Jump to content


Thought on overheating


Recommended Posts

Hello Group. I don't post often but I follow discussions on this forum daily.

I have a restored to factory specs 71 series 1 Z and have done everything seen in this forum to solve my cars warm disposition. The latest, which had a large impact on the gage reading, was to correct the gage reading by adding 5 ohms of resistance in series with the heat sensor. I used Joseph Demers article in the summer 2003 Sports Z mag

to validate and correct the gage. Instead of physically taking out the gage and risking breaking it by moving the needle as he suggested, I used a correcting resistance at the heat sensor.

anyway, my thought and question to all.

With the close proximity of the thermostat housing and heat sensor to the exhaust manifold, how likely is it, in your opinions, that the heat sensor is being adversely affected by this parasitic heat and is measuring exhaust manifold heat along with coolant water temp?

I did use an infra-red thermometer and got a temp reading on my car of 240+ F

on the bottom of the thermostat housing where the temp sensor is located and a reading of 195 F at the top of the housing. All other areas of the engine read 185-195 F range.

These are just my observations and would be interested to hear your thoughts.

Link to comment
Share on other sites

OK, this is my opinion since you asked for one :)

The temp sending unit is an imersion type of sensor, the sensor is in the fluid. These types of sensors typically are pretty resistant to outside sources, and with the true sensor being a distance from the outside, any outside heat would be drawn away from the sensor by the cooling fluid. I would say that in real life, if the head of the sensor was 240 and the bulb was in 190 degree fluid the reading from the bulb would probably be within + or - 2-4 degrees of the true fluid temp.

I use a lot of these at work, sometimes with the fluid hot and the head of the sensor cold, like -40C and the reading is the same if you had the head temp at 100C. Of course the instruments I'm using at work are a much better quailty than the sensor in the car but in relation the effects should be the same.

Of course the best way is to measure the fluid in the radiator with a bulb type of therometer and get a true reading of the temp with your expected gauge results.

I would have to say also (another of my opinions) that I've seen many posts on "high temps" one way or another and I wonder if there is too much hair splitting, I mean it is an engine, the temp varies, sometimes it will get "hot" but not overheated. The factory gauge was meant to be a general indicator, not a calibrated gauge, if you want exact temps install a quality instrument. With todays oils temp ranges can be much higher and still safe compaired to what was available 30 years ago.

Don't take anything I said wrong, you asked for opinions and you got mine :) They are like most things you get for free.... and like that one part of the body, everyone has one :)

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
  • Recently Browsing   0 members

    • No registered users viewing this page.
  • Who's Online   2 Members, 0 Anonymous, 242 Guests (See full list)

  • Create New...

Important Information

By using this site, you agree to our Privacy Policy and Guidelines. We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.