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Replacing Spark Plug Tube


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Just got done with my spark plug change and noticed some oil in one of the spark plug tubes. From some digging around, it sounds like its either an o-ring or the tube itself so I'm planning on just replacing the whole thing. What is a good way to do this? Is it possible to just pull the tube out and just replacing an o-ring if that's all it is? I noticed on Pelican Parts they also tell you to use the Porsche grease. What do I grease and is there a similar common grease that doesn't cost $38, which is way more than the parts to fix it?

Any suggestions much appreciated. It's a 99 996 with 90,500 miles.

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Just got done with my spark plug change and noticed some oil in one of the spark plug tubes. From some digging around, it sounds like its either an o-ring or the tube itself so I'm planning on just replacing the whole thing. What is a good way to do this? Is it possible to just pull the tube out and just replacing an o-ring if that's all it is? I noticed on Pelican Parts they also tell you to use the Porsche grease. What do I grease and is there a similar common grease that doesn't cost $38, which is way more than the parts to fix it?

Any suggestions much appreciated. It's a 99 996 with 90,500 miles.

The grease is just to protect the o-rings while the tube is being reinstalled. In reality, just about any lubricant will work. Unless the tube is damaged, all you need is new o-rings. To pull the tubes, Porsche makes a ridiculously expensive tool, or you can use a $1 expanding one inch (2.54cm) transom plug that you can find a any boat yard............ Works like a charm.......

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Edited by JFP in PA
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The factory workshop manual reccommends that the engine be warm when you change the tubes out. Either by driving it or heating it up. Does anyone know what the factory grease is? ie silicone, etc?

It appears to be silicone, but as I said, just about any lubricant will work as it is only used to help keep the o-rings in place while replacing the tubes. In a pinch, we have used use motor oil and have never had a problem.

Warming the engine helps get stuck tubes out if they are really balky.......usually, they just pop right out.

Edited by JFP in PA
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Let me start off by stating this is the first time I have worked on a Porsche. Most of my wrenching has been done on Alfa's and BMW's. I am impressed with this Porsches engine layout. I thought it would be much worse than it has been. When you peek under the car or look in the engine compartment it looks like 10 lbs of Sh*t stuffed in a 5 lb sack!! But I am not impressed with this stupid spark plug tube. They had to know when they concocted this design it would leak.

I too am in the process of doing the 60K service on my 1999 C2 Cab which includes replacement of the spark plugs. Because I read here on Renntech that the spark plug tubes often leak and possibly crack I also ordered 6 new tubes and all new seals. I have only done the passenger side, and discovered that 2 of the 3 seals were deformed and leaking oil. Those deformed seals must have become deformed by Otto when he popped them in the motor in Stuttgart. There is no way they could break and creep like that with time. I used a synthetic grease to lube them up and they easily popped right in.

Of note, the spark plugs I found in my motor were Bosch, not Beru. I ordered new Bosch ones from Pelican.

I went to West Marine who is a marine retailer to locate the T handle rubber expanding transom plug. The plug was $6. The 1" (25.4mm) plug was too small. The spark plug tube is 26.3mm dia. Even when I screwed the plug in as tight as I could get it, the plug wouldn't expand large enough to fit tight inside the tube. So I ended up buying a 1-1/4" plug and trimmed it down to fit. I used razor blades and a peanut grinder with a wire wheel to shape the plug. The reshaped plug worked perfectly and easily pulled the tubes out.

You will note from the pictures how oily everything was. (My first clue my O rings had failed!) Despite this, the car never leaked oil on the ground or used oil. The tube leak was probably contained mostly by the outer seal. Although some did seep past. The tubes were full of oil, even on the one good seal.

It took 3 cans of carb cleaner on the passenger side, and one can of electrical contact cleaner to clean up the 3 coil packs and plugs. I presprayed with an engine degreaser and let sit overnight before I cleaned with the carb cleaner. It looks much better. All of the coil packs were fine and had no cracks.

Some people have noted it helps to remove the muffflers. ABSOLUTELY. I don't see how you can do this job otherwise. At least not with normal sized hands. Plus I didn't want to take any chances with the tube removal, spark plug threading and replacement of the coil packs. Considering how easy it is to drop the muffflers it's a no brainer. Most of these pics are the passenger side which is the "easy" side. The drivers side is worse. I started on the drivers side and gave up, then moved to the passenger side. That's tonight.

To remove the muffler you need to loosen the two 19mm bolts on the round cat to muffler clamp. Push the clamp towards the cat side until the clamp is flush with the end of the pipe. Then there are 3 nuts which have to be removed from the plate which is attached to the bracket with the 4 pipe supports. The muffler is free at this point. You need to remove the rear tire too because the muffler slides forward and then down. I didn't know what I was doing, so I also removed the 2 very long bolts which bolt the muffler to the bracket, but in hindsight I don't think I needed to do that. That's it and then you have excellent access.

Picture "tube 2" shows the support plate with the 3 holes that have the three nuts which have to be removed to seperate the muffler from the support bracket. Picture "tube 3" shows the muffler bracket before I removed the muffler with one of the two long bolts, that I don't think I needed to remove.

Lastly, despite the warnings against using anti seize, I lightly used it. I have 30 years of experience (weekend warrior) of working on all aluminum engines, and I have never once had a problem with anti seize. I use the gold Lubro Moly brand and am careful when I torque fasteners. When I replace these plugs next time, I know they won't be seized and will screw out safely. It makes no sense to me to not use anti seize on a spark plug. When water, aluminum and steel are connected together it makes sense to me to use anti seize.

All this work was done on a cold motor, not a warm one as suggested by PAG in the workshop manual.

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Edited by Cefalu
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Great write up and great pics. So nice to see that clean engine. Hope you got the other side done.

cheers.gif

Wish me luck, tonight I do the drivers side. I hope all I find are bad seals and not cracked tubes where pieces are missing! I read a post where someone had a tube that cracked and they left a chunk of plastic in the motor.

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Great write up and great pics. So nice to see that clean engine. Hope you got the other side done.

:cheers:

Wish me luck, tonight I do the drivers side. I hope all I find are bad seals and not cracked tubes where pieces are missing! I read a post where someone had a tube that cracked and they left a chunk of plastic in the motor.

That was a great post. Wish you'd have made it last week before I did MY plugs! :)(I pulled Berus out and replaced them with Bosch)

I managed to do the job without taking anything off but next time I have to get in there, I'll pull this up do it your way. What really helped me was cutting a small piece of allen wrench to hand spin the coil bolts off after I loosened them. Made things much easier but probably not as easy as your way.

Just pulled my tube tonight and found a kinked front O-ring was the culprit (looks like yours). My Wal-Mart boat plug worked perfectly after I made sure it was tight in the tube. Fortunately I only needed to repair one tube. How are your spark plug connectors? The one in my leaky tube was shot and also had to be replaced. I'm guessing being exposed to hot oil for who knows how long didn't help its longevity.

Good luck!:cheers:

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No drama finishing up. beerchug.gifbeerchug.gif

You are crazy if you don't take the exhaust off to do this job. In fact I would warn any one who is considering doing this job for the first time that you need to drop the exhaust so you can see what the heck you are doing. otherwise, 3 of the 6 spark plugs you will be doing by feel.

If I were only changing the spark plugs, I might be tempted to leave the exhaust in place now that I have this job under my belt. But for those of you who have engines with tubes and O rings, you should R&R the O rings when you replace the spark plugs anyway. They are going to leak with time, and it makes a mess. I used 1 can of engine cleaner, 6 cans of carb cleaner and one can of electrical contact cleaner to clean up the oily mess.

The exhaust takes 5 minutes to drop and 5 minutes to install on each side. 10 easily accessesd nuts total. You will drive yourself insane trying to R&R the upper allen screws of the coil packs with the exhaust in place. It will also be very difficult to pop the tubes and spark plugs in and out working with little light or hand space.

What I found interesting was 4 of 6 inner O rings were pinched when the motor was built. If you look at the pictures below, every drivers side O ring was pinched out of place when the motor was built. You will also note that the pinch was at the bottom of the tube every time. AND the part number lines up with the pinch. For whatever reason, they installed the tube so the part number was facing down. One O ring was totally cut, and one looked fine. 5 of 6 failed.

NOTE: the green O rings are a new PAG part # that superseded the orange ones installed at the factory.

You need to be very careful when you connect the plug to the coil pack. Its not an easy fit. It takes some massaging and you need to hear the "click" to confirm the plug properly connected to the coil pack. Very hard to do with the mufflers in place. Since this was my first coil pack R&R, I wanted a visual confirmation as well, and you can't do that with the mufflers in place.

With the spark plug tubes removed I was able to see what the inside of the head looked like, and I was very happy. Totally clean and looked excellent for a 57K miles motor.

Tomorrow night I put the plastic cover back on the bottom of the car, replace the serpentine belt and my 60K service is done.

Ho finito

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All my spark plug connectors and coil packs were fine. I cleaned them up with throttle body cleaner and they looked great so they all went back in. I replaced the tubes and O rings as a matter of precaution. I didn't want to go through this again because I tried to save $1.50 on an O ring. I had also heard that the tubes sometimes crack so I replaced all of them also. In hindsight, my tubes looked fine and I probably didn't need to replace them.

I wanted to see how well the O rings seated after I installed a new tube, so I tried to pull a tube out with the boat plug contraption. It just slipped and I couldn't get the tube out. So I hope that meant I had a good seal. I was also very careful to apply even pressure on the tube when I installed them so I wouldnt get the O ring pinched when they went back in.

The coil packs are held in place with 5mm allen head bolts. A normal 5mm allen socket is too long to fit on 3 of them. I also cut a 1/2" long piece of allen wrench off and inserted it in a 5mm 1/4" drive socket with a wobble extension to get at the upper coil pack bolts. I used a low profile stubby 1/4" ratchet. That combo worket just fine. To break them loose I used the typical angled allen wrench.

1/4" drive sockets/ratchets/extensions and the 5/8" magnetic spark plug socket I picked up for $6 on eBay were key to working in the tight space. No duct tape required as I have heard others use. I used wobble socket extensions instead of universals in the crooked connections. Pelican advertises a german made magnetic 13/16" socket for the 996's for $50, but the plugs are 5/8". Go for the $6 5/8" magnetic eBay one.

And the three nuts on the muffler bracket go really speedy if you have an air ratchet to screw/unscrew. I had no trouble at all with the two 17mm nuts on the clamping sleeve once I shot them with liquid wrench and let them sit overnight. The mufflers were a breeze to drop.

This won't be a bad job next time.

Edited by Cefalu
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  • 1 month later...
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Question. Are the tubes normally holding oil back in the engine? If you were to take the tubes out, without first having drained the engine of oil, would oil pour out the spark plug holes?

The tubes are oil returns - so if you let the car sit a few minutes most of the oil should be back in the crankcase. Maybe a few drips but oil will not gush out.

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  • 3 years later...

I am doing the tube seals on my 996 c2 3.4l at the moment. A have a few tips that might help. I used a small piece of a bycycle tire inner tube over the 1" boat bung. Works great.

Also because of the lack of space to tighten the bung properly on aft most plug tube, I cut a slot in a 1/4 drive socket that slips over bung handle to be able to tighten it properly. Hope this helps

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