Jeep Cherokee running Hot - Help Please!!!
Newbie
Joined: May 2014
Posts: 16
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Well looks like I need to start tracking down my cooling problems. The PO has replaced the entire cooling system including the HD radiator and I took a quick 90 mile round trip and this is what was happening on the way home. the temp was 93 out.
and yes i need to clean her....
and yes i need to clean her....
CF Veteran
Joined: Aug 2009
Posts: 5,676
Likes: 301
From: WV
Year: '96
Model: Cherokee
The ScanGauge plugs into the ALDL under the dash and displays what the ECM is seeing/reading.....similar to the scan tool at the dealership being plugged into the ALDL port under the dash.
Factory dash gauges are "rigged" to point where the designers/engineers want them to point. As long as coolant temps r within predetermined parameters set by said designers/engineers, coolant temps r "normal".
One of those parameters is 160F.....when 160F coolant temp is reached within X amount of time after cold engine start-up, a normal warm-up cycle is counted by the ECM. If 160 is not reached in X amount of time, a CEL is set, at least on OBD-II systems. Another one of those parameters is 218F....the temp when the ECM turns on the efan. 218 is where the designers/engineers decided decided things r getting a little toasty, but not overheating, so that's the temp they want the efan on to cool things down a little.
Think about it this way.....if the dash gauge fluctuated between 160 and 218 a lot, the line of XJs (and other cars as well) at the dealership, along with their furious owners, would be a mile long.........and for no reason at all because the gauge is indicating normal parameters. To prevent the long lines at dealership service departments, designers/engineers "rig" temp gauges to point in a very narrow area on the gauge as long as temps remain within "normal" parameters. Jeep/Chrysler, for what ever reason decided to print the number 210 in the middle of the gauge. Most others just have a "C" and "H" on the gauge and the need points to the middle.....just like the XJ points to the middle.
Use a scan tool (or just about any after market temp gauge) to monitor temps and one will see how temps do "cycle" up/down in various different daily and seaonal driving conditions. The "rigged" factory dash gauge just sits there in the same spot as long as things remain within normal parameters that designers/engineers have predetermined.
Factory dash gauges are "rigged" to point where the designers/engineers want them to point. As long as coolant temps r within predetermined parameters set by said designers/engineers, coolant temps r "normal".
One of those parameters is 160F.....when 160F coolant temp is reached within X amount of time after cold engine start-up, a normal warm-up cycle is counted by the ECM. If 160 is not reached in X amount of time, a CEL is set, at least on OBD-II systems. Another one of those parameters is 218F....the temp when the ECM turns on the efan. 218 is where the designers/engineers decided decided things r getting a little toasty, but not overheating, so that's the temp they want the efan on to cool things down a little.
Think about it this way.....if the dash gauge fluctuated between 160 and 218 a lot, the line of XJs (and other cars as well) at the dealership, along with their furious owners, would be a mile long.........and for no reason at all because the gauge is indicating normal parameters. To prevent the long lines at dealership service departments, designers/engineers "rig" temp gauges to point in a very narrow area on the gauge as long as temps remain within "normal" parameters. Jeep/Chrysler, for what ever reason decided to print the number 210 in the middle of the gauge. Most others just have a "C" and "H" on the gauge and the need points to the middle.....just like the XJ points to the middle.
Use a scan tool (or just about any after market temp gauge) to monitor temps and one will see how temps do "cycle" up/down in various different daily and seaonal driving conditions. The "rigged" factory dash gauge just sits there in the same spot as long as things remain within normal parameters that designers/engineers have predetermined.
CF Veteran
Joined: Aug 2009
Posts: 5,676
Likes: 301
From: WV
Year: '96
Model: Cherokee
CF Veteran
Joined: Aug 2009
Posts: 5,676
Likes: 301
From: WV
Year: '96
Model: Cherokee
CF Veteran
Joined: May 2012
Posts: 7,965
Likes: 964
From: Lost in the wilds of Virginia
Year: 1998 Classic (I'll get it running soon....) and 02 Grand
Model: Cherokee (XJ)
Engine: 4.0
CF Veteran
Joined: Nov 2009
Posts: 8,172
Likes: 17
From: The Republic of TEXAS
Year: 1998
Model: Cherokee
Engine: 4.0L HO
Something tells me that even though neither of u reach 210, u r probably not doomed.
FWIW, here's a really cheap digital gauge from Trail Tech that would eliminate guessing which hash mark is what temp. The sending unit would mount in the 3/4" heater hose close to the stat cover.
http://www.trailtech.net/digital-gau...rature/722-eh1
Since u both have OBD-II XJs, the ScanGauge is really neat, plugs in under the dash and move it from one OBD-II vehicle to the next.
FWIW, here's a really cheap digital gauge from Trail Tech that would eliminate guessing which hash mark is what temp.
The sending unit would mount in the 3/4" heater hose close to the stat cover.http://www.trailtech.net/digital-gau...rature/722-eh1
Since u both have OBD-II XJs, the ScanGauge is really neat, plugs in under the dash and move it from one OBD-II vehicle to the next.
Last edited by djb383; Jul 13, 2014 at 10:51 PM.
Newbie
Joined: May 2014
Posts: 16
Likes: 0
CF Veteran
Joined: Nov 2009
Posts: 8,172
Likes: 17
From: The Republic of TEXAS
Year: 1998
Model: Cherokee
Engine: 4.0L HO
Well looks like I need to start tracking down my cooling problems. The PO has replaced the entire cooling system including the HD radiator and I took a quick 90 mile round trip and this is what was happening on the way home. the temp was 93 out.
and yes i need to clean her....
and yes i need to clean her....
Herp Derp Jerp
Joined: Nov 2011
Posts: 18,251
Likes: 17
From: Parham, ON
Year: 1999
Model: Cherokee
Engine: 4.0L OBD-II
In early models, the ECT gauge in the cluster is an analog unit driven directly by a thermistor. It is not rigged whatsoever.
I am not sure how models that utilize the CCD bus operate, though I suspect it's the same as I see far too much variance on my own to support the notion of manipulated behaviour.
However, to support djb383's assertion, 195-218°F can be considered the normal operating range. The fact that most XJs run around 210°F isn't actually documented and is more of a defacto standard (even the leakdown test in the FSM says "normal" without elaborating).
Fuel for the fire... bwahahaa
