jeeper31

Started a previous post about the head being stripped where the spark plug is. Well brought car for gas and started it up and heard a loud bang. Turns out the spark plug was shot out of the engine and put a nice dent in the hood. (Assuming it loosened up) Had to drive home on three cylinders. Need to know did I do anymore damage. Is it as simple as retapping the hole and putting the plug back in?

Please help....

Porsche-O-Phile

I would probably have a shop sleeve a new threaded insert into it, but you'll have to pull the head for it.

Dave951M

Was the plug not fully screwed in or are the threads messed up? If it's the threads, they can be repaired with a helicoil kit. NAPA carries them. I'd advise learning how to use it on something other than the head at first.

jeeper31

Was screwed in but not torqued to specs. How easy/hard is the kit? Did i do any more damage by driving it. How hard to pull the head?

Zero10

Probably didn't do more damage by driving it.
I would advise against doing any work on the spark plug holes with the head still on the car. A few tiny metal filings fall inside the combustion chamber, and you'll score the cylinders.

Pulling the head isn't that bad. On an S it's a little worse than on an 8V, but still can be done in about 2-3 hours. Requires removal of the timing belts, cams, intake and exhaust manifolds.
Now, as for the exhaust manifolds, you can just remove the studs, and leave the manifolds in place. As for the intake, if you detach it from the motor, you can lift it out of the way to get the head off. Saves a lot of disassembly.

Dave951M

Helicoil "can" be done without removing the head, but I still recommend practicing on something else first. I have seen plugs that weren't torqued back most of the way out and then go flying. It may be that only the first couple of turns of the threads are damaged. You may be able to use a tap and just chase the threads to repair them. IF you go that route, I'd recommend putting the piston at the top of it's stroke and put some oily, greasy rag into the bottom of the hole. Then put some grease in the channels on the sides of the tap and slowly engage the threads and just chase them only as far as necessary to get a good thread again.

There's probably no serious damage done if you didn't drive it too much like that. I've seen cases where a plug wasn't torqued in a race engine. Imagine what 12:1 comp can do to an unsecured plug. All we had to do to get back on the track the next day was the tap trick. Saved a head job and lots of hours.

jeeper31

How about reassembly> How difficult. the belts need to be retentioned?

Any good procedural write-ups?

Yabo

www.clarks-garage.com probably has something on removing the head.

Also, To remove the head you have to take off the timing belt. and exhaust manifold. Sorry..

Edit - HEre's the link for removal and installation of the cylinder head via clarks-garage.
http://www.clarks-garage.com/shop-manual/cyl-02.htm

jns

Actually, the Ford F150s have a problem with plugs flying out of the heads because of not enough threads in the head. Do some research on Ford truck enthusiasts and check out their repairs. They are advising against using a helicoil because it will fail. There is a steel insert that's been used and some people are getting those put in with the head still on(you have to pull the F150's body or whole engine out to pull the heads). I don't know if I'd do that with the head on. Look up steel inserts and timesert.com for info. Good luck!

Brett944Cab2

Wurth timesert is a lot better. Many will tell you that Helicoils are worthless. Timesert is not that hard to put in - I did it as a novice. Problem is finding someone with a kit to let you steal one.

Don't know how you'd get the timesert done without taking the head off, though.

Skunk Workz

No problem...the timesert thread cutter for spark plug threads have 2 sizes on it...one to match what's left of your threads (if any..no matter,it guides you straight into the hole anyhow). All you need to do is use some really thick,sticky grease on the tap,work it in by hand about 1-1.5 revolutions,back it out,clean it off to remove alu from the cutter,put new grease on it,do another 1.5 rev's...repeat until breaktrough/touchdown of tool. If you are careful,no chips will enter the cylinder,it will all be stuck to the grease.

Then,bring out a light source,to see if you can see any remaining chips in the grease left in the spark plug hole. Usually there is very little left,most comes out with the tool,but if you use too much grease at the tool,there might be "blobs" there...with possible chips in it. If you see any,use a thin screwdriver without grease...the grease (and the chips) remaining will stick to the dry part of the 'driver.

Then use a clean rag,with solvent on it,to clean off any residual grease in the hole (use a rag that doesn't leave bits of itself...a "tough one"...as you will need to guide it down,and swirl it about with a long screwdriver) , to prevent "lubing" of the insert,making it back out again when you change plugs next time.

Been doing that on a lot of engines...no problems. Problems come when people hurry too much,they forget putting grease on the tap,they do too many revolutions before backing out to clean the tap of chips (which makes the grease and chips in the channels of the tap fall into the cylinder),or they think it will be better using power tools..of which you have no control of what you do in such a procedure.

dmanderson

Dan,
This just occurred to me 2 weeks ago with my 16 valve Jetta. I was able to gingerly thread the plug back in. There was some damage to the top of the threads but it went in. I was unable to get it in all the way, but I was able to drive the 40 miles home. At home, with the engine still warm, the plug went in the rest of the way. The next day I pulled it out to look at it and it came out well. My friend, a VW tech, said the absolute best way to go is to do nothing. I was asking about alternatives, and he said they all can result in problems and if the dealer has to guarantee the work, they replace the head. I put a little antisieze compound on the threads and was actually able to thread it 3/4 of the way in with just my fingers. I do not know if you have tried threading it in, but doing so gingerly should not cause any additional damage. It sure beats pulling the head. Good luck.

Porsche-O-Phile

My concern would be metal falling into the cylinder. Since the head material is aluminum it is non-ferrous and will not be able to be extracted with a magnet. Compressed air might work, but I still say removal of the head is the best way. It's an excuse to change the H.G., clean up the pistons & valves and do those belts anyway.

Brett944Cab2

The plug holes on my S2 are down *deep*. If I remember on a Timesert, there's an adapter that you drive the insert with. If that's not 4+" long, I'm not sure how you would get to the plug threads, much less see what you were doing down in the deep, dark hole.

- excerpt from Unintentionally Sexual Car Repair Posts, 2005 edition

Stan944

It happened to me too, about 2 years ago. I put all 4 new plugs then, and they've been sitting firm since. No damage that I'm aware off, but your case might be different.