overheating...

I have searched around all day on and off with no real luck.
90 xj, 4.0, aw4, d35/d30

The story is, I go out to start my Jeep up yesterday to let it warm up some. It was in the single digits so I wanted it to be nice and warm once I was ready to go. Came back out maybe 20 minutes later to find the needle buried. Thing is it has all relatively new parts on it. I'm assuming 6 months old or less. They all still have the new shine. Parts include thermostat, water pump, radiator, and fan clutch. All new replacements from napa or Advance possibly a combination. I know the guy that did it all and he gets all his stuff from one or the other. Question is what could it be. It's a new style radiator by the way.

Is that the first time you let it idle that long since the work was done?

Possibly some air in the system.

When you say "new style" radiator, does that mean you have the open system?

I don't know anything about living or driving in the single digit temps (thank god). I wonder if its possible with an air bubble, some overnight freezing might cause an obstruction.

Also wondering if normal driving in those low temps might mask a cooling issue, only discovered because it was just sitting still in idle for 20 minutes (which seems like a long time)

First question did coolant leak out overnight, did something leak, like a freeze plug, or the weep hole on the water pump. If it is full of coolant the T-stat is bad, stuck closed. We have had many T-stats that were bad right off the store shelf. China junk IMHO. I have switched to using Murray brand T-stats, made in Israel. O'Reily stocks them.

I'm hoping for the T-stat. No leaks I can see. We been covered up at work so I haven't had a chance to get in the shop to check it out. I have idled it for longer in much warmer temps. It's been 6ish months since work. By new style radiator I do mean open system. Thanks for suggestions guys. I'll be pulling the thermostat tomorrow and putting in a new one.

Thermostat was the culprit. Not even a year old yet maybe not even 6 months yet. Thanks guys.

Ecomike said:

If it is full of coolant the T-stat is bad, stuck closed.

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:yelclap:

98xjeepy said:

Thermostat was the culprit. Not even a year old yet maybe not even 6 months yet. Thanks guys.

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Nothing but factory stats for me anymore. 83501426. Quick warm-ups in winter and stays at proper temp in summer.

Have you replaced your coolant cap with the volvo one? Works and fits much better. Napa 703-1396.

No Volvo cap for me been switched over to the open style cooling system. This thing has always run slightly warm. About one to two needle widths past 210. Any suggestions?

98xjeepy said:

No Volvo cap for me been switched over to the open style cooling system. This thing has always run slightly warm. About one to two needle widths past 210. Any suggestions?

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Check for an exhaust leak at the flange donut, blowing hot exhaust onto the block.

What is the antifreeze protection set at? Was it checked when it was replaced?

If the coolant froze, or turned to slush in the radiator, it will also cause an overheat.