Legend
has it that Porsche stifleld the amount of air available to the engine in order
to take a couple of bhp of the performance so the upcoming 993 would be more
powerful than the 964. Get more air -> go faster. Probably a myth but do
it for the great sound.
A design fault on engines up to August 1993 that you MUST
fix if not already done so is to add ventilation to the distributor to prevent
ozone perishing the distributor drive belt. If this breaks you will be
running on one plug per cylinder and will end up with poor performance and
possible damage. Click the damaged belt photo (thanks to Marv de Beque) to
see my summary of the issues and solutions from Vent kit installation, belt
inspection and change, distributor removal and distributor cap and rotor
replacement.
The 964 has a reputation for oil leaks. This reputation results from the following article from Bruce Anderson's Porsche 911 Performance Handbook. Hope Bruce won't mind me quoting below. For the facts check out a couple of surveys we ran on our 964 SmartGroup, Oil Leaks, Myths and Truths and Top End Rebuilds, Myths and Truths.
"There have been a few problems with the 964 engines that are worth mentioning. One is a cylinder head leakage problem on some of the earlier cars. The cars built in 1989 (K), 1990 (L), and 1991 (M) had the engines that are susceptible to a cylinder head to cylinder leaking problem. The early cars were those built up to 62 M 06836, M64.01 for the manual transmission cars and 62 M 52757, M64.02 for the Tiptronic cars. During the model year 1991 Porsche fitted their 964 engines with a modified cylinder and cylinder head gasket or seal. The original 964 engines did not have a head gasket and there has been some oil leakage at the joint between the head and the cylinder. The way that the original heads and cylinders were machined there was a small gap left out at the edge where the head studs were. Distortion of the heads caused by the head tourquing from the head studs was believed to be the source of this leak.
Actually only a very small percentage of the cars had this leak, but while the cars were on warranty Porsche updated any of the cars found to be leaking. Leaking was defined as wet to the touch and not just showing signs of having leaked some time in the past. The update was to change the pistons and cylinders to cylinders that had a 32 mm larger, 145 mm diameter seating surface so that the heads would not be distorted out by the cylinder head studs when the heads were torqued and expanded and contracted with heat.
There was also a slot around the cylinder bore in by the cylinder bore where they placed a seal ring. The original seal ring was made of pure graphite on an aluminium backing. Because of the larger flush mating surfaces it was possible to change from Dilavar cylinder head studs to more reliable steel studs. The later engines with wider head contact surface and a head gasket seem to be much less likely to leak."
Common
problem that turns up all the time on the message boards it that of a fuel smell
inside the car. Mark Schettenhelm and Luis Arisso have written up a
detailed procedure on how to cure this.
If
your oil-level gauge starts acting erratically or shoots to the top, it is
almost certainly a faulty oil-level sender unit in the oil tank. This just
happened to me and I decided to change the unit myself.
Concerned that your oil cooler fan is not working properly? Same with the air-conditioning condenser blower fan? Would like to manually switch on the oil cooler fan for those special occasions. Check out John Kerr's instructions here
Pete
Squires shows in you words and pictures how to remove your failed starter motor
and fit a new or refurbished one.
Adrian
Streather has written a brief overview of two of the more complex 964 systems.
Click the image on the left for the overview in Acrobat format (176k .pdf - will
take a while to load on 56k).
Adrian says "Hopefully this overview will provide 964 owners with
sufficient knowledge to allow a reasonable level of understanding of how these
systems operate. This knowledge will I hope assist in reducing any repair costs.
A full description of operation of these systems will be included in my book on
the 964 currently being prepared by
Bentley publishers." See
www.adrianstreather.com
for more information.
Adrian Streather has written a brief overview of the 964 Turbo engine and
related systems. Hopefully it will provide 964 turbo enthusiasts sufficient
knowledge to allow a level of understanding of how these systems operate.
Click the photo for Adrian's article in Adobe PDF format (577Kb).
