I have a theory on the IMS failure

[Johnny Danger]

Originally Posted by JFP in PA

Couple of “fly’s in the ointment”………. TIPS do have IMS failures, just not at the rate the manuals do. As there are far fewer TIPS, that would seem to appropriate.

The cars that get the loving Hell beat out of them, street and track, seem to fail less frequently; cars that are low mileage and babied seem to fail more frequently than cars that are beat on. So much for the smooth shifting scenario……………….


Cars that get past the IMS "sweet spot" miles (45-60K) seem to go forever (125-225K miles not unusual), regardless of how they are treated.

Yikes ! My "garage princess" only has 17k original miles on the odometer. If I at least start talking dirty to her will it prevent IMS ?????????

[Lobo1186]

that might actually do the trick... that is if "talking dirty" means driving WOT through the hills in a local mountain pass!

[Topless]

Originally Posted by edbelton

The other day I let a friend of mine drive my 98... and all of the sudden I have this moment of inspiration where I came up with this brilliant theory (LOL, we need to blame it on something) about the IMS failure based on the way he drove it. I learned driving in a stick shift car, I never owned an automatic car, and I think my dad taught me well, so I am always trying to make my driving as smooth as possible. Anyone can drive stick, but what really makes a difference is the way you shift. Shifting should be almost unnoticeable. You need to aim for quality when you shift, not shifting like crazy as many people do. Well this friend of mine would realease the clutch in a very abrupt way, not once, or twice, but pretty much all the time. Multiply that for 15K miles and you have an stressed engine due to abrupt changes in torque ( that stresses the timing axel and thus the bearing) , or underreving prior to stall, or when the ac kicks in (sometimes my rpm drops below 500 and I hear some noise from the engine if I am in gear), add everything up and there is your IMS failure. That why, accoding to what I read, that boxsters with automatic transmission are less prone to it, shifting is usually smooth and there is no stalling at a red light or underreving due to not pushing the gas enough. I dont know, it could be the biggest BS you guys have ever heard, but in my mind it makes sence. It is evident that there is a flaw, and that the engine shoud be designed to take it, but this car is not a toy, it is by far the hardest I have ever driven, it is not easy to deal with the extra hard clutch and shifting isnt always smooth. After driving it for a couple of months I took my old vw corrado for a ride.......boy, I thought the clutch had broken, it went all the way in as if it had no spring, so soft, so easy to drive....

I think this has some merit. Heavily loading that bearing with poor shifting technique during times of limited lubrication (cold engine) could very well be a factor. Add long oil change intervals with Mobil 1, long periods of non-use with garage queens, and a possible poor bearing alignment when new and you have the IMS failure matrix.

JFP is right that there is a higher incidence of failure between 40-60K miles but they can and do fail at nearly every mileage logged. I don't agree that hitting the track is necessarily hard on the IMS due to rough shifting. Seasoned track guys often have the smoothest and most seamless shifts. They have learned that it is not necessary to flog the car in order to turn some quick laps.

[landrovered]

I am smelling a wives tale in the making.

You need data, scientific data to analyze and then you need to test a theory in reality to see if the hypothesis is correct.

The only person that seems to be doing that is Jake. As much as I disagree with his marketing approach and fear mongering he is approaching it from a scientific standpoint and I applaud him for that.

What was interesting to me were the comments that he made recently about abusing the Boxster motor intentionally to blow it up and cause failure. All of the things he was doing were like fingernails on the chalkboard to me, reving a cold engine, banging on the limiter in first gear, the list was long. Reading it was aweful. Last I heard he had not blown it up yet.

The point is that you can have as many Eureka moments as you want but without research, data and experimentation you may as well make sacrifices to a head of cabbage, it will be just as effective as this speculation.

Not trying to piss anyone off but I felt the need to say something here.

[jacabean]

I personally do not think there is any particular reason for these failures other than poor design of this area. I believe if you are going to get a failure it will not have anything to do with the way you drive or oil types or change intervals. Basically, if it's going to happen it's gonna happen regardless of what you do.
You guys need to understand that there are tens of thousands of boxsters out there. thousands of which will never see this problem. Roll the dice , that is how i look at it. the odds are in your favor.
Do i believe this is a problem? Yes! there is no excuse for the amount of failures that have been happening for a car that cost as much as they do. 911 owners paying over a 100 grand for a car that blows up! these cars should run to 200k for what they cost.

If your not hitting the rev. limiter every know and then you should'nt own a porsche sports car!

Just my 2cents

[Quickurt]

Sometimes we Krauts live up to our hard-headed reputations.
Long, long ago, in a galaxy not too far away, Porsche made a 1300 CC 356 engine with roller bearing main bearings. Great little motor.....until you "lugged" it one time and Kaput! the roller bearings self destructed within short order. For those who don't understand the term "lugged" it is what happens when you drop the RPM too low in gear and then try to accelerate away. It's a nasty sound and a really nasty vibration that does terrible things to your crankshaft, bearings, connecting rods and pistons.
In any case, Porsche went back to plain main bearings and the problem went away with the change. So..................can someone explain why Porsche would put more roller or ball bearings inside the engine????
The only explanation I can come up with is the distance the intermediate shaft is from other pressure lubed rotating shafts and they are saving the porting/runners/tubing to get pressure oil to it?

[roadracer311]

I've thought for a while now that lugging the motor probably contributes to the RMS failures. Explains why the tips fail less often (the production numbers for tips are higher than you might think, or at least they were prior to 2007 when I was researching to buy mine.) So it was interesting to see some history (from Quickurt) of lugging a motor leading to roller bearing failure.

It would be interesting to know if Porsches in countries with higher octane fuel also have the same level of RMS failures. Lugging can also cause pinging (even with a car designed to tune on the fly to eliminate pinging). Pinging can send all sorts of forces and vibrations through a car