# Catch can line freezing?



## SconnieGTI (Jun 10, 2012)

Hey guys, figure this would probably do me better here than in the 1.8T forum. Also searched but haven't really found much that helps me yet. 

I've got your typical, basic bolt-on and tuned mk4 1.8T and now that winter hit, I'm having an issue with one of my catch can lines freezing up almost nightly. It's the line that runs from near the crank case to the can. Every morning I can grab the line near the t-fitting and its crunchy inside. I have to take the line off and clear out all the slush inside otherwise the car smokes like all hell from the exhaust. 

I've got the 42DD stealth can, and have it mounted on the driver side headlight cover trim right at the front of the engine bay. The line in question had to make an upward turn to reach the can inlet which caused it to pinch a little bit. Thinking that was the issue, I cut the line and added an L fitting to relieve some of the tension where it was binding. However, this morning it was frozen again. 

Anybody have an idea what the issue is? My buddy has the exact same setup, lives in the same town so we have the same weather and hasn't had any issues with it freezing. I've also emptied the can thinking it was just full and condensation was backing up into the line but it still freezes. 

Thanks in advance.


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## wolfcastle (Jul 28, 2006)

i wouldn't worry too much about that. You vent water vapor from the case through that line....so if water vapor is in that line then it can freeze. Your friends driving habits/what brand of oil he is running/oil levels can make a difference. Lots of variables there


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## SconnieGTI (Jun 10, 2012)

wolfcastle said:


> i wouldn't worry too much about that. You vent water vapor from the case through that line....so if water vapor is in that line then it can freeze. Your friends driving habits/what brand of oil he is running/oil levels can make a difference. Lots of variables there


Is there any way to keep it from freezing? Because Wisconsin winters are long so it will get real tedious if I have to do the whole process each time I go to turn my car on lol. 

Would moving the can to the strut tower or possibly the firewall so that it's closer to heat help evaporate some of that condensation? Or is that just wishful thinking?


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## 12V_VR (Aug 11, 2010)

SconnieGTI said:


> Is there any way to keep it from freezing? Because Wisconsin winters are long so it will get real tedious if I have to do the whole process each time I go to turn my car on lol.
> 
> Would moving the can to the strut tower or possibly the firewall so that it's closer to heat help evaporate some of that condensation? Or is that just wishful thinking?


you can't just leave it be and let lines heat up and melt the ice ? There's going to be water vapor in the lines no matter what you do. This isn't as big of a deal as your making it.


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## SconnieGTI (Jun 10, 2012)

12V_VR said:


> you can't just leave it be and let lines heat up and melt the ice ? There's going to be water vapor in the lines no matter what you do. This isn't as big of a deal as your making it.


The car pours out an obnoxious amount of smoke and idles like crap when the line is frozen. I was assuming those weren't signs of things working properly.


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## 12V_VR (Aug 11, 2010)

Is it frozen solid or like a thin sheet of ice on the walls of the tube? If it's frozen solid you have some other problem. It is normal for cars to smoke more when it's cold out on a cold start.


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## SconnieGTI (Jun 10, 2012)

12V_VR said:


> Is it frozen solid or like a thin sheet of ice on the walls of the tube? If it's frozen solid you have some other problem. It is normal for cars to smoke more when it's cold out on a cold start.


Frozen solid. And yes I know some smoke/steam is normal on cold starts when it's cold. When I say smoke, I mean so much smoke that it gets inside the cabin if the wind is blowing right an the heat is on. But as soon as I clear the line it goes away within a minute or so.


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## 12V_VR (Aug 11, 2010)

I'm no expert but that doesn't look right. Or is there a section in the line where it droops for water and oil to form into a puddle and freeze like that ?


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## wolfcastle (Jul 28, 2006)

Check your oil level....you might have too much in your motor


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## SconnieGTI (Jun 10, 2012)

12V_VR said:


> I'm no expert but that doesn't look right. Or is there a section in the line where it droops for water and oil to form into a puddle and freeze like that ?


That's what I was getting at in the OP when I asked if the can placement could be an issue. The line loops upwards to reach the can inlet. As opposed to if the can was on the firewall, the line would run virtually straight across the bay to the can. 

I'm not sure how much vacuum it takes to feed that oil through the lines so maybe it's not enough to feed through that upward angle the line makes?



wolfcastle said:


> Check your oil level....you might have too much in your motor


I never thought about that. I'll give it a look.


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## wolfcastle (Jul 28, 2006)

That white smegma milky material has been a result of too much oil in the crankcase in my experiences


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## 12V_VR (Aug 11, 2010)

yes check the oil level and adjust the lines and/or catch-can placement to prevent water and oil from pooling and freezing. :thumbup:


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## Yareka (Mar 5, 2002)

Thats a big issue and very normal for catch cans in the winter since most of the byproduct is moisture. When you see excess smoke while its frozen, your crankcase is pushing oil through the rings and burning in combustion. You will overpressurize the crankcase and start leaking from vc and oilpan gaskets if you let it continue. Best bet like you said is to move the can and lines closer to the motor but it still wont help at startup. I would go Vent to Atmosphere during the winter months


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## 12V_VR (Aug 11, 2010)

Update ?


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## SconnieGTI (Jun 10, 2012)

Well, I think I solved the issue. Or at least fixed part of the issue. 

The line from the t-fitting off the crank case that ran to the can was about 1" longer than it really had to be. Which pushed the t-fitting down just slightly, causing a spot for the sludge to pool when the car was off. So I shortened the line a little bit, essentially lifting the t-fitting slightly and it's gone about 4-5 days now with no issues. 

We'll see if it lasts. Seems too simple of a solution to be the actual issue lol.


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## G60 Carat (May 14, 2004)

Yareka said:


> Thats a big issue and very normal for catch cans in the winter since most of the byproduct is moisture. When you see excess smoke while its frozen, your crankcase is pushing oil through the rings and burning in combustion. You will overpressurize the crankcase and start leaking from vc and oilpan gaskets if you let it continue. Best bet like you said is to move the can and lines closer to the motor but it still wont help at startup. I would go Vent to Atmosphere during the winter months


Best advice here^

Run an up size adapter to a bigger hose (say 3/4" hose) as close to the valve cover as you can. The bigger the hose, the less chance of it freezing totally shut. I'd just run the hose straight down, close to the engine to keep it warm as possible and hopefully any residual water going downhill, and dump it out under the car. The catch can should be catching like 90% water vapour, so it's going to freeze no questions there. Everything in the catch can is going to freeze solid, so it's usefulness will be limited in winter.


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## SconnieGTI (Jun 10, 2012)

G60 Carat said:


> Best advice here^
> 
> Run an up size adapter to a bigger hose (say 3/4" hose) as close to the valve cover as you can. The bigger the hose, the less chance of it freezing totally shut. I'd just run the hose straight down, close to the engine to keep it warm as possible and hopefully any residual water going downhill, and dump it out under the car. The catch can should be catching like 90% water vapour, so it's going to freeze no questions there. Everything in the catch can is going to freeze solid, so it's usefulness will be limited in winter.


Correct me if I'm wrong but wouldn't disconnecting the line from the can and running it to drain out underneath the car cause a vacuum leak?


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## G60 Carat (May 14, 2004)

SconnieGTI said:


> Correct me if I'm wrong but wouldn't disconnecting the line from the can and running it to drain out underneath the car cause a vacuum leak?



Nope. 

Well actually it depends, if his catch can is still hooked up to the intake somewhere, then yeah he would have to plug that vacuum line. I don't run any vacuum line to my catch can, as even the best oil separators will let some oil vapor through, and I don't want any of it inside my intercooler pipes. 

But as for venting the crankcase to atmosphere, many do. I have, I just find it makes a mess of my valve cover. (which is why I suggested running a hose down the block to underside of the car) Remember crankcase venting on a healthy motor should be mostly water vapor. It's just water from condensation trapped in the oil, it's released as steam vapor once oil temps get hot enough. But under high revs, you also get some oil mixed in there too. If you get a lot of oil coming out your crankcase vent, it's telling of combustion pressure (Most cars well over 1000 PSI) getting past the rings, and you have some other issues at play.










I do this now, Bottom left of the engine bay, my catch can is vented to atmosphere, and it has baffles inside which helps keep the mess down. I have to drain it like once every 2 weeks. It's almost all water that comes out.


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## waabaah (Jun 24, 2006)

Mine froze during that negative temps in wisconsin too car smoked big time and eventually built enough pressure to start leaking oil in weird places. Thought I put a hole in the block. Lol. Anyway just vent it to atmosphere for the cold temps.


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