'84 f250 300cid,
Just did a tune-up, replaced the thermostat, replaced the oil pan gasket, started the vehicle and let warm up untill the thermostat opened, upper hose got warm and coolant was visibly flowing with the cap off.
Took the truck for a short test drive, noticed a lack of power, only drove it about 3 miles total. When I got it back to the shop the exhaust manifold was GLOWING red. There is plenty of air coming out of the tailpipe, and the restrictor valve that sit's just under the manifold moves freely, so I don't believe it's restricted exhaust.
When I shut the truck off I could hear coolant boiling in the head region. Could there be coolant passages to the exhaust manifold blocked? The temp gauge never went out of range, the heat worked, all cooling systems seemed proper.
When the manifold cooled down the front half was white.
Any experiences or suggestions much appreciated!

 

Check your timing. Retarded timing can cause high exhaust temperature. Would also have a lack of power. All noise and no go.

 

84 was the 1st year for EEC (electronic engine control) in Ford trucks. This consisted of a computer (mounted above the gas pedal), a feedback carburetor, a TFI ignition, a barometric pressure sensor and several other doohickies.
This system controls ignition timing, fuel mixture, idle speed, egr, and air pump valve operation.
To set the timing you have to disconnect the single wire connection (spout) at the distributor, then reconnect afterwards.
This disconnects the computer's control from the distributor enabeling you to set the timing.
If this wire is left disconnected, the timing will stay retarded and the manifold will glow red if the motor is sped up for a short length of time!
Your truck being a 3/4 ton might not have computer but it's worth looking into.
As horton-racing suggests, something is retarding your timing!
Good luck!

 

Doh! I forgot all about the Spout connector. I reset the timing to zero, number one at TDC and the rotor at number one on the distributor. D.I.S. has spoiled me. Thanks guy's. Time to go find a new manifold!

 

The timing needs to be set at 10*BTDC...