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I recently pulled my plugs (BR7EF) to regap from .026 to .022 to try and eliminate a choppiness in rpm on the top end which I thought may be spark blowout. When I pulled the plugs they all looked very similar and all had oil on the threads. Wondering how oil is getting into the cylinders and how much of a problem this is.
Motor is a boneyard 5.3 with like 75k miles. Pulled the pistons and gapped the rings at .026 upper ring gap, .028 lower. 01 z06 cam and springs on otherwise stock heads. MLS head gaskets. 7875 gen2 1.25 AR at 12lbs boost. Combo only has like 200 miles on it.
Mightymouse gen 5+ catch can setup with 12AN hose running from valve cover to can, plumbed as shown:
No smoke that I can tell when cruising around. Definite smoke out the back after boost but not during acceleration, only during decel after I let off the gas. Initially I thought the smoke was from an insufficient drain tube, but didn't really improve after scavenger pump install. Lasts for about 15-20s after letting of the gas. Car does pull hard.
Wondering if my catch can is actually working, I plan to drain it soon.
A couple of questions:
1) is it somewhat normal to get some oil in the cylinders with a turbo setup?
2) is the oil likely hurting the power in any significant way?
3) could the oil be causing spark blowout-like symptoms?
4) what are likely culprits that are causing this?
I recently pulled my plugs (BR7EF) to regap from .026 to .022 to try and eliminate a choppiness in rpm on the top end which I thought may be spark blowout. When I pulled the plugs they all looked very similar and all had oil on the threads. Wondering how oil is getting into the cylinders and how much of a problem this is.
Motor is a boneyard 5.3 with like 75k miles. Pulled the pistons and gapped the rings at .026 upper ring gap, .028 lower. 01 z06 cam and springs on otherwise stock heads. MLS head gaskets. 7875 gen2 1.25 AR at 12lbs boost. Combo only has like 200 miles on it.
Mightymouse gen 5+ catch can setup with 12AN hose running from valve cover to can, plumbed as shown:
No smoke that I can tell when cruising around. Definite smoke out the back after boost but not during acceleration, only during decel after I let off the gas. Initially I thought the smoke was from an insufficient drain tube, but didn't really improve after scavenger pump install. Lasts for about 15-20s after letting of the gas. Car does pull hard.
Wondering if my catch can is actually working, I plan to drain it soon.
A couple of questions:
1) is it somewhat normal to get some oil in the cylinders with a turbo setup?
2) is the oil likely hurting the power in any significant way?
3) could the oil be causing spark blowout-like symptoms?
4) what are likely culprits that are causing this?
Thanks
Stop making any power pulls until you figure this out, there should be no oil on the plugs.
It is not normal for a turbo combo to have that much oil on the plugs period.
Smoke on decel sounds like the engine is sucking oil in when vacuum peaks so check valve seals/guides, check the line running from the valve cover to the air intake, check the air intake for oil, check the line running to the port behind the TB, make sure the can isn't already full and sucking oil into the engine, do a compression test.
Vent your crankcase. Boosted motors need to breathe.
I could say it again, but once should suffice.
Minimum 3/4" ID hose, open to atmosphere.
I am running 12AN to the can, which is supposed to be 3/4 ID and the can does vent to atmosphere under boost. Not the same as direct to atmosphere at all times but seems pretty good. Are you just running a 3/4" hose from your valve cover and letting oily air expel into your engine bay?
I did check the catch can and there was only about half an ounce of oil in there. Not sure what that means. Maybe the oil is getting pulled through the valve seals under decel/vacuum. I don't know if the catch can would help with that.
Either way, is it actually harmful to the engine to boost it with some oil in the cylinders? Especially if it's only under vacuum? Obviously I want to fix the issue but might but be able to tear into it right away.
You need to put a filter on the driver side valve cover instead of running it back intake, that’s why you’re getting oil on the plugs. The rest of your routing is correct.
You need to put a filter on the driver side valve cover instead of running it back intake, that’s why you’re getting oil on the plugs. The rest of your routing is correct.
That's what I did on my last car as well, I put a length of hose off that valve cover with a small filter on the end and ran it into the inner fender.
You need to put a filter on the driver side valve cover instead of running it back intake, that’s why you’re getting oil on the plugs. The rest of your routing is correct.
Funny enough, that's exactly what I have now. I forgot to update the diagram. Did you modify the valve cover at all to get a bigger passageway? Mightymouse said it was fine but now I wonder if this is too small.
It's fine, that's how fresh air enters the crank case. There's a valve inside the catch can that us closed under vacuum so the hose running from the back of the intake to the can pulls vacuum through the can, through the crank case and through the driver side valve cover.
Under pressure, the check valve in the line from the intake closes, the valve inside the catch can opens and the vast majority of the pressure exits out the passenger side cover via the large diameter hose at the oil fill and out the top of the can.
Funny enough, that's exactly what I have now. I forgot to update the diagram. Did you modify the valve cover at all to get a bigger passageway? Mightymouse said it was fine but now I wonder if this is too small.
No I didn’t. That’s how Mighty Mouse told me to do it and it worked for me with my old set up.
Good call! Totally forgot about that, I think its green thread locker you want for this?
I just use a touch of high temp silicone on the tip of the bolt. Tried lots of stuff (PTFE thread sealant, teflon tape, etc...) and a smidge of silicone seemed to work the best. Just be sure to clean the bolt holes between every assembly/disassembly so you don't strip the head.
I added a Mighty Mouse one way check valve on the line coming out of the rear of my driver's side valve cover so it can only take fresh air in, not push anything out. Prior to doing this, my filter at the end of the hose was just allowing oil vapor to come out.
Thanks everyone for all the comments. My heads are not ported. When I swapped springs I did not change valve seals. I think that was an oversight now. I have ordered new valve seals and am planning to replace them this week. I'll update here afterwards with the results.
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Oil getting into cylinders 
