OK long story short.... I was in kill mode and running hard up into 6th, After market oil cap blew off like a missile (think maybe vibrated a little loose but not sure??). Got the car home no issues, Car ran fine. Decided to do the oil cap off while car is running test. Sure enough it was puffing smoke from the oil cap, nothing out the exhaust and oil is clean and full. So I pulled all plugs and did a compression test. 1 = 150 3 = 150 2 = 70 4 = 135 Car starts fine, idles fine, drives fine, does not smoke while driving. No coolant in oil. Head gasket toast? Or other issue? Price guess on head gasket from allpro? OK to still drive like a baby 12 miles to work?
No leak down test. Don't have leak down gauges and didn't feel like buying some and doing the crap again. CP Pistons Manley turbo tuff I-beam rods king bearings ARP head studs BC stage 2 cams BC springs and retainers GS lightweight crank pulley PT 6266 turbo Tial Q BOV Tial 48mm wastegate Rotated intake FMIC TGV deletes Killer B oil pickup Walbro 460 AEM fuel pressure regulator Perrin rails ID2000
No I haven't. I drove it home 35+ miles from C&O with zero issues after it happened. Oil on dip stick looks clean and good of course that doesnt show debris. If it was the rings on Cylinder 2 wouldnt it push oil into combustion camber and smoke?
I hear ya, well it doesn't sound like a head gasket to me but some more investigation is really needed to confirm anything. I would drain the oil and see what it looks like and go from there. Either way, it's going to have to come apart to truly pin point it. Feel free to shoot me a call or email this week and I can run everything by one of my techs to help diagnose it a little more - those guys are the actual experts haha.
The ringland could be cracked and the reason why it seems to be ok....sorry man but sounds like it will have to come apart
Will a leak down tell me if it is ring/piston issue, or head gasket or something else? CP piston have ring land failure?
Anything can fail if not installed right or overdone. You just got this thing on the road didn't you?
The leak down will help determine where the compression leak is coming from to give you a better idea upfront of what you're dealing with. Yes, aftermarket forged pistons are stronger but the factory ones don't fail because they are weak; they fail because Subaru set the top ring gap tolerance too tight for as large a bore the EJ25 has - the same thing can happen with aftermarket pistons if it's not assembled correctly.
Who/or where did you buy your motor?(or have it built)I might be wanting one and wondered about this.
buy an Otoscope from Walmart then read this article, http://rehermorrison.com/tech-talk-89-the-eyes-inside-your-engine/
Haven't had time to do anything honestly but I Sure you are right. Ringland or ring failure. I will for sure post once I have it figured out and what the plans are.
Honestly man it is VERY VERY rare to see a ring land fail on a forged piston. I would be more inclined to think it was in the head than in the bottom if it isn't pushing oil to be honest. If a leak down is done correctly it will tell the tail. If the oil looks good, it isn't using an excessive amount and it has forged pistons, its 90% in the valve job or the head someplace. Hope this helps, I think we charge 100 bucks or something for a diagnosis if you want us to tell you for sure just give Mike a call. If there is any help we can give free over the phone we are happy to do that too.
Since this is a CP piston engine with the harder alloy, I'm in agreement with Cicio. I'm inclined to say either valve or spark plug thread failure (like the pic below).
Would valve issue cause low compression? I need to figure it out for sure, because the I have new short block plans but if I have head issues Ill need that addressed. Also if the head has formed a crack can it be welded / fixed? Mike, if I take a day off work and drive up to top speed can you guys do the diagnosis while I wait?
Won't know 100 percent until I pull the motor but it's either pistion Ringland failure, ring failure or I ovaled the cylinder. Most like I ovaled the cylinder because I was running the car hard in kill mode at 25psi. High boost and non reinforced blocks don't mix well. But we know cylinder 2 was leaking 90%! And it's not head related. That was my main concern.
25 psi isn't high boost....I ran 28 psi on the 2.0L for 50k miles! My built 2.5L was running 28 psi daily.
Depends on the compression ratio mine is nearly 8.8:1 so I doubt I'll see anything that high on my 93 map.
Mine was a hybrid....wrx heads. My CR was quite high to. Granted I did run methanol injection though.
Meth / water changes everything. Ryan runs 93octane and so does Justin (and myself). For non pinned blocks 23-24psi is absolutely plenty for the size turbo's we run. In fact Ryan and I have the same precision turbo. Believe me I was very tempted to turn mine up at the 1/2 mile this Saturday to break 150mph, but after reviewing my datalog last night from one of my runs, my inlet air temp went from 109 to 148 for the duration of the 1/2 mile run. Once it crossed 130 it started to pull timing and I even saw a couple 1.4's feedback knock (not concerning really) but it definitely confirms that I am on the limit of 93octane with that boost level.
Also Ryan Chris and I are trying to get together for him to drop off my hoist and stand. As soon as he does it's yours to use, and of course let me know when the rebuild happens i'm there bro