catch can fuel issue

[drwarz]

I built the bottom end of the s54 in my car last year and replaced all the seals as well as the valve stem seals in the head. Now I get a good amount of fuel in the catch can. I know it’s e85 as it looks, smells and lights on fire like e85. Is there a seal that could be leaking fuel from the injectors into the crankcase when it’s under pressure? This one has me stumped for now.

[smee123]

That's e85 in your oil basically, making it past the rings due to blow by. Do a compression and leak down test. Did you bore and hone the block? What rings did you use and how were they gapped? The rings rings didn't seat basically.

[Syfon]

OP how did you run the motor in after first start?

I rebuilt mine a couple years back (stock bottom end with new rings, block honed, etc.). First start up was ~30min varying revs between 1.5-3k, then oil/filter change and a about ~500km of driving constantly varying revs and, most importantly, using 3rd & 4th gears to load the motor up while driving up hills. This way the compression gets behind the rings and forces them into the bores thereby seating them and not allowing any fuel or oil to leak past.

[enjoy_m3]

Did you use OEM valve stem seals? Or elring ones. I bought both and noticed the elring has a larger hole for the valve stem than the OEM BMW one. I suspect this may be a contributing issue on my oil consumption.

[Syfon]

I used elring on mine. No issues

[nextelbuddy]

This is normal...at least for boosted cars. I have a stock s54 tuned on e85 at 530whp 11psi and my catch can is about the size of a can of coke. My catch can in the winter time or and very humid times fills up very quickly.. I would say probably has to be emptied once every 2 weeks for me.

My catch can contents is not oil, it's straight up Just e85 moisture

Not really e85. It's more moisture that smells like 85.

My compression is fine. My leak down is fine. I change my oil every 5000 mi and burn about half a quart 10w60


If your compression numbers are consistent and your leak down numbers are within spec, then any moisture that's filling up into your catch can on cold winter days or humid days that's completely normal with e85.

My catch can has a line running from the top of the valve cover to the catch can and the catch can normally would go back to the intake but since I'm Turbo I don't want my turbo filling up with any sludgy oil

So I have a little filter on top of my catch. Can that just vents it

If yours is like this, then you can certainly run that return line into a Venturi attachment to your exhaust and it will suck out that moisture right back out the exhaust.