"Normal" Engine Temperature

I swear - I searched everything I could think of...

What temperatures do you usually see on your water temperature?

My unmodified '99 (4.0L / AW4 / NP242 w/ 112,000 miles) shows at or slightly above 210. I've verified the guage readings with a non-contact thermometer on the thermostat housing.

I'm still chasing the overheating transmission and trans fluid dumping on the exhaust - and it seems that if the tranny fluid is being pre-heated to a higher than normal temp, it could be a contributing factor.

Thanks - Merry Christmas
Larry

STL Enterprises said:

What temperatures do you usually see on your water temperature?
Larry

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210 or less than a needle width from it at all times.

Normal operating temperature is 210-215*F for the 4.0 - but I've been able to lower it to about 190*F or so. Look for my Cooling FAQ (upcoming, once I pick up the threads,) for details on how to do just that.

No negative impact on fuel mileage or efficency, or emissions (I think they're lower...) Success? I've been running that way for four years or so...

5-90

the first year i had my xj it ran 165 all the time. about a year ago it started running at 200. would flushing the heater core and the coolant system bring some of that temp difference back?

Probably not - design temperature for the AMC242I6 is 210-215, like I said earlier. If you're running consistently so low, I'd think your thermostat was just not there (which would make your engine take forever to warm up, and would increase coolant flow so you'd run a little cooler. Useful, but hardly recommended.)

A system flush, however, is a good idea - you should do it every two years. You'll want a "hard" flush if you don't know when it was done last, or if it's been more than five years - if you stick to the biennial flush, a gallon or so of vinegar and a half-hour runtime is usually enough to break everything loose - then refill with coolant and DISTILLED, PURIFIED, or REVERSE OSMOSIS FILTERED water - NOT rpt NOT tap water! Using tap water will result in scale formation inside of about a month, and increased operating temperatures. You can get any of the three above at a hardware store, a grocery store, a drug store, or from a vending machine (if you have them in your area.)

This water is also a MUST for a battery that needs topping-off, and really should be used with your washer fluid if you use a concentrate (it simplifies things - I get a 6oz bottle that will fit into a coffee cup, which reduces space that I need for fluid storage.)

You can check to see if you have a thermostat by pulling the upper hose from the engine, and either sticking your finger or a flexible something down the fitting - it should stop at about the point where the fittings bolts to the head. If you can stick something in more than a few inches, get a thermostat and gasket, and replace them.

5-90

streetpirate said:

the first year i had my xj it ran 165 all the time. about a year ago it started running at 200. would flushing the heater core and the coolant system bring some of that temp difference back?

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165 is too low. The engine is designed to run with a 195 degree thermostst, which typically results in an operating temp of around 210 on the gauge.

5-90 said:

Normal operating temperature is 210-215*F for the 4.0 - but I've been able to lower it to about 190*F or so. Look for my Cooling FAQ (upcoming, once I pick up the threads,) for details on how to do just that.

No negative impact on fuel mileage or efficency, or emissions (I think they're lower...) Success? I've been running that way for four years or so...

5-90

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I got the same results with mine by putting a 180* thermostat in.

Mine actually runs at 165-175 so I think it has a 160º thermo in it.. because it usually never runs higher than that

My XJ does 130-135 %99 of the time.

XJ4x4 said:

My XJ does 130-135 %99 of the time.

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Your temp gauge doesn't work.

Mine used to run 175* til I replaced the 160* thermo with a 195* thermo. Now it gets up to 205ish where it is supposed to be. Running that low temp could form condensation inside the engine and give you a false alarm of a blown head gasket by showing traces of water on the dipstick.