Engine temp rises above normal at idle
08-27-2010 | 03:07 PM
#16
Member
Joined: May 2010
Posts: 198
Likes: 0
From: Portland OR
Year: 96
Model: Cherokee
Engine: 4 liter
It's probably the Thermal clutch. It's not engaging anymore when it's up to temp. Airflow is increased when you're moving and drops temps and the clutch isn't spinning enough at idle.
Is your electric fan kicking on when it's supposed to , around 218-220, and kicking off around 200-210?
If not it's the temp sensor on the thermostat housing. The relay that kicks on the elec. fan when you use A/C is just fo rteh A/C.
There is a seperate sender that kicks the E fan on when engine temps rise. Just befcause it works and cools with a/c doesn't mean it is working as an auxillary cooling device passively/non driver activated.
Also, be sure to check the weep hole in the bottom of the water pump for crap leaking out like a whitish green deposit. It's hard to see without a flashlight from the bottom.
Either way it's time for a new thermal clutch if you haven't replaced it.
Don't get a stock one, get one for a 97-98 Grand Cherokee. Get the HD fan NAPA part 272310.
this one here
The guy may try to offer the MAX Cool version, but it won't fit. DO NOT get the MAX Cool. Get #272310 only 41.99. It's a little bigger but totally fits with no mods.
The stock fan at best pulls 50-70% of the shaft speed at temp. The Grand HD one pulls 70-90% at temp. It makes a lot more of a turbine whir, but once you get used to it ( I think it sounds kinda cool) , and the all around lower running temps, you'll love it.
Is your electric fan kicking on when it's supposed to , around 218-220, and kicking off around 200-210?
If not it's the temp sensor on the thermostat housing. The relay that kicks on the elec. fan when you use A/C is just fo rteh A/C.
There is a seperate sender that kicks the E fan on when engine temps rise. Just befcause it works and cools with a/c doesn't mean it is working as an auxillary cooling device passively/non driver activated.
Also, be sure to check the weep hole in the bottom of the water pump for crap leaking out like a whitish green deposit. It's hard to see without a flashlight from the bottom.
Either way it's time for a new thermal clutch if you haven't replaced it.
Don't get a stock one, get one for a 97-98 Grand Cherokee. Get the HD fan NAPA part 272310.
this one here
The guy may try to offer the MAX Cool version, but it won't fit. DO NOT get the MAX Cool. Get #272310 only 41.99. It's a little bigger but totally fits with no mods.
The stock fan at best pulls 50-70% of the shaft speed at temp. The Grand HD one pulls 70-90% at temp. It makes a lot more of a turbine whir, but once you get used to it ( I think it sounds kinda cool) , and the all around lower running temps, you'll love it.
Last edited by Solomon7; 08-27-2010 at 03:22 PM.
08-27-2010 | 04:19 PM
#17
CF Veteran
Joined: Jul 2009
Posts: 1,640
Likes: 0
From: Keesler AFB, MS
Year: 1998 XJ
Model: Cherokee
Engine: 4.0L
It's probably the Thermal clutch. It's not engaging anymore when it's up to temp. Airflow is increased when you're moving and drops temps and the clutch isn't spinning enough at idle.
Is your electric fan kicking on when it's supposed to , around 218-220, and kicking off around 200-210?
If not it's the temp sensor on the thermostat housing. The relay that kicks on the elec. fan when you use A/C is just fo rteh A/C.
There is a seperate sender that kicks the E fan on when engine temps rise. Just befcause it works and cools with a/c doesn't mean it is working as an auxillary cooling device passively/non driver activated.
Also, be sure to check the weep hole in the bottom of the water pump for crap leaking out like a whitish green deposit. It's hard to see without a flashlight from the bottom.
Either way it's time for a new thermal clutch if you haven't replaced it.
Don't get a stock one, get one for a 97-98 Grand Cherokee. Get the HD fan NAPA part 272310.
this one here
The guy may try to offer the MAX Cool version, but it won't fit. DO NOT get the MAX Cool. Get #272310 only 41.99. It's a little bigger but totally fits with no mods.
The stock fan at best pulls 50-70% of the shaft speed at temp. The Grand HD one pulls 70-90% at temp. It makes a lot more of a turbine whir, but once you get used to it ( I think it sounds kinda cool) , and the all around lower running temps, you'll love it.
Is your electric fan kicking on when it's supposed to , around 218-220, and kicking off around 200-210?
If not it's the temp sensor on the thermostat housing. The relay that kicks on the elec. fan when you use A/C is just fo rteh A/C.
There is a seperate sender that kicks the E fan on when engine temps rise. Just befcause it works and cools with a/c doesn't mean it is working as an auxillary cooling device passively/non driver activated.
Also, be sure to check the weep hole in the bottom of the water pump for crap leaking out like a whitish green deposit. It's hard to see without a flashlight from the bottom.
Either way it's time for a new thermal clutch if you haven't replaced it.
Don't get a stock one, get one for a 97-98 Grand Cherokee. Get the HD fan NAPA part 272310.
this one here
The guy may try to offer the MAX Cool version, but it won't fit. DO NOT get the MAX Cool. Get #272310 only 41.99. It's a little bigger but totally fits with no mods.
The stock fan at best pulls 50-70% of the shaft speed at temp. The Grand HD one pulls 70-90% at temp. It makes a lot more of a turbine whir, but once you get used to it ( I think it sounds kinda cool) , and the all around lower running temps, you'll love it.
I am interested in the HD fan you are talking about but how much more horse power does it require to turn, Is it a noticeable difference?
08-27-2010 | 04:33 PM
#18
Newbie
Joined: Aug 2010
Posts: 10
Likes: 0
From: stl missouri
Year: 1994
Model: Cherokee
Engine: 4.0 HO
So there it is, Your E fan should come on at 218 without the AC. And if your temp start to drop when your efan comes on then it sounds like all systems work fine besides the part that tells your Efan to turn on. I can't think of the name but i think its the temperature sending unit. If that part name is wrong, someone will correct me.
Now i would not buy that part till someone confirms that the temp sending unit is what causes you fan to come on at 218
Edited ; Actually i just looked up the temp sending unit and got that its only job is to report the temp (should have been common sense, lol)
So someone please post what the part is called that tells you efan to come on around 218
Thanks
Now i would not buy that part till someone confirms that the temp sending unit is what causes you fan to come on at 218
Edited ; Actually i just looked up the temp sending unit and got that its only job is to report the temp (should have been common sense, lol)
So someone please post what the part is called that tells you efan to come on around 218
Thanks
the front one thats easy to change is the one that tells your computer to change the air/fuel mixture and turn on the electric fan depending on the engine temp. located on thermostat housing in front of head
the rear one (a pain in the ***** to change) is for the temp gauge or dummy light depending on you gauge cluster. its in the top of the head in the back passangers side
i found this out because i just got rid of my dummy lights and put in real gauges
hope this is helpfull
the front one my be bad or your heep (no offence its a joke at my house) it will be about 30 bucks from the parts store
08-27-2010 | 05:02 PM
#19
CF Veteran
Joined: Nov 2009
Posts: 8,172
Likes: 17
From: The Republic of TEXAS
Year: 1998
Model: Cherokee
Engine: 4.0L HO
Is that correct? I've not seen 2 temp sending units on our '98, only the 1 in the t-stat housing. Also, nowhere in the FSM does it say the coolant temp sending unit tells your computor to change air/fuel mixture....the O2 sensor(s) does that.
08-30-2010 | 09:12 AM
#21
Thread Starter
Seasoned Member
Joined: Aug 2010
Posts: 296
Likes: 0
From: NYC
Year: 1996
Model: Cherokee
Engine: I6
It's probably the Thermal clutch. It's not engaging anymore when it's up to temp. Airflow is increased when you're moving and drops temps and the clutch isn't spinning enough at idle.
Is your electric fan kicking on when it's supposed to , around 218-220, and kicking off around 200-210?
If not it's the temp sensor on the thermostat housing. The relay that kicks on the elec. fan when you use A/C is just fo rteh A/C.
There is a seperate sender that kicks the E fan on when engine temps rise. Just befcause it works and cools with a/c doesn't mean it is working as an auxillary cooling device passively/non driver activated.
Also, be sure to check the weep hole in the bottom of the water pump for crap leaking out like a whitish green deposit. It's hard to see without a flashlight from the bottom.
Either way it's time for a new thermal clutch if you haven't replaced it.
Don't get a stock one, get one for a 97-98 Grand Cherokee. Get the HD fan NAPA part 272310.
this one here
The guy may try to offer the MAX Cool version, but it won't fit. DO NOT get the MAX Cool. Get #272310 only 41.99. It's a little bigger but totally fits with no mods.
The stock fan at best pulls 50-70% of the shaft speed at temp. The Grand HD one pulls 70-90% at temp. It makes a lot more of a turbine whir, but once you get used to it ( I think it sounds kinda cool) , and the all around lower running temps, you'll love it.
Is your electric fan kicking on when it's supposed to , around 218-220, and kicking off around 200-210?
If not it's the temp sensor on the thermostat housing. The relay that kicks on the elec. fan when you use A/C is just fo rteh A/C.
There is a seperate sender that kicks the E fan on when engine temps rise. Just befcause it works and cools with a/c doesn't mean it is working as an auxillary cooling device passively/non driver activated.
Also, be sure to check the weep hole in the bottom of the water pump for crap leaking out like a whitish green deposit. It's hard to see without a flashlight from the bottom.
Either way it's time for a new thermal clutch if you haven't replaced it.
Don't get a stock one, get one for a 97-98 Grand Cherokee. Get the HD fan NAPA part 272310.
this one here
The guy may try to offer the MAX Cool version, but it won't fit. DO NOT get the MAX Cool. Get #272310 only 41.99. It's a little bigger but totally fits with no mods.
The stock fan at best pulls 50-70% of the shaft speed at temp. The Grand HD one pulls 70-90% at temp. It makes a lot more of a turbine whir, but once you get used to it ( I think it sounds kinda cool) , and the all around lower running temps, you'll love it.
08-30-2010 | 09:18 AM
#22
Thread Starter
Seasoned Member
Joined: Aug 2010
Posts: 296
Likes: 0
From: NYC
Year: 1996
Model: Cherokee
Engine: I6
Little update since I spent around 20 hrs with the Jeep this weekend (fixing & cleaning odds & ends, stereo repair, etc)
After a long day Saturday, took a ride to pick up some chinese food for dinner. This was around 10 PM and it was pretty cool outside.
Parked, left the Jeep idling, and went in to place my order. Came back out to diagnose the issue with my stereo.
I happen to look at the cluster while checking the volume on the radio and see its crept up to like 235-240 range. I hear no fan on or nothing. So I put the AC on to get the fan going and this helped manage the temp a little, so i just shut the Jeep off then.
Sounds like the fan is not engaging at 218 as it should.
So, in order to fix this issue and maybe run a "little" cooler......what parts does it sound like are required to be replaced?
Fan clutch, t-stat, and temp sensor? Do the water pump while I am at it?
After a long day Saturday, took a ride to pick up some chinese food for dinner. This was around 10 PM and it was pretty cool outside.
Parked, left the Jeep idling, and went in to place my order. Came back out to diagnose the issue with my stereo.
I happen to look at the cluster while checking the volume on the radio and see its crept up to like 235-240 range. I hear no fan on or nothing. So I put the AC on to get the fan going and this helped manage the temp a little, so i just shut the Jeep off then.
Sounds like the fan is not engaging at 218 as it should.
So, in order to fix this issue and maybe run a "little" cooler......what parts does it sound like are required to be replaced?
Fan clutch, t-stat, and temp sensor? Do the water pump while I am at it?
08-30-2010 | 04:26 PM
#28
CF Veteran
Joined: Nov 2009
Posts: 8,172
Likes: 17
From: The Republic of TEXAS
Year: 1998
Model: Cherokee
Engine: 4.0L HO
On '98 and later (maybe earlier) sending units don't even control the gauges. A signal is sent by a sensor (coolant temp sensor for example) to the ECM/PCM. That info is analyzed by the ECM/PCM and the ECM/PCM controls the position of the gauge needle. If there's a short/bad connection between the ECM/PCM and the efan motor, the efan won't work but the sensor could be fine. When it comes down to electrical woes, life ain't no beach.
08-30-2010 | 05:11 PM
#29
Senior Member
Joined: May 2010
Posts: 889
Likes: 2
From: Detroit, MI
Year: 1994
Model: Cherokee
Engine: 4.0
FWIW, I put a new radiator in last week. Ordinary parts house rad for $109. Heat gauge is exactly where it was with the last one. It's 90+ degrees today and 100% humidity and no problems so far.