Spark Plug Imploded/Melted and Now Needs Re-Tapped?

[importrp]

I was recently driving in the mountains and the check engine light came on, the car started shaking, etc. I figured I had a cylinder misfiring, so I immediately pulled over and turned the vehicle off. Opened the hood, had the wife start the car, and could feel air coming out from around the seal on the center coil in the front. It was obvious that was my problem.

This is where it gets weird. I pulled the coil out, and much to my surprise, the plug came right out with the coil. The top portion of the plug looked like it had broken off or melted and the coil and plug were melted together.

Here is a picture:



I quickly determined that I could get a new plug in, so had it towed to the dealer. The dealer doesn't seem to have a good explanation as to why this happened. They are claiming they've never seem this before. I asked about 5 times if they thought there was any other internal damage other than the spark plug tube area needing to be re-tapped, and they are telling me there isn't.

They want $350 for a tool/kit to do the work and anywhere from $300-400 in labor, depending on how much they need to take apart to get at it.

Has anyone else had this happen? Any advice anyone can give me? Anyone know where I could find the re-tap tool/kit for less? Thoughts on if there could be any other internal damage that I should be worried about? I have a lot more questions than they seem are able to answer.

Thank you in advance!!

[gwilki]

Many years ago, I stripped the plug hole on a racing bike. We did a helicoil insert while in the pits. I don't know what is involved doing this in an MDX, but you may want to look into it.

[SuperTech]

I've seen that before a few times, and the majority of the time, the cylinder head is pretty much done.

The electrode broke off the spark plug. Where'd that go? Bang around the cylinder a bit before damaging a valve on the way out?

[AC_MDX]

The spark plug broke inside the engine cylinder and messed up everything, a valve got broken/loose, the rings broke and the piston/valves/spark-plug messed up, or something very bad happened there.

They need to open the the cylinder head to see what the damage was to the cylinder, cam, engine head, rings, etc..

That is not a re-tap only issue.. You will be wasting your money and you will have to pay a lot extra to fix the real issue...

AC

Originally Posted by importrp

I was recently driving in the mountains and the check engine light came on, the car started shaking, etc. I figured I had a cylinder misfiring, so I immediately pulled over and turned the vehicle off. Opened the hood, had the wife start the car, and could feel air coming out from around the seal on the center coil in the front. It was obvious that was my problem.

This is where it gets weird. I pulled the coil out, and much to my surprise, the plug came right out with the coil. The top portion of the plug looked like it had broken off or melted and the coil and plug were melted together.

Here is a picture:



I quickly determined that I could get a new plug in, so had it towed to the dealer. The dealer doesn't seem to have a good explanation as to why this happened. They are claiming they've never seem this before. I asked about 5 times if they thought there was any other internal damage other than the spark plug tube area needing to be re-tapped, and they are telling me there isn't.

They want $350 for a tool/kit to do the work and anywhere from $300-400 in labor, depending on how much they need to take apart to get at it.

Has anyone else had this happen? Any advice anyone can give me? Anyone know where I could find the re-tap tool/kit for less? Thoughts on if there could be any other internal damage that I should be worried about? I have a lot more questions than they seem are able to answer.

Thank you in advance!!

[ninor]

Originally Posted by importrp

I was recently driving in the mountains and the check engine light came on

Odds are, your engine is done. It is hard to see from your picture the exact extent of the spark plug missing/melted, but it sure looks like it is game over. Also the fact that you just pulled the spark plug out with the coil would indicate that head is probably melted in that area. There is no other way that those threads would just "let go" of the spark plug.
If it is confirmed that engine is done, I would look up used engine as opposed to have dealer "fix" yours as this can easily turn into to one of those never ending fixes upon fixes.

What type of gas were you running?

Regards,

Nino

[Dominik-X]

Sorry to say but there could be seriuos damage done to that engine. A friend's engine on a 08 TL recently was replaced because a spark plug got loose inside the head and broke inside, part of it scratched the cylinder wall and bye bye engine.

[HardCorps325]

I agree ith the above comments. This can happen if the plug wasn't torqued correctly. I think I remember seeing something in a manual about this recently, but not sure if it was an Acura/Honda manual or a Mitsubishi.

[NewMDXOwner]

You can use Helicoil inserts to repair the thread (if it is really damaged, but I seriously doubt it) and put in a new spark plug. That part is doable, but I am afraid there must have been some damage to that cylinder as others have said.

Something similar happened to a car of mine (a Ford), even though not to the extent that I saw in your picture. The car was running so lean that the electrode just got corroded enough to break and fall into the engine. It never ran the same after that. Very rough idle but it managed to pass smog checks every year so I kept on driving it until around 180K miles when I opened up the heads to take care of a head gasket leak. That's when I saw the damage that the engine suffered. The piston is all pitted up as is the head, but the cylinder wall somehow remains undamaged. Since it was an old car, I just sanded down the damaged area and put things back. It did last another 80k miles when I traded it in during the "cash for clunker" program.

So my advice to you is this. Since this happens on cylinder number 5, taking the head off is not too much trouble if you are mechanically inclined. Then you can do a really good inspection of the damage. If the cylinder wall is damaged, you are probably better off scrapping that engine in favor of a used one. If the cylinder wall is OK, then just smooth out the piston and the head as long as the damage is not too extensive. Otherwise, you are looking at replacing those. The Helicoil would also be much easier to do with the head out of the engine. Then just slap things back together and see how it runs. Obviously, it will never be the same as a new engine, but it will get you from home to work. However, if the car is new or if you are really attached to it, then I would suggest a rebuilt or used engine.

As for how that condition develops, I can only venture a guess that the spark plug has been loose in there for a very long time. That does several terrible things.

Normally, the head is cooled by water and that kept the spark plug cooled as long as the spark plug is torqued down and had good contact with the head. During combustion, the hot gas will leak past the thread and heat up the spark plug which is not being cooled sufficiently by the head (because it's loose); that's why the thread on the spark plug has pretty much disintegrated. However, the thread on the head should have been OK if I am a betting man.

During the suction part of the cycle, air is leaking into the cylinder, which makes the mixture lean, and that would increase the cumbustion temperature, further worsening the situation.

At any rate, check the thread on the head first before you do the Helicoil thingy; you may only have to run a tap and chase the threads.

Good luck and sorry for the long winded post.

[adr5]

Let me chime in with others, this is not good. All the pieces that broke off were banging around the engine for a while. It is possible the pieces were small and just worked their way out of the exhaust, but they might have been big and done damage before they went out or they might still be in there. The only want to know is to look inside the engine. Ideally they have a small camera they can put into the cylinder via the spark plug hole and then look around in side. If it looks clear they can then repair the threads. If there is damage, they should not waste their time repairing the threads in the car because no matter what the repair will involve pulling the head and it is easier to repair the threads with the head on a bench. If it looks good in side and they repair the threads with the head in the car, they should then do a compression test. That is how they can really tell if there was any damage. Without doing a compression test, they are just guessing that there is no internal damage. Also, why are they asking your to pay for the tools to do the fix? They should have the tools and if they don't, they should pay for their own tools. Not to mention that they are guessing at the cost to do the fix after they buy the tools. That gives me a really bad feeling about the mechanics at that dealer. So much so that I would not trust them to do the fix. Basically they are asking you to pay for their tools and then pay for them to learn how to do it on your car.

[gwilki]

I don't want to hijack the thread, but it's interesting that even all the visible damage could be done without one of the fancy electronic sensors picking up something wrong. It would appear that that plug has not been doing anything for some time, but no warning lights, buzzers??

[shadymdx]

Just out of curiosity how many miles are on your car or better yet how many miles were on those plugs?

[G. COLTON]

I think that it is clear that the head must be removed from the engine to do the repair properly.

It is also clear to me that it is unlikely that damage was done that the entire engine must be replaced.

I also would do no further business with a shop that wanted you to buy tools.

George

[AC_MDX]

You may just need to replace one cylinder sleeve, and piston/rod, or you may want to rebore all your engine cylinders, which means bigger pistons which means slightly more power..

Though, you need to check if the engine head, cam, valves, and other components suffered any damage, which means the engine head has to be removed and checked, the pistons/rods have to be checked and if they are broken/cracked, then more checks have to be done to the crankshaft etc.

[shadymdx]

I recently took apart the engine on my buddys 2005 mini cooper S for the exact same reason. He was driving to work and the engine light came on and the car started to misfire and made a loud pop. He had the car towed to my house. I pulled the coil packs off and could smell a distinctive burning smell from cylinder #2. I went to remove the plug and the whole tip had blew off and was rattlling ariund inside the cylinder. We pulled the head off and saw that the piston top was wrecked and the wall was scored. At thatpoint i told my buddy we can do it the cheap way which was to hone out that one cylinder and put a .10 over factory piston and replace the valve or do it right and overhaul the whole motor and freshen the head. Well $3500 later the car runs stronger than ever...

[harry1]

Given the potentially fatal or serious damage to the engine, I leap to the question of what if any warranty coverage does the OP have? Did a dealer do the last plug replacement? What plugs were used? Is this from your 2011 MDX?

I would suggest trying to chase down the service cause and oherwise attempt to put an engine replacement back on Acura if appropriate.