I put a small catch can on my 99.5 Jetta TDI months ago. I got the car about a year ago with 350k miles on it and no history. The intercooler had a lot of oil in it, so I put a drain(screw) in and check it often. I still get some oil in the intercooler, but it's not at critical state yet. I put a small catch can on it months ago to try to determine if the oil comes more from the top of the engine or the turbo. There is a lot of turbulence under the oil fill cap, but I don't know how much is acceptable, honestly. The catch can I put on also catches some oil, but it is not excessive. I'm thinking the intercooler may never have been drained, but who knows. Now, getting to my question(s)... My catch can is not 'vented', and is a closed system essentially. I see some catch cans with vents/filters on them. Is this better/necessary, or is there not much difference in the two? If I were to just run a vent down under the car and do away with the catch can altogether, would there be issues with the hose being open, or are diesels different? I'm open for catch can opinions and suggestions. Thanks.
Catch can question.
- Thread starter mk4mr
- Start date
STDOUBT
Veteran Member
Once the oil is drained from the intercooler, you shouldn't have to ever worry about excessive oil accumulation in there as long as you drive the car like it wants to be driven. Fast and hard!
FWIW I think catch cans are pointless on the ALH at least (no idea if the newer A4's are all that different).
If you're concerned about future soot buildup in the intake, just get the Dynamic EGR tweak from Malone and call it good.
FWIW I think catch cans are pointless on the ALH at least (no idea if the newer A4's are all that different).
If you're concerned about future soot buildup in the intake, just get the Dynamic EGR tweak from Malone and call it good.
STDOUBT
Veteran Member
Also, I bought a length of hose to run my blowby out to atmo, but didn't even open the box yet because I realized there's very little point. No, I don't think it will hurt anything - some people talk about moisture incursion, or icing up and blocking off, bah. Just cut a split up the side. Messy and more trouble than it's worth IMO. Others disagree.
mittzlepick
Veteran Member
- Joined
- Mar 18, 2001
- Location
- union maine
- TDI
- 2004 jetta wagon (365k)2001 wagon tire burner 6spd 2003 wagon(417k)
Totally useless
Rrusse11
Veteran Member
In my experience, limited and anectodal, installing my catch can has really helped my turbo. Prior to its installation, I could feel a "step" in the boost curve under hard acceleration, I believe the VNT mechanism regulating the boost. With coked blades there was a perceptible lag. After a recommendation to install one from Jeff of Rocketchip on this issue (the 17/22 is notorious for coked blades and overboosting,) after well over a year now, boost is quicker and smoother.
My $.02
I felt led to install a catch can in the beginning because the car was hydro-locked in at least 2 cylinders, and the PO just couldn't seem to tell me anything about what happened to the car. This is my first TDI, and I installed the catch can in hopes of being able to save the car and maybe keep it from killing itself before I could learn enough to fix the issues. I have been re-checking the drain in the intercooler about once a month for the last 9 or 10 months, and I am getting maybe a teaspoon to drain out. I know that's not 'great', but with 355k miles and obvious abuse, it's doing better than I expected it to. I guess my next decision is whether to just delete the catch can altogether and vent to atmosphere, or if I should just leave the catch can in place, since it's already there. I'll probably leave it, seeing as it doesn't appear to be 'hurting' anything. There's is zero rust on the car, so I will likely entertain the idea of keeping it alive as long as it has the will to keep going. The EGR has been removed, but hasn't been deleted, so I will be sending the ECU in for a tune/delete at some point, but I have to decide what tune I want to do(nothing extreme). I'll put it this way...I just put a new DMF kit in the trans, and I don't want to go beyond what it can handle. I have to assume I still have stock/original turbo, injectors and nozzles, so there are looming expenditures on the horizon, but maybe they will not fail all at once.