Advice wanted on stripped threads

[WI wide body]

I have an '86 Carrera. The 3.2 engine is stock and not used for DE or track. It is a Euro version engine. Has about 78K miles and ran fine. Decided to do a tune-up and found that #6 plug would not tighten properly!

Didn't force it and removed the plug. No trace of metal on it or the old plug.

Removed the valve cover and used a pic (like the dentists use) to determine that there are still threads in there, actually could count about 12 or 13 while sliding the pic from the bottom up. So now I'm thinking that maybe there is a thread insert in there that is slipping. Is that possible? I've found that most of the time when an insert strips it comes out with the bolt or screw...or in this case it should have come out with the plug.

So what are my options and is there a quick and easy way to tighten the insert if that is in fact what's the problem? Or if the original threads are bad can I tap mand install an insert without dropping the engine?

Thanx much.

Ed C

[cgarr]

Stick a magnet down there and that will tell you if it has an insert, if not I would get a thread chaser first. could just be some carbon? and get a mirror and light to see whats down there.

[KTL]

I agree with Craig. Go to the local parts store and get a spark plug thread chaser. If no metal shavings came out on the threads of your plug, I think the threads in the head are gummed up. I recently experienced this on my 2.0L turbo in my Laser. 2 plugs came out nice and smooth and the other two felt like they were stripping the heck out of the threads as I removed them. I patiently put some penetrating lube in the spark plug holes and slowly removed them.

If the threads are indeed bad, it's going to be tough to get a repair insert in there. Especially considering it's cyl. #6 way in the back where space is limited. If there is an insert in there, it should be tightening as you loosen the spark plug, since the inserts are typically left hand threads, no?

[WI wide body]

Thx Craig, that magnet thing should hyave been the first thing I thought of when I suspected an insert. Been retired 11 years and it might be the alzheimers kicking in!!

As for the threads being dirty or carboned up...that still should not prevent the plug from tightening up...I think...unless it's like that magnet thing that I missed.

[WI wide body]

Okay, just checked the #6 plug hole with a magnet and there is not a thread insert in there. So there goes my theory about the insert slipping.

Now, why can I clearly feel the threads in the hole and yet the plug will not tighten??

[dtw]

Originally Posted by WI wide body

Okay, just checked the #6 plug hole with a magnet and there is not a thread insert in there. So there goes my theory about the insert slipping.

Now, why can I clearly feel the threads in the hole and yet the plug will not tighten??

#6? I will bet you a beer it is b/c you haven't actually started the threads. Happens to me on that hole all the time. Pull another plug from a known-good hole, stick your pick down that one, and see if the feel/profile of those threads is the same as your suspect/#6 hole. I bet they are the same.

[KTL]

Oh. I didn't interpret the problem as you couldn't get the plug to tighten. I assumed you were having problems with the plug binding and feeling too tight too soon.

[cgarr]

What does the plug do, go almost all the way in then stop just before it bottoms? or does it just keep spinning and will not tighten?

[WI wide body]

Dave, almost certain that the plug is going into the threads correctly. Removed the valve cover and I can get a pretty shot at getting the correct angle. Plus, I measured the top of the plug in #6 to the valve casting and it was pretty much the same as the other two.

Kevin, the problem is that it will not tighten.

Craig, it appears to be threading in fine when I'm using the hand spinner on top of the extension for the spark plug socket but as soon as I seem to reach the bottom and use a ratchet is slips. Makes no sense to me since the threads really feel good when I check them with the dentist pic.

At least I do know now that the magnet told me there is not an insert spinning in there.

What about using some high temp/high strength threadlocker on the plug threads?

[dtw]

Unless somebody here has tricks for installing timeserts without getting shavings in the combustion chamber, I'd yank the head and do a proper install.

Now of course, with me, that'd end up in a $10k engine rebuild due to "while I'm in there" syndrome, but that's just me...

[WI wide body]

Originally Posted by dtw

Unless somebody here has tricks for installing timeserts without getting shavings in the combustion chamber, I'd yank the head and do a proper install.

Now of course, with me, that'd end up in a $10k engine rebuild due to "while I'm in there" syndrome, but that's just me...

That's exactly what I'm afraid of happening on this deal!!!

[cgarr]

I have installed coils in VW engines before, run them up to TDC and grease up the tap to help hold the cuttings then install the coil, the problem with these heads is that the plug hole is rather deep but with the engine out I bet it could be done, might have to make some special extensions.

[WI wide body]

Originally Posted by WI wide body

Dave, almost certain that the plug is going into the threads correctly. Removed the valve cover and I can get a pretty shot at getting the correct angle. Plus, I measured the top of the plug in #6 to the valve casting and it was pretty much the same as the other two.

Kevin, the problem is that it will not tighten.

Craig, it appears to be threading in fine when I'm using the hand spinner on top of the extension for the spark plug socket but as soon as I seem to reach the bottom and use a ratchet is slips. Makes no sense to me since the threads really feel good when I check them with the dentist pic.

At least I do know now that the magnet told me there is not an insert spinning in there.

What about using some high temp/high strength threadlocker on the plug threads?

Dave, I hate to admit it but you may have been right!!

I was about to ask you exactly how dumb you thought I was per not being able to know if and when the damn plug was even getting started in the threads...but it now appears that may have been a rhetorical question on my part!

Here's what happened, I also didn't think that cleaning up the threads (as Craig auggested) would have any affect on the plug not toghtening (since even dirty threads will not cause it to slip) but I did get a collapsible back-tap and ran it from the bottom up on the threads. Not much, if anything, showed up on the tap or the grease I put on the bottom of the back-tap.

Then I carefully aligned/inserted the plug...just as I had done the first few times...and it screwed in with my finger spiinner wheel just as it had before. but this time it did tighten up when I used the ratchet!

I have no damn clue why it worked this time except that I initially was doing what Dave mentioned.

So unless #6 blows out when I start ip up...this story has a happy ending!!

And I thank all for the advice/suggestions...since if nothing else talking about it prevented me from doing something even dumber on the spur of the moment that might have even caused more problems or been unnecessary.

Dave, I appear to owe you one!

[notmytarga]

Here's MY theory.... When I use the spark plug wrench with the hex handle from my tool kit this happens to me. I think that the adapter is coming off the spark plug when switching to the socket to tighten. I have to push pretty hard to get the 6 point extension to engage because of the rubber inside. This happens on all my plugs but I can imagine #6 being the most challenging and prone to this. Are you using a rubber type spark socket??

Hope all is well and tight now.

[dtw]

Hey man, this is NOT one of those "I told you so" situations. Definitely did not think you were dumb. It is just that me and all my local friends have all been there and done that with #6. In fact I was doing a leakdown test last week on a motor and was utterly shocked, but I got the tester installed in #6 on the 2nd try. Did another motor a couple weeks ago and I simply could not get the damn thing in. Had to come in and do it the next day; I was just getting too pissed and was about to take my hammer and bash something expensive and German.

Anyway - cheers - am real glad to hear you got it squared away. The beer I'll be hoisting soon will be in your honor.

[WI wide body]

Originally Posted by dtw

Hey man, this is NOT one of those "I told you so" situations. Definitely did not think you were dumb. It is just that me and all my local friends have all been there and done that with #6. In fact I was doing a leakdown test last week on a motor and was utterly shocked, but I got the tester installed in #6 on the 2nd try. Did another motor a couple weeks ago and I simply could not get the damn thing in. Had to come in and do it the next day; I was just getting too pissed and was about to take my hammer and bash something expensive and German.

Anyway - cheers - am real glad to hear you got it squared away. The beer I'll be hoisting soon will be in your honor.

Nah, I know what you meant and was just kidding around. It's just embarrassing to miss something that simple. Right after I retired my former company would often ask to me to travel to our foreign factories to help with various mechanical issues since I had been a Mach. Repair Dept. supervisor. They were like paid vacations to places like Germany, Madrid, Bogota, Sydney & Melbourne, Budapest, England, etc etc. I wonder what they would say if they realized I sometimes can't find the damn hole for a spark plug!!!

Anyhow, fired it up after supper and it took off fine. A storm came up so I didn't get it up to temp but I expect no issues.

Got another easy one for you: Does it make any real difference and do you have a preference on how the wires are routed at the top of the distributor?

Naturally I used all the retainers and clips and seperators to keep the wires apart but I changed the way they were packed around the top of the distributor. Any thoughts on this will be welcomed...not as much as I appreciated the #6 thread thing...but still appreciated!!

[dtw]

Yes, I find the engine runs better if you put them in the order of 1, 6, 2, 4, 3, 5. OOOPS kidding again. Nah, as long as the wires are not bound up against each other or against another engine part, they should be fine...

[WI wide body]

Originally Posted by dtw

Yes, I find the engine runs better if you put them in the order of 1, 6, 2, 4, 3, 5. OOOPS kidding again. Nah, as long as the wires are not bound up against each other or against another engine part, they should be fine...

You mean that it's not really 1,2,3,4,5,6?

Hey, for 17 years I lived in Danville, VA right across the border from you and you must know what a challenge to logic that was!

Take care...and thanks again.