Sealed beam?!?

[Bonnewagon]

What a blast from the past. I had the outer high/low port side sealed beam fill up with an inch of water. It was dark looking lately but I did not know why. When I took it off to see, there was all that water. There was stuff growing inside. I haven't seen that in decades. How does it get in? And why doesn't it get out? Inquiring minds want to know. Worse, when I scrounged through my headlight collection, a lot did not work. I am going to have to order some and stash them for later. Helpful tip: replace the crappy sheet metal screws the factory used to retain the stainless bezels. use stainless steel sheet metal screws. You are welcome.

 

[pagrunt]

There must be a top gap in the sealant used to bond the glass housing & outer lense. Only an issue with halogen bulbs. AS for those screws, all the fefreshed buckets for both cars got stainless screws as part of the refreshing cause those plain steel ones were a bad bean counter's idea.

 

[Bonnewagon]

the sealant used to bond the glass housing & outer lense

While going through my stash of bulbs, I set a likely looking one on the work bench. When I went to pick it up later, the whole front lens fell off! It was like the bulb was made of two parts glued together and it failed. I had no idea that was how they are made. That would explain the water getting inside. And yet with that much water, both beams still worked.

The bulbs seem to be pretty available. Any advice on the 'extra bright' versions? LED versions are $100?!?

Another thing- I see 'low', 'high' and 'low/high' one for sale. Aren't all the three prong bulbs 'low/high' ?

 

[08Malibu]

While going through my stash of bulbs, I set a likely looking one on the work bench. When I went to pick it up later, the whole front lens fell off! It was like the bulb was made of two parts glued together and it failed. I had no idea that was how they are made. That would explain the water getting inside. And yet with that much water, both beams still worked.

The bulbs seem to be pretty available. Any advice on the 'extra bright' versions? LED versions are $100?!?

Another thing- I see 'low', 'high' and 'low/high' one for sale. Aren't all the three prong bulbs 'low/high' ?

Had the same thing happen to one I had on the shelf. Unfortunately the lense hit the floor and broke.

 

[69hurstolds]

Not going to insult your intelligence here, but only providing extra info for those who may not know about the G-body quad headlamp affairs.

If you got the rectangular 4 x 6, the three prong is technically a low beam/high beam, aka 4652, or GM p/n 5966200 from the factory. But they usually just call them low beams, notated as "2A" on the bulb. High beams are notated as a 1A on the bulb (non-halogen were 4651, or GM p/n 5966201, halogens were H4651, or GM p/n 5930567).

"Low beams" are three prongs. Tan wire to low beam, green wire to high beam which jumpers over to the high beam bulb, and a black ground. G-cars are set up that the low beams go off during the high beam operation, but get power through the high beam circuit, thus all 4 are headlights light up. They do this because they have a spare lamp circuit that comes on (green wire) when the bright lights are on. The high beam selector switch in the column takes power away from the tan wire (low beam only) and provides power through the green wire to the spare element in the low beam bulb and the high beam at the same time. There are other cars that have the low beams go off when the high beams are on. (I believe the 87/88 is like this, but I can't recall) So in reality, there's 2 elements in the low beam bulb, the low circuit and high circuit. This is why sometimes when only ONE element goes out on a low-beam bulb, it can light up in the other mode. It can mess with your head if you don't know about that 2nd low beam circuit.

 

[Bonnewagon]

the lense hit the floor and broke.

Same here. Surprised the crap out of me!

So in reality, there's 2 elements in the low beam bulb, the low circuit and high circuit. This is why sometimes when only ONE element goes out on a low-beam bulb, it can light up in the other mode. It can mess with your head if you don't know about that 2nd low beam circuit.

That is exactly what happened. I had no idea about this. I just replaced bulbs by either the 1A or 2A designation. So are the 1A high beams actually brighter? Because mine all look the same when they are on. Or maybe they are just old?

 

[Bonnewagon]

When I look at RockAuto for my actual 1983 Bonneville lights, they are listed as either high or low beam [4651 and 4656]. But I have a 1981 LeMans nose and those are listed as 'high and low beam' [6054]. The wiring is the original Bonneville, I wonder if the 'high/low' bulbs would work with that wiring? Maybe not if the low beam wiring is not there for the two high only bulbs. Maybe I can re-wire with some Firebird sockets I have.

 

[69hurstolds]

Age can have an affect on the old style headlamps. Especially if the glue doesn't hold and they get fogged. However, the way the lenses are cut and the reflectors make the difference most of the time.

Oh, H4656 works too as the replacement for 4652. Forgot about that. AFAIK, the H4656 is a halogen low beam. I don't know if they ever came in a "regular" lamp, only halogens I've seen.

BTW, the 1A and 2A designators isn't the number of filaments. It's the classification of maximum candlepower output. Forget what those limits are, but that's what it's for.

One thing that lots of people do is have the low/high beam circuits run relays to power 12V directly from the battery to the headlights. This puts FULL 12V (nominal) to the lamps instead of having to run through teeny little wiring to get maximum brightness. Lots of ways to wire those relays up, btw.

Here's just ONE example from a Chevy Truck forum. Other than the shape of the bulb, it would be exactly how the G-bodies are setup. It shows one way how you can get full power to your headlamps with only two cube relays and a bit of battery positive wiring and some ground wiring. You still want to run an inline fuse as well for the battery wire, just in case. Of course, if you want it to look factory, you're going to have to get creative to hide it.

 

[Bonnewagon]

BTW, the 1A and 2A designators isn't the number of filaments.

Both my 3 lug 2 filament low beam bulbs are 2A, and both my 2 lug single filament high beam lugs are 1A. If the number is candlepower I would think it would be the other way around?

The high beam selector switch in the column takes power away from the tan wire (low beam only) and provides power through the green wire to the spare element in the low beam bulb and the high beam at the same time.

So in 'high' the low beam is still a low beam? Why do that I wonder? It would make more sense to be a 'high' and a 'low' so that in 'high' all four would be high beams. Maybe the smart move would be to get some of those 6054 'high and low' bulbs that are actual high beams when enabled and put them in the low beam spots.

I went back to the 4656 that broke and clipped out the actual bulb inside. Both filaments looked identical. So I guess they are really both 'low' otherwise a 'low/high' would be wound differently like an 1157 tail/brake light bulb.

 

[69hurstolds]

You would think 1A would be less but no. 1A is higher candlepower output than a 2A bulb. AFAIK, there isn’t any other designator like 3 or something.

I’m not an electrical engineer so I have no idea why they made the bulb circuits the way they did. Maybe the fact that 4 x 6 bulbs are kinda small, along with many other 4 lamp systems, but look at a 93-97 Camaro if you want to see tiny headlights.