CJ7 replaced radiator - now it runs hotter? - JeepForum.com
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post #1 of 33 Old 07-12-2020, 04:58 PM Thread Starter
mhobson3
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CJ7 replaced radiator - now it runs hotter?

Hello everyone - hope you all are doing well!

I recently purchased a 1983 CJ7 258. I knew it had a pinhole radiator leak, so I put some Bar's Stop-Leak in it until I could save up a little cash to put a new radiator in it. I actually ended up spending the money to re-core the original radiator (not cheap lol!). Before the radiator replacement, the Jeep ran at the center of the temperature gauge all day long with no problems. I replaced the radiator and I also replaced the thermostat while I was at it. Now that it is all back together, it actually runs hotter on the gauge (somewhere between 2/3 and 3/4 of the way up on the gauge). It's still in the green on the gauge, but that seems abnormal to me with a new radiator and thermostat. Did I do something wrong? What would your advice be?

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post #2 of 33 Old 07-12-2020, 05:32 PM
CJ7-Tim
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What temperature rating thermostat was installed, and what temp is specified ? Did you install a Stant thermostat, or some cheap crappy store brand Chinese thermostat ?

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post #3 of 33 Old 07-12-2020, 05:34 PM Thread Starter
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Originally Posted by CJ7-Tim View Post
What temperature rating thermostat was installed, and what temp is specified ? Did you install a Stant thermostat, or some cheap crappy store brand Chinese thermostat ?
I put a new Stant 195 in it - 195 was the temp rating of the old thermostat that was in there so I just went with that.
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post #4 of 33 Old 07-12-2020, 05:37 PM
CJ7-Tim
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So, assuming the Stop-Leak leak stuff isn't buggering up anything, it's fine.
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post #5 of 33 Old 07-12-2020, 05:40 PM Thread Starter
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Originally Posted by CJ7-Tim View Post
So, assuming the Stop-Leak leak stuff isn't buggering up anything, it's fine.
I just figured it would at least run the same temp on the gauge, if not cooler with a new radiator. I'm going to be wheeling in the desert and if it's already hitting 2/3rds of the way up on the gauge at my house where it's 75-80 degrees, I guess I worry when I take it out to where it's 100+ that it's going to have problems.
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post #6 of 33 Old 07-12-2020, 06:12 PM
80cj
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Do you still have the old thermostat? Maybe you can try reinstalling it and see if your old normal temperature returns. Also, is the new radiator core the same thickess and fin count as the old one
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post #7 of 33 Old 07-12-2020, 06:19 PM Thread Starter
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Do you still have the old thermostat? Maybe you can try reinstalling it and see if your old normal temperature returns. Also, is the new radiator core the same thickess and fin count as the old one
The radiator is the same radiator that was in it - I just had it re-cored and then I installed it. The old thermostat looked pretty shot when I pulled it, so I tossed it. It's pretty puzzling to be honest, but maybe I'll just have to get used to it running at it's new "normal" temperature.
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post #8 of 33 Old 07-12-2020, 06:33 PM
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Originally Posted by mhobson3 View Post
The radiator is the same radiator that was in it - I just had it re-cored and then I installed it. The old thermostat looked pretty shot when I pulled it, so I tossed it. It's pretty puzzling to be honest, but maybe I'll just have to get used to it running at it's new "normal" temperature.
Is it possible that the recoring job was not well done? (excess solder etc?)

I should note that if you've run through muddy water you may want to flush through the fins with a garden hose. When I did that some hidden mud came out and the hot weather temperature dropped noticeably.
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post #9 of 33 Old 07-12-2020, 06:36 PM Thread Starter
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Is it possible that the recoring job was not well done? (excess solder etc?)

I should note that if you've run through muddy water you may want to flush through the fins with a garden hose. When I did that some hidden mud came out and the hot weather temperature dropped noticeably.
I hope not, but it's always possible. How would I even check that?
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post #10 of 33 Old 07-12-2020, 06:47 PM
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I hope not, but it's always possible. How would I even check that?
After I posted, I was thinking that same thing, I don't know.

However,I would consider doing a system flush with a reputable cleaner, then flush clear with water (if you have not done this already) then refill. It is possible that the leak fix is reducing your heat transfer.
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post #11 of 33 Old 07-12-2020, 07:31 PM Thread Starter
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Originally Posted by jay-h View Post
After I posted, I was thinking that same thing, I don't know.

However,I would consider doing a system flush with a reputable cleaner, then flush clear with water (if you have not done this already) then refill. It is possible that the leak fix is reducing your heat transfer.
I used my garden hose and blasted through the thermostat opening pretty good before I put everything back together. I made sure the water was running clear before I was done. I'm a Jeep N00b so I'm not too sure if that is even an acceptable way of doing it lol.

BTW I appreciate everyone's input - this is really helpful for me!
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post #12 of 33 Old 07-12-2020, 08:40 PM
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An IR thermometer may give you some piece of mind - they aren’t expensive - and its easy to have an idea of the temp at the thermostat. Just an idea.....
https://www.amazon.com/dp/B00837ZGRY..._dI8cFb96BM727
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post #13 of 33 Old 07-12-2020, 08:55 PM Thread Starter
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Originally Posted by ccoyle71 View Post
An IR thermometer may give you some piece of mind - they aren’t expensive - and its easy to have an idea of the temp at the thermostat. Just an idea.....
https://www.amazon.com/dp/B00837ZGRY..._dI8cFb96BM727
Thanks for the advice - what would be an acceptable temperature reading at the thermostat?
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post #14 of 33 Old 07-13-2020, 04:37 AM
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195F +/- 5 is the coolant temperature, you may see a bit less on an infrared thermometer as you are not directly measuring the coolant.

You should only see the temperature the thermostat is allowing to pass. It should be closing and opening all the time as your cooling system is capable of running cooler than that. the job of the thermostat is to keep coolant IN the engine until it heats up enough. The job of the radiator is to cool it more than enough.
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post #15 of 33 Old 07-13-2020, 04:51 AM
CJ7-Tim
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An old thermostat that was weak or stuck open can easily allow the engine temp to run on the low side. "Normal" is about 195*-210*.
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