mtnance

What is the best temp range for a 96 4x4 4.0L? It's currently reading around 220 - 235 and at times almost gets into the red but drops to 220,..and goes back and forth with city driving. Doesn't change real fast but shouldn't it pretty much get to a temp and then stay unless idling for an extended time?

jebmccall

210 is what the 4.0 runs at normally. get a 195 thermostat.

TYQUAN

It appears you have an issue with the cooling system. Check your mechanical and electrical fans for a problem. Even under severe duty applications your truck shouldn't get that hot. Use a 195 degree t-stat. If the truck runs too cool the computer will stay in open loop and you'll get very poor gas mileage.

99KeeSport

Just be sure you buy a FAIL-OPEN thermostat.

tjwalker

Most 4.0 engines run in the 200-210 range. If you truly are running in the 220-235 range, (can be verified by pointing an infrared thermometer at the thermostat housing) there is something wrong with your cooling system.

Always a good time to review status of ALL components when symptomatic. Thermostat (use a 195) radiator cap, radiator, water pump, fan clutch, hoses.

Dollar for dollar, there is no better money spent than that spent on cooling system maintenance.

cruiser54

MotoRad at O'Reilly's.

mtnance

Thanks guys,...got an O'Reilly's close by. I've already got new hoses to replace the old, since I have no idea when that was done.

djb383

What guarantees a "fail safe" "fail open" t-stat will open????????

mtnance

Can't answer that, don't know. Can only assume it will stay open if it fails allowing a little extra time to get to the repairs.

tjwalker

Many thermostats are designed to stay open if they fail.

I buy my stats directly from Jeep. 195 degree for the 4.0 Never had a fail in 38 years with a factory stat...... They are well worth the extra what $3.00 or so?? They also have the little "jiggle valve" at the 12:00 position which I've always liked.....

I buy plenty of aftermarket parts. Thermostats (and crank sensors and oil pressure sending units) are not one of them. There are plenty of crapola cheap-charlie thermostats on the market. Buyer beware for something that is going to cycle THOUSANDS of times in your engine.

kjc

What they all said. X2 on the 'fix overheating problems'
Good time for at least a flush, and all of what tjwalker said.

N8N

I've heard that Robertshaw thermostats are good, but have never used one, because no parts stores ever seem to sell them. If you are mail ordering a bunch of stuff, that's what I'd get. Failing that, I agree dealership is probably a good idea. Thermostats are cheap but highly mission critical.

djb383

Seems kinda gimmicky to me. If the t-stat is wide open and the motor is overheating, seems like the t-stat is fine and something else is causing overheating.

cruiser54

I think it means it won't fail shut.

djb383

I can see it locking open due to something else causing overheating...... but what guarantees it will open? That's why it seems gimmicky to me and that's what I want a guarantee on......that it will open.