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Lots of blow-by collected(Catch can)

Hodginsa

Hodginsa

youtube.com/seanhodgins
Joined
Sep 18, 2005
Location
Ontario
Well after my turbo install I put in an oil catch can, just one of those square aluminum ones off ebay for 15$. I started to notice it fills up pretty fast, really fast if I push the motor a lot. I understand that my motor has got 330,000km on it so its probably a little worn resulting in more blow by. What I dont understand is why worn piston rings cause more, I guess I don't understand how the blow by is created and what it is made up, because it surely doesn't smell just like oil, more like a mixture of oil gas and water(which makes sence)...

How does the worn rings actually end up causing the blow by to leave the engine?
Could the fact that its winter and my catch can is aluminum and therefore very cold causing me to have a lot more blow by because its cooling the gases leaving the engine just that much more and allowing more of it to become liquid? My oil catch can is located behind the battery beside the radiator(in front of driver side headlight)

I'm kind of thinking its because of the location of the aluminum catch can because if I just ran it straight from the breather box to the intake pipe I bet there would be a lot less blow by being thrown into my turbo...


Any Ideas guys? I'm probably due for a rebuild anyway(and throw some low comp turbo pistons).. Not really looking forward to it though.

Also, since my car was N/A it had the little plastic flame trap in that hose. Turbos don't have that right? I removed it because I was pretty sure they didn't but I'm just double checking.
 
Blowby is gas from the combustion chamber getting past the rings and into your crankcase.

Some oil exists as vapor inside of your crankcase (when your engine is running). Increased blowby is pushing out that oil vapor+blowby gases from the combustion chamber out to the catch can.

When your worn rings allow the combustion chamber gases by them they cause an increase of pressure in the crank case. That pressure has to go somewhere so it chooses the path of least resistance. In some people's cases that path is through their engine seals but because you have a breather box installed the path of least resistance is through your breather box. the worse your rings are the worse the amount of blowby which will result in increased pressure in your crankcase and in turn more oil/gas in your breather box

Worn rings can also let gasoline by them (during the compression stroke) which will dilute your oil and can cause problems with bearings (like make them fail) so if you think they are going its a good idea to get them replaced.
 
Thanks for the response. Its not that my oil smells like gas, just the blow by doesn't just smell like oil alone, which I know is normal.. I understand now that its the combustion pressure pushing the oil gases out, before I thought it was the oil gases from being burned in the combustion chamber leaving the engine haha, which is why I was confused about it

I was just wondering if its the location of where my catch can is that its causing more blow by to turn back into oil before going back into the engine because of how cold it always is.
My engine was pretty much babied before being turbo'd so even at 330k kms I would think the rings should be relatively good, but who knows..
 
I know that an N/A that is freshly +T'ed tend to exibit flaws like blow-by and smoking for a short time. I would stop analyzing it for at leats 500 miles...then start looking for faults. This is just my expierience and $0.02.
 
How is the can hooked up? I would expect a hose from the breather box to the catch can, then another hose from the catch can to .....where? Pre-turbo intake hose? Open air under the car or in the frame rail?
 
There is probably some validity to the fact that because your breather box is outside of the hot engine, the oil vapor is condensing in the cool breather box. Better than going through your intercooler and condensing in there :)

I wouldn't be worried about it, after all, its kind of the point of the thing isn't it?
 
We'll im just worried because its winter and cold, and the blow by freezes in the catch can so I can't empty it.. frustrating, and the indicator tube that says how full it is, it permanently frozen so I can't read how full it is, cause it says its always full when its not lol
 
crazy0000 said:
We'll im just worried because its winter and cold, and the blow by freezes in the catch can so I can't empty it.. frustrating, and the indicator tube that says how full it is, it permanently frozen so I can't read how full it is, cause it says its always full when its not lol
Click to expand...

turbos also dont have a vac line hooked up to the flame trap housing
 
Yeah I took that off when I turbo'd it...

Im talking about an aftermarket catch can with an indicator tube. Like this one
6b10_1.JPG
 
mine fills up pretty quick, takes a week or so of massive abuse, fills up with just oil though, no crazy water freezing or anything like that.

when i have a broken piston it will fill in less than 30 mins.
 
crazy0000 said:
Thanks for the response. Its not that my oil smells like gas, just the blow by doesn't just smell like oil alone, which I know is normal.. I understand now that its the combustion pressure pushing the oil gases out, before I thought it was the oil gases from being burned in the combustion chamber leaving the engine haha, which is why I was confused about it

I was just wondering if its the location of where my catch can is that its causing more blow by to turn back into oil before going back into the engine because of how cold it always is.
My engine was pretty much babied before being turbo'd so even at 330k kms I would think the rings should be relatively good, but who knows..
Click to expand...

if its cold and you're going through a lot of heat up and cold cool downs you will get more condensate build up in the engine than you would if say it was summer. also clearances open up a tick more in the cold, this can also cause a bit more on startup.

on a side note, you don't have the other side of the breather going to the plumbing post turbo, do you? Also unhook the vaccum line going to the breather box.
 
Hmm.. Yeah pretty much everytime I drive anywhere, even short distances I make sure it reaches operating temp(I baby my car alot..:oops:), even if that means driving a bit farther lol..

The plumbing goes to the stock pre-turbo hose, and that vac line is disconnected, no boost is going to my crank case guys :-P

Its not bothering me much at all, I was more just curious, its not like its making me fill up my oil every couple of days, my oil level is actually quite solid. Don't seem to burn any either. It just filled up a couple times so I noticed it blowing a bit of liquid oil into the compressor of my turbo when it was full. On a warmer day Ill actually remove the catch can from my car and bring it inside and clean it with some hot water and go fresh from there and then check the level of it after a few days. I just hate working with that stuff, the smell stains EVERYTHING even your hands through latex gloves, and your clothes even if they don't touch it. its nasty stuff.
 
So it was surprisingly warm today so I emptied my catch can, the test begins! Stuff that comes out is very liquidy, but still is like oil :wtf:... Maybe there is alot of water in the air right now. And its all condensing in my catch can.
 
He means the small one that goes to the intake manifold(That N/A have), If they did that would add new meaning to "positive crankcase ventilation" as you would now be boosting the crankcase of your engine and spitting out oil from every which seal.
 
from brickboard faq...
Does my Turbo have a "flame trap"? [John Sargent/Editor] While the turbo engine does not have the plastic flame arrestor insert, it has all the other hoses, fittings, and breather box that can clog up. You still have to inspect and clean as necessary.
Click to expand...


and on this page i found on google, there is a picture. the small nipple hooks to the intake manifold, and the larger ends hook to the crankcase breather box, and the pre-turbo hose. so, they DO have a connection to manifold pressure.

oil in the catch can, unless its like a quart of oil for a drive to work, is normal. NORMALLY, that would be introduced into the intake, and burned, or collected in the breather box, and drained back into the oil pan.
 
My bad! It makes a lot of sense now to have that vacuum hose. For some reason I had the idea that I had to take that off when I turbo'd the car.. This might also be my problem for lots of the blow-by, because the system in the intake manifold is in vacuum a lot more of the time than being in boost.

Ill put it back on and see what happens.
 
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