RMS may be back 997 GT3
06-05-2008, 01:10 PM
#46
The RSs seem to be similarly affected -- my RS started leaking at 1700 miles or so -- the original fix (performed December 2007) didn't work, and it started leaking again 300 miles later (or so). I just had the "new" fix performed last week. Having close to 50% of all GT3s and GT3RSs leaking is shocking indeed.
06-05-2008, 01:41 PM
#47
I received a response from a reputable Porsche technical resource regarding RMS leak issues. He points to crank case pressure as a likely cause of oil leaks even if the RMS is properly installed. This issue was discussed on previous posts. It seems that even a properly installed RMS can not hold back oil if the crank case pressure is excessive. I am no expert but here are the comments:
The GT-3 case is really a modified 993 engine case with water cooled cylinders and heads. These were generally leak-free. If the engines are assembled incorrectly, they can leak but this would be the exception rather than the norm. If the crankcase pressure builds up enough without relief, the pressure can force oil past the seal, even if it is good. . The breather lines and oil/air separators must be checked for ventilation.
Hope the above comments help, I am not sure how the pressure is suppose to be reduced but it sounds like an option that should be addressed.
The GT-3 case is really a modified 993 engine case with water cooled cylinders and heads. These were generally leak-free. If the engines are assembled incorrectly, they can leak but this would be the exception rather than the norm. If the crankcase pressure builds up enough without relief, the pressure can force oil past the seal, even if it is good. . The breather lines and oil/air separators must be checked for ventilation.
Hope the above comments help, I am not sure how the pressure is suppose to be reduced but it sounds like an option that should be addressed.
06-05-2008, 03:31 PM
#48
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I received a response from a reputable Porsche technical resource regarding RMS leak issues. He points to crank case pressure as a likely cause of oil leaks even if the RMS is properly installed. This issue was discussed on previous posts. It seems that even a properly installed RMS can not hold back oil if the crank case pressure is excessive. I am no expert but here are the comments:
The GT-3 case is really a modified 993 engine case with water cooled cylinders and heads. These were generally leak-free. If the engines are assembled incorrectly, they can leak but this would be the exception rather than the norm. If the crankcase pressure builds up enough without relief, the pressure can force oil past the seal, even if it is good. . The breather lines and oil/air separators must be checked for ventilation.
Hope the above comments help, I am not sure how the pressure is suppose to be reduced but it sounds like an option that should be addressed.
The GT-3 case is really a modified 993 engine case with water cooled cylinders and heads. These were generally leak-free. If the engines are assembled incorrectly, they can leak but this would be the exception rather than the norm. If the crankcase pressure builds up enough without relief, the pressure can force oil past the seal, even if it is good. . The breather lines and oil/air separators must be checked for ventilation.
Hope the above comments help, I am not sure how the pressure is suppose to be reduced but it sounds like an option that should be addressed.
06-05-2008, 11:26 PM
#49
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hey f4pilot, dan gave me the mesage you called. Will try you tomorrow to catch up.. Either way doesn't seem like fun;( I'd still get them to try the 996gt3 one. I know it has a better seal for sure.
06-06-2008, 12:18 AM
#50
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The crankcase is not a 993 part, they had 964 part numbers through, I believe, mid-996 GT3 production and are now essentially the same casting but with a 996 or 997 part number. 993s and 964s run at similarly "high" oil pressures and do not see this issue with any sort of regularity.
Last edited by WHB Porsche; 06-06-2008 at 01:13 AM.
06-06-2008, 01:06 AM
#51
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Actually, my understanding is that it's the gt1 racing derrivitive of the 964 block with water jackets for cooling, at least in the heads. Later used in the 996tt, 996gt3, etc. The 993/993tt block is more of the pure 964 version, unlike the gt1 racing counterpart that required more cooling for higher hp.
Nonetheless, always wondered why one almost never sees this phenomina in the turbo engines, I would think, if anything, it would be more prevalent.
Nonetheless, always wondered why one almost never sees this phenomina in the turbo engines, I would think, if anything, it would be more prevalent.
06-06-2008, 01:15 AM
#52
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Actually, my understanding is that it's the gt1 racing derrivitive of the 964 block with water jackets for cooling, at least in the heads. Later used in the 996tt, 996gt3, etc. The 993/993tt block is more of the pure 964 version, unlike the gt1 racing counterpart that required more cooling for higher hp.
Nonetheless, always wondered why one almost never sees this phenomina in the turbo engines, I would think, if anything, it would be more prevalent.
Nonetheless, always wondered why one almost never sees this phenomina in the turbo engines, I would think, if anything, it would be more prevalent.
06-07-2008, 05:40 PM
#54
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https://rennlist.com/forums/993-forum/435236-new-porsche-two-piece-crankcase.html
And the Wikipedia entry on GT3:
http://en.wikipedia.org/wiki/Porsche_911_GT3
In GT3 configuration, this so called "split" crankcase (meaning the parting line of crankcase is on the crankshaft centerline) uses, instead of a fan and finned cylinders, separate water jackets added onto each side of the crankcase to cool banks of 3 cylinders with water pumped though a radiator. Thus, the GT3 engine is very similar to the completely water cooled 962 racing car's engine, which is also based on this same crankcase. The 962 differs, however, by using 6 individual cylinder heads while the GT1/GT3, like the air and water cooled Porsche 959, uses 2 cylinder heads, each covering a bank of 3 cylinders. The GT3 engine could thus also be thought of as similar to a 959 engine, but with water-cooled cylinders.
Up to early model year 2004 GT3 production, the basic casting used for the crankcase of the GT3 was exactly the same as the air-cooled engine and one could see the "964" casting number on the bottom of the crankcase and areas normally machined in the air-cooled application that are not machined for use in the water-cooled application. The crankcase casting was changed in mid-2004 to a "996" casting number crankcase to eliminate these external air-cooled remnants, but internally it is the same.
Up to early model year 2004 GT3 production, the basic casting used for the crankcase of the GT3 was exactly the same as the air-cooled engine and one could see the "964" casting number on the bottom of the crankcase and areas normally machined in the air-cooled application that are not machined for use in the water-cooled application. The crankcase casting was changed in mid-2004 to a "996" casting number crankcase to eliminate these external air-cooled remnants, but internally it is the same.
06-08-2008, 09:45 PM
#55
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Back to the point of the thread ie Rear main seals (RMS) I should get my car back this week with its thr=ird seal installed. How many have you had. Since it is a slow Sunday night who is the leader in the clubhouse on seal replacements and the mileage on your car.
06-09-2008, 05:20 AM
#56
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I don't think that the oil pressure being generated by the oil pump(s) is the concern. Rather it's the "gas" pressure inside the engine and lack of relief that is the problem, right? In other words the engine casing is not venting sufficiently?
06-09-2008, 08:58 AM
#58
lets throw another monkey wrench into the mix... my 07 GT3 started to leak at around 900 miles... now with 1200 on the clock and coming back from a 60 mile run... no leaks... this time... oil pressure is at 5 bars with engine rpm above 2000 rpms...
I am in no ways delusional about my rms fixing itself as I fully expect it to leak again on the next time out, but a rather interesting point that our rms issues may be caused by improper crankcase venting???
good o'porsche... its not a P-car unless it leaks
I am in no ways delusional about my rms fixing itself as I fully expect it to leak again on the next time out, but a rather interesting point that our rms issues may be caused by improper crankcase venting???
good o'porsche... its not a P-car unless it leaks
06-09-2008, 01:11 PM
#59
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Interesting point, is there better crankcase venting on turbo motors?
I think it would be the same, still can't figure out why you almost never see these leaks on a turbo.
I think it would be the same, still can't figure out why you almost never see these leaks on a turbo.
06-09-2008, 02:21 PM
#60
According to my source, the cases for the turbo and GT3's is the same, but the internals are different. The problem is how the pressure in the case is released, he said that perhaps the current ventilation system is flawed, therefore oil pushes past the RMS even if the seal is not defective and properly installed. The source by the way is one of the technical editors for Excellence Magazine. He was very informative, unfortunately most of what he said was way over my head. My only interest is owning a very cool/expensive car that does not leak. I did that with my 996 GT3.