Older boxster buying tips????

[m0b1liz3]

Hello, I am in Melbourne. I test drove a few cars recently including a Z4, boxster, 350z. I fell in love with the handling of the boxter and overall experience. But....

IMS? It sounds like there is a decent engine failure rate out there and no one seems to advertise that they have had their boxter IMS replaced to prevent this.

Can someone advise me about how to go about purchasing an older boxster and not having it live at the local mechanic/cost mega$$?

[AndyS]

Hi,

Have a read of the IMS topic under 996/997 section of the forum. The boxter and 996 engines are very similar with the same Intermediate shaft set up. See if you can get your hands of a copy of Total 911 that has the article. It mentions failure rate at around 5%. Generally not worth doing a preventative repair as failure rate quite low but cost to change required parts to prevent possible future failure runs at around 10-20% of a rebuild.

Good luck

[myred911]

Greetings,

This is my summary of the general wisdom on the IMS.

• If the IMS on an older Boxter has not failed by now it will not in the future
• The repair may already have been done under warranty - check service records.
• Get a PPI from an independant workshop - good insurance
• IMS failure seems to be related to cars doing short runs with the engine not warming up and thus allowing oil to penetrate the bearing space.
• Give the Boxter a workout - a track day seems appropriate or on one of our legendary Sunday Targa runs.
• Get to know yr car by changing the oil and check the oil for swarf - failure is imminent
• Failures are usually catastrophic - the photos are gruesome
• I am told by my favourite tech that when this issue first surfaced here in OZ, Porsche replaced the entire engine rather than bother with a dismantle and replace. The old block was then re-manufactured to current specs.
• Buy an aircooled 911

My 2c worth

rEd

[matt]

New to posting but been doing a lot of research on IMS rear bearing. The bearing is self lubricating & therefore sealed. Seal can dry out & get brittle. If engine oil gets into the bearing, past the seal, it can wash out the lubricant. Bearing is OK as long as it keeps getting engine oil, but if it dries out, the balls can wear & fail.

Note that replacement bearings can be ordered from Pelican Parts or for a bit more money, Charles Navarro of LN Engineering has designed a ceramic replacement bearing. Both are from USA.

I haven't tried either, I just keep he revs up (keep engine oil splashing around) & change the oil regularly. I've also installed a magnetic plug in sump plug to keep an eye on signs of internal wear.

Cheers,

Matt

[mikefocke]

The Pelican kit is not available yet. For a comparison of the advertised kits, see My link.

IMS replacements have not been done routinely so I would assume one has NOT been done. No parts have been available from Porsche, surprisingly. And any parts from Porsche would use the same materials and lubrication scheme already known to fail. (RMS replacements are more routine and those parts have been improved by Porsche.)

IMS bearings can fail anytime...from 5k to 300k. They don't all fail but some do and they often take an engine with them.

The LN bearing uses much better bearing material, mounting hardware and a different lubrication system than the original Porsche one. Over 3k have been installed to date, some as long as 3 years ago. No reported failures. LN sells the tools and provides instructions though it is better to have a mechanic who has done one before to do it. The ideal time is at clutch replacement time and do the RMS replacement at the same time. The Pelican kit uses the same material as the Porsche bearing and thus is going to be less expensive though how long lived it will be is unknown.

The IMS has 3 designs over the '97-'08 run of M96 engines. You can't be absolutely sure which you have until you pull the transmission off and look at the mounting hardware. Which means you can't order the right kit until you have your car disabled. Unfortunately, the last design Porsche used for the IMS requires the removal of the engine, disassembly of the crankcase and exchange of the entire shaft just to replace the bearing. See the LN web site for more detailed info.

Frequent oil changes with good oil and inspection of the debris trapped by the oil filter can help increase your odds of detecting the problem in the early stages but the bearing can go from healthy to complete failure in a time far shorter than any oil change interval you are likely to use. Likewise the magnetic drain plug can alert you but again you only look at it every so often.

There is word that there may be a pre-failure detection product available before the end of 2011. It won't be cheap (except when compared to an engine replacement) but it does have a chance of detecting a problem before you are ready to do an oil change and gets you alerted to the need for the immediate bearing replacement before your engine suffers damage that would require a complete rebuild. It doesn't require engine or trans removal, the average owner should be able to install it in 2 hours. It provides an audio and visual alarm. See flat6innovations.com.

The failure rate is no where near that sometimes cited on the forums. My guess is ~1-2% per car/year. But no one but Porsche knows and they aren't telling. Plenty of other cars/motors have similar failure rates so don't over-react to this...you just happen to have more honest information thanks to the many people who really love their Porsches.

IMS = Intermediate Shaft...part of the valve timing chain.

RMS = Rear Main Seal...seals the hole in the block in which the crankshaft rides.