TRCM
NAXJA Forum User
- Location
- Newport News,VA
I have 2 jeeps, one is a 96 cherokee sport, the other is an 88 cherokee pioneer.. both 4.0/aw4 combos (except the 96 is the HO variety and the 88 is the non-HO renix variety).
I'm trying to figure out what is going on with the low heat and cool engine temps (plus lousy mpg on the 88).
coolant levels are fine on both
readings taken with engines hot, but idling
88 info
-interior heat is 114 deg (center top duct on vent)
-temp of coolant to the heater core is 140-145
-temp of coolant from the heater core is 55-60
-outside air is ~ 25 deg
-coolant to radiator shows 184 deg, then drops suddenly to 174 when the tstat opens, and climbs back up to 184 or so
-tstat isn't open but a few seconds it seems by the temp changes
-fan clutch is stiff, engine temp seems to make no difference
-engine temp gage shows ~ 180-185 deg
96 info
-interior heat is 124 deg (center top duct on vent)
-temp of coolant to the heater core is 130
-temp of coolant from the heater core is 80
-outside air is ~ 25 deg
-coolant to radiator shows 188-190 and fairly constant (no significant drop when tstat opens)
-fan clutch is easy to turn, even when engine is warm
-engine temp shows ~180-185 deg
Now, on the 88, the temp diff across the heater core is 85-90 deg. When you add in the outside air temp, you get 110-115, which is exactly what it reads inside. But on the 96, the temp diff across the heater core is only ~ 50 deg, which when added to the outside air temp should give you 75 deg inside, but I am getting 124. So, something is different and I'm not sure what.
The heat in the 96 is adequate but could be better, while the 88 is less than adequate. I am sure the tstat in the 88 is bad (not working right and cycling excessively), and the fan clutch is also suspect (which when combined may answer the lousy mpg), but I am not sure if the heater core in the 88 needs to be flushed or not. Not sure if it will help, as it seems at first glance to be working well because the temp drop in coolant equals the temp increase in air flow. But when I compare it to the 96, the temp drop across the heater core does not equal the increase in air temp inside the cab.
Looking for some advice on what may be causing the differences and how to remedy them. I know the renix era engines are notorious for lousy mpg when the engine runs cold, which may answer part of my problem, but as for the heat, a new tstat may help, as if it adds 10 deg to the engine temp, it should also add 10 deg to the air temp in the cab, which would get me back to the same as the 96.
Thoughts/ideas/jokes ???????
I'm trying to figure out what is going on with the low heat and cool engine temps (plus lousy mpg on the 88).
coolant levels are fine on both
readings taken with engines hot, but idling
88 info
-interior heat is 114 deg (center top duct on vent)
-temp of coolant to the heater core is 140-145
-temp of coolant from the heater core is 55-60
-outside air is ~ 25 deg
-coolant to radiator shows 184 deg, then drops suddenly to 174 when the tstat opens, and climbs back up to 184 or so
-tstat isn't open but a few seconds it seems by the temp changes
-fan clutch is stiff, engine temp seems to make no difference
-engine temp gage shows ~ 180-185 deg
96 info
-interior heat is 124 deg (center top duct on vent)
-temp of coolant to the heater core is 130
-temp of coolant from the heater core is 80
-outside air is ~ 25 deg
-coolant to radiator shows 188-190 and fairly constant (no significant drop when tstat opens)
-fan clutch is easy to turn, even when engine is warm
-engine temp shows ~180-185 deg
Now, on the 88, the temp diff across the heater core is 85-90 deg. When you add in the outside air temp, you get 110-115, which is exactly what it reads inside. But on the 96, the temp diff across the heater core is only ~ 50 deg, which when added to the outside air temp should give you 75 deg inside, but I am getting 124. So, something is different and I'm not sure what.
The heat in the 96 is adequate but could be better, while the 88 is less than adequate. I am sure the tstat in the 88 is bad (not working right and cycling excessively), and the fan clutch is also suspect (which when combined may answer the lousy mpg), but I am not sure if the heater core in the 88 needs to be flushed or not. Not sure if it will help, as it seems at first glance to be working well because the temp drop in coolant equals the temp increase in air flow. But when I compare it to the 96, the temp drop across the heater core does not equal the increase in air temp inside the cab.
Looking for some advice on what may be causing the differences and how to remedy them. I know the renix era engines are notorious for lousy mpg when the engine runs cold, which may answer part of my problem, but as for the heat, a new tstat may help, as if it adds 10 deg to the engine temp, it should also add 10 deg to the air temp in the cab, which would get me back to the same as the 96.
Thoughts/ideas/jokes ???????