Q&A Prob­lems re­solved

Michael Clev­er­ley of Clev­er­ley Re­paired Cars, ex­pert on all things MX-5, an­swers your ques­tions

Total MX-5 - - CONTENTS -

Fried electrics, a sod­den boot, and im­proved heel and toe­ing keep our MX-5 ex­pert busy this is­sue

SMELLS LIKE… Q

My mk3 has started to make a lot of noise all of a sud­den and smells of fumes. Have you any idea what has hap­pened please?

A

It sounds to me like a prob­lem with the ex­haust sys­tem. The mk3 ex­haust sys­tem is quite heavy, and now that they are get­ting older we have seen a num­ber of them crack­ing just on the weld be­hind the bomb-shaped cen­tre si­lencer. The cure is to ei­ther re­place the part (maybe a good time for an up­grade) or it’s quite easy to re-weld the pipe, as the break is usu­ally very clean. To do this I tend to tack weld it whilst on the car (with the bat­tery dis­con­nected) and then lower the sys­tem to the ground to weld it com­pletely. It is pos­si­ble to do in situ but much harder to achieve a neat re­sult.

THE LIGHT STUFF Q

Whilst driv­ing my car at night re­cently I could smell burn­ing and now my lights don’t flick be­tween main and dip re­li­ably: what’s go­ing on?

A

This was a cus­tomer of ours with a rare prob­lem on an MX-5 – an elec­tri­cal fault! Gen­er­ally with MX-5S if I have an elec­tri­cal fault I check for any non-stan­dard ad­di­tions to the car first, as the orig­i­nal electrics are very re­li­able. In this case hav­ing re­moved the headlight stalk and found the ter­mi­nals melted. I de­cided to look for the cause, as they are not a prob­lem usu­ally.

It seemed as though the stalk had been sub­jected to a high elec­tri­cal load. On these early cars the stalk switches the lights from main to dip with­out a re­lay to take the strain. With this in mind I popped the head­lamps up and re­moved the light units. The sealed beams had been re­placed with halo­gen, a con­ver­sion, which is nor­mally OK. Look­ing at the bulbs, they were a very high out­put type draw­ing more than stan­dard am­per­age – too much for the switch con­tacts to cope with. The cure in this case was a sec­ond­hand dip switch trig­ger­ing a re­lay that sup­plies the power to the bulbs. It’s a sim­ple wiring job that any com­pe­tent DIY en­thu­si­ast should be able to carry out.

PLAY­ING FOOT­SIE Q

I’m look­ing to do some track­days in my mk3 but am hav­ing trou­ble heel and toe­ing in it – is there some­thing that can be done with the ped­als to make it eas­ier?

A

One of our cus­tomers asked us to do some up­grades on their mk3 2.0 Sport in prepa­ra­tion for track­day use. We fit­ted up­rated coilovers, up­rated brake pads and care­fully aligned the sus­pen­sion to a more sporty spec. Also we re­placed the man­i­fold with a stain­less steel de­cat unit. A

remap saw 175bhp on the dyno.

She was very pleased with the re­sults. How­ever, she was hav­ing trou­ble heel and toe­ing, so we looked at im­prov­ing the pedal setup to suit her. We needed to raise the throt­tle pad and bring it closer to the brake. The pedal on a mk3 is a moulded plas­tic item so we couldn’t bend it or weld to it.

So we mod­i­fied a com­mer­cially avail­able alu­minium pedal pad us­ing some 6mm-thick rub­ber sheet glued to its back, trim­ming the ends to suit the car and fi­nally bonded and screwed the pad to the throt­tle pedal, mov­ing it slightly closer to the brake pedal at the same time. Re­mem­ber when do­ing mod­i­fi­ca­tions of this type you must be cer­tain that the work done is safe and se­cure.

LEAK­ING ‘FRANKEN­STEIN’ BOLTS A PAIN IN THE NECK Q

My mk1 keeps leak­ing wa­ter into the boot. I can’t see where it’s com­ing from – what should I look for please?

A

Check the boot seals are in good con­di­tion: I would en­sure that the ae­rial is se­cure and its seal in­tact. In­spect the drain hole in the petrol flap area to make sure it’s clear and its gas­ket is in good con­di­tion.

The next ar­eas to con­sider are the bolts (known as ‘Franken­stein’ bolts, for ob­vi­ous rea­sons) that se­cure the rear of the hardtop in place. With these and the plain bolts fit­ted to stan­dard cars there is an Oring at the base of the bolt and a gas­ket un­der the chromium fin­ish­ing plate. Re­move the bolt care­fully so as not to break its cap­tive nut free, or strip the crosshead out. Lift the plate up and clean; re­seal the gas­ket us­ing sil­i­cone sealant. Re­fit the bolt with grease on its threads and sil­i­cone on the O-ring. Ad­dress­ing these points should en­sure a wa­ter­tight boot on mk1s and 2s.

STICKY SIT­U­A­TION Q

If I drive at 60mph or more for a few min­utes in my mk2 the power drops off and the car drifts about on the road: there’s some jud­der­ing through the steer­ing wheel, too – please can you tell me what on earth is go­ing on?

A

This cus­tomer was driv­ing his mk2 to us for an MOT test from a fair dis­tance away. We re­ceived a pan­icked call from him say­ing that the car’s en­gine was play­ing up. He de­scribed loss of power when driv­ing at 60mph for five min­utes or more, the car drift­ing about on the road, and some jud­der­ing through the wheel. After stop­ping for a few min­utes all was well again.

He ar­rived a bit late and said at slower speed the car was OK, so I agreed to carry out the MOT and see what turned up dur­ing the process. As it hap­pened, the car sailed through the emis­sion test and passed the MOT. The only thing I could see that wasn’t quite right was a slightly stick­ing off­side front brake – the disc was black and the rust around the edges bright red, a sure sign of trou­ble!

I dis­cussed the prob­lem with the owner and after a bit of in­ter­ro­ga­tion we as­cer­tained that the car would drift to the left un­der brak­ing when the jud­der­ing was tak­ing place. I con­cluded that the power loss was not an en­gine fault, but brakes bind­ing hard after get­ting hot which even­tu­ally over­heated and jud­dered fol­lowed by fad­ing, hence the poor brak­ing per­for­mance at the time. The funny thing is that they passed the MOT test and only had slight signs of stick­ing when ro­tat­ing the wheel, although one disc was ob­vi­ously get­ting hot.

The cure was to strip the calipers (al­ways do both), clean the pis­tons, rub­ber grease the seals and re-as­sem­ble. Fresh brake fluid and the car’s ‘en­gine fault’ was fixed!

Headlight stalk ter­mi­nals can melt, but it’s a very rare fault in a mk1

Mk3 ex­haust welds are start­ing to crack with age, but can be re-welded

Disc show­ing signs of ex­ces­sive heat Strip­ping down the brake caliper and lu­bri­cat­ing the com­po­nents with ap­pro­pri­ate grease solved an ‘en­gine’ prob­lem

Mod­i­fied af­ter­mar­ket throt­tle pedal helps heel and toe­ing in a mk3

Pos­si­ble site of wa­ter ingress

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