2002 Corolla Stripped Coil On Plug Solution?

[notaloafer]

So this is kind-of ironic, I spent a bunch of time being careful not to strip out the actual spark plug holes (which I didn't) after I put in new plugs.

However, I did manage to over-torque the 10mm bolt that holds the coil over the spark plug. How do I go about fixing that? I can't seem to find anyone else who was as dumb as me to do that, only people who managed to strip the actual spark plug. Can I tap/dye it, or will that let the shavings into the valve cover if I drill it out? It's being held in there now by about 1 thread - should I just cut my losses and ignore it? My car has bad oil control rings and the oil manages to push its way all the way up through the spark plugs, so I don't want to have a leak at the top if possible.

Please help. Thanks!

[Bennie]

Broken bolt:
If it is broken off with a little bit of the stud still sticking out I would try to unscrew it with a vise grip. You could also try to cut a slot in it with a dremel and unscrew it with a flat head screw driver. Another option would be to try to drill a hole in the stud and use an easy out. I'm pretty sure these are low grade bolts so that's definitely an option. Either way I would chase the threads with a tap when you are done to make sure it doesn't happen again. Be extreamly careful not to cross-thread it with the tap.

Oil above the park plugs:
My money would be on a leaky valve cover gasket. The gasket has an o-ring around each spark plug socket and when they start leaking oil will drain right around the plugs.

[notaloafer]

The bolt isn't stuck in the thread - the problem is that I stripped out the threads so when I tighten down the bolt, it has nothing to thread into. It has about 1 thread left in there that isn't stripped. Does it matter if I just ignore it? Like you said, it's a low-grade bolt. It doesn't really do anything except keep the spark plug coil in place. The coil isn't going anywhere anyways with the cover on.

As far as the oil leak goes, I had a lengthy discussion with the Toyota dealer about it. I did a compression test yesterday - all of my numbers are 210+ where the factory ship setting is 218 so there's no problem there. The repair guy from Toyota told me that most likely the oil is getting up into the cylinders because of bad oil control rings in the very bottom and because the oil is in there, it's sealing up the old piston rings and giving me great compression. From there it's just managing to work it's way up into the spark plugs. If you think he's wrong, let me know - I don't want to go to the extent of changing out the gaskets if it isn't going to work (that's a medium sized job).

Basically I have the oil leak to thank for excellent compression, if that makes sense. My car consumes about 1 quart of oil every 670 miles, which again the Toyota guy said is pretty normal for 145,000 miles. However I have heard people on here say that is BS... I don't really know who to believe!

[Bitter]

you can heli-coil that. they sell the kits at Pepboys for most sizes.

[Bennie]

I definitely agree with Bitter, Heli-coil it. I don't think the holes go all the way through the valve cover so you don't need to worry about shavings but be careful not to drill through it.

I find it hard to believe that oil was making it past the spark plugs. That would mean compression was also making it past the spark plugs. It actually make me laugh. Unless they are not tightend down or something. It really does sound like a valve cover gasket to me.

Unfortunately on our cars burning oil is common. I don't think 670 a qt is very good but if it doesn't get worse than your doing ok. Just keep it full of clean oil.

[notaloafer]

I guess I may have over-exaggerated my problem a little bit. The spark plug bottoms are coated in oil (the threads) - there isn't any oil on the actual coil. My car is running great right now even with the burning problem so I think I'm just going to ignore it.

I ran a compression test on it and got 210+ on every plug which is pretty amazing since it has 145,000 miles on the engine. The dealer told me the reason I'm getting such great compression is because the oil is sealing up the piston rings and giving me factory-new compression. Does that make sense? I guess what he's saying is that I should be thankful for my oil leak because it's giving my engine like-new power. Haha.

I will go ahead and heli-coil the thread when I get a chance. Right now the coil is staying on just fine and isn't causing any problems with the general running of the engine. It's just that it's really loose since there is only like 1 thread left holding the plug in.

[fishexpo101]

Oil squirted into the cylinders will generally raise the compression if the rings are bad - so in a sense, the dealership was telling the truth - if that was the case in your engine, there isn't enough information presented in your posts to tell that.

If there is oil in the bottom of the plug well, coating the threads and base of the plug, and around the coil on plug module - likely you have a bad o-ring(s) on the valvecover. A pretty easy fix - should be several DIY guides floating around here that would help you out, if you haven't tackled this before. Might also help slow the physical oil leak as well.

If the plug electrodes and porcelain are drenched in oil - then I'd say you have an excessive oil consumption issue. If it is on the threads only - leak in the valvecover gasket/plug o-rings.

[notaloafer]

There was a trace amount of oil on the actual coils themselves. However, the threads on the spark plugs were coated completely in oil. The ceramic part is pretty clean as you can see. There is black soot in my exhaust, but when I start my engine I'm not getting any smoke at all. I know the car isn't dripping oil because I've parked it on a completely clean driveway for days and nothing has come out. Is this enough detail for an accurate diagnosis?


Here are the plugs that have only been in the engine for about 3,000 miles. I didn't wipe them down, these are them as-is:

[Bennie]

It doesn't look like you need to worry about the valve cover gasket.

Basically it's an elmination process for what's happening to the oil. If it's not leaking it externaly on to the ground, internaly in to the cooling system (you'd know in a hurry if you looked at the coolant), then it's burning it.

If you are driving at night with a car behind you, put the thing to the floor and see if it's spitting out some smoke. It's easy to see at night with headlights shining behind you. That was when I could really see it back when mine burned oil.

[notaloafer]

Well if I know that it is for-sure burning oil, now it's time to figure out where it's going.

1) I am loosing 1 qt every 670 miles
2) There are no visible signs of leaking
3) There is soot in the exhaust (not sure if that matters or not)
4) My spark plug threads are covered in oil (all 4)
5) There is very a very slight amount of oil on some of the spark plug coils and the porcelain (a few drips, see photo)

According to fishexpo, this means a valve cover gasket leak? Any other input on that? I don't really want to bother taking it apart if it isn't going to fix the problem (or at least make it less consuming).

Thanks!!

[Bennie]

At 670miles per quart with no sign of major leaks..... it's the piston rings.

And yes, the oil on top of the spark plug (the part you are calling the coil I think) indicates you need a valve cover gasket.