Best of Deals Car Reviews Repair Shops Cars A-Z Radio Show

Oil in Cylinders, 99 Honda Accord

So I’ve got this that lawn ornament of a 99 Honda Accord 4cyl (190k miles or so) in my yard. I’d had a problem with thick carbon build-up on the spark plugs electrodes, which was blamed on poor timing. So at the recommendation of the dealer mechanic, I did an ECU swap. Put the new computer in and started the car, seemed fine! Let it idle awhile then drove it in a big circle. Did OK for maybe a minute or two, then stopped and has never started again.

The immediate cause seems easy to diagnose: oil on the spark plug electrodes. It’s easy to check: pull the spark plugs out, clean them off, put them back in, crank it for a bit (it may catch a little) then pull them back out and they are covered in oil again.

Since two compression tests have come back roses, I’d suspect the problem is up top. But here’s my question: why all 4 cylinders? If leaky valve gaskets were the problem, for instance, how likely is it that they’d go bad in all 4 cylinders? Is there something else that could cause an oil leak in all 4 cylinders that’s a more likely explanation?

EDIT: Where I had previously written “terminals” has been corrected to “electrodes”.

The valve cover gasket along with the spark plug well gaskets need to be replaced.

Common problem on Honda engines.


How does the oil get from there into the cylinders? There isn’t oil in the spark plug wells.

But if that’s what I need, it may be relevant that I did that procedure in the year before all these problems started; replaced some plug gaskets and the valve cover gasket. Then the dealer re-replaced the valve cover gasket after I didn’t get it all quite sealed.

You said there’s oil on the spark plug terminals.

The spark plug terminals connect to the spark plugs in the spark plug wells.


My bad, my terminology was incorrect. The oil is on the electrodes. I’ll edit the original post.

Then check for a plugged PCV valve.

If crankcase pressure builds under the valve cover, it can force oil past the spark plug well gaskets whether they’re new or not.


Cleaned the PCV off and did the old suck-and-blow test; air went through easily one way. Cleaned the plugs off and tried again, no dice. Starting to worry about about the starter motor; i’ve been trying to get this Honda going for awhile, and I think she’s starting to strain.

So, you’re sure it’s oil and not carbon from an over-rich condition?

It’s wet and cleans off easily with a rag.

Yeah, that’s weird. Could be all the oil rings on the pistons are worn/stuck. You’d still get good compression.

Do you still have your old ECU?

Have you charged the battery?
Leave it half full and you’ll soon need another.
When the car was running did it smoke and/or use more than a qt of oil in 1000 miles?
Could be bad valve guides or guide seals, or gunked up oil control rings and still have good compression.
Did you buy it used? Previous owner could have been lax with oil changes.
If you pull off the intake manifold you can take a look at the valve stems and the backs of the valve heads.
If they’re encrusted then you know the oil is coming through the guides.
If the valves look clean then it’s coming from the rings.

Whoa…WAIT…Tester makes a good point (as usual)…those engines are notorious for leaking oil down into the plug wells…and a lot of it.

But if you say electrode then thats on the piston side.

This cannot be the case without you CROP DUSTING the entire neighborhood in blue oil smoke…so…which is it? Crop Dusting…or no Crop Dusting…should be ez to tell here.

Next time you do a test run…run it for a while then…STOP…Look down into the plug wells…put something down there if you need to and see if the oil has not collected in the plug well, PRIOR TO loosening and removing the plugs.

If you have a lot of oil in the well…it will coat the entire plug as you remove it all the way down to the electrode…and this can confuse you if you arent experienced in this.

But if you postulate that the plugs are oil fouling to the point of not firing…Then you will have ENORMOUS amounts of blue smoke out the tailpipe…so much in fact that you would be encouraged to shut it down…if the neighbors didn’t force you to shut it down.

You need to look into the plug wells and their gaskets like Tester mentioned…this is more than a valid check and has firm place in reality.


Reverting to a common question I often ask; what ARE the compression numbers?

There are many instances of numbers claimed to be good and in reality they are not.

It should also be mentioned that one can have great compression numbers and still have piston ring issues; usually due to the oil control rings.

I seem to recall a call on the Car Talk radio program about this, and Ray suggested it might be caused by faulty oil control rings on the pistons. There’s rings for compression and rings for controlling the oil I guess, and it is possible for the compression to measure ok by oil somehow still gets past the oil control rings and into the cylinders.

edit: It might be they are just stuck. I wonder if there’s a way worth trying to unstick them.

…NONE of us should be ignoring the fact that each of us would probably see his blue oil smoke if his Electrodes were truly coated in oil to the point of fouling out and not sparking.

No Blue Smoke ? No oil on electrodes… The oil will appear on the electrode as you remove the plug…sitting in a well of oil. Happens all the time like this.

If he isnt Crop Dusting…there is no oil in the combustion chamber…period.

and since the Accord Valve cover fails at the plug wells and is very well known… PLease…look there first. But like I said…no oil smoke…no oil in combustion chamber


Vehicles will burn oil and NOT smoke. It’s a matter of how much oil is burning. Small amounts and you won’t notice it at all.

Not ones that wet the electrode sir… SMOKE SMOKE SMOKE… But yes they can burn oil and not smoke…much

NOT when the electrode is oil soaked however Abso-Effing-loutely-not. I am fairly certain this guys electrodes are getting the drip down effect when he pulls them from the head…and they are sitting in a well full of oil. They arent actually wet inside the head…but get wet when removed.

Besides…the symptom I am talking about…and what Tester started…is beyond easy to verify and check…hell it required no tools even. So check it…and then move on…but do NOT ignore it.

Especially when 95% or more of Accord Valve cover gaskets are replaced because of oil in the plug wells…its super super well known and massively common. If you wait long enough an Accord will stop running…and you pull any plug wire and it literally makes a sucking sound as it comes out of the near full plug well…full of oil. It literally grounds out the iginition.

Now…does this OP know the difference between and insulator and the electrode? I dunno… Oil soaked ELECTRODES…will make smoke like you cant imagine…oil soaked insulators…will stop sparking and seem fouled…when in reality whatever wet the insulator is providing a nice path to ground and robbing the electrode of that nice little arc of energy.


Could sludge be blocking the drains in the head and causing oil to accumulate up to the valve stems?