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Premium Member
1966 Convertible 6cyl 4sp
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165 Posts
Discussion Starter · #4 ·
Is it overheating?
It hasn't overheated but the needle goes from near the C around town to near the H on the freeway. And on a warm day it's really close to the H.
I did put a new 180 T-Stat in recently and want to try to make sure I'm seeing normal operation or if I need to chase down an issue before I end up with a real problem.
 

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Premium Member
1966 Convertible 6cyl 4sp
Joined
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165 Posts
Discussion Starter · #5 · (Edited)
It could be. It could also be a partially plugged cooling system, water pump with a worn-out impeller, defective thermostat (failing to open all the way) or radiator with poor fin conductivity. Timing could also be an issue... improperly calibrated distributor advance, bad vacuum advance diaphragm or leaky supply, defective Spark Control Valve at the carburetor, vacuum leak somewhere, etc.
Thanks
I have recently done a new:
  • Water pump
  • 180 TStat
  • Cap
  • Carb Spacer
  • Heater Core
  • All Hoses
That's why I was leaning towards timing - especially since it's primarily an issue at freeway speed.
 

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Premium Member
1966 Convertible 6cyl 4sp
Joined
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165 Posts
Discussion Starter · #8 ·
What kind of rpm do you run at on the freeway? If that 4 spd isn't original maybe you're geared kinda low.
Running the original Dagenham 4sp and 3:20 gears. I've got a tach installed but not quite wired up yet - so not sure yet what my RPMs are. Just put on some new shoes 195/70/R14

Land vehicle Speedometer Odometer Vehicle Tachometer
 

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Premium Member
1966 Convertible 6cyl 4sp
Joined
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165 Posts
Discussion Starter · #14 ·
High rpm/high speed excessive heat is usually crap in the radiator. If it’s ever had stop leak in it, that’ll do it for sure. That stuff sucks.
Hard to know what's been poured into the radiator over the years or what work has (or hasn't been done to it). From what I can see of the inside it looks pretty good - but before I take it too far from home on a warm day I gotta chase this down.

Pretty sure there's no spring in that lower hose - need to get that squared away.
Motor vehicle Automotive tire Rim Gas Engineering

Motor vehicle Automotive tire Hood Automotive exterior Automotive design
 

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Premium Member
1966 Convertible 6cyl 4sp
Joined
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165 Posts
Discussion Starter · #17 ·
C6ZE - is that the original radiator?

For me it was a partially plugged radiator. Could go 30-40 miles on interstate, then would heat up. Let cool down for a bit, and then it'd do it again. Wasn't so hot in town though at low speeds. Replaced radiator, problem solved.
I was told that it had been "recored" and the top of the radiator was saved and welded to the new cores. I know nothing about radiators - can anyone tell from the pictures if that looks to be true ?
 

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Premium Member
1966 Convertible 6cyl 4sp
Joined
·
165 Posts
Discussion Starter · #24 ·
It could be. It could also be a partially plugged cooling system, water pump with a worn-out impeller, defective thermostat (failing to open all the way) or radiator with poor fin conductivity. Timing could also be an issue... improperly calibrated distributor advance, bad vacuum advance diaphragm or leaky supply, defective Spark Control Valve at the carburetor, vacuum leak somewhere, etc.
Well you can add really bad Rear Wheel Bearing to this list. I knew it was going (could hear it) but I didn't realize how bad it was until the axle was out. Could barely turn it by hand. I guess I've been dragging around my right rear tire/wheel for a while. The Mustang is running quite a bit cooler, quieter, and rolling better now too.
 
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