There's three sensors right next to the thermostat housing. I broke one changing my thermostat. Was wondering what it is? I know one is the coolant sensor. But what about the other two. Have looked for a diagram showing what they are but hard to find one for a 1982 S10 2.8 manual transmission.

 

Back then, before fuel injection, lots of tricks were used to decrease emissions startup output, including modified carburetors with electronic controls. Be willing to bet one was for the choke or something on the carb; the other for ignition timing advancement control. The EPA was pretty strict on startup emissions, so GM did what they could do, like adding that stupid
aluminum heat tube from the exhaust manifold to the air-cleaner inlet nozzle. But lots of vehicle manufacturers did that.

 

Ok thanks but do I really need them. Yeah I know I'll need the coolant sensor but can't I just plug the whole and eliminate the other two?

 

If your S-10 starts and runs fine without them, and you don't have to worry about passing smog-laws, then sure, you can run it like it is. Me, I'd be finding out where they went, as
timing advance could cost you power and gas-mileage. I'd at least make sure to insulate any wires or any exposed connections if I were you.

I did find a vacuum diagram. Looks like these 2.8 liter motors used a vacuum advance delay device, like many vehicles did, no matter who made them. Its a small little plastic valve that slows down the vacuum to the ignition advance diaphragm mounted on your distributor for smog. If you want you can run a straight hose from the carb to the timing advance canister, or even a piece of plastic or copper tube to shunt this POS device out. Should have better pickup and power, Just make sure your engine doesn't have any knock (it likely won't). We used to bypass these things all the time back then and run the ignition timing up as high as it would go before any knocking occurred. Worked real good for more HP .

 

The coolant sensor is the only one that is actually wired. The other two are connected with vacuum lines.

 

Can you trace the vacuum hoses back to origin? I am quite interested in this issue. Sure glad new high HP F-I engines that don't have all that c**p, and don't need all those stupid old smog-control devices, like smog pumps, and all the vacuum hoses and wires and other make-shift gimmicks, that the US vehicle manufacturers had to use to pass all the smog laws, way back then.

 

Here are a couple of pics of the senors. One went to back behind the carb and the other one teed off to a another part of emissions.

 

Here are a couple of pics of the senors. One went to back behind the carb and the other one teed off to a another part of emissions.

 

Don't worry that this is the 1982 5.0 liter (305 cubic inch) motor. The vacuum system is the same on the 2.8 liter S-10 engine, but I couldn't find a good jpg or image file of the 2.8 engine vacuum hose to upload here.


Pretty sure that one is for your vapor canister. The other one is likely either for the distributor vacuum advance and/or EGR valve. Back then this was used to wait until the engine warmed up to keep emissions system down and the EGR from working,as they had much larger ports back then, and would make the cold engine not run very well Yeah, back then, they used aluminum parts, not plastic, like the replacement unit you would have to buy nowadays:.