while i was installing a new thermostat i accidentally broke the top of a unit off that sits on the thermostat housing. theres two little units that stick out, the one i broke is on the drivers side, and there are two vacuum lines connected to it, and now i have a loud hissing sound when i drive, so i stuck a golf tee in that port. what did i break and how do i go about replacing it? thanks

1987 z28 305 4 barrel

 

Follow the vacuum lines and see where they go... there's 2 vacuum switches up there, one in the water outlet and one in the intake manifold; one of them is the thermal vacuum switch for the EGR, the other is a TVS for the heat-riser valve. I can never remember which one is which.

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"So many Mustangs, so little time..."
ICON Motorsports

 

ok, one of the units has a few wires that go into a loom and that loom runs into a bigger loom which goes towards the passenger side firewall. the other unit on the thermo housing (which is the broken one) has two plastic hoses that go into a rubber connector of some sort, and one of the houses runs into the carb, on the same line that goes to my pcv valve. the other hose goes somewhere towards my number 8 plug. i dont seem to lose any power, earlier today i hung with an auto 89 5.0gt, which isnt bad for my lg4.