Crankcase breathers, what do y'all think?
 

My old 4v setup used to spew oil out of the valve cover breather when I hammered around on my buggy. Any of you folks use catchcans or breathers? I bought two, thinking to put one connected to the valve cover breather, and one that screws into the dipstick hole. Crankcase pressure better released with these or are they a non-factor?

I run catch cans on all my 4 strokes. My lawn mowers even have em.

The one on my buggy is made out of pvc pipe. Closed system, one hose coming from the valve cover, one goes to the intake tube, and a drain on the bottom. I drain it about once a week when the buggy is run hard.

If you have so much oil coming out of the breather hose that you need a catch can, a couple of things comes to mind, you are making long (20 miles and up) wide open runs. You are running ultra high compression (12:1 and up), or you have massive blow past the rings, and it's time for a rebuild.

All engines suck a small amount of oil out of the crankcase vent all the time. Esp when you have the most basic of basic of baffles in the valve cover like these things do. The spinning cam creates an oil "cloud". Even a low compression freshly rebuilt engine. Also a small amount of water condensation builds up a catch can will separate, leads to the oil lasting longer.

I'll say I've rebuilt countless engines over the years and since I started using catch cans 15 or so years ago the amount of grime and carbon deposits has been cut to near nothing. Oil tests (in my race engines) has proved the oil was cleaner at changes vs not running one. Enough to prove to me they have their merits. Why I run one on everything from my lawnmower to my daily drivers now. Everything 4 stroke that is.

Blow by is compression leaking past the rings and burnt gases pressurizing the crankcase blowing oil and exhaust out the vent. A whole different ballgame and even a catch can will not help there. If you only ride a few minutes and filling up a half pint catch can you know something is wrong.

Okay, maybe I am miss interpreting what a catch can is on these little engines. When I build a "large" VW engine, we add breathers to both valve covers, and run them up to the sides of a sealed box filled with coarse steel wool. On the bottom of the box, a hose is attached to the stock breather location on the engine, to allow any oil to drain back. On the top of the box, a hose is ran to a top of one of the air cleaners (dual carbs), to draw off any water vapor or condensation. So I assume that a catch can must do something similar (we call them breather boxes). However, on these little engines, how do you get the collected oil to return to the engine? On both of my buggies (hammerhead 170, and pumped up Joyner 250), I run a long breather hose up high, then install a clear fuel filter on the end. This allows the harmful vapors to escape, without loosing any oil, and I can watch the color of the filter to see what is going on.

Do you have a pic of your catch can? I am really curious on how it works.

You do not return the oil back to the engine, that defeats the purpose of removing the condensation out of it. You do not want to dump the milky sludge back in, you are trying to remove it. I'll try to remember to take a picture of it but it is not very descriptive of what it does. Just a blue (painted) canister.

https://cdn.shopify.com/s/files/1/26...g?v=1527002850

Venting it to atmosphere allows it to vent but doesn't create a positive ventilation. Also just allows the fine oil and water mist to collect in the tube and drain back down into the engine.

We rode hard today and I'll take a picture of the milky sludge when I drain it also if it's not raining.

The advantages of positive crankcase ventilation are real!

Yeah, I think all my 4V heads have pushed a decent amount of oil out of the breather. It's a stroked motor so probably running a bit higher compression than stock. I bought one that screwed into the dipstick area, but never drove with it in because it just seemed like it pushed oil out of the crankcase and away from things that needed it. I have a hose with a Uni breather filter run up under that rack from the valve cover, but after a decent run it's dripping oil all over the place.

How about this one? https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

Yeah, got one similar on the way.

Looks like it'll work. Mine is about the size of a coke can.

I have one. Haven't used it yet as I'm in the process of putting the buggy back together after having it powder coated.

It looks to be fairly good quality, but I still have to figure out a way to connect it to the redneck filter tube and reduce the size of the catch can connectors.

I'm probably not going to connect it to the intake, just need something to collect the oil.

Drill and tap the filter tube for a barb fitting. To reduce the size, Are the barbs threaded?

If you are not gonna connect it back ya might as well save some money and just run a hose with a filter on the end.

You really are giving up low end torque by not running positive crankcase ventilation. The smaller the engine, the more of a plus it is.

Lets see if I can get these to work

barb in intake tube
https://i.imgur.com/Q0D0qqcm.jpg

catch can
https://i.imgur.com/LHY2gfwm.jpg

Anyway you can post larger pics? They are to small to see detail.

Click on this and look at the album
https://imgur.com/gallery/PqndLQl

And yeah it's dirty as crap. Been raining here so much we ride on dry days instead of washing it.

Thanks for the pics. They explain a lot. I like your carb spacer getting it over the frame.

As a side effect longer intake runners also help produce torque down low. Of coarse what the runner grows the intake needs to shrink, thats why my redneck intake is short.

That catch can is about redneck as it gets, just some 2 inch pvc and 2 end caps. The fitting going in has a piece of tube inside it that extends it to about 1/2 inch off the bottom. I then packed the inside with stainless steel pot scrubbers. I like using pot scrubbers because they don't break down like steel wool does (even SS steel wool). In the bottom for a drain I tapped the cap and put a bolt in it. Later on I plan on putting a real on/off drain. I then painted it so it doesn't look like the plumbing section of a hardware store. I think I have about $2 in the whole thing because I had to buy one barb, the rest was stuff I already had in my shop. I do wish I would had made it a inch or 2 longer to have a bit more capacity but it works. We drained it the other day, if I'm thinking straight I'll try to get a picture next time I drain it (in a few days) to show exactly what does come out.

It looks like the tube you are using from the valve cover is painted copper tubing? Is that to handle the heat at the valve cover? Good tip on using pot scrubbers. Thanks.

All the vacuum and vent hoses are silicone. I ran out of black and had to use blue between the intake and can.