Thinking of buying a 97 Boxster - Engine Failure Question

[splatch]

I am thinking of buying a 1997 Boxster with approximately 100k on it. I wanted to know if the RMS and Intermediate shaft failures typically stop happening after a certain mileage? I know with the 99 Miatas, the #4 bearings typically fail before 40-50k with very very few cases occurring afterwards. I know boxsters havent been around long enough to really rack up mileage, but I figured if anyone would know, it would be someone here.

My experience tells me that if a car has made it to 100k without such a failure, it probably is not a faulty engine. I just wanted to make sure I am not off the mark, as I do not have much experience with Boxsters.

The car needs some other work, too, and I didn't want to get involved with a failing engine as it is far beyond my capability, and I do not have a spare 9k to spend on a new engine.

There is a relatively new thread here but it doesn't address the high mileage question that I have and that others will surely have as the cars gain more mileage.

[chiefsalami]

With this type of car, you want to go for the lowest mileage, newest one you can. 100k miles is A LOT for a Boxster. I think that may be the highest mileage one I've heard of. If you do decide to pursue it, spend the $300 or so it costs to do a "pre-sale inspection" at a dealer. It will be the best spent money on this car. They can tell you about any issues the car may have at that point.

[Ronzi]

Just from a wear standpoint, there is no reason to believe the engine would be worn out any more than a 100,000 mile Miata. Typically, late model Porsche engines should be pretty long-lived, a couple hundred K at least.
As said, if at all possible, take it to a dealer for a PPI. They can pull up the warranty history from the VIN, and at least be able to tell you if an engine has been replaced under warranty. My assumption here is that there are no maint. records with the car.
Some of our forum members have said the RMS is a "wear" item, and can be expected to fail eventually on every engine. Once the RMS makes it past the premature failure period, how long with it last? I haven't seen any evidence that would lead me to believe anybody knows.
If the car has been maintained properly during it's 100k miles, it could be a decent buy. If not, it could be a disaster waiting to happen ... to you.
The used car world does not seem to me to be short of Boxsters, so you might think about passing on this one, particularly if it has known needs, and look for a better car.

[denverpete]

I cannot, for the life of me, think of a single reason to buy a Boxster with 100k miles on it. Not one.

Even if this is the steal of the century, the maintenance costs are going to kill you. Hell, a new top is a couple grand at minimum. Why bother? There are so very many used Boxsters out there with low miles for relatively low money. You don't mention how much they are asking for this 100k miles Boxster but I'd be willing to be that whatever the asking price for another $3-5K you could get one with under 40k miles - and newer! Trust me - they aren't exactly flying off the used car lots so you should be able to negotiate pretty strongly.

I also strongly disagree with Chiefsalami that you want the lowest mileage. I think this forum has pretty much shown that you really want a Boxster with around 30K miles on it. Any possible engine failure is severely reduced after those miles. An older Boxster with low miles is ironically a risk. The vehicle hasn't been driven and unfortunately problems seem to crop up when the new owner starts driving it every day (see also: ME).

As to the RMS - I don't think mileage has much to do with it. It seems like a gremlin that just pokes it's nasty little German head up randomly....

[MNBoxster]

Originally Posted by denverpete

...As to the RMS - I don't think mileage has much to do with it. It seems like a gremlin that just pokes it's nasty little German head up randomly....

Hi,

All good points, but as far as RMS goes, the majority which fail prematurely do so under 30k mi., usually under 24k mi. There have been failures at higher mileages, but these are rare. So much so, that there well may be other issues at play in these instances.

But, the Main Seal on any car is a wear item. The Front and Rear Seals on your Chevy Smallblock or Honda 4 will eventually wear out.

These seals are essentially a rubber (sometimes synthetic, leather or cardboard depending on the car) lip which is precision engineered to rub (read direct contact) against the circumference of the crankshaft as it spins, this is what provides the seal and keeps the Oil in. Think of it as similar to a rubber doughnut with a shaft running through the middle which presses against the doughnut around it's whole inside diameter.

The crankshaft theoretically spins on a stable axis, but eventually, due to wear in the bearing shells, it's axis changes slightly (or it will wobble slightly) and it will exert more pressure, and therefore wear, to one part of the seal and away from the opposite part. When this happens, the seal is compromised and the seal leaks.

One of the keys to a long-lived seal is to have it centered on the Crankshaft's spin axis, and this is where Porsche has had some difficulty. The M96 engine block halves are cast using a proprietary casting method developed by, and adopted from, Audi. The advantage of this type of casting theoretically removes any need for post- cast machining the block to center bore the Crankshaft opening. This means less $$ to produce the engine and more profit for the manufacturer. But, it also eliminates the possibility of post-machining of the Block halves because no excess material is present, as in conventional casting, to machine away; this is why a bad block cannot be saved.

But, the tolerances are not as good as if the block were precision center-bored. If the block is really off the seal will not center-align with the spin axis of the Crankshaft (Porsche measures the block on failed RMS to determine whether to refit a seal or the engine entirely) . The original Seals were not able to tolerate much variance by flexing sufficiently to maintain a proper seal. The redesigned seals and those from the Cayenne block, do seem to be more flexible and capable of accomodating greater variances better than the original seal. This is why for many, it's a one-time repair. But, for others, the variance is too great and it will consistently fail or require engine replacement. Of course, should a Crankshaft be inaccurately machined and slip through Quality Control, it too would cause a premature failure of the seal, but these are probably as rare as the same occurance in a Honda. Also, should there be a burr on the Crankshaft, this too can tear the seal and cause it to fail. The seal will also sometimes scar the Crankshaft by wearing a groove into it. The original seal is set 11mm deep into the Block, but Porsche recommends seating a replacement seal 13mm deep. This way, it comes into contact with a fresh, smooth part of the Crankshaft.

Also, each of the materials used in making the seal have their own lifespan. Rubber and other materials harden with time and heat cycling and the seal becomes less pliable. At this point, it is less able to endure the stress placed on it and it can wear or crack, again loosing it's integrity and a leak develops. Due to greater manufacturing tolerances and better materials, these seals now last a very long time, somewhere in the neighborhood of 150k-250k mi., but still not forever...

Happy Motoring!... Jim'99

[denverpete]

Yeah, that's pretty much what I meant to say. I would have gone into much deeper detail of course but I'm a man of few wo

[NickCats]

Originally Posted by MNBoxster

All good points, but as far as RMS goes, the majority which fail prematurely do so under 30k mi., usually under 24k mi. There have been failures at higher mileages, but these are rare. So much so, that there well may be other issues at play in these instances.

Jim,

Great info. Question for you, I recently brought my 99 Box in for the 30k. Dealer said that I have a very minor leak in the RMS but not to worry about it at this time but to keep that in mind. Garage floor has been clean with no evidence of leaking fluids. Due to the 30k miles, am I past the point of RMS "failure" though I may still have problems in the future ?

[MikenOH]

sounds like a good deal, if your PPI gives you a "clean" bill of health. It would be useful if the owner has a list of all items replaced--top, brakes,wheels bearings, suspension--which will give you a handle on what your short term maintenance items might be.

As I see it, if you get a terrific deal on the front end, you can deal with the expenses down the road since you've avoided the depreciation. If you check the archives here, there have been a number of guys buying low mileage newer cars at higher prices that they've had to put big $ in shortly there after. In my view, that's the worst of both world