Spark plug tube seal leaks

[Schnell Gelb]

EDIT: The short version is the aftermarket tubes supplied with the engine rebuild kit were under size at the inner end and out of round ! Details 12 posts below.

This is a request for ideas on what mistakes I must have made replacing the spark plug tubes and seals on my 2001 S.Yes. I searched and read lots of posts. I already have both the recommended diy tools for removing the tubes.With googling I found lots of successful installations but little discussion of stupid(me) mistakes !

I fitted all new spark plug tubes and seals when I rebuilt the engine. On an engine stand this is an easy job to do perfectly .Or it should be .

Some of the seals leak.Some don't . The engine has run no more than 1 hour since the rebuild was completed What did I do wrong?

All the tubes are set to the same depth int the camshaft cover.None are loose.In fact they are very tight and will be difficult to remove - the 0.90" washer+long bolt tool will help.The tubes are too tight for the transom plug tool to work.

The worst leak is not sufficient to get past the seals on the coil - yet. The inside of the worst tube has a thick coating of oil after no more than 1 hour running time since rebuild.

I know that (silicone)sealant is not recommended but read that some people do use  sealer on the  seals. They use 'sensor-safe" sealant a.k.a 'Form In Place Gasket" or Hardex. Good idea?

The vulnerable seal seems to be the smallest one Part # 999-707-343-41.The large ,orange seal at the outer end of the tube  is part # 999-707-25-40 and seems less likely to leak ? There is no significant pressure in the crankcase . So what is forcing the oil out ? Just a poorly seated seal allowing surface tension and gravity to leak?

Specifically what sealer is recommended for tube seals that won't otherwise seal? Permatex black Ultra? Drei bond?

I know if sealant is applied, only a very thin coating on the seal should be used. There are cautionary  comments on  excessive amounts of sealer drop off into the engine.

I'll pull the tubes and buy new seals but need to learn from your suggestions on how to avoid getting more leaks before I waste more parts and time.

Thank you for your ideas an help.

Interesting to note that this tube design was upgraded for the 2004 model.

 

 

Edited March 17, 2017 by Schnell Gelb

[JFP in PA]

We use a dielectric silicone grease on plug tube seals.  Some simply use engine oil, but in any case you need to make sure they are lubricated as they can be pretty easy to dislodge when installing the tubes.  You should never use any type of sealant on these O-rings.

[Schnell Gelb]

I'll translate for others.JFP is being polite and gentle with his assessment of my mechanical work.

I suspect that lubed or not I must have failed to seat the small,inner seal correctly. So they all must be removed and start over with new,new seals.

Interesting that you can use dielectric silicone grease but not silicone(or other) sealant. I emphasize this point because there is a lot of mention of using Permatex Ultra grey or black on the Internet but with other engines that have threaded metal spark plug tubes (Toyota for example).

Thanks for your kind and speedy response JFP.

Edited March 15, 2017 by Schnell Gelb

[JFP in PA]

Silicone grease is extremely slippery and allows O-ring seals to slip into their groove recesses without getting pinched or cut in the process.  Silicone sealant on the other hand is very tacky, transfers to whatever it touches, and then dries to form a bond to what ever it touched, so if you get an O-ring pinched or out of position in its mating grooves (which is actually easier to do when using the tacky sealant) it will not only leak, but is now adhered to the components.  So when it does leak, you now have a bigger headache trying to clean up the mating surfaces before putting new replacement parts in.  Often, this entails removing the cam covers, which is not a lot of fun with the engine still in the car.

 

The small inner O-ring on the plug tube (the black one in the photo) has to pop into a machined recess in the cylinder head without getting cut or coming out of the groove on the tube in order to form an oil tight seal, so lubrication is the key.  The larger O-ring is less prone to pop out of place, but also benefits from lubrication as well.  The entire process is to install the rings onto the tube dry, then apply a thin coating of silicone grease to the outside of the O-rings.  The tube will go right into place with minimal effort and the rings will form an oil tight seal.  And then it is Miller time.......................

 

 

And before anyone asks, the lower tool is the factory item for extracting the tubes.

[Schnell Gelb]

Thank you for the details JFP. I appreciate you taking the time to share with us gems that must have been hard-won. These gems certainly do not appear in Bentley or the FSM !

Tool - I used the all-thread+ custom sized washer technique.It was not elegant. Prying on the end of the hack tool is not very controlled use of force in a rather confined space.  An upgrade to the tool I used would be to insert the end of the thread through a large(42mm) socket, then attach a washer+nut. Tighten the nut to progressively extract the tube. Must be something wrong with this simple idea to modify  the much discussed bolt+washer tool - or someone else would have proposed it long ago ?

The new large orange seals on my new tubes had already begun to enlarge. they were no longer tight in the groove on the tube. Yes they came as part of a rebuild kit with which I have already had a similar problem (Heat Exchanger leak).

The spark plug tube seal dimensions are a puzzle. On the Pelican site they give seemingly odd measurements for their Victor Reinz seals. Maybe that is their trick part? Use a smaller internal diameter but thicker seal so it fits tighter but has the same effective o.d. when stretched into place in the groove on the tube? I am not doubting their measurements - just noting they seem odd when spec'd to 2 decimal spaces in mm .Certainly not  generic 'o' ring sizes

Outer Spark Plug Tube O-Ring, 27.94 X 5.33

Inner Spark Plug Tube O-Ring, 25.07 X 2.62

Here is a link to their page: http://www.pelicanparts.com/catalog/SuperCat/1048/POR_1048_ELIGNT_pg1.htm#item3

For those searching for Renntech  threads on this subject - I found lots in the 996 Section that also apply to the Boxster in general terms.

Edited March 15, 2017 by Schnell Gelb

[JFP in PA]

I just did a quick check of the PET, and Porsche agrees with the dimensions Pelican lists, but Porsche also lists two different inner and outer O-rings depending upon the year and model of the engine (3.2 vs. 2.7L), which usually means there is something different.  Pelican is well known for listing parts that almost fit, either because they are aftermarket or just listed incorrectly, which is why over the years we have purchased very little from them.  We get our plug tube O-rings direct from Porsche, and they fit correctly.

[Schnell Gelb]

How many of the "leaking spark plug tube seal" complaints are caused by fitting the 3,2 seals  to a 2.7 and vice versa,I wonder? Or out of spec seals.

The vehicle is a 2001 S., so 3,2l engine.This is the appropriate Pelican page:http://www.pelicanparts.com/catalog/SuperCat/1048/POR_1048_ELIGNT_pg1.htm#item3

Pelican lists the same part number & dimensions a for a 2001, 2.7l engine. I mention this to alert others to a potential problem.Pelican sell both an aftermarket product(Victor Reinz) and a Porsche part.

To help others follow JFP's advice, the PET reference to the seals and tube  I just found is :

Page 001, KAT 20, UPD 248, Illustration # 103-00. The Position numbers are 28 and 29.

The part numbers I found are below but please verify.  I have noted in brackets the dimension of the groove each seal fits into on the tubes- so you can see how much each 'o' ring is stretched when new. My large O rings were a sloppy fit after less than 1 hour run time ! The inner seals were tight but possibly too thin. Sunset Porsche time!

999 707 343 40 (inner) 25,07 x 2.62mm  - (27mm)

999 707 215 40 (outer) 27.94 x 5.33mm  - ( 29mm)

Here is a link to Sunset Porsche at which you can use your Renntech Member discount(must donate to Renntech to get this member benefit/discount).

http://www.sunsetporscheparts.com/porsche/911/99970734341/2002-year/gt2-trim/3-6l-h6-gas-engine/engine-cat/engine-parts-scat/?part_name=flange-o-ring

I hope this helps others avoid the waste of time and money I incurred.Thanks to JFP for supplying all the missing knowledge.

Edited March 15, 2017 by Schnell Gelb

[SpawnyWhippet]

I also did this and got the upgraded Beru coil packs with larger heads. I used a 1" boat transom plug off ebay for $5 to pull the oil tubes and replaced all the o rings.

 

The whole job, including the correct OEM Beru coil packs, spark plugs, oil plug tube tool and o rings (all off Amazon or ebay) cost 30% less than the Porsche dealer was going to charge just to sell me the coil packs (no labor or tax!)

 

[Schnell Gelb]

If the seals are new (like mine) or have sealant on them, it may be impossible to remove the tubes with the transom plug. I had to use the 'bolt+washer" tool because the outer orange seal was so tight. If you crank up the transom plug too much with brittle tubes ,they may break.Then you have the anxiety of extracting all the broken plastic .

Some have mentioned that the 1" transom pug was too small in diameter. Wrapping it with sandpaper is reported to be helpful.

The washer+bolt method is not mine. The first diy guide+photos I noticed was in a post by Healthservices here:

http://986forum.com/forums/diy-project-guides/52150-spark-plug-tubes.html

Edited March 16, 2017 by Schnell Gelb

[JFP in PA]

These also work pretty well:

 

[Schnell Gelb]

Ah yes, Battery terminal spreaders.

[Ddavidoff]

+1 on the washer bolt method. Worked well for me.


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[Schnell Gelb]

I now have 3 sets of spark plug tubes and seals. So I measured them all carefully to identify the cause of the leakage. The leaking tube+seal combo is under-size and out of round at the inner end. The groove in the leaking tubes measured 26.45mm at the inner end - over 0.5mm smaller than the OEM item.Obviously this measurement varies according to the location in the groove you choose because it is out of round ! It is somewhat oval in cross section and fits into a perfectly round hole in the camshaft cover! No amount of seal swapping could have corrected these 2 defects at the inner end of the leaking  aftermarket spark plug tubes.

At the outer end, the groove was oversized by an even larger amount. No wonder I had a hard time removing the tubes !

Just buy from Sunset !

Edited March 17, 2017 by Schnell Gelb

[JFP in PA]

You always need to be careful where you source parts for these cars; cheap parts rarely end up being good choices, and some vendors are well known for pushing aftermarket stuff as being "OEM" when it really isn't.

[Schnell Gelb]

For what I spent on this one simple issue I could have bought at full retail from the local Porsche dealer several times over ! And not to mention the time .

Hopefully others will benefit from my experience and measurements- if the tubes are under-size and out of round there is no seal  that will work ! Utterly useless parts .

Edited March 17, 2017 by Schnell Gelb

[mikefocke]

Might want to mention what the kit name, SKU, source was to prevent others from getting the same improper parts.

[Schnell Gelb]

Thanks Mike, As I suggested previously " Just buy from Sunset ! " Just phone them .Give the VIN & No problems.

The difficulties began with Interchange/crossover numbers.Same story with Heat Exchanger seals and O2 sensors.

[Keither32]

I have  2014 Boxster S and I've noticed a slight smell of burning oil. Thinking it might be a spark plug tube leaking. Since the car is still under warranty I'll take it to the dealer for an oil change. 

If it is a tube leaking will warranty cover that? Only 8500 miles on car.

[Loren]

1 hour ago, Keither32 said:

I have  2014 Boxster S and I've noticed a slight smell of burning oil. Thinking it might be a spark plug tube leaking. Since the car is still under warranty I'll take it to the dealer for an oil change. 

If it is a tube leaking will warranty cover that? Only 8500 miles on car.

 

Your 981 engine is very different from the early Boxsters. The good news is design is such that you do not have oil tubes.

The bad news is that your leak is likely elsewhere.

[Keither32]

54 minutes ago, Loren said:

 

Your 981 engine is very different from the early Boxsters. The good news is design is such that you do not have oil tubes.

The bad news is that your leak is likely elsewhere.

 

Thank you Loren for the quick reply.

I have an appointment at the dealer this Tuesday, guess I'll find out then.

 

I'm doing an edit. Found out that the smell is normal on the 981 and other models.  There are no leaks that I can see.  My 986 had a similar smell and that lead me to believe I had a leak.

 

Any recommendations for a service manual for the 981 Boxster?  I've seen a few links for online downloads.

 

Thanks again,

 

Keith

Edited April 2, 2017 by Keither32
add info