There are a couple of reasons your RX-8 may develop Low Compression issues, the most notable of which is the wearing of internal engine components.
In theory the RX-8’s Renesis engine should be capable of running for well over 250,000 miles and in some cases around the world, they have! Unfortunately the engine does not respond well to the type of driving that the cars are subjected to here in the UK. By that, we mean idling in traffic, short runs day-in and day-out particularly can cause peculiar patterns of wear to various internal engine components such as the stationary gear bearings, apex seals and rotor housings.
It doesn’t help that failing ignition coils also exaggerate the wear on those internal components as un-burnt fuel that left behind from incomplete ignition causes a condition known as ‘bore wash’. Oil doesn’t stick to petrol, bore wash is literally the un-burnt fuel washing away the oil layer designed to lubricate your RX-8’s seals and the resulting lack of lubrication causes a chattering and thus excessive wear to the seals and other internal components as well.
Due to the way in which apex seals are lubricated, the centre of the flat seal surface often wears faster that the outer edges. Over time this causes a gas leakage which runs past the seals because the developing ‘bowed’ edge doesn’t sit correctly against the flat edge of the rotor housings.This wear can also severely damage the rotor housings as well.
After the centre of the seals has worn, it can leave the seal edges raised slightly. These prominent edges then cause more pressure to be applied (and to a smaller surface area of the housing) causing the housings to ‘chip’ and score. The wear often means that they cannot be reused when the time comes to rebuild the engine.
In some cases the seals just wear out naturally, the level of vertical wear exceeds the point in which the apex seal springs can no longer take up the slack causing further gas leakage and thus less compression. Though this kind of wear does not often show until well past the 100,000 miles mark, and when it does, is normally pre-cursed by another type of failure.
Each cause of low compression, results in the same symptoms, most common an inability to restart the car at operating temperature (within 3-5 minutes after the vehicle has been switched off, it will refuse to restart and will need to be left to cool down for at least 15 minutes in order for restarting to be possible). Other symptoms can be low power output accompanied by an uneven idle level. Eventually these will develop into cutting out at idle and then refusing to start at all.
Unfortunately the only effective fix for low compression, is to have the engine stripped and fully rebuilt or to replace the engine altogether. For more information, contact us or read online more about our engine rebuild services.