7 Ways to Keep Your M96 Engine Going Strong

Intermediate Shaft Bearing Retrofit

The biggest hype surrounding the M96 engine has been the relatively high number of intermediate shaft (IMS) bearing failures. Unlike the air-cooled Mezger engines used until 1998 (and in some of the 996/997 Turbo, GT3, and GT2 models) the M96 used a sealed ball-bearing to support the end of the IMS nearest the flywheel because of Porsche used one cylinder head casting to fit either bank. Despite several revisions, the permanent lubricant inside of the bearing can wash out, then engine oil with combustion by-products will accelerate failure. Once that happens the valvetrain components contact the pistons and cause catastrophic engine failure. While most estimate the IMS bearing failure rate at just 8-10% of M96 engines, most agree an upgraded IMS bearing be retrofitted as preventative maintenance and replaced on a 6 year/75,000 mile service interval. Similarly, an IMS Solution kit to replace the sealed bearing with an oil-pressure fed unit can be installed for a lifetime fix, at twice the cost of the regular replacement.

Water Pump

Another failure that can easily wreak havoc on the M96 engine is a bad water pump. These water pumps use plastic impeller blades that are prone to cracking, fragmentation, and subsequent engine overheating. Because of the positioning of the coolant temperature sensor outside of the engine, the temperature gauge won't alert the driver until its too late. To make matters worse, broken impeller blades are sent into the water passages where they can wedge and cause a localized hot spot that will eventually crack or warp the cylinder head(s). Changing the water pump on a 3-year basis, regardless of mileage, can help limit the chances of these problems occurring, and this is a fairly simple DIY project that is easy on the wallet. Remember, the water pump is submerged in coolant even when not being driven, hence the time-based service interval.

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Air/Oil Separator

The Air/Oil Separator (AOS) routes vapors from the crankcase back into the intake manifold to be burned off. Unfortunately, the AOS line that returns accumulated engine oil back to the crankcase is located below the oil level line, and if the AOS membrane fails, oil can work its way to the intake manifold where it can accumulate. Early symptoms of AOS failure can be an occasional puff of smoke out the exhaust. However, aggressive track driving with sharp turns and heavy breaking can send enough accumulated oil into the combustion chamber to hydro lock the engine and bend rods. The AOS itself is perhaps one of the cheaper maintenance parts on the list, but replacing them can be quite involved for novice mechanics; labor is the most expensive portion of this job. 

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Oil Change and Oil Analysis

Porsche originally recommended extended oil change intervals of up to 15,000 miles for M96 engines, but due to the IMS bearing and other issues, it has been determined that these are far too long. Since contaminated engine oil accelerates wear on the IMS bearing, oil should be promptly changed every 6 months or on 3,000-5,000 mile intervals with a quality 5w-40 or even 15w-50 engine oil. In addition to frequent oil change intervals, an aftermarket magnetic drain plug will catch ferrous metals not caught by the filter and can give an early indication of an impending IMS bearing failure. A spin-on filter and adapter can add further protection by deleting the factory filter bypass for full flow filtration instead of the original paper cartridge. Finally, sending oil samples off for analysis will give a detailed breakdown of how their engine is performing and wearing. Regardless of which preventative other maintenance you do, a frequent oil drain interval is a must to prolong the life of the M96.

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Oil Pan and Baffles

Some M96 engines have on-track oil starvation issues directly related to the high G-forces associated with track driving. In addition to using a high-quality engine oil that is well-suited for the race track, a deep sump oil pan and oil pan baffles can help prevent oiling issues. A deep sump pan will add up to 2 additional quarts of engine oil capacity to reduce the chance of oil-starvation from oil not being returned to the pan fast enough. Similarly, pan baffles work to ensure a constant supply of oil pressure by keeping oil around the centrally located oil pickup. Most kits will also include updated 997 pick up tubes to get oil back to the pan as quickly as possible. Here is a link to purchasing a technosump package. 

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Control piston

Vehicles/engines affected: 2005 up to 2006 Boxster (987)/Boxster S (987) with M96 engine.

When warming up the car, do you ever hear a terrible screeching sound when the RPMs get around 2,000? In many cases that awful sound is coming from the control piston in the oil pump. To remedy this issue all you need to do is to install a modified control piston into the oil pump cover. 

1) Remove the cover for the rear underbody. Place a container underneath the oil pump cover. Remove the screw plug/control piston. The contact surface in the oil pump cover can become damaged if an unsuitable tool is used for removing the control piston.

 Damage to the contact surface can cause the control piston to stick.

 This can reduce the oil pressure and damage the engine.

 If the control piston does not come out of the oil pump cover by itself, pull it out carefully using a suitable extraction device.

 2) Remove the control piston. 3) Lightly oil the new control piston and use a new sealing ring. 4.) Install the new control piston. 5) Tighten the screw plug with a torque wrench to 37 ft.lbs. 6) Install the cover for the rear underbody. 7) Check engine oil level display in the instrument cluster and top off oil if need be.

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Drive it!

Contrary to popular belief, actually driving your M96-equipped Porsche regularly and in a spirited manner tends to prolong engine life. Experts from Flat 6 Innovations and LN Engineering have found cars that sit unused for long periods of time tend to exhibit more problems than those that are regularly driven. In addition, they find that owners who baby the car and are light-footed on the gas also have a higher failure rate than those driven aggressively. Avoid higher gears in order to keep the revs above 2,500 rpm, avoid revs above 4,000 rpm until the engine oil is fully up to temperature, and regularly exploit the upper rpm range of the engine once it is warmed up. Despite some of their flaws, these M96 cars are still great vehicles that can be enjoyed for years to come as long as they are regularly used and receive proper maintenance. 

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For more advice on maintaining your Porsche check out the how to sections of Rennlist.com