60 Buick vacuum switch mystery

I'm restoring the engine compartment on my 60 Le Sabre and am puzzled by a vacuum operated switch I found under the hood. Its located at the glass bowl fuel filter bracket. The switch is disk shaped, has a small vacuum line and two wire leads. What's the purpose of this switch?

Another question is how is it mounted ? Mine was zip-tied to the radiator hose but it appears from a picture in the new issue of Hemmings Classic Car that the switch is mounted to the fuel bowl bracket. ANt help with this is much appreciated

Hi,

I looked in my Buick parts manual , and it lists in group #1.150 : Switch, Water Temperature part #1998874 (for all '60 models) , and describes it

: Switch, temp. indicator vac.- assm to fuel filter brkt.

I thought it might be for the 'idiot' lights for hot/cold, but it lists another water temp switch in the right cyl head for '60-'63 all full size models. I owned a '60 LeSabre Convertible the same color inside and out as the one in the new Classic Cars mag, but it's been so long ago, I can't remember the switch you're referring to.

I'll try to research this a little more and get back to you.

kaycee

Thanks for the reply Kaycee. You right in that there is another temperature sending unit in the right head. The wiring for these two piece (Sending unit and vacuum switch) are interconnected. What the purpose of the vacuum switch, I can't figure out?

Page 10-89 of the 1960 chassis manual (if you have one)

If not, here is what it says.

If the engine cooling system is not functioning properly and the water temp reaches 248 degrees, the HOT indicator will be turned on by the temperature switch (in the head). As a test circuit to check whether the HOT indicator bulb is functioning properly, a vacuum switch is incorporated into its circuit. When the engine is not running, but the ignition is switched ON, the temp vacuum switch completes the circuit from the HOT indicator to the OIL indicator. As there is no oil pressure, the HOT indicator light is grounded by the oil pressure switch and is lit. When the engine is started, the temp vacuum switch opens and the this test circuit is the HOT indicator is then controlled by the temperature switch.

HIGHLY INTERESTING, ADAM! I guess that's confirmation that when the "HOT" light isn't lit, everything's as it should be when the engine is running?

Enjoy!

NTX5467

I forgot to mention - the way that vacuum switch mounts, is a clip that is molded into the white plastic on the bottom side of the switch itself. It just clips into the hole that is on top of the bracket.

Well that's a nice explanation of a strange set-up. I'm sure its a 1960 only item. I don't recall seeing this on any other Buicks..

Well, can anyone help with a replacement vacuum switch? The rubber pad on mine is toast!

Thanks again, Joe V.

Cool information. This is what this forum is best for. If I ever get a 60 ( which I hope to someday) then we'll be forewarned about this little tidbit. Thanks for asking Tberd, and thanks for the info Adam.

Thank the Buick chassis manual!

That , and the guy willing to dig up the pertinent part and post it here too.

When I was doing the engine compartment in Hank's 60, I had the same question, but didn't think to post it here. Just tonight, I dug up the answer because I was stumped, too.

Nice to know!

It was a bit difficult to find, since there was no direct section I could look in to find it. I just had to thumb through the book...and finally found it in the electrical section.

My temp lights have not been working. I was about ready to tackle this project. Your info will help me check the circuit on my Invicta Custom.

Bob

I'm restoring the engine compartment on my 60 Le Sabre and am puzzled by a vacuum operated switch I found under the hood. Its located at the glass bowl fuel filter bracket. The switch is disk shaped, has a small vacuum line and two wire leads. What's the purpose of this switch?

Another question is how is it mounted ? Mine was zip-tied to the radiator hose but it appears from a picture in the new issue of Hemmings Classic Car that the switch is mounted to the fuel bowl bracket. ANt help with this is much appreciated

Hi Joe,

Actually, it's my car that is in Hemmings, and the switch has a split prong on its underside that snaps into a hole on the bracket.

Sorry to hop on this topic so late; looks like you already got an explanation. But in case it helps, I'm attaching a Service Bulletin on this very topic--in addition to an explanation, it includes a wiring diagram to show how it all operates. Apparently this Rube Goldberg arrangement has caused confusion since it was new. I'm not sure how many years they continued with it.

Email me if the picture I've posted is not clear enough, and I'll send it directly to you.

Hi Greg,

The car looks great in Hemmings. I contacted you several years ago when I first purchased my Le Sabre Convertible. I was going to contact you thru your web site if i couldn't get some help here, but these guys are great!

The bulletin came thru a little rough, but I was able to read it. I didn't realize the 60 Buick had both hot and cold lights. I'm missing the clip that hold the vacuum swith in place. A picture of it would be nice if you find time.

Thanks in advance,

Joe V.

The clip is part of the plastic housing, from what I remember. If you don't have it on there, it's broken off.

The clip is part of the plastic housing, from what I remember. If you don't have it on there, it's broken off.

In the famous words of Johnny Carson's sidekick Ed McMahon....."You are CORRECT, sir!"

As I recall, the "clip" that's on the housing is a small plastic... (excuse me)... "tit" that is split and has a barb on the end of each half. Like the way some wiring harness clips work.

If it is broken off, you can get creative with black RTV to hold the switch in place (the attachment is on underside where no one will see it).

For a close-up of the switch, there is a picture of mine in the same Hemmings magazine. Not in the actual article about my car, but in the editor's general story about unrestored cars...there are several thumbnail-type shots of close-up details from unrestored cars. One of them is my vacuum switch.

I know this is a semi old thread, but the vacuum switch (#1998874) was also used on the '67 Camaro and '68 Corvette air conditioning circuit. As such, the rubber cap (#1950656) is available if you look for a "'67 Camaro air conditiong vacuum switch rubber cap". One example is here

Camaro Central 1967-2010 Camaro Parts.

Hello, I have 2 buick electra's 1960, the vacuum switch near the carburator is for stopping starting. So when you push the gas pedal the engine starter works, when the engine is running you get vacuum on the switch and the power to the starter is stopped. So very easy it only works with the original carburator, the car isn't started with the key but with the gas pedal and the starter stops when it has vacuum, nothing to do with cooling. But maybe they replaced the carburator and connected the 2 wires to each other and something with the ignition (key).

That is a different switch that they are talking about. What you are talking about is the starter switch on the side of the carburettor, whereas they are discussing the vacuum switch to control the COLD and HOT instrument panel lamps.

Here is a photo of each

OK, that -switch-, it is connected with the right head water temp. sender wires.

Reviving an old post that I found because I did not have a Hot light with the ignition on and engine not running.

I got thinking about this. The only function that switch has is to prevent the hot light from turning on when the engine is running and you have low oil pressure. If you short out the contacts on the switch, the light will test with ignition on and engine stopped, as will the oil. With the engine running, if you loose oil pressure or the engine overheats, BOTH the Oil and Hot lights will come on. I can live with that in that at least I know the hot light wasn't burnt out when I started the engine.

Your switch may be broken and you may not know it. Since it is a normally closed switch with no vacuum, your hot light will test with ignition on. But, you may have a bad diaphragm on the switch that is causing a vacuum leak and possibly misfire at idle. If you lost oil pressure, your hot light would also come on and the oil would also come on if the engine got hot.

In my case, the switch contacts were dirty (as well as the diaphragm broken) and so it was open with no vacuum. I cleaned it out and cleaned the contacts so that I have reliable continuity thru the switch and ordered a new diaphragm from here http://www.heartbeatcitycamaro.com/store/product/12737/Camaro-AC-Vacuum-switch-rubber-cap-1967/ I ordered 2 since they are cheap, that way I am sure to NOT screw up the first one. I'll post back when I receive it and attempt to fix the switch to correct operation. Meanwhile, I have a jumper in the plug and the vacuum line plugged.