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PCV “Blowby” and Oil Surge

GTIfan99

Autocross Champion
Location
FL
This thread isn’t super old, so I’ll revive it. I have this setup and it’s not really working for me. I would get smoke after any section of successive corners on track. I put the ECS CC on, and the smoke just takes a couple laps to return—the catch can fills up.

So, I ran a line from the catch can drain down to the oil pan. No smoke, catch can doesn’t fill up. But now I’m going through half a quart of oil a session. So it’s going somewhere.

It’s not obvious to me why the drain line would create that issue. The PCV system just drains back into the oil pan. There should be a slight vacuum on the drain line, if anything, from the oil pump.

My hypothesis is that is doesn’t drain quite fast enough to keep the can from filling up. So, I’m still getting a bit of blow by, but not as much as I was when I was getting clouds of smoke. Theoretically, I could test it by closing the drain and just continuing to do hot laps when it starts to smoke and see how much oil I lose. But, I can’t get myself to keep my foot in it when the rear window turns
Oil is being burned, returned, or leaking out the car. Not many more options.

As far as, BM vs BL, li don't think it matters. If you're filling the CC, the pcv is bad. I've seen brand new PCV's, both BM and BL that were bad from the factory. It looks like a quality control issue.
 

GTIfan99

Autocross Champion
Location
FL
So this is kind of where I’m at. I’m not getting a lot of oil in my little BMS catch can with latest rev PCV, but I do think about the condition that I’ve had and wonder about the future of the engine.

Unsure if my rings are faulty and need to be replaced, but I’ll have to have a look and see. If the rings do need to be replaced, would I be getting the engine built? I can’t imagine just replacing the rings without some new pistons, and I wouldn’t get that done without having the other internals replaced as well, correct? Sorry I’m a bit unfamiliar with engine builds but it seems like replacing piston rings would lead to a full build. Is there a cheaper or better alternative?
I'm not and expert or engine builder, but my understanding is that VW moved from liners to a hard coating on the bare cylinder walls of the block. Once you're through that coating, your block is a giant paper weight, unless you plan on installing sleeves for the rebuild.

Again, not an expert, someone chime in if I'm off base, but that's my understanding.

The cheaper alternative is finding a low mileage engine out of a rear-ended car.
 

scrllock

Autocross Champion
Location
MI
Honestly
I'm not and expert or engine builder, but my understanding is that VW moved from liners to a hard coating on the bare cylinder walls of the block. Once you're through that coating, your block is a giant paper weight, unless you plan on installing sleeves for the rebuild.

Again, not an expert, someone chime in if I'm off base, but that's my understanding.

The cheaper alternative is finding a low mileage engine out of a rear-ended car.
afaik the cylinder coating is done to the aluminum blocks, not our cast iron ones. you can definitely just bore out to 83mm and have it honed. this is what's done to the majority of built motors out there.

So this is kind of where I’m at. I’m not getting a lot of oil in my little BMS catch can with latest rev PCV, but I do think about the condition that I’ve had and wonder about the future of the engine.

Unsure if my rings are faulty and need to be replaced, but I’ll have to have a look and see. If the rings do need to be replaced, would I be getting the engine built? I can’t imagine just replacing the rings without some new pistons, and I wouldn’t get that done without having the other internals replaced as well, correct? Sorry I’m a bit unfamiliar with engine builds but it seems like replacing piston rings would lead to a full build. Is there a cheaper or better alternative?
You might be able to have it rebuilt with completely stock internals (if it doesn't need a bore) but it would likely be cheaper to use stronger aftermarket internals. And I'm not sure if you could, say, mix-and-match aftermarket and OE rods/pistons, as most I've seen are made for larger aftermarket wrist pins anyway.

The cheapest solution is probably to do what I just did and buy a low-mileage used longblock with good compression and hope it hasn't been abused. This is all assuming that your rings actually need replacing, tho.
 

Superfreak

Autocross Champion
Location
Denver
Car(s)
‘19 M2C, ‘05 Taco
more of a question of half fast or superfreak, not sure who's having actual issues but it's not mr. fan99
I did a lot of really hard driving up and down a mountain pass the other night, and have also been doing a lot of WOT logging in the past few weeks. I checked the catch can again yesterday and there was maybe 3-5 ml, hardly anything. Stoked that the new rev pcv seems to be operating pretty well. Hopefully good when I get to the track, but we’ll see.
 

Half fast

Go Kart Newbie
Location
Jersey City
Car(s)
Mk7 GTI
more of a question of half fast or superfreak, not sure who's having actual issues but it's not mr. fan99
I haven't. But, the car doesn't have any issues except on the track. Granted, I moved to NYC so the only time it gets driven at this point is driving on the interstate to the track or back home to Ohio, and then at the track. Also, it runs fine otherwise, the bumper isn't black, no fuel in the oil, etc. I've got one or two more events this year, and as long as the car runs fine through those, I'll just figure it out over the winter.

It just seems like the head is filling up with oil then getting blown out of the exhaust. I've got an IS38, quite a bit of suspension work, and I run slicks. The back section of Mid Ohio is 6 successive turns with a fair amount of elevation change, so there's a lot of lateral Gs going into the car. Then the last corner is a right hander up a hill, so you turn the car and once it starts to rotate, it's WOT (and then a massive cloud of smoke).
 

berserker6

Drag Racing Champion
Location
South Jersey
Car(s)
2018 Golf R
I haven't. But, the car doesn't have any issues except on the track. Granted, I moved to NYC so the only time it gets driven at this point is driving on the interstate to the track or back home to Ohio, and then at the track. Also, it runs fine otherwise, the bumper isn't black, no fuel in the oil, etc. I've got one or two more events this year, and as long as the car runs fine through those, I'll just figure it out over the winter.

It just seems like the head is filling up with oil then getting blown out of the exhaust. I've got an IS38, quite a bit of suspension work, and I run slicks. The back section of Mid Ohio is 6 successive turns with a fair amount of elevation change, so there's a lot of lateral Gs going into the car. Then the last corner is a right hander up a hill, so you turn the car and once it starts to rotate, it's WOT (and then a massive cloud of smoke).
That sounds like a blast. 👍
 

odessa.filez

Autocross Champion
Location
Roswell, GA
Car(s)
2016 GSW 1.8tsi auto
2016 GSW, 1.8 TSI, 118k miles.
Recently proactively replaced pcv with oe revision AP.

At a PCA autocross yesterday, finally experienced blowby on 3 runs. One was 'severe' as I was able to slow through the timing exit, pick up my timing slip and see the large oil cloud come wafting through behind me (lol what a sight!). This drew a lot of attention from others and some unsolicited advice, including from a nice guy who owns a repair shop.

Temps were high, probably over a 100 ambient on the asphalt. 60 plus second course. Oil temps rising to 150-155. Problem started after a re-run on my first run (back to back basically). Again, first time it's happened ever. Third event on this new PCV.

Sooo....thinking I'll play it by ear to see if the issue continues in a less stressful environment.

Any consequence to living with the condition if it continues? I'm thinking dirtier valves but what else?
 
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