running hot..

[88swampedmj]

how can i tell if my radiator is clogged?

my 91 runs warm around 210 or so.. little under sometimes over it gets warm quick and stays warm..

 

i have the water pump off my blown 4.0 i may swap but i wanna check other stuff first..

[Rokhound]

i thought that was were they were to run :dunno: that is what mine runs but like i said i don't no

[88swampedmj]

well when i first got it, driving home for oklahoma it ran ok.. then warm then warmer.. like 230 or so.. its been doin ok lately now it looks like its gonna start goin back up again so i was wonderin how to test things.. i think the blades on the water pump maybe bad, i can squeez the hose easily while the truck is on.. so maybe the pump isnt pumpin much?

[Rokhound]

could it be a faulty thermostat

[Oizarod115]

thermostats go bad VERY easily, and don't last long even under perfect conditions.

 

they sometimes stick half open restricting flow, sometimes stick shut, sometimes stick open.

 

replacing that is two bolts, and some RTV and a gasket. VERY easy compared to the waterpump... which isn't hard, but its a PITA, i'd try thermostat first, itll cost you under 5 bucks including gas to the parts house.

[CWLONGSHOT]

With the fact 195 T stat, it will run almost to 210. You could put in a 180 T stat, but I would not advise the 160 many people say to put in. The 4.0's seem to like it hot.

 

Flush the system, install new T stat and refil with 50-50 mix abd call it good. Be sure to bleed all the air out or you will have more overheating problems.

 

I'll be doing mine here next month.

 

CW

[Pete M]

210 is where it's supposed to be.

What does the bottom of the radiator look like? All the bad rads I've delt with were bad enough to look like crap at the bottom, i.e. missing or damaged fins, lots of corrosion, etc.

[Oizarod115]

210 is where it's supposed to be.

What does the bottom of the radiator look like? All the bad rads I've delt with were bad enough to look like crap at the bottom, i.e. missing or damaged fins, lots of corrosion, etc.

 

i swapped a radiator out of mine that looked fine, just little pebble dents and such. but the new one i put in dropped temps 50~degrees. :dunno:

[Pete M]

If anyone has a closed-system 4.0L and the temps don't ever get above 200, that might indicate a t-stat that's stuck open.

[88swampedmj]

mines open system, it went above 210 on the highway home i watched it carefully.. it should be ok but i don't wanna be stuck out somewhere bc it overheats bad one day

[Oizarod115]

mines open system, it went above 210 on the highway home i watched it carefully.. it should be ok but i don't wanna be stuck out somewhere bc it overheats bad one day

 

side note: he lives in TEXAS.

 

i'd try some type of a flush man. and possibly a thermostat. we swapped engines on my bro's jeep swapped in the same rad, same waterpump, new 185 thermostat, literally the ONLY difference was the engine the coolant was going through. we pressure washed it (at a carwash ran the high pressure through it for a few min's) then swapped it... closed system thing runs 150*

(thermostat is bad apparently)

 

moral of this story is, flushing, and thermostats matter. :brows:

[Eagle]

moral of this story is, flushing, and thermostats matter. :brows:

Roger that.

 

And Pete is correct -- the engine should run at 210 on the gauge with a 195* thermostat. Don't forget, the whole purpose of a thermostat is to keep the temperature UP, not down. If the factory had wanted the engine to run at 180 they would have used a 180-degree thermostat. Trying to "cure" a cooling problem by running a colder thermostat is only attempting to mask the symptoms, and probably doomed to failure. After all, if the cooling system isn't capable of keeping the temperature down to 195 (210 at the gauge), why would a rational person think that same system would run any cooler with a colder thermostat in there? Open is open ... once it opens, it can't cool any better.

[88swampedmj]

iam guessin mines fine then, i was just makin sure bc iam takin a 100 mile trip tommorow and don't wanna any suprises

[HOrnbrod]

thermostats go bad VERY easily, and don't last long even under perfect conditions. they sometimes stick half open restricting flow, sometimes stick shut, sometimes stick open. replacing that is two bolts, and some RTV and a gasket. VERY easy compared to the waterpump... which isn't hard, but its a PITA, i'd try thermostat first, itll cost you under 5 bucks including gas to the parts house.

 

One thing I'd recommend when replacing stats is to use an OEM part. They have a small bypass hole in the inner flange to allow some coolant flow even if it's stuck closed. Or you can always drill you own.