2H Oil catch can

[Granite Grinder]

Here's the story: I acquired a 1987 HJ60 with a blown motor (ring failure on cyl 3). This HJ has a turbo on it (DIY at a local shop) I replaced the 2H with another 2H with 360,000KM's on it (I know, I know... not a great candidate for a turbo) It's working fine, boost is set for 10lbs, egt's are (on average) running around 900º F, pre turbo. Like any high mileage diesel, I have a bit of blow-by. It's not too bad but I thought I'd clean it up with an oil catch can. Also, a fellow cruiserhead suggested that I route the crankcase gases out of the intake, which in his mind will prolong engine life. This fellow is very adamant and has strong opinions, reminds me of Wayne So, I figure nothing ventured, nothing gained. I install a Cuzco (sp) catch can, and yes, it helped clean up the smoke from the tailpipe (somewhat). Two days after I installed it the front crank seal let loose... hmm, I knew it needed replacing, but didn't think it would start puking like it did. Replaced the seal and the next day I get another leak... now I'm suspicious. I start the truck up and loosen the oil filler cap... it starts dancing on the neck. Uh ho, that would mean the crankcase is getting pressurized. OK, that explains the seals all letting loose, but why would the catch can be creating back pressure? The can is quite large with 5/8" hose on the in and out. There weren't any instructions, but how hard could it be. No labeling in/out, I tried blowing through both sides of the hose and there didn't appear to be any restriction. Is the can just physically to small to handle the volume? Thought I'd ask here to get any feedback.
GG

 

[amaurer]

Air blowing out the filler cap is totally normal; you'll find it does exactly the same thing, even if you take the catch can off. On my 3B with no can, the filler cap hole puffs about equally as the stink tube.

That said, I put too small lines on my stin ktube once and leaked through every seal, so it definitely can happen.

Where did you plumb the line from the can into the intake? Before / after the air filter? Before / after the turbo?

 

[Granite Grinder]

When I returned the set-up back to stock (OK, not quite stock with a turbo) the filler cap stopped dancing. I agree amaurer, there is always a slight amount of air blowing out the filler, but not enough to push the filler cap off. The hose that comes off the rocker cover is plumbed into the air intake tube, post air filter. I basically "broke" that line to install the catch can i.e. rocker-> catch can-> air intake.
GG

 

[o8ko8k]

I just added an oil catch can to my 2h turbo and got the same result. What became of this problem? My thought was there may be a tad bit of vacuum lag adding an extra 300ml of volume? Now I'm replacing pushrod cover seals. I don't think i blew the front timing cover seal though thankfully.

 

[Freewheel]

interesting. I had the crankcase vent hose bend and constrict when I installed a turbo years ago. ) It blew the timing cover seals out which was a messy problem for a few years until I had the motor rebuilt. It doesn't seem to take much constriction to pressurize the crankcase and blow seals.