TJ running too cold

[Mopud]

Morning folks,

I'm having a few issues getting the TJ up to operating temperature. Changed the thermostat from China crap to factory genuine and it certainly did help but not completely.

I've got my novak thermo activating at 96-97 degrees.. the fan controller is a Derale unit and will deactivate once it goes 3-4 degrees below the activation temp (so 92-93 it'll switch off).

With a 195f thermostat, technically it opens at 90-91 degrees. When is the best time to set the thermo fan to switch on? Most of the time the car runs so cool the thermo fan doesn't even get a chance to come on anyway.

On freeway runs it'll hit low 80s and idling it'll be lucky to crack 93-94 - only excessive idling and extreme heat will the fan actually switch on.

Cheers,
Mopud

[Dustbowl]

Mopud, those temps look awesome to me, nothing too cold about them

[Mopud]

Originally Posted by Dustbowl

Mopud, those temps look awesome to me, nothing too cold about them

Summer hasn't quite kicked yet either so i should be grateful for the low readings. But low 80s on freeway drives is ok?? Thought it might be a little too low? Thanks pal

[Dustbowl]

Originally Posted by Mopud

Summer hasn't quite kicked yet either so i should be grateful for the low readings. But low 80s on freeway drives is ok?? Thought it might be a little too low? Thanks pal

No not at all, I'f it were in the 60's there would be an issue, but those temps are a tribute to your excellent cooling system, I assume you must have gone for a triple+ core copper radiator and replaced the water pump, with your stroker, on top of a good thermo and excellent airflow, your motor loves you!

You will be greatfull on the next 40+ degree day

[Mopud]

Yes sir, Answer D, all of the above. I know optimum running temp for these engines is ~99c so I was of the logic that temps should be as close to that as possible.

It's been leaning out on the top end so I was thinking it could be temp related especially with the CEL coming on and off when running on the freeway; previously temps would drop to low-mid 70s - with the new tstat, temps are staying in the 80s so far though so I'll have to see if there's any change in that front but the issue is likely something else.

Thanks for the words of comfort, at least I know i'll be good for summer - I think it's the first time I've been able to say that in a good 5 years!

[Dustbowl]

Hahaha have you looked at replacing your temp sensor?
It can directly effect your fuel injection, idler control and ultimately stuff up your fuel air balance (too lean or too rich), this may also effect your overall answer.
I have heard of gauges reading right on the dash but telling the computer it's minus thirty!

[bonza]

Originally Posted by Mopud

Morning folks,

I'm having a few issues getting the TJ up to operating temperature. Changed the thermostat from China crap to factory genuine and it certainly did help but not completely.

I've got my novak thermo activating at 96-97 degrees.. the fan controller is a Derale unit and will deactivate once it goes 3-4 degrees below the activation temp (so 92-93 it'll switch off).

With a 195f thermostat, technically it opens at 90-91 degrees. When is the best time to set the thermo fan to switch on? Most of the time the car runs so cool the thermo fan doesn't even get a chance to come on anyway.

On freeway runs it'll hit low 80s and idling it'll be lucky to crack 93-94 - only excessive idling and extreme heat will the fan actually switch on.

Cheers,
Mopud

for a start your fan is cycling on correctly. it shouldn't come on if the temperature is below the thermostat setting. when the thermostat is closed there is just a pool of static water in the radiator that is not circulating thru the engine so having the fan running in that situation is useless

when the thermostat cracks open at 91C water begins to flow thru the radiator. if moving at speed the airflow passing thru the radiator should be enough to cool the water prior to it re-entering the engine block.

if the coolant temperature near the thermostat goes over about 95C it should be wide open allowing maximum coolant flow so that the radiator combined with with an airflow can then do its job. when it exceeds this temperature even more, the fan comes on to provide additional airflow thru the radiator and bring down the water temperature prior to it re-entering the engine block. the temperature sensor is located the thermostat housing to measure coolant temperature

a thermostat sets the lowest coolant temperature so if your engine is running at low 80'sC the stat should be shut closed, but there could and should be a trickle of coolant leaking pass the thermostat in the closed position, or perhaps your temperature readings are not that accurate

low to mid 80'C is nothing to worry about though, thats what my Jeep runs at during cooler days, rarely exceeding 95C on the hottest of days

as an aside Stant thermostats are about the best. they have a "jiggle" valve in the flange that always allow a small constant flow into the radiator and help with bleeding any air out of the system. some drill a 1/16" hole in the flange for the same reason. and yes, dont use Cina stats, your engine is worth more than the $2 you would save