Oil catch can?

[DanMan_S]

The technical term for what a "catch can" does is coalesce. The function is to remove liquids saturated into a flow of a gas.

 

Air Compressor systems have various methods to coalesce as do aircraft air conditioning/pressurization systems.

 

The simplest form of a coalescing device is an expansion type that allows the saturated gas to cool and slow. This allows the liquid vapor to form into droplets that stick to the chamber walls. These types are commonly seen for air compressor systems, with a clear bowl and drain valve. They are effective, but leave room for improvement.

 

When you add a type of baffle or labyrinth path for the gas to the above chamber, it increases the efficiency in removing liquid. The changes in direction allow inertia to force contact of droplets, formed from expansion, with the chamber walls. Centrifugal separators also rely on the inertia of the droplets to go to the outer wall because they are heavier than the gas. Centrifugal designs are difficult to make efficient with low flow rates.

 

Filter type coalescing systems are most often a combination of the above designs. They are almost always combined with expansion types. In many cases, labyrinth design is combined in at least a minimal way. Large airplanes use a type of filter, along with an expansion chamber to coalesce water out cabin air before it is sent to the cabin. The filter is simply a surface for the liquid droplets to adhere to. In these airplane a/c systems, it is a fabric stretched over a conical screen, in a larger cylindrical chamber (can). You often see a filter added to those "water separators " in compressor lines. This is not really for particulate removal, although it will do that. It is to provide more surface for droplets to adhere (coalesce).

 

The liquid in a crankcase vent flow will contain a significant amount of water vapor along with the oil vapor . This is condensation formed during cooling in the crankcase.

 

Excellent post!! My engineering firm does some CFD design of filters & separators for different pipeline applications, so I always get abit annoyed when people call the technology snake oil in a automotive application. As I have detailed CFD results and physical testing data to say otherwise, there is no magic to it, just basic thermodynamics and fluid dynamics.

Edited April 9, 2015 by DanMan_S

[Jsdirt]

I've got oil in my can after a 600 mile drive (and a little water too) - that's enough proof for me!

 

Edited April 9, 2015 by Jsdirt

[Spurshot]

 

Excellent post!! My engineering firm does some CFD design of filters & separators for different pipeline applications, so I always get abit annoyed when people call the technology snake oil in a automotive application. As I have detailed CFD results and physical testing data to say otherwise, there is no magic to it, just basic thermodynamics and fluid dynamics.

 

Come on Dan...CFD is snake oil. jus yankin your chain....

Edited April 9, 2015 by spurshot

[Spurshot]

I've got oil in my can after a 600 mile drive (and a little water too) - that's enough proof for me!

 

 

 

Looks like a lot of water and a little oil.

[Jsdirt]

Yeah, -40°F wind chills will do that. Will be darkening up in the coming months ... I HOPE. Weather has been galactically craptastic this year ...

[Spurshot]

Yeah, -40°F wind chills will do that. Will be darkening up in the coming months ... I HOPE. Weather has been galactically craptastic this year ...

 

You guys have had more than your share of it....

[Silverado-Hareek]

I was draining about 6 oz of an oil/water mixture back in winter every 650 miles. It's down to about 2 oz over the same mileage now in the warmer spring weather.

 

 

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[Silverado-Hareek]

The good news: I did the BG induction service yesterday and the truck seems to be running great afterwards, no issues so far *knocks on wood*

 

The bad news: I could not get before and after pictures of the valves. The way the intake is designed on these engines, you can't get the borescope in there because of all the bends and turns. We would have had to remove the intake manifold to see the valves and I wasn't about to do that on an engine with only 15k miles.

 

So the catch can debate will have to rage on. I will say I have not really noticed much of an improvement with the truck as others have reported. It honestly wasn't really running bad before I did the service, I just wanted to get in before 15k miles to take advantage of BG's warranty. So if guys without catch cans are noting an improvement in performance after the service and I'm not noticing much of anything, I'd argue that's evidence in favor of the catch can doing what people say it should be doing....keeping the valves clean. I only had 11,500 miles on the truck when I installed the catch can so there wasn't much time for a lot of build-up to happen and dramatically affect performance, although I don't doubt that some buildup did occur and the service yesterday took care of it.

 

 

EDIT: Forgot to add it was about $78 in materials and $117 in labor for the BG service so $195 total. You have to get your oil changed as well afterwards so factor that into the total if you're considering doing this service.

Edited April 15, 2015 by Silverado-Hareek

[GuyGene]

Whew boys, I spent he whole morning reading all the posts! Me old haid is spinning. Here's my conclusion, correct me if I'm wrong. I thought I was one time...

 

Which truck maker does not use direct injection? If none, I'll keep my 13 year old truck and keep fixing what breaks as needed.

 

I have come to loathe direct injection engines. What a stupid engineering system! Valves getting that gunked up because of it?!? Somebody mentioned Toyota developed a system to send some fuel over the valves to keep them clean. So, makers know this is a serious problem.

 

I'm wanting a new truck, but have decided to try my best to not get direct injection.

 

Ok boys, tell me wha' I'm missing.

Edited April 16, 2015 by GuyGene

[Jon A]

Well, direct injection allows you to have more power, better mileage and better emissions. The first two are good to have for the consumer, the last one is why you're going to have trouble finding any engine that isn't direct injected in a year or two. Every improvement comes with some sort of side effects, learning to deal with them is the best solution. Unless you don't mind driving antiques (or "classics") the rest of your life.

[Jsdirt]

It seems the insatiable quest for "clean air" & fuel mileage has caused more problems to our vehicles (and our country .. but that's another topic for another day ...) than good. I guess clean air trumps quality. Why not? In this day and age animal's lives trump human life ...

 

 

Yet, I still have asthma with all this clean air around me ....

[Jon A]

Didn't you know CO2 causes asthma now? It's much deadlier than it used to be. It's the "new science" from the religious left.

[kzinge1]

Installed my Elite Engineering can a couple weeks ago. Very nice quality, easy install and good price. Checked it after 50 miles and already has some oil in there. Will check again after about 500 miles.

 

Edited April 16, 2015 by kzinge1

[chevy2tuff2006]

Installed my Elite Engineering can a couple weeks ago. Very nice quality, easy install and good price. Checked it after 50 miles and already has some oil in there. Will check again after about 500 miles.

 

Nice have the same setup but one question. Do you hear a sound like a vacuum leak coming from your can.... with the hood shut walk by that corner of the truck with the engine running does it sounds like a vacuum leak. I have this and I'm wondering if its just the air inside of somewhat empty can making the vacuum leak sound or if I have a hose that has a hole in it or one of my elbow in the can leaking?

[Jsdirt]

If you had a vac leak big enough to hear, you'd more than likely have a check engine light on, along with some very poor running.