Published on 05/21/2018
In the 90's Porsche had to switch from air cooled engines to water cooled ones to pass the new EURO 3 norms.
The "new generation" engine (water cooled) arrives in 1996 with the Porsche Boxster, followed by the 996, the Cayman, the 997 and the 991.
Porsche only had the experience of the water cooled 924 ; 944 ; 968 and 928.
In 1995, the Porsche group financial situation was not at its best.
Are these engines reliable? I get this question asked to me daily.
So here are my answers: with Porsche, for their 996 and 997 models, the turbo GT2 or GT3 engines do not have the same lower engine than the standard versions (it approximately is the 964 RSR 3.8 cm3 one so there is no intermediate shaft bearing). Thus, this problem does not exist on those models.
Concerning these other models: 996 997 Boxster, Cayman in 2.7 ; 3.2 ; 3.4 ; 3.6 and 3.8 it is a real problem. However, solutions do exist on the first versions.
The transversal intermediate shaft came equipped with a single or double row bearing since 1996.
Neither the simple nor the double row bearing resists to breakage, the main cause is:
The 6 mm axle that holds the whole distribution of the camshaft chains (DOHC)
First problem is that the axle breaks and the second one is that this bearing is sealed with a plastic protection (RSR). Just imagine the state of the grease inside after 100'000 km and approximately 2'500 hours of usage.
That is because a car with 100'000 km is not always in motion, but the engine still runs, at stop signs, in traffic, etc. It is constantly being used as soon as the engine runs.
The ceramic version of the simple bearing is guaranteed for 80'000 km. The axle goes from 6 mm to 8 mm, but the lubrication is still not fully solved.
For the double row bearing, the axle goes from 6 mm to 8 mm too and the bearing is of the same manufacture as an original part. It is guaranteed for 80'000 km as well.
The lower engine consists of three parts. There are two cylinder crankcases and one big central part: the crankshaft block that is fixed between the two cases. It is not anymore how it used to be with 2 cases, 6 cylinders and 6 cylinder heads.
On the old engines, the cylinders had a surface treatment called NIKASIL that reduced the piston friction and prevented any seizure. On the water-cooled versions, the treatment was not of the same quality. It goes from 140 microns on a 993 to 4 microns on a 667. So, it resists less to the natural wear of the engine. That is why it is capital to use the correct engine oil. The time of the 15w40 ; 10w40 and 5w40 as passed. I recommend using Mobil 1 oil in 15w40 ; 10w40 and 5w40 (recommended by Porsche (A40 homologation)) for a GT4 or a GT3. The quality is better than a standard 5w40. That would help with a better lubrification and thus prevent a piston cylinder seizure. That happens most of the time on the piston number 1 or 6 (it is the least cooled part of the engine).
My second recommandation is about the replacement of the coolant.
Be careful with Porsches since 1996: you have to fill in type A40 antifreeze that has been homologated by Porsche (the color is violet pink), not the dealership one and especially not the supermarket one.
Concerning the 996 and 997 filling processes, you will need to use a special apparatus to fill the 22.5 liters. Otherwise, some air would be stuck in the circuit... Especially in the front radiator or in the front shield. The fan will often go into the front bumper and it could already be too late. The risks are: problems with the cylinder head gasket, start of a cylinder seizure, cylinder ovalization or even breaking.
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