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87 Caballero Amarillo, original 305/200-4R, QJ
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That's the EFE TVS. If you are running the stock exhaust, you probably want to hook it back up. If you remove it, you are likely to lose a little coolant until you plug it.
A little? Lol. The efe-tvs is a thermal switch. When the coolant warms up enough, it closes and blocks vacuum downstream from it, without affecting the carburetor vacuum supply.

So in a smog delete, it's totally unnecessary equipment now, but either needs to stay or be plugged, if removed it'll dump coolant like nobody's business as it's screwed directly into the thermostat housing.

What's important is making sure the EFE on the passenger exhaust downpipe is tied wide open or deleted entirely, otherwise the exhaust from that side of the engine will get dumped right back into the intake/pcv.

Smog deletes should be Done, or Undone, half measures only lead to complications elsewhere.
 

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87 Caballero Amarillo, original 305/200-4R, QJ
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1,754 Posts
Well yes, it does, since it puts fuel rich exhaust eventually back into the carburator, through the egr/pcv, and has the benefit of helping to warm the top of the block/intake, which shortens the warm up time, so startup period of richness is shorter and you end up saving fuel, especially on northern cars in winter time.

But if deleting the smog, egr, etc or have a southern car where you'd be lucky to see 40ish° on a cold morning, the efe doesn't really have any worthwhile function, it's just something more to become unreliable or a potential source of vacuum leak.
 

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87 Caballero Amarillo, original 305/200-4R, QJ
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1,754 Posts
The efe is way down in the back on the exhaust, right before it hits the manifold. It'll have a vacuum tube stuck into it. (or used to.)

And no, there should be very little coolant loss, if any, when removing the efe-tvs, just don't run the motor prior or after removal until it's plugged. It's a pressure fitting, it is stuck in the coolant path, so remember to seal it good, a standard bolt will leak.
 

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87 Caballero Amarillo, original 305/200-4R, QJ
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1,754 Posts
I'm surprised that Remove Smog Stuff thread is not stickied
I'm not. Tampering with a vehicle's emissions control system is illegal under the Clean Air Act (CAA). The CAA also prohibits manufacturing, selling, offering for sale and installing aftermarket devices which effectively defeat those controls.

While technically some are covered under exemptions due to age, most of us aren't, if you have a car that came with smog, it should have smog. But without government testing and oversight, like yearly emissions testing, it's left upto local/state authorities to enforce. Which they mostly don't.

By 'stickying' the delete, you go from public sharing of info, which is a First Amendment protected activity, to an endorsed Activity, which isn't covered and could land NECOA in legal trouble, like what happened to the Diesel Brothers who had youtube videos proving violations.

 
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