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Discussion Starter #1
Im wanting to know if anyone has ever had problems with there head light burning out all the time, but just the low beams? My head light take turns burning out left the right ect... this happens just about every other day. Today I had to replace the right side and by the time I got to the other side it was burn out:dunno: im very confused as to what is going on. Thanks Ray
 

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I only had three H7 bulbs burn out on my (2002 E39) in the past three years, an average of about one a year but in this headlight bulb thread, people do mention that the bulbs I use burn out too quickly.

Maybe we should keep some stats starting now ...

 

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1) What type of bulbs are you using?

2) Are you touching the glass portion of the bulbs at all when you install them? This can lead to quick bulb failure.

3) Has the wiring of the bulbs been hacked into in any way?

4) Are you sure they're burnt out? Or is there a bad connection causing them to simply go out?

5) The voltage regulator on your alternator could be going out and causing voltage spikes. Do the bulbs burn out only when the car is running?

My money's on some kind of voltage spike causing them to blow. Not sure if there's a relay for the low beams (I assume you have halogen), but this could be a factor.
 

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I vote for #2. I've not had a bulb burn out since I've owned the car (2001).

Whenever I replace a halogen bulb, just to be safe, I wipe the glass with an alcohol wetted rag. Hand oil will cause the bulb to overheat, sometimes to shatter.
 

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As a rule of thumb, wipe the glass portion of the bulb with alcohol to remove any grease from the hand etc.

Another possibility of frequently burned bulb is bad alternator regulator.
 

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Discussion Starter #9
I am using the only brand carried in my town, and all they have is the sylvania h7st silver star. I make sure to not touch the bulbs I was wearing gloves.Took a good look at the wiring and didnt see any splices. Havent had a problem with them not wanting to seat. Im not sure on how to check my voltage regulator could you shed some light on that, or just replace the alt.?
 

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Silverstars are known to burn out very quickly -- they also filter light, so you don't get as much light on the road, despite their claims.

Most automotive chain stores can perform a rudimentary check of the charging system. If you have a voltmeter, you can use it to check the voltage across the battery terminals with the car running -- it should be a constant 14.5 volts or so (if I remember correctly).

On many alternators the voltage regulator is internal, but on some it's external -- someone else will have to pipe in on the case of the 97 540I.

A hint from my experience -- and I am not saying this is happening for sure, you will need a proper diagnosis -- I had both of the high beams blow at once on one of my cars, and sure enough, the alternator died about a month later.
 

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Discussion Starter #11
thanks for the info ill do some more research on it and try to get a different brand. do you recommend any brand of bulb?
 

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it really sounds like a short. try checking the wires that are connected to the low beams, and make sure they are properly insulated. then spray electrical cleaner to clean the wires and bulb holder. make sure the contacts on the bulb holder are clean of any dirt or grease. if you noticed any part that is not properly insulated, use electrical tape to better insulate them.

please report back if that helps:)
 

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Get a digital voltmeter at Harbor Freight for $5.00.
Sit in the car with engine running, probe the cigarette lighter terminals and take reading with different engine rpm's.
It is an easy way to diagnose a bad alternator.

Standard procedure for Bosch alternator:
http://caunter.ca/volvo960/vp14805.pdf

Voltage should be around 13 to 15V max.
Above 2000 rpm, Voltage should stay at 15 V max.
 
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