1997cc SOHC vacuum \ air intake system
4th Generation Exhaust system (all models)
4th Generation Clutch Assembly from pedal to plate (all models)
4th Generation Strut\Spring suspension assembly (all models)
Watch out for the following.
No known problems on any unit 2.0/2.2/2.3
There is a known fault with the bearings on the main shaft of the distributor (this is the shaft your rotor arm is fitted on). When the bearings 'go' you will hear what's known as the 'Death Screech' coming from, what seems like the engine. Stop the car immediately - the friction which is generated from the shaft rotating with worn bearings is enough to MELT the inside of the distributor - A new distributor from the dealer is £450. Apparently it is possible to just replace the worn bearings - speak to your dealer about this.
This seems more prone than usual to overheating/bursting/splitting/leaking (you get the picture) - I've no idea why, perhaps the front of the car is too 'open' and stones come through the grill causing damage ? Anyway, a new rad. will set you back around £150 from an independent radiator specialist or you can get the 'core' of the rad. replaced for just under £100.
All Preludes (83-96) are fitted with disks all-round (vented to front / solid to rear). The rear disks/calliper's are a constant problem on all three models. The calliper's are prone to seizing and the disks tend to rust on the outer part of the surface due to poor contact with the pads. If you change the pads make sure the calliper winds back without too much effort - if it is difficult to turn it is likely that the calliper is rusting from the inside and will need either stripping or replacing (the Tokiko rear calliper's are around £90 each on an exchange basis - A new unit will cost around £300 from Honda).
Clutch Master Cylinder
This seems to have a short life (as far as I'm concerned) of around 30,000 miles (I guess it does depend on how/where you drive) I tend to do a lot of 'town' driving so I suppose the part is likely to wear quicker but not this quick ! If you have gear selection problems or the pedal seems sticky/jerky when you lift your foot off the clutch pedal then the cylinder is 'on it's last legs' - also check for fluid at the back of the pedal this indicates a leaking seal - Make sure your clutch fluid is topped up and get the cylinder replaced immediately. Considering this part is merely a small hydraulic pump (mini shock absorber) the dealers charge around £130 plus vat which I think is a downright rip-off when you compare it to a similar part which can be found on a Land Rover for just £14 !!
Timing & Idle Related Faults
If you're suffering from uneven idle (i.e. the idle raises from 900 to 2000 rpm) then there a good chance the idle control valve is either sticking or damaged. This sits under the throttle body (trace the air intake hose to the fuel injection chamber - where the hose is clipped to the side of the chamber - that's the throttle body) It monitors the air intake into the fuel injection chamber and sets the idle appropriately. This should be replaced by the dealer (sorry)
If you are using excessive fuel and suffering from uneven running then it's likely the oxygen sensor is faulty (this sits in the exhaust manifold at the front of the engine). This cannot be repaired, only replaced (are you seated ?) at a cost of £352 plus vat (fitting extra) - If you're sensor does go try ringing round a few Japanese breaker yards - they'll sell you one for around £30-40 and it'll probably be good for a few years.
This tends to rattle whilst driving if the runners have not been properly greased. The sound is a kind of tapping/knocking which seems as if its coming from the rear of the car. Use a silicon based aerosol lubricant (like Valvoline High Performance Silicon Spray) on the roof 'tracks' - do not use WD40 as it evaporates (quickly).