Are most engine replacements in "stick" driven 996's??

I was wondering about this...don't want to start a riot or want to hear anything negative....just read a couple of recent posts about engine replacements and since I have a tip (I know I know....but I love it) and was wondering if it also happened to tip 996's I also understand that there are more stick driven P's out there, but maybe we can figure out a ratio or something.

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Hi Nick, Don't know the answer to your question but was curious if you have had your tip on the track for any DE's? It seems like the tip would be great for that. Please let me know. Thanks, Andy T

Nicolaas - it seems like most cars requiting engine replacement are cars with a 6-speed. However, as you said there are more 6-speed cars than Tip cars. I don't know if there will be enough data to be able to determine an accurate propensity for engine problems. However, I do think you should be OK. If you start with the 993 guys theory that 996's aren't real Porsches, and extend that another level and state that cars with Tips aren't real 996's, that means you won't have any engine problems because your Tip isn't a real 996!

That's a really good question. The C4S 3.8 has a lot of driveline lash, it is easy to hear as you go on and off the gas at low speed. Perhaps the older cars have some of that too, but not as easy to hear. The torque converter would isolate the engine from all that.

Well, I know one area of powertrain failure that the tip keeps at bay. One reason for IMS failure is that it was poorly designed and there is pressure on the shaft, the tip transmission is bolted more securely and in a way thet puts less stress on the shaft thus 1 less cause of engine failure, it obviously has nothing to do that could help a slipped sleeve or porous block.

According to the piece Excellence did on the 996 recently, yes, manual transmission cars have extra stresses that lead to some of the problems that result in failures. Something to do with the flywheel being unsupported at the end of the crankshaft... I don't recall exactly. But I don't think that it would be a strong correlation to engine failures in general. The true failures, as opposed to the replacements that resulted from failed RMSs, aren't related to this I think.

I wonder if there are more failures in early, 99-00 C2s versus C4s? I have heard that the C4s engines and bodies were builty differently than the C2 in a different factory? BTW my neighbor has an 04 Boxster with a tip that grenaded at 25k, two days after she bought it, covered on original warranty. It was owned by a older woman as the prior owner. This owner drives it pretty hard we'll see how this one lasts.

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Very interesting. The tips will have more reinforcement and the torque converter will add an extra degree of separation between the engine and transmission. I heard that the C4S, being similar to the Turbo with its AWD, has extra reinforcement for the front diff. My friend's 02 Boxster S's (Tiptronic) engine gave way at 30k. He had the car since new as well.

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AFAIK, there was more than one supplier for engine blocks in 986/996s. But I'm pretty certain there is only one assembly facility for 911s.

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My C4 suffered IMS failure so it definitely didn't eradicate it.

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Now that's my kind of woman.

I was thinking that maybe a part of the engine failure are caused by a lack of driver skill....driving stick and revving to high when engine is cold can do a lot of harm in the long run....but I guess this would be detected when they do a read out. Still if you drive the P hard when cold and don't wait till the engine is 180 or higher...with a tip you really have to step the P on it's tail to go over 3500 rpm in any gear (mine sits in 5th gear at 45mph, but with a stick it is easy to forget to shift or downshift to early or to the wrong gear...especially when your other car is an automatic.

If you do a money-shift, you've got bigger probs than the IMS/RMS.

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no. Rms seal leaks seamed to be more common on manual trans cars, but thats a skerwed perception. theres more manual trans cars on the road. The could be a small amount of extra strain on the crank (not the ims) on a manual trans car due to the extra load of the input shaft. The manual trans is bolted just as securely as the automatic. Ims failure effects manual and automatic cars equally. I dont know why or how, I dont belive its a design issue becasue I would see it more then I do if it effected every car, I dont belive its a maitnece issue, I dont belive its a bad batch of parts becasue it spreads many years with few failures. Im to the point were Im suspecting drivers. People not warming up the car before hammering on it, but even that is purley speculation. The failure point is the support bearing and of corse there is load on it but thats how bearings work, thats not why they fail.

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I hear that alot, the weight of the dual massflywheel casuse leaks due to the lack of the rear crank bearing. I doubt it, the flywheel/clucth assy weights 20 lbs or so, The torque convertor on a tip weighs 20-25 ( ive never weighed one but they are heavy) and the weight is "longer" putting more of a stess on the crank. Really RMS failures is a thing of the past, the new seal has a 99% sucess rate. Its been over a year since I have changed any RMS seal

Brad, You know I respect your knowledge and kindness to share it, but I have to disagree with your disagreement. THis is from PCA website mentioning why tips leak less and are bolted differently, there is another article talking about less stress on IMS but I can't find it at the moment. "Bruce Anderson saw this, and reminded me of Scott Slauson's writeup which covered this, in which he notes that the Tiptronic is better off. Here is the writeup: "The Rear engine oil leak seems to affect close to 100% of all the Boxsters and 996's. Most of these leaks are viewed as a rear main seal when in fact they are several different ones. Do to the reputation of the rear main seals any leak in the bell housing are has been considered one. They include the bearing cover, rear case bolts, porous case and of course the rear main seal." "The porous cases mainly affected the early Boxsters MY97 and some MY98's as described in the cylinder liner article." "The bearing covers affected primarily all the Boxsters up to MY99 and to include the 996 for MY99. They utilized an O-ring for sealing the bearing cover and standard 6mm bolts. These O-rings tended to fail at a high rate. These O-rings were replaced in production with another bearing cover that incorporated a 3 way sealing ring. Basically it was like getting the sealing capabilities of 3 O-rings side by side. Should the sealing surface area of the first one fail you still had the second and third wiper to stop the oil. The 3 bolts that hold this bearing cover in were also replaced with micro encapsulated ones. These would seal the threads on installation and stop the oil from wicking through the case." "Now the number one leak that continues to be an issue to all of the 996's and the Boxster's (986) is the rear main seal leak. This issue has been more problematic with the manual transmissions than the automatics. This makes sense when you understand the actual design of the engine. The crankshaft is mounted in a cradle that is intern bolted between the case halves. The tail of the crankshaft is also unsupported do to the chain drive for the intermediate shaft. Now at this point add the weight of the clutch and flywheel to the end of the crankshaft. This now can either cause the crankshaft cradle assemble to slowly move in a downward position or allow the seal to move and fatigue. A seal can be replaced and work effectively should the crank assemble still be ok when checked. Porsche has a tool number 9699/1 that slides around the crankshaft and into the case. Should the tool not insert then the engine would be replaced. This replacement was at a high rate do to the design of the tool. Since the tolerance was so tight you could not insert the tool at times. This was do to the trapped air at the end of the crankshaft. The problem was easily cured by drilling a 1/8" hole in the face of the tool , thus allowing a proper check." "Now to get to why the Tiptronics (automatics) leak less. Remember that unsupported weight at the end of the crankshaft with the manual transmission earlier? This is supported now by the Tiptronic. Granted the torque converter is also bolted to the crankshaft, however it is supported by the oil pump bearing. This extra support takes the load off of the crankshaft and reduces the oscillations to the seal and the crankshaft carrier." "The next question is what to do about an actual rear main seal leak. One is to replace the engine should the crankshaft fail its location with the 9699/1 tool. Lets say the crankshaft checks out ok then what do you do besides installing another seal. Replace the rear case bolts and intermediate shaft bearing if it falls in the early range of cars. Another well proven repair is to epoxy the threads on the back of the case bolts and the case halves just above and below the seal. This seams to retain the position of the seal to a very high success rate. The epoxy will not stop the possibility of the carrier from moving, however it will keep another seal from leaking. This has been 95% successful with 1% for the seal and 4% with crankshafts eventually moving. " Joel Reiser - PCA WebSite - 7/8/2005"

everyone is entitled to an opinion, maybe some day Ill make a web site to make my self more credible. Bottom line Why did they leak...............................poor seal design if it was anything else the new seal wouldnt have fixed it. new seals dont leak

The crankshaft is mounted in a cradle that is intern bolted between the case halves. The tail of the crankshaft is also unsupported do to the chain drive for the intermediate shaft. Funny Stuff! I guess some people think the crank simply floats freely in the case? I guess when you don't have the correct answer, anything sounds possible.

From the September Excellence piece: "It's been a bigger problem with manual transmission cars than automatics. In the manual cars, the heavy dual-mass flywheel and clutch are hung out on the end of a largely unsupported crankshaft. All of this extra weight can cause the crankshaft cradle assembly to slowly move downward or allow the seal to move and fatigue. If the flywheel and clutch are not well balanced, they can further exacerbate the problem. The seal can be replaced and work effectively so long as the crank assembly is still centered in the crankcase. To check if it's still centered, Porsche uses a gauge (tool number 9699/1) that slides around the crankshaft and into the case. If the tool does not fit, the engine should be replaced." A couple of things stand out, here. One is that there are two possible ways that the design can cause the seal to fail, and an improved seal would seem to me to be the cure for only one of them. The second is that it seems like variability in how "well balanced" the flywheel and clutch are could account for why some cars suffer more than others. So, 99firehawk has an opposing view with his "it's just a seal" argument. And 1999Porsche911 disagrees that the crankshaft is "largely unsupported." Comments, guys?

I cant belive that a flywheel and clucth puts any more weighted force on a the crank then a torque convertor. Even if you had specfic percentage data it would be skewed. You can argue that the tiptronic cars are driven more where manual cars are 3rd-4th ect cars. Or that tip cars are driven less agressively. (im not saying they are but not numbers are right) I base my opinions only on what I see with my own eyes and touch with my own hands, not what I read. If it wasnt a seal the 997s with the new ptfe seal would be leaking every where they are not. The crankshaft................... calling it unsuported is kinda a funny statement. The crank shaft is not suported on the tail end, unlike most other engines. But really I dont think it matters, And here is why There are no rods past the last main bearing all reciprocating force should be taken up by the main beraings not after. Beyond that you are talking about forces that bend a iron crank shaft but not enough to warp it. The ims shaft puts pressure on the crankshaft. Well theres about 10000 engine designs set up like that, you just dont see it the same becasue porsche did it in the motor. Theres probaly more unsuported crank from the final bearing cap on most engines to the timing drive gear then from the last cap to the ims drive gear on a m96 motor

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You can appreciate, I'm sure, the ironic dilemma this creates for the rest of us.