Sealed beam headlights - any good?

[MGFmad]

I need to replace one of my sealed beams and on looking through the large history file with the car, it seems to have needed a replacement every year, even though its not covered many miles.

Are sealed beams prone to not lasting very long? They are not expensive to replace but if I am going to have to do it regularly, I might be as well getting a halogen replacement kit.

Just wondered if this is normal.

[bmcecosse]

Usually they last for many years - mine have ! But it may be that modern replacements are not as good as the Lucas originals. If you intend to drive at night and actually see where you are going, you would be wise to change to Halogen units.

[wanderinstar]

If you do go the halogen replacement route, use Xenon bulbs. They are 30% brighter and it shows.

[bmcecosse]

I agree -fitted them to my Meriva and it makes quite a difference. My Traveller never goes out in the dark!

[simmitc]

Constantly blowing bulbs of any sort could indicate a porr earth. There should be a black lead coming from the headlamp to an earth clip on the inner wing inside the engine bay. Could be worth cleaning the connections. I agree that Xeons are superior; but sealed beams are adequate for most driving. If you go for replacement lamps then it's woth spending a little more to get the genuine Quad-Optic lenses which have a curved front. The cheaper ones are flatter, don't give as much light, and don't last as long.

[MGFmad]

You could be onto something there with the poor earth, the engine bay wiring was in a bad way when we got the car (as was the engine bay! see below)
I have fitted a new front end onto the car, made new earth connections onto the new panels and got rid of these horrible scotchlok connectors. I think I will just go with a new sealed beam unit, its unlikely that the Traveller will get much use after dark.

[Luxobarge]

got rid of these horrible scotchlok connectors.

You did well.

Scotchlok = work of the devil IMO.....

[bmcecosse]

Can't for the life of me see how bad earth could cause bulb failure! It would introduce extra resistance = lower current to the circuit, so dim lamps yes, but bulb blowing no. Vibration is the most likely cause - if the headlamp was say loose in the mounting and could bounce around - then that could shake the filaments and cause early failure. It's also how they can tell if a light was ON in a bad crash - if the filaments are broken then they were OFF, if they are unbroken but 'stretched' - then they were ON.

[simmitc]

A bad earth is typically intermittent in operation. In one situation this might produce a light that is dim, or perhaps one that sometimes works and sometimes doesn’t. In another installation the light might appear to be on constantly, but is actually cycling as resistance builds and collapses through the poor connection. This can be a fast cycle but still simulates on-off actions which produce a surge that shortens bulb life. That's the theory (a bit like an ignition system), and it seems to work in practice.

[bmcecosse]

Sorry - I don't buy it!

[MGFmad]

Can't for the life of me see how bad earth could cause bulb failure! It would introduce extra resistance = lower current to the circuit, so dim lamps yes, but bulb blowing no. Vibration is the most likely cause - if the headlamp was say loose in the mounting and could bounce around - then that could shake the filaments and cause early failure. It's also how they can tell if a light was ON in a bad crash - if the filaments are broken then they were OFF, if they are unbroken but 'stretched' - then they were ON.

BMC you could be right with the vibration theory, this was the state of the front wing when bought-

[bmcecosse]

Could be! Also - not Lucas lights - could be some Foreign Johnny make !

[linearaudio]

The thing that amazed me when I first driv the traveller at night was that I could actually see quite happily with the sealed beam units. This was alarming as I had previously been driving a "modern"-ish Xantia, and I hadn't appreciated just how useless the Halogen lights on that had been. So much for progress, French style!

[Onne]

Morris Minor headlights are the ideal shape for a good beam of light.

All these modern boxes have all sorts of stupid bent backwards and across shapes!

Long live the Lucas 7"

[d_harris]

Imho Sealed beams are more than adequate. If you come across some halogens on the cheap then definatly worth fitting. But if not then they don't make a huge deal of difference, but better if you do get a bulb out (after all, when did you last see a sealed beam unit in a garage?)

[Onne]

Or if a bulb goes when you're on the continent.
Sealed beams are not available there at all.

Halogen conversion is around 30 pounds, so I think cheaper in the long run.

[MGFmad]

Could be! Also - not Lucas lights - could be some Foreign Johnny make !

The last owner had them fitted by his local garage (supplied at the not to attractive price of £17 a go) - it needed a replacement every MOT! the name on the lense is 'Wagner'

I remember fitting a halogen conversion kit to a Mini I had around 10 years ago, it did make a difference. I did think for a while that I may still have to old Mini sealed beams stored away but no luck finding them

[bmcecosse]

Well you can still buy sealed beams and in fact the higher power 75/45 units were available again recently. These are only legal on early cars (not sure of date) and later cars must not have more than 55W lights. But - there is no doubt - halogen lights are far supperior if you wish to drive at night - especially is you fit the 'super white' type bulbs (not the daft blue ones !) which claim to be 30% brighter. I put these in my Meriva main beams and they are much brighter! But my Traveller still has it's poor old standard 60/45 sealed beams- and I had to use it early one morning recently in the dark - and I was horrified at how bad the lights are compared to modern lighting. So - if spending any money on the lights- do go halogen - they really are much much better!

[Luxobarge]

Sorry - I don't buy it!

The main governing factor in a filament bulb's life is how many heating/cooling cycles the filament goes through. If - and I stress if - the "bad earth" is intermittent, then as the car drives, the voltage supplied to the bulb is likely to be fluctuating constantly. This will cause the bulb filament temperature to change frequently - this could be many times a second, thus putting a great deal of stress and fatigue on the filament, which will expire prematurely. Compared to a bulb with good connections and a stable supply voltage, when switched on it will achieve its design temperature and stay there, haqving gon ethrough only one heating cycle, and once "on" it would probably have a very long life - it's the switching on and off that kills them, and a bad intermittent earth will replicate this situation.

A "bad earth" is likely to be intermittent, as it is in effect a bad connection and the motion and vibration of the car is likely to make the miniscule amount of movement in the connection that will change its resistance constantly.

I'm pretty sure I'm right with the above theory - happy to be corrected though!

Cheers

[MoggyTech]

I'm pretty sure I'm right with the above theory - happy to be corrected though!

Cheers

You are spot on.