse and relay. You might be able to see the cluster of relays in one of the pictures.

Im guessing it wont want to push through the check valve I have on my exhaust

Your probably right. But if you get a pump you can bench test it before you go through the effort to mount it. But why have the evac pump if you already have the exhaust evap?

A.J.

[Ondonti]

I was figuring exhaust evac to do the work out of boost, and let the pump "ramp things up" in boost.
Like you, I wouldnt want to run that thing all the time. No PVC system.

BTW, what voltage does that thing use? Maybe you could use a "boost a pump" to run it at a higher voltage if it would handle it.

Adding new relays is a good job. I am too scared of them at the moment but that sounds like something that would give mental comfort (and make some wires happier)

For leaks I just use an air compressor and soapy water.

[A.J.]

I was figuring exhaust evac to do the work out of boost, and let the pump "ramp things up" in boost.
Like you, I wouldnt want to run that thing all the time. No PVC system.

From what I've read about the exhaust evac you should be getting more vacuum at higher rpm's then at idle. Have you run your car with a vacuum gauge on your dipstick tube to see what the actual reading is. I did and that's how I know what my crankcase is doing.

BTW, what voltage does that thing use? Maybe you could use a "boost a pump" to run it at a higher voltage if it would handle it.

It runs on 12 volts like everything else on the car.

Adding new relays is a good job. I am too scared of them at the moment but that sounds like something that would give mental comfort (and make some wires happier)

If you don't know how to run a relay I can explain it, it's really easy once you know. It's cheap insurance to keep from melting wires or fusable links.

For leaks I just use an air compressor and soapy water.

For leaks in an a/c system that's what I do. The evac pump is only held together with silicone. I might blow it apart. Besides I need the smoke machine for other things and it only produces 2 p.s.i.

A.J.

[zin]

This reminds me of a customer we had (NOS) that was using a pair of vacuum pumps from a Caddy (diesel?) on his Big Block Chevy racecar. He had good success and was using as an advantage over the comp. He even mounted the things inside the car with him! That really confused people!

Sounds like you may have come up with a newer version! I was going to say that I was concerned that they didn't pull enough volume (only 3"), but now that you've got it over 10", seems like it's a non-problem! I'm curious, is it a J/Y piece or did you buy it new? Also, how's it dealing with oil mist going through it? I wouldn't think it would be a problem, but you did mention it's held together with silicon so...

Mike

[Ondonti]

From what I've read about the exhaust evac you should be getting more vacuum at higher rpm's then at idle. Have you run your car with a vacuum gauge on your dipstick tube to see what the actual reading is. I did and that's how I know what my crankcase is doing.
A.J.

Oh, my motor is a mess right now for blowbye, Its more an issue of wanting to be creative for the future. I cant fix my problems with good evac. I cant pull very much vac from the 3.0 heads or oil wont drain so i want to be able to pull most of it from the front of the oil pan under boost.

This isn't really the place for me to get into my specifics.

I have always been interested in an electric smog pump but I had never seen one. Just a bunch of vague readings of mine to tempt me on the idea.

[A.J.]

Sounds like you may have come up with a newer version! I was going to say that I was concerned that they didn't pull enough volume (only 3"), but now that you've got it over 10", seems like it's a non-problem! I'm curious, is it a J/Y piece or did you buy it new? Also, how's it dealing with oil mist going through it? I wouldn't think it would be a problem, but you did mention it's held together with silicon so...

Mike

My PCV pulls 10"-13" HG. My evac pump only pulls 3" HG.

I have the evac pump pulling through the catch can. I haven't looking inside the evac pump yet to see but it can't be much.

Yes it is a j/y piece. I got it for $20 (1/2 off day) off of a mid 90's Buick Roadmaster V-8

A.J.

[Reaper1]

Interesting. I've been told the early Northstar engines have something similar and have been looking for one for a while. Now that I know other engines may have something that'll work I'm happy!

[A.J.]

Interesting. I've been told the early Northstar engines have something similar and have been looking for one for a while. Now that I know other engines may have something that'll work I'm happy!

I know that the late 90's and 2000's Chevy pick-ups have them also. That was the first place I saw one because I had to diagnose a bad exhaust check valve. I couldn't find a Chevy truck in the j/y that had one and I came across the Buick by chance. I bet the Chevy Caprice with a V-8 would have them too. It's that same engine that was in that Buick

A.J.

[RoadWarrior222]

Interesting stuff. These are supposed to help fuel economy too. I hear that on good rings they are meant to encourage zero blowby, all the bang stays in the bucket.

I think my old '88 Jimmy with the 2.8 TBI (60* V6) had a belt driven one. I'd be inclined to slave one of those off the AC belt or something. Any vane type pump is meant to be somewhat adaptable.

[Ondonti]

LT1's are not very easy to find in the yard.

[zin]

A lot of the newer GM cars will have them, GM, like most makers like to use the same units on lots of stuff if they can. The Electric EGR is a good example, the same unit is on almost anything that needs one, since the computer controls the "output" they can all be the same and just run at a different duty cycle...

Mike

[A.J.]

I was bored at work today so I did some stuff. I took apart my check valve so everyone can see what's inside. I also did a vacuum test on my evac pump now that I have it sealed properly. My evac pump still pulls 3" HG.

The check valve:
I bought the brass pieces at ACE. They are 5/8 barb fittinging with 3/8-18 NPT thread. The check ball is a steel ball that my friends kid had for his sling shot. I don't know where he got them, possibly at a sporting goods store. The spring is out of a Honda brake booster check valve. The screen is metal and I had bought a sheet of it at Home Depot. It's the same stuff I used to hold the steel wool in place in my catch can.







A.J.

[Reaper1]

Nice fab work!!

[RoadWarrior222]

Cool check valve, I might copy it for another project.