Car seems to not heat up

[lgbnaf7]

I have a 1989 Mustang GT Convertible. It is completely stock. I was driving around last week and I noticed that it wasn't warming completely up according to the temperature gauge. I don't know the proper thermostat increments on the dash but according to the lines the car heats up to the third line in the range from 130 to 270. It is in the normal range according to the gauge. I assumed my thermostat was stuck open so I replaced it with a 180 degree one and I still have the same issue. I know running cool should be a great thing but I know there is something wrong. Any suggestions?

 

[68keyblr]

Mine does exactly the same thing...third line. I think it's just the stock gauge. It's not terribly accurate.

I've switched out the sending unit and it's still the same. I know the gauge works though, because I had a bad radiator and the temp read much higher before I replaced the radiator.

 

[ninety15.0]

Yup the stock gauge is piece of crap. It is only good for telling you the difference between Stone Cold, OK, and HOT. I run an autometer electric water temp gauge now and i am much happier knowing exactly whats going on. I can see the temp rise 5 degrees when going up a big hill on the highway...and then see it drop those 5 degrees as soon as i let off the gas a bit. World of difference!

 

[lgbnaf7]

temp

I put in a new 180 degree thermostat thinking the stock was stuck open. Still Nothing.

 

[ninety15.0]

You need a better gauge...the stock gauge is horribly inaccurate

 

[HISSIN50]

As mentioned, get a real gauge to know what's going on.