What is this?
Safety Car
Joined: Jun 2004
Posts: 4,360
Likes: 221
From: Beecher Illinois
EFE valve. (edit...TVS(switch) FOR the EFE system)
When the vehicle operating temp gets up to normal and the thermostat opens the hot coolant hitting it opens(or closes?) (edit...CLOSES) the vacuum line to release and open the heat riser valve between the exhaust manifold and exhaust pipe. (edit...vacuum holds the heat riser closed)
When the heat riser is closed it forces hot exhaust through the intake manifold under the carb for quicker warmups.
Emissions stuff
edit...accuracy!! see post 8
When the vehicle operating temp gets up to normal and the thermostat opens the hot coolant hitting it opens(or closes?) (edit...CLOSES) the vacuum line to release and open the heat riser valve between the exhaust manifold and exhaust pipe. (edit...vacuum holds the heat riser closed)
When the heat riser is closed it forces hot exhaust through the intake manifold under the carb for quicker warmups.
Emissions stuff
edit...accuracy!! see post 8
Last edited by KapsSA; Jan 22, 2011 at 03:22 AM.
Safety Car
Joined: Sep 2005
Posts: 4,056
Likes: 99
From: Southeast, Tennessee
St. Jude Donor '09 thru '26
EFE valve.
When the vehicle operating temp gets up to normal and the thermostat opens the hot coolant hitting it opens(or closes?) the vacuum line to release and open the heat riser valve between the exhaust manifold and exhaust pipe.
When the heat riser is closed it forces hot exhaust through the intake manifold under the carb for quicker warmups.
Emissions stuff
When the vehicle operating temp gets up to normal and the thermostat opens the hot coolant hitting it opens(or closes?) the vacuum line to release and open the heat riser valve between the exhaust manifold and exhaust pipe.
When the heat riser is closed it forces hot exhaust through the intake manifold under the carb for quicker warmups.
Emissions stuff
Melting Slicks
Joined: May 2007
Posts: 3,246
Likes: 4
From: Bay Area CA
EFE valve.
When the vehicle operating temp gets up to normal and the thermostat opens the hot coolant hitting it opens(or closes?) the vacuum line to release and open the heat riser valve between the exhaust manifold and exhaust pipe.
When the heat riser is closed it forces hot exhaust through the intake manifold under the carb for quicker warmups.
Emissions stuff
When the vehicle operating temp gets up to normal and the thermostat opens the hot coolant hitting it opens(or closes?) the vacuum line to release and open the heat riser valve between the exhaust manifold and exhaust pipe.
When the heat riser is closed it forces hot exhaust through the intake manifold under the carb for quicker warmups.
Emissions stuff
Safety Car
Joined: Jun 2004
Posts: 4,360
Likes: 221
From: Beecher Illinois
Burning Brakes
Joined: Apr 2007
Posts: 1,178
Likes: 15
From: Montreal Quebec
EFE valve.
When the vehicle operating temp gets up to normal and the thermostat opens the hot coolant hitting it opens(or closes?) the vacuum line to release and open the heat riser valve between the exhaust manifold and exhaust pipe.
When the heat riser is closed it forces hot exhaust through the intake manifold under the carb for quicker warmups.
Emissions stuff
When the vehicle operating temp gets up to normal and the thermostat opens the hot coolant hitting it opens(or closes?) the vacuum line to release and open the heat riser valve between the exhaust manifold and exhaust pipe.
When the heat riser is closed it forces hot exhaust through the intake manifold under the carb for quicker warmups.
Emissions stuff
Acting as a coolant sensor in the 80's
Safety Car
Joined: Jun 2004
Posts: 4,360
Likes: 221
From: Beecher Illinois
OK, just to be totally correct.....
That is actually a 'TVS'(thermal vacuum switch) FOR the 'EFE'(early fuel evaporation) system.
And vacuum going through the TVS CLOSES the heat riser. Upon reaching operating temp the vacuum is shut off allowing the riser to open.
Love my shop manual!
That is actually a 'TVS'(thermal vacuum switch) FOR the 'EFE'(early fuel evaporation) system.
And vacuum going through the TVS CLOSES the heat riser. Upon reaching operating temp the vacuum is shut off allowing the riser to open.
Love my shop manual!
Last edited by KapsSA; Jan 22, 2011 at 03:09 AM.
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