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Old 03-07-2008, 08:13 PM   #1
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Oil leaking to spark plugs ( '93Civic Dx )

After having my oil chaged at a Wal-Mart lube center, my car started smoking from the engine compartment. Oil also began leaking from around the valve cover.
Turns out they overfilled the engine with oil ( but by only half a quart )
I drove the car around 40 or so miles before it started smoking, and then quickly drained the excess oil.
As of around 4 monts ago, I also changed the gasket ( which when I pulled off looked undamaged )

What I'd like to ask about is why that I am still getting oil leaking into the # 1 and #4 spark plug chamber.

Is there an additional gasket that I missed or something ?

Also, what damage could this do to the engine ( having the oil leak into the spark plug chamber )
I would think that since the spark plugs screw in tightly and seal the chamber from oill leakage, that it would not really have an effect except to make the spark plugs oily when I go to pull them out.
Am I wrong in assuming this ?
Any advice would be appreciated.

Thanks !

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Old 03-07-2008, 10:19 PM   #2
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If the spark plug tube had a whole lot of oil in it (like the plug completely submerged) and you unscrewed the plug to replace it or whatever, the excess oil would drain down into the combustion chamber and possibly hydro-lock the engine when you crank it.
Also, oil just sitting in the tubes can soak into the spark plug wires, screwing with their conductivity/longevity.

To answer your gasket question, the valve cover has the one big seal around it's perimeter (which I assume is the one you replaced) and then 4 smaller seals - one at the top of each spark plug tube.
If you replaced all of those and it's still leaking, there are also o-rings down near the bottom of the tubes. Those rings seal the body of each tube to the cylinder head casting. Replacing the o-rings requires removing a good portion of the valve train... I wouldn't try it unless you're fairly confident in your mechanical abilities (it's possible to snap large, important chunks of aluminum during reassembly, and requires adjusting the valves afterwards).

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Old 03-08-2008, 08:09 AM   #3
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As Bobski said, on a D series Honda, there are two seals in each spark plug tube. The first seals between the valve cover and holes in the rocker arm assembly, the second, an o-ring, is further down, and seals the hole in the valve cover assy to the head. Since you changed the valve cover gasket and didn't mention changing the four valve cover spark plug seals, I'd say it is likely that this is where it is leaking. I would take a flashlight and look in the leaky spark plug tubes and try to see if it is leakingabout 1 1/2" from the top of the tube (valve cover seal), or about 3'4" down (the o-ring between the rocker arm assy and head).

The valve cover seals are easy to change, just pull the valve cover and replace them and put a new va;ve cover gasket in. The other ones require removing the rocker arm assy to get to the o-rings. You should get a Helms manual to do this, but it isn't that difficult. One tip I will give you that I learned the hard way, only loosen the bolts on the exhaust side of the rocker arm assy, do not remove them from the assy. They are what holds it together, once it is out of the car. I did this on my CRX and putting the whole thing back together was one big puzzle.
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Old 03-09-2008, 03:01 PM   #4
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The amount of oil leaking into the chamber is just enough to make the threads on the plugs look as if they have been brushed with oil vs. the others which come out clean.
It is not even enough to create a drip, but still has me concerned.
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Old 03-09-2008, 03:34 PM   #5
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are the relevant plugs near the oil fill cap?
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