Q&A Technical issues solved
Michael Cleverley of Cleverley Repaired Cars, expert on all things MX-5, answers your questions
This issue: yellowing lights, a power-sapping alarm, and a spongy clutch
BRING ON THE NOISE
QThe door speakers of my mk1 rattle and sound poor. Is it easy to change them?
AThese cars are getting old and things like the speakers are starting to cause trouble – they get damp and the cones soften leading to failure.
Remove the door card by prising out the blanking plugs from the door pull and unscrewing the three crosshead screws. There is a crosshead screw behind the internal door release handle – remove that and take out the plastic trim that it retains. Cars with manual winding windows need the handle removing: do this by removing the horseshoe clip that is behind the winder (a strip of cloth looped behind the handle and pulled down, or fiddling with a screwdriver will prise the clip off without too much difficulty). Now the door card is removed by prising the clips out along the sides and bottom edge of the door using a trim tool or screwdriver, being careful not to scratch the paint.
Lift the card out and upwards to release it from the door top. Now replace the speaker. We like to fit upgraded units, such as those made by Alpine, to improve sound quality. Generally they’re a straight fit, but you may need to change the two wire connections to suit. Whilst in there, why not lube the window cables and door locks.
Reassemble once you’ve checked the speaker works.
TOO MELLOW YELLOW
QI have a mk2 and the headlamps have failed the MOT test because of poor light output. The lenses are yellow and cloudy. New lights are expensive, so is there anything I can do?
AThe headlight lenses on most cars are plastic – this has the advantage of being tough, lightweight, safer in an accident and, I presume, cheaper to make. They work well but unfortunately some will degrade over time and ‘yellow’.
Eventually the brightness reduces and even high-output bulbs won’t improve night vision. Incidentally, the bulbs used in these lights are designed not to cause this degradation and using normal bulbs can speed up the yellowing process.
New light units are costly. However, if you’re prepared for a bit of effort, Autoglym and others sell renovation kits. These involve a series of abrasive pads that you use with water. Working from coarse to fine, you buff the wet lens using a cordless drill, finally polishing the lens with the supplied compound. Surprisingly good results can be achieved with some elbow grease.
BABY IT’S COLD INSIDE…
QI have a 2.0-litre mk3 and the heater output is rather poor – what should I check for this please?
AAs long as the heater fan is blowing correctly, look to the cooling system for problems.
First check that the coolant level is not very low: if it is, air locks can stop the heater working. Find and cure the leak then refill the system with the correct FL22 coolant.
Next you need to check the operation of the thermostat. When the engine is cold, the thermostat should be closed so coolant in the radiator should not be circulating when the engine is running. This gives a fast warm-up. Check this by feeling the temperature of the top hose running to the radiator.
The top radiator hose should stay cool until the temp gauge reads about halfway. As the thermostat then opens, the top hose should heat up quite quickly indicating that coolant is now flowing through the radiator. At this point the thermostat should open and close to maintain running temperature (just below boiling point). If the coolant flows through the radiator immediately after a cold start – indicated by the top hose slowly warming up soon after the engine is started – or before running temperature is reached, you need to replace the thermostat.
This is quite an awkward task on a mk3. It’s located on the inlet side of the engine under the manifold towards the front of the engine. Removing the throttle body just about gives enough access to carry out the task. The cooling system selfbleeds when you run the engine. With correct running temperature the heater should be very effective and fuel economy will be improved.
Incidentally a Ford equivalent from a similar aged Duratecengined car is the same as the Mazda’s thermostat but quite a bit cheaper.
DON’T BE ALARMED
QMy mk1’s battery keeps going flat after a couple of days’ inactivity. I’ve changed the battery and checked it charges, with no joy – any ideas?
AMazda electrics and batteries are very reliable: even on old ones we don’t have many problems. With this particular car we re-checked the charging and the new battery condition, which seemed fine.
Next we placed an ammeter into the positive circuit of the battery. No discharge was recorded. We noted that the car was fitted with an aftermarket alarm system, which when armed caused a current draw of more than ten amps! Although alarm systems do create a slight discharge, this is rather more than normal.
After talking to the customer we decided to return the car to standard. We removed a rat’s nest of wires, made good the original wiring and the problem was cured. All alarms draw a small amount of current that shouldn’t cause a problem, but it is really important to install them neatly and with good connections or else reliability is likely to suffer.
QI’m having trouble engaging gears, particularly reverse. The clutch pedal feels softer than it used to. Please can you offer some advice as to why?
AAll generations of MX-5 use an hydraulic clutch mechanism. It’s reliable and as a result is often ignored.
Just like the brakes, the fluid used is hygroscopic (absorbs moisture from the atmosphere) so can deteriorate over time. This causes corrosion in the master and slave cylinders, leading to a failure. If the fluid in the clutch master cylinder is brown or black in colour then it should be changed. If changing the fluid makes no improvement I suggest replacing the clutch master and slave cylinders.
It’s straightforward. The master cylinder is mounted through the scuttle using two nuts, one reached from the footwell and one from the engine bay. The pushrod can be left connected to the pedal.
Carefully remove the slave cylinder feed pipe catching any fluid drips (the fluid strips paint). The clutch slave cylinder bolts to the gearbox using two 12mm-headed bolts: again remove the feed pipe being careful to catch the fluid drips.
Once new master and slave cylinders have been fitted, check the master cylinder pushrod adjustment at the pedal. There should be slight free-play before the pedal starts to move the pushrod. Bleed out by filling the master cylinder with fresh brake fluid.
A helper will be needed to operate the clutch. Open the bleed nipple on the slave cylinder and ask your helper to fully depress the clutch. When fully depressed, close the nipple and ask your helper to release the clutch pedal.
Repeat until air-free fluid flows from the slave cylinder. After this the clutch hydraulics should be as good as new, and pedal feel back to normal.
With the door card removed, replacing the speaker is relatively simple
Bringing a mk2 headlight back to life using an Autoglym renovation kit: very satisfying
Problems with your cabin heater can be caused by a defective thermostat – if it is faulty, its location on the engine will make fitting a replacement an awkward task
Aftermarket alarm systems, particularly when poorly installed, can sap charge from your battery and drain it within a couple of days: get rid!
Knackered clutch master cylinder and attendant pushrod assembly – replacement is fairly straightforward, but you’ll need a friend to help