OCBen

Oh, I never called him that. His posts speak for themselves. I just wanted to give you a heads-up in case you thought you were dealing with someone on your level.

Btw, thanks for going through the trouble of putting together your informative posts complete with photos. I'm sure there are many here who will appreciate it. Maybe 99firehawk can post similar pics of a 3.8L 997 engine, if he feels like going through as much trouble you did.

Are you a Porsche technician as well? Just curious about your 'technical guru' avatar tag.

MMD

Right. The idea is to mate the crankshaft to the crankcase for concentricity as far as the seal seat is concerned and the problem of RMS failure would be solved. It's too expensive and you say complicated (apparently) for Porsche to do this.

MMD

Absolutely GLAD to have my posts speak for themselves.

Which level are we talking about? I know you (and I and 99% of the people on this board) would never be hired at Porsche as engineers.

Talking about the amateur/hobbiest level? That's great! I'm absolutely glad to have my posts speak for themselves..., get it? Nice how you jump in from nowhere and start trashing anything I say; you don't even have corrections or a counter argument!

Quit harassing me.

BTW, just for fun: I like your "level" in your post where you agrue against the use of jackstands saying us$20 Chinese-made wheel ramps are sufficient for working under the car. LOL

cdodkin

Interesting....

Apparently, buying a newer Porsche (997) doesn't automatically make you the sort of individual who can hold a civilized conversation!

Either way - for those of you still basking in the greater Porsche glow, believing that they have your best interests at heart rather than profit margins - sorry to burst your bubble.

Your 997 has the same basic issues as the 996 & 986 when it comes to RMS - namely that the design leaves the engine prone to developing RMS and IMS leaks over time.

Newer RMS seals make this happen less frequently, but the issue is still there - time will tell how many are eventually effected as the 997 power plant ages.

It's cheap enough for Porsche to fix under warranty, rather than re-design the engine, or do a complete recall of existing units in the field.

As for the rest of the mud-slinging cr@p - sort yourself out kids - each side is as bad as the other - in fact, you're probably more similar than you'd care to admit, and that's why you keep on at each other ad nauseam.

OCBen

Here's a perfect opportunity to let your posts speak for themselves.

Show me where I have ever proclaimed myself 997 Forum leader and I will gladly paypal you $100.00. Should be pretty easy for you if you are in the habit of speaking the truth. But if you were lying again this will prove to the thousands here that you indeed are in the habit of posting misinformation, and shouldn't be trusted. And this little challenge will be an excellent proof of that.

What happened at that favorite forum of yours? Did they finally catch on to you?

JasonAndreas

That just means I have access to a large library of reference material, a digital camera and lots of spare time.

Its not (that I think its) too complicated or expensive. When Porsche (I'm not sure if Kolbenschmidt is now responsible for the machining operations on the M97 like they are with the Cayenne engine block) machine the opening and then install the crankshaft, it is concentric to the opening at least to whatever DIN tolerance they spec. If it wasn't the RMS would leak a lot sooner (like on the engine dyno.) So if after X miles you have oil leaking past the RMS because the crankshaft is no longer concentric to the opening then something has moved? And no amount of machine work performed by the factory on that opening is going to fix the problem.

cdodkin

Jason,

I believe that the issue of concentric opening is only a small part of the RMS issue - specifically the feature that has lead to engine replacements under warranty.

The vast majority of RMS issues have occurred where seals have either worn on the crank, or the crank has sat in one offset position for a long time causing deformation of the seal, and hence a leak. (People who don't drive their cars often!)

It's the lack of support of the long shaft at this point that leaves 997, 996 and 986 engines prone to some eccentric movement of the shaft, and hence excessive wear and/or distortion of the seal.

New seals are more elastic, and hence seem to adjust to the variations without leaking as often.

JasonAndreas

I was thinking of these problems as being in the minority? Both are the cause of RMS leaks on other engines but at no where near the same frequency as what the M96 experienced. And Porsche has used the same style & material RMS for many iterations of 911 going back many years and not experienced leaks to the same magnitude. If this was the main reason for the M96 leak the other engines would have experienced something similar? You see these types of leaks on the GT3 and TT but they only happen occasionally.

The new seals are made from PTFE so as they heat up the inner lip will try to flatten out (plastic memory) and tighten the seal against the crankshaft. That is why they no longer need the tensioning spring used by the previous style RMS.

Crazy Canuck

cdodkin

Only the M96 engine onwards has this issue, as this is a design issue with the long unsupported shaft that simply didn't exist in the earlier engines.

996 TT and GT3 use the older 'watercooled' design bottom end, and hence dodge the RMS bullet.

So the RMS stayed the same, but the engine design changed - and the RMS was no longer up to the job.

Hence the development during the life of the 996 of the 997 model PTFE seal as you mention.

The problem with RMS is that it has more than one cause, and the ones that got attention were the ones that required engine replacements.

These are I believe the minority - the majority of RMS replacements are simply seal swaps, where the shaft has worn the old seal, or deformed it, leading to eventual oil leakage.

This does not require that you replace the engine - in fact it's mostly a cosmetic issue, with little actual negative effect on the car, other than slight oil loss.

Crazy Canuck

There are many examples of GT3s which have suffered from RMS.

cdodkin

Interesting - search for rms fail in the 996 GT2/GT3 forum - you get two hits, non of which are rms failures

Do the same in the 996 forum, you get 85 hits.

That tell you anything?

The 996 GT3 cars use a 964 derived crank case so they don’t suffer the same probs as the later designed 986 (boxster ) & 996 cases & cranks,
i.e. they use the earlier designed conventional rotary seal not the hard plastic RMS which fails.

So the very very few RMS failures in these cars should not be confused with the general 996/986 RMS failures.

It's not the same deal, not the same part, not the same issue.

AllanJ

Mine has an RMS issue - just not bad enough yet for a warranty replacement. It'll probably start leaking when my warranty is up.

PTEC

I still don't get why people **** the bed when they see a 997 with an RMS leak. Early cars were fitted with the old seal, fact. Another fact is the new seal is much, much improved so just take the thing in and have it fixed.

JasonAndreas

I know we will never know the exact number but there were so many that required multiple repair jobs (still to this day) that it rules out the seal as being the main source of the problem.

The thing is the sealing area really didn't change but one major thing that did was the separation of the bearing support/gear carrier from the crankcase.

What part of the M96 crankshaft is unsupported? The M64 and M96/M97 both have seven bearing supports with nearly exactly the same spacing and support widths.

Force of habit. People automatically assume all M97 based engines have the newer style seals but they don't and not everyone knows that?