Temp gauge reading hot

[Jarrett]

Hi guys,

Yeah, what's happening is the temp gauge went up to the red and the "check gauges" warning light came on (it's an 06 TJ 4.0ltr with 57000ks on it). But when I checked the engine everything was in order. I've got a production sedan and know what over heating engines look and feel like. Then when I took off down the road the reading went back to just over 100 (half way). Three weeks ago the opposite happened, after getting out of it I walked past the front of it and it had a fair bit of heat coming off it but the gauge read normal. Any help would be great.

Cheers,

Jc.


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[Jarrett]

Hi All, just an update on the temp gauge. It seems it is heating up at idle and there is faint boiling sound from the top rad hose after you turn the engine off. I found the clutch fan to be a bit too "free" at temperature so I changed it out with a factory new one. It's made a difference but it still sits over 100 at Idle. I'm in the Pilbara so it's quite hot (over 40). What do others find there temp gauge sitting at? Cheers Jc.


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[wes]

Mine always sits just under 100 - all day, every day - needle might as well be painted on.

Actually a couple of times it snuck up a flies dick over 100 when I was in your neighbourhood but that was doing long hauls on the highway all day with the AC on.

I'm guessing you are not losing coolant otherwise you would have mentioned it.

[Tonka Jeep]

Replace your thermostat for a hi-flow unit, opens at same temp. Dropped temps in mine from 98-100 to 90-92.

Currently my fan clutch is stuffed and locked on, temp sits at 88-90. It's 42C here at the moment so equivalent temps!

[Jarrett]

Thanks for the replies guys, I did think my temp was up a bit, I mean just under half shouldn't be to much to expect. I'll order a hi flow thermo and update on the situation. Also it's got the red (rather weak looking) coolant in it, is there any recommendations on types of coolant? I might mix up a stronger brew for it.


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[Jarrett]

Hi guys, well I fitted the new 180 thermostat and there is no difference in the temp, it still sits at just over 100. It doesn't creep up at Idle anymore but what's happened now is the heater tap seems to be stuck and I'm unable to open the heater core so I can't bleed the air out of it. As I can't find the it under the bonnet I'm guessing it must be under the dash. If anyone knows where it's located I'd like to open it manually to run the new coolant through it. Thanks guys.


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[darksidecustoms]

If TJ 4.0s are anything like the XJ 4.0s then there is something not quite right. Pressure test to spec, burp the system to make sure there are no air locks and thoroughly back flush the whole system to make sure there is no crud blocking the radiator replacing with quality 33% premix. Only then should you need to start replacing items.
XJs also don't run right with anything other than the 195*F thermostat and can end up with long term problems. Unless you've changed the clutch fan to match the lower temp of the thermostat by engaging earlier it won't be effective anyway.
XJ 4.0s are normal from 95 to 105*C if it helps.
Do you have auto or manual trans?