Proper cooling system operation?

[Poorboy]

This issue is most noticeable while on the highway.

Earlier last week I installed a waterpump and thermostat in my 1996 XJ with 4.0l engine. Now while driving the temp gage has a wide swing from between the first hash mark (170 degree f?) to just under the 210 degree mark.

This vehicle does have heavy duty cooling with the two row radiator.

Sitting in traffic, it never gets much above 210, but once I'm back on the highway, the swing returns.

Is this normal?

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[Carves]

Sounds like they gave you a 170* or 180* t'stat.

... or its a 195* that isnt working properly.

[Poorboy]

Thermostat was stamped as a 195 on the housing. It's not a big deal for me to swap it out later. For now, I'll just live with it. Still need to replace the radiator anyway due to a pinhole.

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[Poorboy]

I want to see what the ECM sees temp wise. Time to dig out the scantool and get some live data. Also, heater output is consistent. HOT with no discernable change.

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[Cheromaniac]

Earlier last week I installed a waterpump and thermostat in my 1996 XJ with 4.0l engine. Now while driving the temp gage has a wide swing from between the first hash mark (170 degree f?) to just under the 210 degree mark.

You'd expect the temp. gauge to swing either side of 210*F when driving in the city as the electric fan cycles on/off but on the highway, the gauge should remain steady somewhere between the first hash mark and the middle.
My guess is that since you just recently serviced the cooling system, you could still have an air pocket inside the system. Just park the Jeep nose up and with the engine cold, start it up and while it's idling, gradually top up the radiator while gently squeezing the upper radiator hose to evacuate any remaining air.

[Poorboy]

I did that this morning. Rad cap off to observe any possible bubbles. No bubbles seen even after reaching op temp. Temp swing minimal at idle sitting still (as expected) The t-stat I put in has a jiggle pin to bleed any air. I'm going to take this thing on a fairly lengthy cruise in the next couple days and see how it does. I did top off the reservoir yesterday as I expected it would need. I'll be attaching my scantool some time today and see what it says....

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