Thermal Vacuum Switch (TVS) for EFE
 

For any of you who still have your original EFE system on the passenger side exhaust manifold, here's a part number. I was replacing my thermostat and broke one of the hose nipples off the TVS. I went to my local Chevy dealer and ordered a replacement. The part number for the TVS is 4007803. This is for a carbed LG4 and the switch is a two nipple affair. The one I broke I believe to be the original as it looks nothing like the replacement. In the future, I will be more careful when removing/installing the t-stat housing. One of the nipples is right in the way when getting to the driver side bolt. I probably could have bought the switch from Autozone or O'Reilly but wasn't sure if there is a specific temp associated with it. Now I know that they are all pretty much the same.

Re: Thermal Vacuum Switch (TVS) for EFE
 

That part # is good info.

Those things are somewhat generic; since all they do, is control the coolant temp at which they change from sending exhaust to the underside of the intake, to not doing so. Plainly something that's not a "critical" point at all, really; a great deal of error could be tolerated without any noticeable effect. Especially for emissions inspection, since that is done with the car basically as fully hot as they can get it, IOW well above the "transition" point.

I seem to recall having to buy one myself when I lived right by you out there, in Carlsbad... gotta keep all that stuff in working order, as you know...

http://www.autozone.com/autozone/par...96537&cmpid=cj

Out of curiosity, how much did the GM store charge for that?

Re: Thermal Vacuum Switch (TVS) for EFE
 

GM's price for one of those is $34.72. I was able to get the wholesale price which was $5 off. Oddly enough, the GM part looks exactly like Autozone's E916 which is one third the price. I would have had to order it either way, and the dealer had it to me in a day. I won't purchase another one from them.

Re: Thermal Vacuum Switch (TVS) for EFE
 

In this day and time, that's maybe not so odd; for all we g00bz out here can possibly know, the Acme Vacuum Switch Co. over in Lower Elbonia makes em ALL, and sells em to GM, AZ, whoever, to do with as they pleeze. ;) Kinda like O2 sensors: you see people on ALL the GM and Frod boards all the time, ragging on those, and telling everybody "don't use Bosch, stick with 'genuine {flavor of the week}"; .... but I'm sure at least a few of us realize, Bosch INVENTED the O2 sensor, and still holds the patents on it, and makes quite a few of the OEMs even though they don't say "Bosch" on the box. The whole auto industry these days isn't NEAR as vertically integrated as it was in the 50s and 60s, when GM, Frod, Xler, the Euro-peons, the Japs, and whoever else, made EVERY SINGLE PIECE of EVERY SINGLE VEHICLE all on their own FROM SCRATCH. Nowadays most parts come from companies that supply the same subsystems to several OEMs, and all the OEM is, is an "assembly" operation, that writes up a spec sheet for all the subsystems and puts it out to bid; not a "design" one at all. (beyond the wrinkles in the sheet metal and the font the stickers are printed in, anyway) The world is changing.

Re: Thermal Vacuum Switch (TVS) for EFE
 

On my Lg4 I have this switch, but It's not connected to anything. Is there a diagram which shows me where it's supposed to go? I've only had the car a few days and don't have a manual for it yet. Guess I need to get one

Re: Thermal Vacuum Switch (TVS) for EFE
 

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Re: Thermal Vacuum Switch (TVS) for EFE
 

Thanks. It seems to run great without it, but I hate having it open like that. I'll see if I can fix it

Re: Thermal Vacuum Switch (TVS) for EFE
 

These depictions are actually pretty good. Since you are in Texas 58mark, I suppose you may not be required to have it connected. But in the interest of keeping my car well maintained, I want all systems to be functioning as it came from the factory. Yours could also be disconnected because the EFE valve at the exhaust manifold is bound up. Also, I live in California and everything under the hood is scrutinized during smog check!

Re: Thermal Vacuum Switch (TVS) for EFE
 

Is this the kind of thing that can throw a code?

Re: Thermal Vacuum Switch (TVS) for EFE
 

no code. the system's only function is to divert exhaust gas during warmup through the intake manifold to warm up the intake charge. it helps assist with cold weather warmup. if you haven't experienced any cold weather warm up issues, you're probably fine without it.

if you decide to connect it be sure you ensure that it functions correctly and opens completely when vacuum is not applied. with age the valve can stick, forcing exhaust through the manifold continuously.

Re: Thermal Vacuum Switch (TVS) for EFE
 

Agreed. They sometimes stick closed. If that happens it feels like you're driving around with a banana stuck in the tailpipe when you dig deep in the throttle.

Re: Thermal Vacuum Switch (TVS) for EFE
 

When I looked up the part number in my system it actually came up as 14007803. This is the customer's pride and joy and he wants to keep everything original. We changed the tune in the eprom and the system works even better than when it was new. Better emissions, better power, better economy. Besides making sure that the valve doesn't stick closed you might want to pull a vacuum on it before you hook it up as the small diaphragm inside it is known to fail and you will be introducing a vacuum leak into the system if you hook it back up. O'Reilly part number is PVS48. The one for the purge TVS is 10055876 but I could only find it NOS.