75 Eldorado thermal vacuum switch

[Tpicks55]

Im hooking up vacuum lines on the engine and I have to go to the EFE thermal vacuum switch on the left front side of the engine.  all nipples are broken off so I need a new one but cant seem to find a replacement. Any one have a source?

[Scot Minesinger]

USA Parts 304-724-6600 sells this thermal switch, just got one a month ago or so. 

[Glen]

Rock Auto sells it too: 

[EAM 17806]

USA Parts 304-724-6600 sells this thermal switch, just got one a month ago or so.

If you have a land phone use their 800 number, 1-800-872-2013. EAM

[Tpicks55]

Thank you all for the responses. 

[mgbeda]

I don't know if your '75 Eldo might be different from my '76 DeVille from Ohio, could very well be, but on my EFE switch there are only two vacuum ports plus a little vent.

Since I didn't want to use something with several plugged off ports (too messy) I found an EFE switch at NAPA from an '80's GM truck that had the identical configuration as mine, but a different temperature point.  It turns off the EFE at 90 deg F instead of 130 deg F.  I've tested it and it works fine, and I don't really care about the lower cut off temperature since I drove the thing for years with the EFE stuck off and never noticed.

-mB

[Tpicks55]

What was the part number?

[mgbeda]

I was afraid you were going to ask that...   I will hunt around.  I should have the receipt in my "Bessie" file, if I was feeling organized that day.

-mB

[TJ Hopland]

Some of the applications for these types of switches that vented port is a critical part of the operation.   It may be a thing where in one mode the connected device gets full vacuum and operates but when the temp changes it cuts off the vacuum supply and vents the device through that open/filter port.   If you don't have that open port the device may not relax fast enough or at all so it won't do what its supposed to do.    I don't remember what it was on but I ran into that one time.   I'm thinking that what ever it was was actually allowed to 'flop in the breeze' so that is why the port had to be open to allow that.    Problem started for me because I put a cap on what I thought was a port with a missing cap or hose. 

[Tpicks55]

I understand what you are saying TJ as the manual does show one port open whit no hose attached.  Thanks for the info.

[mgbeda]

My apologies, i do not have the receipt in the file where it should be.  I will see if i can get the number from the part itself, or maybe I can go through the steps I used to find it in the first place.

TJ is correct about the vent port.  On this switch (and the original) there is a third semi-port which is rectangular and has a tiny foam piece in it (so you can't attach a hose to it).  That opens the circuit supplying vacuum to the EFE valve to outside air so the vacuum drops to O and the valve opens as soon as the car warms up.

-mB

[mgbeda]

I finally found the one I used.  It is from Napa, Part Number: CRB 229031, Product Line: Echlin Fuel System.

http://www.napaonline.com/Catalog/CatalogItemDetail.aspx/Ported-Vacuum-Switch/_/R-CRB229031_0354263824

For my '76 DeVille, with carburetor, it fits perfectly, looks identical to the original, and works.  I did some tests where I'd connect a vacuum gauge to it's line and I watched it provide vacuum when the engine was cold and then the vacuum would drop to zero when the engine warmed up.  It switches at 90 deg F instead of the 150 deg F the original switched at, but, considering most people say you don't even need the EFE at all, I'm not worried about it turning off 60 degrees sooner.

I had also seriously considered the CRB 229058, but while the temperature was much closer to original (130), I wasn't sure it was plumbed the same way internally, because the arrangement of the ports looks different.  But it might have worked if I had tried it.

-mB

[Tpicks55]

Thanks so much I appreciate it.

[Tpicks55]

Unfortunately Napa doesnt have the one I need as mine has a 3/4 in npt base.   

[mgbeda]

Huh.  Well I guess the thread size was a '75 to '76 difference.  Or Eldo vs. DeVille difference.  Or Ohio vs.  wherever difference.  I've found that there are a lot of annoying details like that where emissions controls are concerned.

That NAPA site lets you search by things like thread size, or hose size, or temperature (that's how I found the one I used).  The trick is first you have to "filter" by at least one category before it offers all the other filters.  For example, I searched for "Ported Vacuum Switch" and then filtered by brand (Echlin):

http://www.napaonline.com/Catalog/Result.aspx/_/Ntt-Ported%20Vacuum%20Switch/Ntk-Keyword/Nty-1/N-4294872752/Ne-1000000

Unfortunately nothing showed up for 3/4 inch NPT.

By the way, I hope I'm not being dumb by mentioning this, but did you know that an NPT dimension like 1/2 inch has no relation to a real dimension?  For instance NPT 1/2 inch has an OD of 0.84 inches.  Forgive me if you already knew that.

-mB

[Tpicks55]

Thanks for the heads up on that I was the dumb one, yea I measured it by micromitter so I thought it was 3/4.  I'll check for 1/2 I appreciate the info.