robsst

I have a 96 Maxima GLE with 134k miles. A few weeks ago, I shot the spark plug all the way out of the #6 cylinder. According to the stealership, it was laying on top of the engine in pieces, and the ignition coil was destroyed. The plug had been bouncing up and down in the tube for at least 50 mile. The spark plugs threads had been completely stripped out of the engine. I used a Helicoil kit to fix the threads (and I am pretty sure I got all the shavings out). All of the spark plug parts were recovered (and did not end up in the cylinder), but I did not see any of the plastic parts from the ignition coil. The entire extension of the ignition coil was missing (it is possible that the stealership chucked it).

The engine feels like it is running good and the CEL is not lit, but at idle there is a lot of noise, almost like the valves are tapping (very noticable outside the car, but not very noticable sitting inside the car). As I rev the engine a little (say 1500 rpms) the sound becomes much less noticable. I took it in the other day and the mechanic at the stealership said it was a bad noise, and was scared to drive the car.

Yesterday, I was popping out the spark plugs to put some anti-seize compound on the plugs (I forgot to do this when I put them in the first time). I noticed that bottom of the spark plug had a smooth black shine to it. It looked almost like it had been painted with a gloss black paint. These plugs have only been in the car for about 600 miles.

Could this be the result of the plastic parts of the ignition coil melting and coating the inside of the engine?

Do you think this engine will last? Should I use something like sea foam to try to clean it out?

I am going to check for CEL codes anyway, but I don't expect any.

All suggestions and thought are welcome...

Thanks!

njmaxseltd

iTrader: (19)

If you really want to see if anything got into that cylinder you have 2 choices.

1) Find somebody with a really small camara and probe it down into the cylinder.
2) Pull the head off the car.

Or you can keep on driving it and see what happens.

ryant35

iTrader: (3)

Are you the guy who thought that you could blow the problem out by driving up hills & running your engine hard and caused the spark plug to blow out?
If so, try that again maybe it will work this time.

robsst

njmaxseltd - Thanks for the suggestions, it's appreciated. Unfortunately, I don't know anyone with a really small camera, nor do I know enough to put the head off.

ryant35 - Yes that's me. How many guys are driving around with misfires, seems like there are quite a few out there. I thought I just got some bad gas, so yeah, I put in some gas conditioner and ran it hard. How was I supposed to know that the spark plug was loose. I don't know jack about cars, I've never even done an oil change myself. At least I have the 'nads to try and fix it!

ryant35

iTrader: (3)

If the valves are tapping it probably has nothing to do with the spark plug work you did. As for the work you did, that was a pretty big job to tackle with little or advanced experience.

I think it may have something to do with timing, but if the timing is off enought to cause tapping it would probaly run badly.

Anyway I was just giving you a hard time.

famouspork

Hello!
I would personnaly never rethread anything myself (and I was a machinist before)so congrats on taking up the job.But I have a feeling that maybe the threads you have made might not be aligned straight and the spark plug might be at an angle,or there might be a small amount of air lost through the threads...just a thought..

robsst

No hard feelings....
I had just spent my entire weekend doing various repairs and maint on 2 Maxs, and Infiniti and a Ford Pickup (Yuck), plus rebuilding my computer thanks to a virus. (I now hate those f'ing fuel filters!).

When I was getting ready to tap the hole, I pulled the valve (and cam) cover to see if I could get closer to the actual hole. I did notice that one of the top cams for the #6 cylinder did not have the smooth sharp edge like the other ones. On the rounded portion of the cam (bottom of the egg shape) I noticed that there was a rough edge sticking out to the side, almost like it had been mushroomed by a hammer. Otherwise, the cam itself appeared smooth and properly round to the eye.

Is is likely that running the car hard with an open cylinder (no compression at all because the spark plug was missing) beat up the cams or the valves for that cylinder???

If so, how hard/expensive is it to replace the cams and/or adjust the valves?

robsst

Actually, I am pretty sure the hole is straight and tight. The tap itself is specifically designed to use the remains of the existing hole as a guide, plus the socket wrench for the tap barely fit into the shaft above the hole. I couldn't have forced it out of center if I wanted too. Additionally, I used RTV (as instructed) on the helicoil to ensure it was air tight.

ryant35

iTrader: (3)

Running with out compression won't damage cams or valves, it may damage your catalystic converter because of unburned gas blowing through the engine, not to mention fire hazard if the gas doesn't burn in the cat.

Dodge's new Hemi cars have cylinder shutdown at crusing speeds to save on mileage. The engine controller shutsdown the spark & the fuel injector, so there is no damage to the cat.

robsst

Thanks for the info...

I am glad to know that running with no compression didn't hurt the engine.

I don't know if this might trigger some ideas, but when I pulled the valve cover, I did notice that some of the cams appeared clean and shiny, while others appeared to have a light brown coating (burnt oil?). I also had a blown seal in the valve cover around one of the spark plug tubes (the one that blew out in fact). I already replaced the seal.