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It seems like Porsche has been replacing a few rear main oils seals, and if they still leak you get a new motor. This has been going on for years. Prior to the second generation seal they would cut the spring to tighten the sealing lip against the crank or try a 993 seal. At a tech session in April Peter Smith showed us 2 new tools that had just come out for the RMS issue.

In this picture the transmission, clutch and flywheel have been removed. You can see the end of the crankshaft - the holes are for the bolts for the flywheel. The round black thing is the RMS, and you tell from the number of 'dimples' that it is the new style seal. Below the crank is the intermediate shaft. The 3 bolt holes are for the intermediate shaft cover, which is removed in this picture. There is a seal on the cover which can also leak, and a second generation seal for the intermediate shaft.

rear_seal_4.sized.jpg

This a fuzzy picture of a new style seal on the parts counter. This is the seal that went into production in Feburary 2000 and, yes, this seal has not solved all RMS problems as some car with the new style seal also leak. The true problem is with the M96 motor.

seal1.sized.jpg

These are the special tools for the RMS. On the left is the orignial tool used to push in/seat the seal into it's bore. Next is the new tool to seat the seal. The next 2 tools are the same. A go-no-go fixture to determine if the seal bore is concentric to the crankshaft.

seal_tools.sized.jpg

This is the new fixture tool again. The mechanics used to measure with a caliper the distance from the crankshaft to the seal bore in several places to determine if they were concentric to each other. If the variation is .03mm or less you get a replacement seal. If more than .03mm you get a new motor. Now with the new fixture they attempt to slide the tool over the crank and into the seal bore. If the fixture goes in you get a replacement seal. If it does not go in you get a new motor. With the go-no-go fixture the mechanic no longer has to measure with a caliper. Jeff

seal_fixture_tool_001.sized.jpg

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Some more pictures. In the second picture you can see the old and new style seal for the intermediate shaft. The new style seal will not fit on the old intermediate shaft cover, as you can see the seal is wider than the old black O-ring style seal. So to get the new style seal you have to replace the cover. Jeff

rear_seal2.jpg

rear_seal3.sized.jpg

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  • 1 month later...
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I also have a January 1997 that has never leaked from the rear main seal. It seems to be a hit or miss. Some newer cars leak and replacement motors also leak. I think there is something wrong with the M96 design. One day your crank is concentric to the seal and months later after the replacement seal has been installed and it leaks, it is not. Something is moving and until PCNA or PAG lets a mechanic take a motor apart rather ship it back on a pallet....

Peter split the cases on a Boxster and I will try to get his pictures. The new seal installer tool sets the seal farther into the crankcase housing vs. the old tool that set it flush. Time will tell if that is the fix. When I asked Peter why some replacement motors were also leaking he gave a reason, you do not know when the replacement motor was put together. The new seal started production in Feb 2000 but the new tools came out around March 2003.

To answer your question. If it has not leaked for 6 years then you are ok since it would have shown up by now. Any seal will eventually fail from normal wear however.

Peter with his new toys.

tech_session_4_12_056.sized.jpg

tech_session_4_12_057.sized.jpg

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  • 4 weeks later...
  • 3 months later...

toolpants,

Since my RMS just failied and Porsche is going to supply me with a "new" remanufactured engine, I was doing some research on the topic and found your post on the RMS. I must say that this is an excellent description of the seal and the repair process.

:clapping:

In your post, you talk about installing the new RMS with a tool that sets the seal farther into the bore than the original, stock configuration. The reason behind this "deeper" installation is for improved sealing. The RMS is a lip-type radial seal. To accomplish this seal, it must exerts some radial pressure on the crankshaft sealing journal. Over time, the seal wears a small groove into the crankshaft journal. Additionally, the area inboard of the seal (engine side) is "clean" and free from corrosion. So, when you install the new seal deeper into the bore, you are using a "virgin" area of the sealing surface that is also free of dirt, rust, or other surface irregularities.

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  • 5 months later...
I also have a January 1997 that has never leaked from the rear main seal.  It seems to be a hit or miss.  Some newer cars leak and replacement motors also leak.  I think there is something wrong with the M96 design.  One day your crank is concentric to the seal and months later after the replacement seal has been installed and it leaks, it is not.  Something is moving and until PCNA or PAG lets a mechanic take a motor apart rather ship it back on a pallet....

Peter split the cases on a Boxster and I will try to get his pictures.  The new seal installer tool sets the seal farther into the crankcase housing vs. the old tool that set it flush.  Time will tell if that is the fix.  When I asked Peter why some replacement motors were also leaking he gave a reason, you do not know when the replacement motor was put together.  The new seal started production in Feb 2000 but the new tools came out around March 2003.

To answer your question.  If it has not leaked for 6 years then you are ok since it would have shown up by now.  Any seal will eventually fail from normal wear however.

My first S was a Dec 2001 built car. The motor failed completely at 900 miles it was being run in as well, absolutely no harsh treatment. My new car was built in June 2002 (warranty replacement), its going in next week for an RMS (14000 miles).

The interesting thing is you comment about the crank shaft moving around. I have an intermittent problem with the clutch pedal. sometimes its beautifully smooth, other times it feels as if theirs bubbles in the hydraulic fluid, ie sticky uneven. No one seems to be able to give me any clues on this, could they be linked?

Edited by VR6-er
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This may help:

PORSCHE 996 CLUTCH OPERATING LEVER UPDATE

This includes items necessary to update the clutch operation of early 996 Porsches. The purpose of the update was to eliminate the creaking noise commonly heard from the bell housing during clutch operation.

Part # 012 114 719 B – Lever

Part # 012 141 777 B – Ball Pin

Part # 012 141 741 - retainer

Scott

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  • 8 months later...
Some more pictures.  In the second picture you can see the old and new style seal for the intermediate shaft.  The new style seal will not fit on the old intermediate shaft cover, as you can see the seal is wider than the old black O-ring style seal.  So to get the new style seal you have to replace the cover.  Jeff

rear_seal2.jpg

rear_seal3.sized.jpg

Do you have the part number for the new style INS seal?

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Some more pictures.  In the second picture you can see the old and new style seal for the intermediate shaft.  The new style seal will not fit on the old intermediate shaft cover, as you can see the seal is wider than the old black O-ring style seal.  So to get the new style seal you have to replace the cover.  Jeff

rear_seal2.jpg

rear_seal3.sized.jpg

Do you have the part number for the new style INS seal?

996 105 171 56 New style tooth-type chain

996 105 171 55 Old style roller-type chain - no longer available

996 105 901 01 New style intermediate shaft with bearing cover. Includes 996 105 017 01

996 105 015 63 Old style intermediate shaft - no longer available

996 102 011 56 New style crankshaft

996 102 011 57 Old style crankshaft - no longer available

996 105 180 55 New style chain tensioner

996 105 180 54 Old style chain tensioner - still available

996 105 017 01 New intermediate shaft-bearing flange with sealing ring

Old style bearing flange - not available as individual part

999 707 391 40 Old style O-ring - no longer available

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  • 8 months later...
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4th generation seal.

http://www.renntech.org/forums/index.php?showtopic=6175

This time it is a Cayenne style. It comes with the green plastic installation ring shown in the first picture, which protects the sealing lip as the seal is pressed into place. Then the plastic ring is removed. I removed it for the second and third pictures.

What is unique is that there is no spring for the lip. The lip material is very pliable because it is made of a different material. For these reasons I think that is why there is the plastic ring. My pen is pointing to the area of where the spring would be on any other 'normal' oil seal, and where it was on the prior generations.

post-4-1129329662_thumb.jpg

post-4-1129329709_thumb.jpg

post-4-1129329764_thumb.jpg

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  • 2 months later...
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And here it goes in.

1999 Boxster in for the 15k service and the tech sees the oil leak.

The second picture shows the original seal on the left which has been removed from the engine, next to the Cayenne style seal that will be put in. You can see the screw that is put in the back of the seal so that the seal can be pulled out.

The third is the crankshaft with the seal removed and the tech holding the new seal up to it.

The fourth is the tool used to install the seal.

post-4-1134781101_thumb.jpg

post-4-1134782620_thumb.jpg

post-4-1134783555_thumb.jpg

post-4-1134783899_thumb.jpg

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The go-no-go measuring tool has not changed. I was told that they have seen repeat leakers and the tool always fit. So the tool is much to do about nothing. They still measure the crankshaft by hand like was done before the tool came out.

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  • 1 month later...

Just FYI in case you guys missed my threads on this n the 996 section:

My 7th RMS has now stopped leaking all of its own!

The 7th RMS went in Feb last year and shortly after (about 2 weeks) it began to leak again. (Note this is the 3rd generation seal)

With the leaking RMS and after a Major service I drove it 3000 miles to Spain and back to Liverpool UK.

Had no problems but the seal continued to leak. Then aftre I had covered about 6000 miles it suddenly ceased leaking and has not leaked now in a further 5000 miles. I have done 2 oil changes in thet period using Mobil 0/40 and still no leaks.

I still don't trust it though ;)

Edited by Scouser
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  • 3 months later...

Jeff I just read this post of yours from back in Jan. Hahaha.

Well, it is leaking again...well not exactly dripping just sweating this time. But the car still runs great at approaching 55,000 miles. Just did a 660 mile trip to Scrotland yesterday no problems.

It's due to have the 8th seal and "apparently" the one that will fix it forever on Monday. Only time will tell ;)

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