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My factory temp gauge on my 1966 Mustang reads high when engine is at proper temp, checked with temp gun.. i was wondering if this is a common problem or common fix. The Gauge reads to almost out of the "bracket" towards H and the car temp is sitting around where it should be. I remember reading somewhere early production oem thermostats or temp senders were a bit smaller than newer production ones and that the best bet is to find one on ebay. If that is the solution i wouldnt mind but they are a bit pricey.. like 20+ dollars for a sender...:poop::poop:

Anyway the car is a 1966 with a 1988 5.0 swap. I wouldnt be surprised if the 302 runs a bit hotter than the 289 did and effects the gauge that way. But am not 100% sure
Thanks for any info in advance.
 

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If you are sure the temp is fine,why worry about it ? I have not done it but the gauge itself supposedly has an adjustment. Your sender is most likely fine.
 

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If the sender in the car is aftermarket replacement, it's most likely crap. No one manufactures a Ford temp sender with the correct Ω values. Best thing is to get an original Autolite or Motorcraft sender. They rarely go bad, so pulling one out of a junk engine or intake should be fine.
 

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I remember reading somewhere early production oem thermostats or temp senders were a bit smaller than newer production ones and that the best bet is to find one on ebay. If that is the solution i wouldnt mind but they are a bit pricey.. like 20+ dollars for a sender…

Anyway the car is a 1966 with a 1988 5.0 swap. I wouldnt be surprised if the 302 runs a bit hotter than the 289 did and effects the gauge that way. But am not 100% sure
Yes, the early Mustangs had a smaller diameter sender, but the Ω values were the same in all Ford cars of the period.

I would consider $20 for a part that actually works properly a bargain, compared to the crap that retails $5-$10 but does not work properly.

Whether you have a 66 289 or 88 5.0, you should have a 190° thermostat, so the running temp would be the same either way.
 

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Also remember that a couple things can affect the temp sender performance. If your fuel gauge ALSO seems to read high you could have a instrument voltage regulator (IVR) that is putting out too much voltage. Your temperature gauge can also be out of calibration. If you want to check your sender you can pull the lead from it and use an ohmmeter between the sender lead and the sender base and compare the values with this chart, below. Note that the engine has to be fully warmed up :)) ).
744571
 
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