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1G 1 black spark plug. Burning oil at WOT

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Anthony Boni

5+ Year Contributor
213
23
May 13, 2018
Wrightstown, New_Jersey
Hello. I’ll get straight to the point. This is going to be a bit of a longer post! I have one black spark plug on cylinder two, and I’m burning oil at WOT. Here is what I have diagnosed:

Recently built 6 bolt motor. 2.3 stroker, your average wiseco piston/eagle rod combo. Roughly 1,000 miles on the build now. Compression test all 4, 185-190 all across. Leak down is great on each cylinder as well. I don’t have a number of actual leakage I can post because the second gauge on my leakdown tester does not work. If I had to put a number on the amount of leakage, I’d hypothesize less than 5% on each cylinder. I can hardly hear any air at all coming from the oil filler cap. I have to really listen to hear it. No air escaping the intake/exhaust valves, no air pressurizing the coolant system, no air escaping another cylinder.

Leakdown and compression tests are good. So I removed the exhaust manifold to inspect the valve stem seals for leakage. I’ve attach pictures so you can view them as well. #1 looks completely dry, 2-4 looks a LITTLE damp around the valve guide tips. It doesn’t look like valve stem seals I’ve seen leak in the past. On the exhaust manifold flange and on the head where the exhaust manifold meets, there was unburnt oil. I’ve attached a picture of that as well.

Next, I removed the intake from my turbo. There was one drip of oil in the compressor housing. No shaft play.

I currently have a dual 10AN oil cap going to a sealed catch can with a single 10AN out to to pre turbo on the intake.

So I didn’t find much in the way of why I’m burning oil at WOT, or where it’s coming from. What else should I be looking into? #2’s plug is substantially darker than the other 3 cylinders. It does not look like oil though, it looks like it’s running rich. I am going to get a borescope to inspect my intake valves for oil, because that’s the only thing I can think of. Thanks.
 

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So the original concern is smoke under boost?
Tried eliminating the pre turbo crankcase vapor feed and then drive/ recreate "smoking" conditions to see if it alleviates the issue? (Just for the purpose of diagnostics)

What weight/type oil are you running?
 
So the original concern is smoke under boost?
Tried to eliminate the pre turbo crankcase vapor feed and recreate "smoking" conditions for the purpose of diagnostics?

What weight/type oil are you running?
I could run it to a vented system and see if it still occurs. That still would not explain why only symptoms of oil burning (assumably) are observed on #2’s spark plug.

I run 20w-50 Valvoline VR1 raging oil.
 
Well I had an issue years ago Weiscos 85.5 stroker.
One cylinder in my case 4 had an oil issue.
It was the piston/ring combo.

If I dig I have the pistons somewhere....they actually didn't look too bad.
But in my case the leakdown was off in the high teens .
 
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Hopefully not your issue, but I ended up re-hone bearing etc since your there and new set of arias pistons and all has been well.
 
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I'm not a fan of Wiseco at all for four stroke pistons, gaskets, bearings, the two stroke stuff is ok, but the bar has been raised years ago and Wiseco has been sitting on its hands depending on name value for sales.
 
Did you break the engine in on conventional oil and switch over after the breakin period?
 
I broke in the motor on the same oil I use now. 20w50 VR1. Gave her low boost acceleration and heavy vacuum deceleration for the first few heat cycles then turned it up. The leakdowns are fine, compression is fine. I’m getting hardly any blow by into the crankcase. Less than my last motor and that one was not consuming oil. It’s not the pistons, nor the rings.
 
I would NEVER break in a motor on synthetic. Rings wont seal properly is why I asked. After break in, use what ever you prefer but I NEVER EVER EVER BREAK IN on synthetic and I've only built motors for 40+ years. Chevys, Fords, Dodges, Saturns, Mitsubishi's you name it, I can build it.
Just pointing out some possible problems since its a fresh motor and shouldn't be using or leaking ANY oil if rebuilt properly and breakin procedures followed.
 
I would NEVER break in a motor on synthetic. Rings wont seal properly is why I asked. After break in, use what ever you prefer but I NEVER EVER EVER BREAK IN on synthetic and I've only built motors for 40+ years. Chevys, Fords, Dodges, Saturns, Mitsubishi's you name it, I can build it.
Just pointing out some possible problems since its a fresh motor and shouldn't be using or leaking ANY oil if rebuilt properly and breakin procedures followed.
VR1 comes in both synthetic and conventional.


I use conventional oil.
 

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Well then you are A OK. :thumb: I was worried. I would next be looking at valve stem seals and valve guides. I had a head that I thought was "good". Ran it and soon after, had oil burning problems on a used shortblock. It was sloopy valve guides. The new seals lasted about a month and were wore out from wiggling around in wore out guides. Might look into that, your #'s look to be ok for the shortblock so I suspect a problem in the head unless you have broken a ring or butted them up under boost.
 
Well then you are A OK. :thumb: I was worried. I would next be looking at valve stem seals and valve guides. I had a head that I thought was "good". Ran it and soon after, had oil burning problems on a used shortblock. It was sloopy valve guides. The new seals lasted about a month and were wore out from wiggling around in wore out guides. Might look into that, your #'s look to be ok for the shortblock so I suspect a problem in the head unless you have broken a ring or butted them up under boost.
I didn’t see your first comment asking if I switched form synthetic to conventional, that was my bad.

My last motor’s ringlands failed from a high boost spike. The rings were destroyed and stacked on top of each other. Zero compression in 2 of the 4 cylinders. I think if I had ANY ring problems, it would have been diagnosed from the compression/leakdown test. But that’s why I’m here, I don’t know everything LOL.

I’m also suspecting the cylinder head. It’s likely the valve guides, as my luck would have it that is the only thing I didn’t replace. New valves, new valve stem seals, but the same valve guides. I was rushing to get the longblock assembled. Impatience may have gotten the best of me.
 

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It's not the end of the world. If you use a Euro tool, you could remove a spring or 2 in the head (put some cord in the cylinder so you don't drop a valve) and then just wiggle the valve stem. If it wiggles at all, its wore. It wouldn't take too long to test that and either check it off or deal with any problem you might find. :thumb:
I'm hoping its its something easier that none of us has suggested for your sake.
Keep us posted.
 
Even if your valve guides are worn out, with 1000 miles on the seals they shouldn't be leaking that much, you might have damaged one when installing it or its popped off the top of the valve guide, also I used Wiseco stuff for years and the four stroke stuff uses low friction thin oil rings packs to free up power, remember that these pistons are for racing only as far as Wiseco is concerned and they do consume oil because of that but that wouldn't explain the problem only being on one cylinder, neither would worn valve guides, they all wear at the same rate unless that head had cracked a guide in that cylinder from a previous valve and piston collision where it affected that cylinder worse than others and the other guides aren't as damaged but still have a little damage that isn't passing as much oil, in any event your going to have to decide if and when you want to pull the cams out and pull the valve springs in that cylinder and dig deeper into the problem, I would be tempted to just drive it more and see if it changes unless its using enough oil to leave a smoke stream, valve seals in general will burn oil after the engine is warm and after you pull away from a red light in town when you have been sitting for a few minutes.
 
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Have you verified that oil is in the cylinder?
I’m unsure how to do that accurately. I can look down the spark plug hole in each cylinder and see a bit of oil with some black charred goodness. I could use a borescope from work. I work in aviation so they have some nice borescopes. It’s a matter of getting one home and back without getting into trouble LOL.


Even if your valve guides are worn out, with 1000 miles on the seals they shouldn't be leaking that much, you might have damaged one when installing it or its popped off the top of the valve guide, also I used Wiseco stuff for years and the four stroke stuff uses low friction thin oil rings packs to free up power, remember that these pistons are for racing only as far as Wiseco is concerned and they do consume oil because of that but that wouldn't explain the problem only being on one cylinder, neither would worn valve guides, they all wear at the same rate unless that head had cracked a guide in that cylinder from a previous valve and piston collision where it affected that cylinder worse than others and the other guides aren't as damaged but still have a little damage that isn't passing as much oil, in any event your going to have to decide if and when you want to pull the cams out and pull the valve springs in that cylinder and dig deeper into the problem, I would be tempted to just drive it more and see if it changes unless its using enough oil to leave a smoke stream, valve seals in general will burn oil after the engine is warm and after you pull away from a red light in town when you have been sitting for a few minutes.

I don’t think I burn oil outside of boost. It doesn’t burn on start up and I don’t think it burns on stop and gos. I’m thinking #2 is running rich for some reason, and I have excess crankcase pressure because I have two 10ANs running to a small mishimoto sealed catch can. In boost I think the crankcase pressure is fighting the turbo oil return and pushing the oil past the seals in the turbo. I did measure crankcase pressure using a 1 bar map sensor, but it was a cheap chinesium sensor that took a poop after a week. So I’m taking those measurements with a grain of salt. Before I start taking stuff apart, I’m going to buy a legit 1 bar map sensor and try to borescope into the cylinders and my intake valve guides to see if they’re leaking
 
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