Oil on spark plug tip after rebuild

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Old Mar 19, 2010 | 11:28 AM
  #1  
shifty35's Avatar
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From: Nashville, TN
Default Oil on spark plug tip after rebuild

Hey everyone! I'll try to summarize what is going on here.

Build consists of: D17A1 crank / rods / pistons in D16Z6 block, using D16Z6 head. Greddy 15g turbo.

NPR piston rings
ACL bearings

Before installation, I broke one of the second compression rings. I ordered a single replacement ring from JE pistons, the only place I could find that sold single rings. It looked pretty much the same as the NPR second compression ring. The JE ring ended up in Cylinder #1. Oil clearances plastigage out to .0015-.002". PCV system is open - valve cover and black box venting to atmosphere, not recirculating. Spark plugs are Autolite 3924.

The engine was broken in as follows: 15 minutes runtime at idle (had a slightly pulsating idle, IACV not right) to allow to get up to operating temp. Performed compression test, I get 205-210-205-220. Plugs look perfect.
Oil used is Shell Rotella T 15W-40. Engine has ~80psi oil pressure cold at idle, 25psi warm.

Let cool overnight.

Next day, start engine - allow to get to operating temp, took for a drive. Lots of varied load in lower gears, some high RPM blasts with ~7psi boost. Lots of mid / high RPM engine braking. This took about 10 minutes.

Changed the oil. Engine is about 1/2 qt overfilled. More driving, less aggressive than before, but still varied RPM / speed / loading, no highway driving.

Noticed it seemed to be missing a bit in upper RPMs, so I pulled the plugs, thinking they were still stock gapped. They were all gapped to ~.035", but the #1 plug was very damp. Pretty sure it's oil. Compression test is still good, ~200 psi in each cylinder. There is no oil in the spark plug tube - the valve cover seals are fine. Only oil on the tip.

Rotated the spark plugs. More driving. Periodically checking / cleaning spark plug #1. Sometimes it has oil on it, sometimes it looks clean. #2-4 all look perfect.

The valve seals were NOT replaced during the rebuild. Seems like they would all have failed rather than just the ones in cylinder #1?

There is no oil in the charge pipes either. The turbo drain is straight, obstruction free, to the top of the oil pan.

At this point, the engine has ~5 hours runtime and 100 miles. I'm primarily concerned that I damaged a ring or installed one upside down on cylinder #1 during installation. I didn't hit them really hard, but I did have several failed attempts to install where I was tapping the piston with a wooden hammer handle.

Sorry for the excessive narrative, any help is appreciated.
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Old Mar 19, 2010 | 05:24 PM
  #2  
lsvtecracer's Avatar
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Joined: Sep 2001
Posts: 1,119
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From: Baton Rouge, LA
Default Re: Oil on spark plug tip after rebuild

Originally Posted by shifty35
Hey everyone! I'll try to summarize what is going on here.

Build consists of: D17A1 crank / rods / pistons in D16Z6 block, using D16Z6 head. Greddy 15g turbo.

NPR piston rings
ACL bearings

Before installation, I broke one of the second compression rings. I ordered a single replacement ring from JE pistons, the only place I could find that sold single rings. It looked pretty much the same as the NPR second compression ring. The JE ring ended up in Cylinder #1. Oil clearances plastigage out to .0015-.002". PCV system is open - valve cover and black box venting to atmosphere, not recirculating. Spark plugs are Autolite 3924.

The engine was broken in as follows: 15 minutes runtime at idle (had a slightly pulsating idle, IACV not right) to allow to get up to operating temp. Performed compression test, I get 205-210-205-220. Plugs look perfect.
Oil used is Shell Rotella T 15W-40. Engine has ~80psi oil pressure cold at idle, 25psi warm.

Let cool overnight.

Next day, start engine - allow to get to operating temp, took for a drive. Lots of varied load in lower gears, some high RPM blasts with ~7psi boost. Lots of mid / high RPM engine braking. This took about 10 minutes.

Changed the oil. Engine is about 1/2 qt overfilled. More driving, less aggressive than before, but still varied RPM / speed / loading, no highway driving.

Noticed it seemed to be missing a bit in upper RPMs, so I pulled the plugs, thinking they were still stock gapped. They were all gapped to ~.035", but the #1 plug was very damp. Pretty sure it's oil. Compression test is still good, ~200 psi in each cylinder. There is no oil in the spark plug tube - the valve cover seals are fine. Only oil on the tip.

Rotated the spark plugs. More driving. Periodically checking / cleaning spark plug #1. Sometimes it has oil on it, sometimes it looks clean. #2-4 all look perfect.

The valve seals were NOT replaced during the rebuild. Seems like they would all have failed rather than just the ones in cylinder #1?

There is no oil in the charge pipes either. The turbo drain is straight, obstruction free, to the top of the oil pan.

At this point, the engine has ~5 hours runtime and 100 miles. I'm primarily concerned that I damaged a ring or installed one upside down on cylinder #1 during installation. I didn't hit them really hard, but I did have several failed attempts to install where I was tapping the piston with a wooden hammer handle.

Sorry for the excessive narrative, any help is appreciated.
Is the car smoking through the tailpipe or catchcan?
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Old Mar 19, 2010 | 07:06 PM
  #3  
shifty35's Avatar
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From: Nashville, TN
Default Re: Oil on spark plug tip after rebuild

Originally Posted by lsvtecracer
Is the car smoking through the tailpipe or catchcan?
No, no smoke at idle - haven't seen any while driving either.
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Old Mar 21, 2010 | 09:26 AM
  #4  
DC4KiD's Avatar
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Joined: Nov 2003
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From: Oakland, CA
Default Re: Oil on spark plug tip after rebuild

You sure it's oil instead gasoline?
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