red97xj

Ok, I have a 99 cobra with 44,000 miles. I had it detailed last fall, filled it with 93 octane, parked it. It has run horrible all spring.... skips and misses like a bad plug or two. Put 4 tanks of 93 thru, helped just a tiny bit.

Bought some autolite coppers, and tore into it. The drivers side all looked normal to me. The passenger side front 2 looked normal. But the back 2 on passenger side look bad. The rear most one even had water about half way up the plug just sitting in the plug well when I pulled the COP off. The rear most 2 COP's were also dirty and kind of water-rust colored. Here are some pics of all 8 plugs. Those 2 were DIRTY. I of course vac'd it all out clean before putting new in.

http://www.flickr.com/photos/jasonkn...in/photostream

http://www.flickr.com/photos/jasonkn...in/photostream

Is it possible the head is leaking water somehow? Or more likely that the detail shop just used to much of the power washer in that area when washing?

Have only put about 20 miles with new plugs, but seems to be running perfect for that 20 miles.

Thanks for all your input! I am new to 4.6's and know nothing about them. (coming from 5.0 fox bodies)

wolverine8490

Most likely had water sitting in the plug holes. I would not worry about it unless it does it again. If the motor was washed off, this will happen.

red97xj

Awesome, that makes me feel better.

Did you look at pics? That back one was NASTY! My jeep plugs don't get that dirty and I submerge it in creeks! lol

wolverine8490

Yeah, your jeep plugs prolly sit on the outside of the head, so water can not get stuck and short the plug wire out.

Any engine where the plugs are recessed down into the head can have issues if the engine is cleaned off. It also happens when the POS plastic intakes on the 2v's bust and spray coolant everywhere. A lot of the time that is how you find out your leaking coolant, when the engine starts missing.

red97xj

Yep, Jeep has a straight 6. Although it is now a 4.6 stroker (stock is 4.0). It is a torque beast!

Good to know, thanks for the quick replys.

ZeroTX

This is really more or less an issue with this design, I think. On other cars, the coil packs are much wider and sealed with an air-tight gasket and two fasteners. Ours are loosely attached. Not impressed with that design really, but other than some issues like this, they do work fine.

red97xj

Yeah, mine is the cobra 32v and it has a little cover with 2 fastners. Even has a little rubber seal all the way around, but looks like it could leak at the rear where all the COP wires come thru.

Red2002GT

Our mechanic at work will use ungodly amounts of dielectric grease between the plug and coil boots on 4.6's to help cut down with stuff like that.

red97xj

I used a dab on each one, and on the plug for cop.

vargas

i don't recommend you wash your engine with a pressure washer. just keep it clean from now on with a rag and some paint thinner. don't use it on the areas where the thinner will cause things to deteriorate, of course. I get compliments all the time on how clean my engine is. All i used was a rag and elbow grease.

anyway, you can have a leak. i had one due to my intake (97 GT).