Tuesday, July 5, 2011

Engine Bay Work

The 993 engine is a real thing of beauty, and can be fairly easy to smarten up. I have used quite a bit of plastic polish on the black bits to make them shiny, cleaned the fan (which is fiddly but noticeable) and have now replaced the Mobil 1 sticker which was old and torn.
Also notice the Porsche 'Motorsound' airbox which has a chrome look intake. This airbox is identical to the standard one, other than a number of small drilled holes on the right hand side which allegedly increases the sound. I don't think it makes any difference at all.

Air con pipes run across the back of the engine left to right with the compressor over on the right.

The engine in the 993 is 'hung' from mounts rather than sitting on mounts if that makes sense. Over time, the mounts succumb to the pulling forces and it's easy to see if they would benefit from being replaced.

The effect this can have on the driving is experience is surprisingly noticeable.

If the engine drops slightly at the back of the car (as happens when the mounts are finished) my understanding is that it's often the case that the gear change is not as smooth. The engine is mated to the gearbox, and extra pressure is put on that coupling making gear changes more notchy.

If you can fit your fingers between the top and bottom of the mount, it's definitely time for new ones!

There are 3 levels of stiffness of engine mount. C2, C4 and RS mounts which are particularly unpliable.
The general consensus is that the C4 mounts offer the best real world improvement whern changing, and that's what I've gone for.

They are hard to photograph since they are right up in the back corners.

At the same time as the mounts were replaced, I cleaned the ISV (Idle Stabilising Valve) which sits at the top of the engine and is a real pig to get off most of the time. However with the engine dropped slightly to gain access to the mounts, it's much easier and is well worthwhile.

The ISV has a butterfly valve which should rotate freely. Over time, the valve becomes sticky and clogged up and results in lumpy idle which makes the car stall easily - especially in reverse. Simply cleaning with WD40  loosens the butterfly valve and makes a tremendous difference to pulling away!

Engine Bay labelled below. Note position of the factory stickers.

1 comment:

  1. Nice post
    one question
    I can't find the proper size mobil-1 sticker
    only one available is half the size of stock
    Where did you find tours?