RMS Horror -truth or chat room Myth?
Discussion
I have just had a 36,000 mile service on a 03 996 the OPC technician reported that the RMS was swetting so it was replaced FOC under warranty. Usualy for a warranty the invoice goes to PCGB I asked for a copy of this so I would know how much it would have cost if I had had to pay it was a couple of hundred quid(£196)what are people moning about?
As the box was out also fitted a new clutch only £320(I only paid for the parts) all done in 3 days car back shiney and new.Having now actualy experenced this issue I think OPC's are dealing with this issue in a realy pro active way.
As the box was out also fitted a new clutch only £320(I only paid for the parts) all done in 3 days car back shiney and new.Having now actualy experenced this issue I think OPC's are dealing with this issue in a realy pro active way.
lightweight said:
it was a couple of hundred quid(£196)what are people moning about?
1) having to pay for it themselves if the car is out of warranty and 2) the possibility of an engine replacement if the seal is not changed in time.
That might be bollox but as a 993 driver it is AFAIK
GreigM said:
The £196 quoted on the invoice is at internal porsche rates, and your average punter would pay closer to £500.
I may be mistaken but according to my OPC most RMS work that they do is good will or warentee work.I have never been a massive OPC fan but feel from my experiance they are getting it right.
As a punter I think a precautanary clutch change at 36K for £300 and change is fantastic added value I now have a lot more faith in my OPC.
depends on how bad the leak.
i had to have a new clutch, flywheel piston and basically half an engine- and i didint notice any oil loss. same as you it was in for service ( 24k on clock at time). as it was out of warranty i had 2 pay 50% of rebuild which came to 3k. and car was off road for 5 weeks, and i couldnt get a loan car from my opc. not a very happy man at the time
i had to have a new clutch, flywheel piston and basically half an engine- and i didint notice any oil loss. same as you it was in for service ( 24k on clock at time). as it was out of warranty i had 2 pay 50% of rebuild which came to 3k. and car was off road for 5 weeks, and i couldnt get a loan car from my opc. not a very happy man at the time
james_j said:
What people are moaning about is the cause of the seal failure. As I understand the situation, it's not the seal at fault. In particular, multiple seal failures indicate a need for rather more drastic corrective action...
I think you've hit the nail on the head. 993s can also suffer from this failure..according to my 'servicer'...but it is far less common. Something to do with camshafts out-of-alignment?? I'm just crossing my fingers..and everything else!!
The truth is that they leak. The myth is that it is not serious.
The cause of the leak is crankshaft eccentricity, usually as a result of wear in the rear main bearing of the crank. The cause of this appears to be down to flywheel/clutch balance and the offset between the flywheel and the main bearing, whereby any small balance load can have a dramatic effect on bearing life.
My guess is that PCGB are happy to replace seals f.o.c. until the cars are well and truly out of warranty, whereby all the proud owners out there will be faced with a huge bill one day for replacing the engine to cure the actual fault.
I stress that these are my opinions, but I believe that they are shared by many in my trade. Would anyone else like to share a relevant comment?
The cause of the leak is crankshaft eccentricity, usually as a result of wear in the rear main bearing of the crank. The cause of this appears to be down to flywheel/clutch balance and the offset between the flywheel and the main bearing, whereby any small balance load can have a dramatic effect on bearing life.
My guess is that PCGB are happy to replace seals f.o.c. until the cars are well and truly out of warranty, whereby all the proud owners out there will be faced with a huge bill one day for replacing the engine to cure the actual fault.
I stress that these are my opinions, but I believe that they are shared by many in my trade. Would anyone else like to share a relevant comment?
The 993 engine is based on the 964 which evolved from the 911 back in 1964. All these engines have their rear main bearing right next to the flywheel, the main bearings are supported directly in the crankcase and do not have a problem whatsoever with premature RMS failure. They all get the odd RMS leak, but this is a trivial issue usually caused by an aged seal after 100,000 miles, once dealt with it does not fail again for a long, long time.
So why the problemwith the new generation engines? The 986/996 had to be redesigned by Porsche to be cheaper to make, i.e.less time consuming to assemble, in order to cut the cost of making their cars to remain competitive (look at the bottom line profit of Porsche Ag, maybethey went too far?). They probably achieved their goal at a price. Known faults of the new generation engines include:
1. RMS failure
2. Intermediate shaft bearing failure
3. Dropped liners
4. Overheating cylinders (caused by the incorrect use of 100% coolant, not a 50/50 mixture)
5. Variocam actuator failure
6. Breather housing oil leaks
All of these will be engineered out of the cars in due course in the usual efficient Porsche way, but that is no comfort for the owner of a problematic engine out of warranty.
Going back to the RMS, unfortunately the cantilevered flywheel, relatively flexible crank & seperate crank cradle (from the crankcase) all contribute to the problem, induced by wobble on the flywheel end leading to premature rear main bearing wear. I believe that Porsche actually have checking tools for the wear on these bearings now, or at least have a measurement for permissible side play, which should indicate the level of the problem. Some engines suffer more than others, I would hope that later engines are better, but I cannot vouch for that.
Guess what though? The GT3 & GT2 do not have the problem. Why? They both use an evolution of the 993 crankcase & crank design, not the new one because it is not strong enough for racing.
The moral of the saga is that if you want to buy a 996 and not worry about your RMS, buy a GT3.
In my opinion.
So why the problemwith the new generation engines? The 986/996 had to be redesigned by Porsche to be cheaper to make, i.e.less time consuming to assemble, in order to cut the cost of making their cars to remain competitive (look at the bottom line profit of Porsche Ag, maybethey went too far?). They probably achieved their goal at a price. Known faults of the new generation engines include:
1. RMS failure
2. Intermediate shaft bearing failure
3. Dropped liners
4. Overheating cylinders (caused by the incorrect use of 100% coolant, not a 50/50 mixture)
5. Variocam actuator failure
6. Breather housing oil leaks
All of these will be engineered out of the cars in due course in the usual efficient Porsche way, but that is no comfort for the owner of a problematic engine out of warranty.
Going back to the RMS, unfortunately the cantilevered flywheel, relatively flexible crank & seperate crank cradle (from the crankcase) all contribute to the problem, induced by wobble on the flywheel end leading to premature rear main bearing wear. I believe that Porsche actually have checking tools for the wear on these bearings now, or at least have a measurement for permissible side play, which should indicate the level of the problem. Some engines suffer more than others, I would hope that later engines are better, but I cannot vouch for that.
Guess what though? The GT3 & GT2 do not have the problem. Why? They both use an evolution of the 993 crankcase & crank design, not the new one because it is not strong enough for racing.
The moral of the saga is that if you want to buy a 996 and not worry about your RMS, buy a GT3.
In my opinion.
orpheus said:
My 2001 C2 is currently in the OPC having the RMS changed for the second time in 6 months! 
Last time, I was told that I'd need to pay half the labour and the rest would be covered under goodwill, but I only ended up paying for the clutch kit.
I was then told that not having paid anything means there's no warranty on the work (!?) so I'm relying on a second goodwill claim. I've been quoted around £380 for half the labour cost, meaning the full bill would likely be over £800.
This would make me really angry. They have a ckeek don't they? Fancy not giving a warranty on this work! Disgusting.
Let's all get back into pre-1997 911s.
ninemeister said:
Going back to the RMS, unfortunately the cantilevered flywheel, relatively flexible crank & seperate crank cradle (from the crankcase) all contribute to the problem, induced by wobble on the flywheel end leading to premature rear main bearing wear. I believe that Porsche actually have checking tools for the wear on these bearings now, or at least have a measurement for permissible side play, which should indicate the level of the problem. Some engines suffer more than others, I would hope that later engines are better, but I cannot vouch for that.
Guess what though? The GT3 & GT2 do not have the problem. Why? They both use an evolution of the 993 crankcase & crank design, not the new one because it is not strong enough for racing.
The moral of the saga is that if you want to buy a 996 and not worry about your RMS, buy a GT3.
In my opinion.
So Colin how would a 996C4S cope with say 481BHP
Colin in theory is it possible to reduce the problem of the bearing wear you describe by having the flywheel and clutch assembly balanced through appropriate drilling of the flywheel to remove a bit of material in the right places. This is something that was done on my race engine once.
Maybe you can offer to replace peoples RMS and balance the flywhel clutch assembly while it is off.
Maybe you can offer to replace peoples RMS and balance the flywhel clutch assembly while it is off.
paulmc said:
Colin in theory is it possible to reduce the problem of the bearing wear you describe by having the flywheel and clutch assembly balanced through appropriate drilling of the flywheel to remove a bit of material in the right places. This is something that was done on my race engine once.
Maybe you can offer to replace peoples RMS and balance the flywhel clutch assembly while it is off.
I thought the same when reading ninemeister's post on the subject, but it seems too facile a solution to not have been implemented already. I suspect that, even if the flywheel, clutch and crank assembly are perfectly balanced, you'd still get some lateral deflection of the crank at natural harmonic frequencies of the ensemble.
The issue is in the design of the block having the RMS a distance away from the last main bearing, so maybe not really resolvable without major design changes. Silly sods - so many years of engineering excellence behind them and they make a cock-up like this....
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