mick h Posted January 25, 2022 Report Share Posted January 25, 2022 HI Everyone A strange happening, don't know if it is coincidence, but doing work around the steering column and speedo, as checking items, burned the dipped beam on two headlamp sealed units. Smoke in the unit. Then another, now burned out a full beam. Voltage at the connectors is less than, but near 12v. Are any of the headlamp filaments not designed for 12v, or could I have done something else wrong? I totally restored this car including all wiring and welding and it has been fine for a couple of years. I just don't want to burn more lamps out if there is some reason behind it. Quote Link to post Share on other sites
RobH Posted January 25, 2022 Report Share Posted January 25, 2022 (edited) Welcome to the forums Mick. The lamps should be built to take a bit more than 14v which is what they may see when the engine is running and giving a charge. Was the engine running at the time it happened ? If so It is just possible something happened to cause the alternator to give out more voltage momentarily, but that depends on the type fitted to your car. Some older styles use the battery as a voltage reference, and if that connection were lost the alternator voltage output might rise. If the engine was not running I don't think there is anything you could have done to cause it, except perhaps if you had both main and dip powered at once for a length of time. That might overheat things if it went on long enough Edited January 25, 2022 by RobH Quote Link to post Share on other sites
mick h Posted January 25, 2022 Author Report Share Posted January 25, 2022 hi thanks for the reply,have only turned the engine over one or two revs??also have a tr4a that im working on and burnt out both of those sealed beab units ????? Quote Link to post Share on other sites
RogerH Posted January 26, 2022 Report Share Posted January 26, 2022 Hi Mick, did you buy the four sealed beams at the same time??? it could be a quality issue with a batch. Have you considered replacing them with H4 bulbs and lenses Roger Quote Link to post Share on other sites
stuart Posted January 26, 2022 Report Share Posted January 26, 2022 Sealed beam units that have been in storage for a very long time (Lets face it we havent really used them for anything for many years) do tend to burn out very quickly when pressed back into service. Just bin them and go to standard H4 or LED if that floats your boat. Stuart. Quote Link to post Share on other sites
keith1948 Posted January 26, 2022 Report Share Posted January 26, 2022 When you say smoke in the unit do you mean inside the sealed beam itself. If you have a hairline crack in the glass then you get white smoke inside and it doesn't work anymore. Had this on one of mine. Must have been dropped at some point before I bought it. There was a tiny chip on one edge and a tiny crack. I was testing it on the bench before fitting and as soon as I fired it up, the heat must have opened the crack and either gas escaped or air rushed in and that was the end of it. Keith Quote Link to post Share on other sites
RobH Posted January 26, 2022 Report Share Posted January 26, 2022 2 minutes ago, keith1948 said: either gas escaped or air rushed in The whole sealed-beam headlight is the bulb and has to be under vacuum - there is no gas fill as these are not halogen. Even minor air leakage is fatal to the filaments. Quote Link to post Share on other sites
mick h Posted January 27, 2022 Author Report Share Posted January 27, 2022 thanks for the help,am going to try h4 bulbs Quote Link to post Share on other sites
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.