Peculiar appetite for bulbs

[zcacogp]

Chaps,

An odd one. My 944 has developed a peculiar appetite for bulbs in the rear lights. More particularly, for the tail light bulbs (which come on when the headlights are on.) I have fitted five new bulbs in the last two months, and things came to a head when I did a 250 mile journey last weekend and arrived to find that both bulbs had blown en route. (That was particularly annoying as I only had one spare.)

I've had the car for six years and the appetite has developed recently, and I have no idea what has caused it. Nothing else has changed electrically and there are no other electrical faults. And it's only the tail lights that are affected.

Is this a known phenomenon or am I just the victim of statistics (or a random collection of bad bulbs - all bought from different places, I'll add)?


Oli.

[Ozzie Osmond]

Where do you buy your bulbs?

I gave up with Halfords years ago and just buy decent ones from the local Merc/BMW dealers.

[zcacogp]

Five bulbs, from memory, as follows;

- Two from local motor factors
- One from MOT station (it was duff when I had the MOT done)
- One from motor factors in Derby
- One in my toolbox, bought yonks ago.


Not all from the same batch, and probably not all from the same manufacturer either.


Oli.

[Prof Prolapse]

Daft question... Are you careful not to get the grease from your fingers on them?

[zcacogp]

PP, They are regular bulbs - not the halogen/quartz things. Does the grease-on-fingers things matter with these as well? I didn't think it did.


Oli.

[LuS1fer]

No idea but I had this with a Toyota Carina II when the brake lights would vanish. The rear lights on that were mounted on a big rubber pad so maybe it's an ineffective earth problem where the poor earth works but causes the bulbs to blow.

[Prof Prolapse]

Greasy bulbs is never a good thing but I couldn't quote significance. Just give them a decent wipe / wear gloves when you fit. It's not a particularly interesting answer but worth a go surely?

[Ozzie Osmond]

zcacogp said:

Five bulbs, from memory, as follows;

- Two from local motor factors
- One from MOT station (it was duff when I had the MOT done)
- One from motor factors in Derby
- One in my toolbox, bought yonks ago.


Not all from the same batch, and probably not all from the same manufacturer either.

Like I said, try bulbs from BMW or Merc dealer - solved my problems.

PS If your voltage regulator is knackered you will blow bulbs frequently - but I doubt that's the case. You can check by connecting a voltmeter to your cigarette lighter and watching it as you drive around. You shouldn't see more than 15 volts maximum at any time (i.e. normal battery charging voltage).

[vrsmxtb]

I've replaced one of my dipped beam bulbs twice (offside), and never the otherside.

[motco]

You should check the line voltage when the engine is above idle. If it is excessive - >14.5v - the regulator on the alternator may have failed. I cannot see how a greasy exterior can affect a standard glass envelope bulb. The quartz ones are much hotter and the contamination etches the envelope.