Monday, 22 June 2015

Engine Ancillaries Overhaul

At our last event at Rockingham we ended up beached in the gravel trap during the final race after the brakes locked and the ABS failed to kick in.

Whilst we initially suspected a failed brake master cylinder, the post race diagnosis was in fact that the alternator had failed.  There is no volt meter display on the Boxster dashboard (unlike its bigger brother 911) and the battery warning light seems to only come in some failures not all. It's not that surprising that the engine ancillaries tend to fail more often when the car is tracked.  With the engine running constantly at high rpm, they get harder use than they are designed for.

We have also been suffering from a leaking power steering pump caused by the vibration of the engine wearing the joint separating the reservoir from the pump.

Having to tackle one of these jobs is quite time consuming due to all the bits you have to remove to gain access. It made sense to change both ancillaries at the same time, making for a pretty long, days work.

There are always "whilst your in there" jobs on any Porsche, so we took the opportunity to fit an ancillary under-drive pulley.  This replaces the crank pulley driving the ancillary belt with a smaller diameter one. The benefit of this is that it slows the alternator, steering and water pumps by around 25% to give them more of a normal life.   As an added bonus, less energy driving the ancillaries in theory adds a few BHP to the engine output.

So drivers seat out, engine covers off, top of the air intake removed and you can at least get some access.  The roll cage makes it even more difficult though.

Tricky Access to Top of Engine with Roll Cage

Reading the factory manual and a few online forums gave us the insight that the alternator required a special procedure to remove it. A few large hammer blows in the right place and it was free it from its mounting. The power steering pump has a more delicate release mechanism for the hydraulic line which came out quickly too with the help of a second pair of hands.

Our car already has the air-con compressor removed which made access easier on the left side of the engine bay.
Ancillaries Removed
Small Under-Drive Pulley

After cleaning up the power steering fluid; which was everywhere, and quite a lot of stones which somehow got on top of the engine.  Don't go in the gravel traps!.  Final refitting included a new shorter drive belt to fit the smaller pulley.

Hopefully this sets up us for a good, trouble free performance in July at Donington Park.