burtiebumfluff

hi all,the main light bulbs on our 2l gx sport 53 plate keep blowing,can any one help with this.thanks richard

alcazar

iTrader: (2)

Get the alternator voltage checked.

When you say, "keep blowing", do you mean you replace a bulb and it blows again?

JDM_Stig

iTrader: (3)

Are you touching the glass when you fit them ?

riiidaa

iTrader: (2)

fuse spec correct?

JDM_Stig

iTrader: (3)

come on then I will bite, how will the fuse rating effect the bulbs?

riiidaa

iTrader: (2)

if it's meant to be 10 and there's a 30 in that slot ?

alcazar

iTrader: (2)

Won't make any difference bud. The purpose of a fuse is only to limit EXCESS current flowing if a fault develops.

A 60W headlight bulb, for example, draws 5Amps on a 12V supply.
Because it draws slightly more for fraction of a second as the bulb filament heats up, the lowest fuse for it would be 7.5A.

But if you put 7.5A or 75A fuses in, it still draws only 5A.

Cpt Jack Sparrow

iTrader: (14)

^^^^ This is very true...

paul98typer

As above, Don't touch the bulb when fitting, any cracks in the lights letting moisture in?
Have problems with our work vans as our garage uses cheapo bulbs, headlights are ok but all other bulbs regularly blow.

riiidaa

iTrader: (2)

I thought the job of a fuse was to blow IF there was a fault.

alcazar

iTrader: (2)

That's right.

But putting in a higher value fuse won't affect whatever it's protecting UNTIL there is a fault.

Cheap bulbs are a PITA: I used to use french supermarket 100W bulbs in a Xantia, as they were only €1.99 each, but ended up replacing them every six months.

ALi-B

iTrader: (1)

Somtimes the bulb can tell you why it blew.

If the glass has gone milky or has a texture to it - water/moisture has got into the fitting. Or someone has touched the glass on the bulb (the oils from your skin cause the glass to fracture when it heats up)

If its black, there is a lack of halogen gas which has caused the metal of the filament to burn off and deposit on the glass. With halogen bulbs, it should re-deposit on the filament. Non halogen bulbs also do this, and thats normal, but can be made worse if the voltage is too high.

If the filament has fell apart at each end of the holder, then this is from "necking" and is a quality issue with the bulb or its operating at too high or too low a voltage...cheap "ultra bright" extra output bulbs can fail early like this as they use thinner filaments to give a brighter light. All filaments fail this way eventually, but obviously they should last for years, not months.

Also dirty/old/corroded bulb connectors can cause bad contact which then generate lots of heat at the base of the bulb and caase it to fail by metling the internal solder joints behind the cap, and possibly melt the connector and wiring too.

burtiebumfluff

the bulbs blow about every two weeks,goes from one side to the other but is it the bulbs,we are buying from halfords

alcazar

iTrader: (2)

As noted.

Flyinspanner

Check headlamps are mounted securely, and the bulb holders, if they are loose, vibrations whilst bulbs are lit could make them burn out.

Check your earths, if bad it could draw more current, and burn them out.
Check main switch, is it high resistance across terminals when in on position? - will draw higher current...

Get alternator output checked ASAP - if over voltage, it can kill your battery too.