I had a nice long chat with Charles Navarro of LN Engineering at the SCCA Motorsports Expo in Charlotte, North Carolina last weekend. He’s half of the team behind the IMS Solution for M96 engines — the other half being Jake Raby of Flat Six Innovations. I wanted to talk to Charles about preventive measures for the driver who occasionally tracks their 996. As the Mark I 996s start to depreciate below $15K, they start to become attractive track toys, but given that a decent rebuilt motor is also $15K, nobody really wants to think of their Porsche as an engine with a disposable wrapper.
Assume for the moment that you have a 2000 996 with manual transmission and 84,000 miles on the odometer. Your clutch and rear main seal were replaced at 67,000 miles, and engine oil analysis shows no signs of abnormal wear. Your car doesn’t make any funny noises at start up or idle. There’s no smoke. You get decent gas mileage, and the car pulls very well (i.e., my car.) If you’re an engineer type, you might describe its operational condition as “nominal.” Most 996 owners seem to suffer under a state of perpetual performance anxiety, just waiting for the lump to implode. I’ve tried to remain outside that camp, but just like wearing suspenders with a belt, it can never hurt to take extra precautions.
So besides the IMS Bearing Retrofit which is well documented, what other preventive measures would Charles recommend?
- Air Oil Separator (AOS): Unless you plan to track your car often, no need to replace proactively. Just check the vacuum at the crankcase. If you are going to see lots of track time, then upgrade to the Motorsports AOS.
- Thermostat & Water Pump: If tracking often, then consider getting a lower temperature thermostat and proactively replace your water pump. Use only genuine Porsche parts and do not use pumps with metal blades as they destroy the housing when they fail.
- Chain Guides: Use your Durametric cable and software to look at cam timing deviation for signs of chain guide wear. Don’t replace unless the timing is off or you see excessive wear (bits of plastic) when you drop the sump cover.
- Ticking Noises: If hot, then probably lifter. If cold, then probably cylinder. If cylinder, then the wear may be at the bottom of the stroke and you won’t see it with a borescope coming in from the cylinder head.
- Oil: Don’t use Mobil 1. Use Driven DT-40. If using other synthetic, make sure it has a high level of zinc for metal longevity. Even if zinc looks good, watch calcium which is a measure of detergent. High levels of calcium may clean away the beneficial zinc.
- Oil Starvation. Since I already have the improved oil baffle, he recommends getting the Two Quart Sump Extension. Since you’re going to replace the IMS bearing, no need to continue to use the IMS Guardian with the low hanging MCD Sensor. Switch back to a regular magnetic drain plug.
How big of a problem is the IMS failure in 996/997 model 911s? We didn’t discuss it at the show, but most estimates range from 1% to 8% of the cars delivered, with the average for all years of this engine being 4.5% (it doesn’t effect GT2/GT3 models). Sure the failure can be catastrophic, but if you think of the IMS Bearing as just another wear item, it really isn’t that daunting. Replacement will cost less than a clutch and should be changed again in 75,000 miles. If you plan to keep your car forever, then go for the permanent solution (aka, the IMS Solution) which is more expensive, but only done once, otherwise, get the bearing retrofit and move on with your life.