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Vacuum questions - 76 Eldorado Convertible

Started by Taure_76Eldorado, January 21, 2023, 06:18:54 AM

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Taure_76Eldorado

Good day. I am bringing back to life a 76 Eldorado section by section and I'm stuck on vacuum. I have the shop manual and I've blown up the vacuum diagram to be able to follow it pretty well but I'm missing an efe thermal vacuum switch (actually don't see where it would go in the engine), my efe valve hose has been severed at some point (probably identifying its no longer operable and was bypassed), I'm missing a couple tees that are identified as necessary in the original setup, and the line from the charcoal canister to the fuel tank is missing.
Questions are:
1. Does anyone here have a 76 with a proper vacuum setup including the proper carburetor that I can get a picture of the setup inside the engine bay to identify and cross reference? I'd pay for that.
2. The part numbers vary for the efe thermal vacuum switch all across the internet, has anyone had any luck identifying and purchasing one from somewhere?
3. Pretty much the same for the efe valve. This one is rusted off of the frame but I may be able to salvage the unit and put it back on to test.
4. Is the line from the charcoal canister rubber or steel with an insulator on that? I can't find a clear picture in the manual.

Any help is greatly appreciated. I'm replacing the intake manifold, egr valve, carb, and distributor over the next few days so I'm knee deep in research, oil, and rust so I'm learning as much as I can every step of the way and I'm willing to share the journey as well.
1976 Eldorado Convertible
Goddess emblem adorned

TJ Hopland

What is your final goal?  Are you just going for a good running car?  Do you have to pass some sort of sniff and visual emissions inspection?   Or are you going for a show quality restoration?
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
80 Eldo Diesel
90 CDV
And other assorted stuff I keep buying for some reason

Taure_76Eldorado

Quote from: TJ Hopland on January 21, 2023, 11:58:01 AMWhat is your final goal?  Are you just going for a good running car?  Do you have to pass some sort of sniff and visual emissions inspection?   Or are you going for a show quality restoration?
Thanks for checking in TJ. My final goal is to get a good running car but I want the engine bay to look like the outside of the car does which is in pretty good shape. It was inherited from my grandad but it was sitting for a while and he had anyone with a wrench work on it at some point during it's life. Right now it's not running and I have to get it running in order to check on the transmission. I have most of everything else under control as I have some history working on these boats but the vacuum connections are kicking my butt.
1976 Eldorado Convertible
Goddess emblem adorned

TJ Hopland

EFE as long as its stuck open (which is the typical fail state) doesn't hurt anything.  The EFE would close when the engine was cold which forced exhaust to cross through a passage in the intake to improve drivibility in those first few minutes.
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
80 Eldo Diesel
90 CDV
And other assorted stuff I keep buying for some reason

benji808

#4
Do you have this vacuum diagram (attached)? I have a 1975 Eldorado, and it's a California car, so a few oddities, but general layout should be similar. I recommend setting it up to spec as much as possible. Assuming the car has not had significant modifications, it's not too difficult and IMO makes future trouble-shooting easier.

1) I think the thing TJ is talking about is on the air cleaner/intake. It takes a manifold vacuum line directly from the manifold into the air cleaner, then a second vacuum line runs from the air cleaner to another portion of the air cleaner intake arm. The first of these connections is shown in the picture "manifold to air cleaner".

2) If you're talking about the thermo vacuum switch, that is hard to see, but it's almost directly under the distributer, about 2" long screwed into the block, and should have two vacuum connections. You can sort of see it under the distributer in the "thermo vacuum switch location" picture. I've also attached a picture of one that is NOT for our cars, but similar size and shape so you have an idea of what you're looking for (it's tough to get a clear picture). As you can see in the vacuum diagram, one of these vacuum lines connects to a "T" on the distributer advance, and the other connects to a steel tube that runs to the EFE valve, which is located on the passenger-side rear of the engine (at least on my car).

3) For the carbon canister, the fuel tank hose connects to steel tubing that should be fairly accessible - see attached "carbon canister to fuel tank" picture - basically look down by the power steering pump hose connections and it should be right there.

Let me know if any of that doesn't make sense...I should be able to provide more pictures as needed. I went through this with my car a few months ago, and hopefully got it right  ;D

35-709

The EFE is an "updated", vacuum operated version, of the heat riser valve that used to open and close by means of a circular, temperature sensitive bi-metal spring.  As with the older, spring type, you want to be sure that if it has failed, it has failed in the open position.  It is controlled by the TVS (thermal vacuum switch) 
1935 Cadillac Sedan resto-mod "Big Red"
1973 Cadillac Caribou - Sold - but still in the family
1950 Jaguar Mark V Saloon resto-mod - Sold
1942 Cadillac 6269 - Sold
1968 Pontiac Bonneville Convertible - Sold
1950 Packard 2dr. Club Sedan
1935 Glenn Pray - Auburn Boattail Speedster, Gen. 2

Taure_76Eldorado

Quote from: TJ Hopland on January 21, 2023, 08:28:43 PMEFE as long as its stuck open (which is the typical fail state) doesn't hurt anything.  The EFE would close when the engine was cold which forced exhaust to cross through a passage in the intake to improve drivibility in those first few minutes.
Thank you TJ. I'm back under the hood this week so I'll be sure to check again whether it is open or closed. I'm less concerned there but I still want to address any and all vacuum leaks.
1976 Eldorado Convertible
Goddess emblem adorned

Taure_76Eldorado

Quote from: benji808 on January 21, 2023, 09:15:16 PMDo you have this vacuum diagram (attached)? I have a 1975 Eldorado, and it's a California car, so a few oddities, but general layout should be similar. I recommend setting it up to spec as much as possible. Assuming the car has not had significant modifications, it's not too difficult and IMO makes future trouble-shooting easier.

1) I think the thing TJ is talking about is on the air cleaner/intake. It takes a manifold vacuum line directly from the manifold into the air cleaner, then a second vacuum line runs from the air cleaner to another portion of the air cleaner intake arm. The first of these connections is shown in the picture "manifold to air cleaner".

2) If you're talking about the thermo vacuum switch, that is hard to see, but it's almost directly under the distributer, about 2" long screwed into the block, and should have two vacuum connections. You can sort of see it under the distributer in the "thermo vacuum switch location" picture. I've also attached a picture of one that is NOT for our cars, but similar size and shape so you have an idea of what you're looking for (it's tough to get a clear picture). As you can see in the vacuum diagram, one of these vacuum lines connects to a "T" on the distributer advance, and the other connects to a steel tube that runs to the EFE valve, which is located on the passenger-side rear of the engine (at least on my car).

3) For the carbon canister, the fuel tank hose connects to steel tubing that should be fairly accessible - see attached "carbon canister to fuel tank" picture - basically look down by the power steering pump hose connections and it should be right there.

Let me know if any of that doesn't make sense...I should be able to provide more pictures as needed. I went through this with my car a few months ago, and hopefully got it right  ;D
Ben, thank you very much for the time that you spent gathering information for me and this project. It is much appreciated and exactly what I was looking looking for. I do have the vacuum diagram you have attached. I was really stuck by where a couple items were supposed to be in relation to what is there now. It became a real head scratcher. Your photos helped eliminate a ton of the issues. I do want to set it up to spec and feel confident when I close the hood that everything is in alignment. Thank you again.
1976 Eldorado Convertible
Goddess emblem adorned

Taure_76Eldorado

Quote from: 35-709 on January 22, 2023, 09:08:39 PMThe EFE is an "updated", vacuum operated version, of the heat riser valve that used to open and close by means of a circular, temperature sensitive bi-metal spring.  As with the older, spring type, you want to be sure that if it has failed, it has failed in the open position.  It is controlled by the TVS (thermal vacuum switch) 
Thank you. I'll be checking this week and I'll be sure to update the thread with some photos and results.
1976 Eldorado Convertible
Goddess emblem adorned