Not reaching operating temp

4x4kingx889 · **Joined:** Sun Jul 17, 2011 6:42 pm **Posts:** 235

I have a brand new OEM t-stat and I am not reaching operating temp I seen another member had this problem but I can't find the thread now this is is 44F weather so no reason why it won't also I might add now the temp needle is at 12 but it is still not near 195..also when it is cold the only way it stay's at 12 is on a hill or with a load it go's right down any idea's why It is not getting around 195f?

Srytrucker · **Posted:** Mon Jan 14, 2013 1:41 am

It is supposed to be just left of 12 and since installing FIA front I have seen it go to 12 exact.

4x4kingx889 · **Joined:** Sun Jul 17, 2011 6:42 pm **Posts:** 235

Yeah but what I am saying even when my gauge is at 12 the jeep is only 170ish

TJ2 · **Posted:** Mon Jan 14, 2013 1:59 am

4x4kingx889 wrote:

Yeah but what I am saying even when my gauge is at 12 the jeep is only 170ish

Yes, 176. That's when the OEM t-stat opens.

4x4kingx889 · **Joined:** Sun Jul 17, 2011 6:42 pm **Posts:** 235

So that's normal even when driving? I thought since its a 195 tstat the temp should at least be in the 180 range

TJ2 · **Posted:** Mon Jan 14, 2013 2:15 am

My info comes from a post by Keith when Kap was beginning to develop his cutaway OEM housing to fit an inexpensive t-stat and make it easily replaceable.

It was from Keith that the 176F number comes. He recommended a 195, and Kap gave the option of 180 or 195. In previous incarnation I was on the short list to get one of his Frankenstats.

I sincerely hope that's still the case.

TJ2

racertracer · **Posted:** Mon Jan 14, 2013 4:53 am

if your temp gage is reading just left of 12 o'clock and your cabin remains cold even when your heater dial and fan is on full blast, then you may be experiencing trapped air in your cooling system. Specifically in in the top end of the engine or in your heater core.

With the engine cold, disconnect the top 5/8" hose connection at the front of the engine nearest the oil fill tube the one with the yellow oil fill cap and allow any trapped air to escape.

If no air escapes then disconnect one of the heater hoses and allow air to escape there.

If that doesn't work then it could be a malfunctioning thermostat. You should test it in boiling water to see if it opens properly or just take it back to Chrysler for a replacement.

I speak from a horrible blown head gasket experience.

The heater worked sporadically from Hot to Cold, an indication to me that trapped air was in the cooling system.

If you are experiencing any of these symptoms, don't take this issue lightly, you must repair it before the head is cooked.

4x4kingx889 · **Joined:** Sun Jul 17, 2011 6:42 pm **Posts:** 235

hmm I thought this system was self bleeding I will try that...should I remove house when it is running?

papaindigo · **Posted:** Mon Jan 14, 2013 4:50 pm

Comments:
1. the OEM tstat is set for ca. 176F. Does that mean every good OEM tstat does it's thing at that temp; I stongly doubt it and would speculate that actual temp is in the 172-180F range for a good OEM tstat. Your gauge reading is only as good or bad as the data produced from the sensor which I suspect is the one on the back of the OEM tstat housing; in any case that sensor may or may not be precise. Bottom line is if your dash gauge sits just a slight bit left of dead vertical your doing fine and your OEM tstat is ok.
2. if the temp gauge fluctuates you have issue(s). High readings are often, especially on the 05, correlated with a bad radiator fan clutch which can be cured by installing a Hayden heavy duty clutch which also cuts the mechanical fan in earlier in an overheat cycle than the OEM fan clutch. Low reading if consistent are a sure sign of a failed/failing OEM tsat.
3. I have seen a small amount of "down" movement associated with a good OEM tstat but only about a needle width and only when coming off a long highway run. If it goes more than that air in the system is possible so follow racer's advise. Alternatively get the Prestone flush-n-fill kit and a length of heater hose; install the flushing "T" in the length of heater hose and put that on the engine in place of the heater hose that runs over the top of the tstat on a cold engine; fill the system with coolant from the tank on the firewall until coolant comes out of the flushing "T"; close tank cap; remove temp hose and reinstall the one you took off (hook up the end at the heater and fill the line with coolant then hook it to the viscous heater). Do a couple of hot to cold drive cycles and check the level of coolant in the tank as it might drop a bit.
4. yes the system is self purging like all modern vehicle cooling systems but is it perfectly self purging, probably not. I'm a fan of making sure as little air is left in the system as possible on a refill which means bleeding air out as high in the system as possible. The vent on the passenger top side of the radiator works or the flushing "T" method or one member even drilled and tapped the top of the tstat for a screw vent.
5. there is no on off valve in the heater core, it works off baffles, so hot coolant circulates in it at all times. I'd consider a gentle flush of the heater core via the 2 heater hoses and a garden hose under minimal pressure.

Finally be sure to use only HOAT antifreeze and most especially not some "universal" crud. Mixing types of antifreeze has been proven to sometimes plug up systems and the forum has pictures to prove it.

Not reaching operating temp

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