Jeep Enthusiast Forums banner

I6 temperature range Normal?

628 Views 19 Replies 11 Participants Last post by  turbogus
Quick question for you all. I have a new (to me) ‘76 CJ7 with an inline 6 cylinder motor. It was a restomod so I’m not too sure what the previous shop did. That said, it has a new radiator, new hoses, looks like a new thermostat housing (or at least cleaned up). I don’t know about the thermostat. My question is, is this normal operating range for the I6? The needle stays there and is in the green but seems to be on the hot side. Normal?

See less See more
1 - 5 of 20 Posts
I'm going through this right now on my 76.

Read: Winter Warrior

Do you have a shroud on your radiator?
Do you know what temp thermostat they put in your engine?

Here are the specs on the gauge scale:
  • OEM Temp. Gauge calibration:

  • Room Temp.....................70 degrees--200 to 400 ohms
  • C (cold)........................ 130 degrees--73 ohms
  • Beginning of band........ ..171 degrees--36 ohms
  • Top of band.................. 242 degrees--13 ohms
  • H (hot)........................ 270 degrees---9 ohms
Thanks for the info! Nope, no shroud. I assume the stock one wouldn't fit the new radiator so they just scrapped it...I may look at picking one up and shaving it down to fit if needed. I assume that will help get the temp down a bit. Regarding the timing, I'm going to leave it alone for now as I need to get it smogged (I missed the cutoff year by 1 in CA) and they may need to adjust it anyway. Photo of the radiator:
See less See more
Thanks guys, will pick up a IR temp gauge. What should it read? Is there any for the hose insulating it? Thanks again for the help.
Your gauge says you are in the green, that is all you need to know!!!! If it goes up from its normal position, then you need to think.

It looks like a new gauge cluster, so may not be as accurate as the original. (not that it was accurate)

As said, for peace of mind you should measure the water temperature just after the thermostat. You will see the stat opening if you have the radiator cap off as well. There is an opening temperature but full open is a bit higher. This depends to an extent on which thermostat was inserted, should have been a 195 but some mistakenly put in lower rated which leads to increased wear and a cooler heater.

Opens at 195F
Fully open at 218F

You should also have a rad cap rated at 14psi. If any less then you will get boil over at a lower temperature.

Efficiency of the system is affected by radiator cleanliness, coolant, pump etc. This is only a concern if the needle starts to creep upwards and even then only if it hits 250F, the boiling point at 14psi.

For peace of mind I would be concerned if it hit 242F for any length of time, which is supposed to be the top of the green band.

At the top of the band the resistance measured is 13 ohms. You can measure this or replicate it with a suitable resistor, but I just match the readings to what my thermometer tells me.

Bagusjeep got a new engine rebuild, a lot has been renewed. Gauge now goes to 2/3 of Green, approx 220 on the gauge maybe. It measures 205. Happy days if it stays there.
Thanks Bagus!! Great info and what I wanted to hear!
That is one reason why I went to an aftermarket gauge that reads in degrees and not C & H. I theory as long as it is in the green you are good. Like you I'd like to see it more in the green for peace of mind.
ThanIs! What aftermarket gauge did you go with? I’m considering switching for peace of mind/future concerns.
1 - 5 of 20 Posts