Ongoing overheating 96 Cherokee, EVERYTHING Replaced (NEED HELP!)
09-03-2012, 03:38 AM
#61
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Year: 1989 xj sport 2dr
Model: Cherokee
Engine: 12 hole bosch Injectors
Original head cracked around #5 and #6 cylinder area. It did eventually have have white smoke.
The owner before me had overheating problems due to a cracked and leaking radiator that he never fixed. That probably cracked the head, which did not show up right away after I bought it. I cannot say that the engine ran hot after I replaced the radiator, because the cracked head problem manifested itself right afterwards.
The replacement used head had a weak rear freeze plug in it that was not replaced by the mechanic, because he didn't know it was weak. But the Jeep was running hot by that point, so in retrospect the plug, and the rubber replacements, were probably blowing from overheating and the resulting overpressure.
During all this there was never oil in the coolant or coolant in the oil.
The head gaskets were never blown with either head.
In both cases, the problem was internal in the head. We found the cracks in the first one after it was pulled.
As I mentioned in #20, no one ever saw the actual internal cracks in the other head. But head # 3 cured my problem. So there was definitely something wrong with #2.
There are a lot of things that can cause overheating, as you can see on this forum. But you have done about all the obvious, as I did.
I can't say with certainty that if you replaced your head, the overheating will go away. But what else is there left to do?
I think if I had to do it all over again, I would buy a brand new head from Carolina head suppliers. The possible hassle of a used head is just not worth it.
The owner before me had overheating problems due to a cracked and leaking radiator that he never fixed. That probably cracked the head, which did not show up right away after I bought it. I cannot say that the engine ran hot after I replaced the radiator, because the cracked head problem manifested itself right afterwards.
The replacement used head had a weak rear freeze plug in it that was not replaced by the mechanic, because he didn't know it was weak. But the Jeep was running hot by that point, so in retrospect the plug, and the rubber replacements, were probably blowing from overheating and the resulting overpressure.
During all this there was never oil in the coolant or coolant in the oil.
The head gaskets were never blown with either head.
In both cases, the problem was internal in the head. We found the cracks in the first one after it was pulled.
As I mentioned in #20, no one ever saw the actual internal cracks in the other head. But head # 3 cured my problem. So there was definitely something wrong with #2.
There are a lot of things that can cause overheating, as you can see on this forum. But you have done about all the obvious, as I did.
I can't say with certainty that if you replaced your head, the overheating will go away. But what else is there left to do?
I think if I had to do it all over again, I would buy a brand new head from Carolina head suppliers. The possible hassle of a used head is just not worth it.
09-03-2012, 07:43 AM
#63
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Year: 1991
Model: Cherokee
Engine: 2001 4.0L
Here is my overheating thread. Might be some stuff to try on the last couple pages.
https://www.cherokeeforum.com/f2/tem...-hills-143387/
Hope this helps you out!
I also just had a customers jeep that was doing this, but completly different fix.
Replaced cooling system, replaced engine, cut off exhaust, went on and on trying stuff to make it not overheat. I finally gave up and took it to a Jeep specialist here in town. They were baffled it still overheated with all of the stuff I had replaced.(mind you it never spilled coolant)
They hooked it to their scan tool ad watched the PCM temp guage. The Jeep was idling at 203* and never went past 210* on test drives, but the dash was still reading 240*.
Replaced the coolant temp sensor at the back of the head, and that helped a little. Now showing 230*.
Replaced the wire and connector for this sensor, and Now shows a steady 210*!!! Since these sensors are resistance value based, Any added resistance is going to throw off your readings....In my case 30* difference!!
It was blowing white smoke when he brought it to me, so I know the old engine had internal issues and of course blamed a head/Gasket.
I didnt read this entire thread, but have you checked temps with an IR gun? This will be a very helpful tool in your situation!!
https://www.cherokeeforum.com/f2/tem...-hills-143387/
Hope this helps you out!
I also just had a customers jeep that was doing this, but completly different fix.
Replaced cooling system, replaced engine, cut off exhaust, went on and on trying stuff to make it not overheat. I finally gave up and took it to a Jeep specialist here in town. They were baffled it still overheated with all of the stuff I had replaced.(mind you it never spilled coolant)
They hooked it to their scan tool ad watched the PCM temp guage. The Jeep was idling at 203* and never went past 210* on test drives, but the dash was still reading 240*.
Replaced the coolant temp sensor at the back of the head, and that helped a little. Now showing 230*.
Replaced the wire and connector for this sensor, and Now shows a steady 210*!!! Since these sensors are resistance value based, Any added resistance is going to throw off your readings....In my case 30* difference!!
It was blowing white smoke when he brought it to me, so I know the old engine had internal issues and of course blamed a head/Gasket.
I didnt read this entire thread, but have you checked temps with an IR gun? This will be a very helpful tool in your situation!!
Last edited by MallCrawlXJ; 09-03-2012 at 07:54 AM.
09-03-2012, 08:51 AM
#64
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09-03-2012, 08:59 AM
#65
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"I didnt read this entire thread, but have you checked temps with an IR gun? This will be a very helpful tool in your situation!!"
Said he used one in his first post.
"Did you check that you don't have a colapsed hose? That may be your problem. It won't let the coolant flow properly."
Said both are good and not collapsing.
Seems after everything he's done and what's been discussed here his problem could be with the engine. Partial blockage or internal damage(crack/cracks). Check out posts 20 and 60.
Said he used one in his first post.
"Did you check that you don't have a colapsed hose? That may be your problem. It won't let the coolant flow properly."
Said both are good and not collapsing.
Seems after everything he's done and what's been discussed here his problem could be with the engine. Partial blockage or internal damage(crack/cracks). Check out posts 20 and 60.
09-03-2012, 09:56 AM
#66
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Year: 2015, 2012
Model: Grand Cherokee (WK2)
Engine: 3.6L
Well, it didn't run 240 all the time, unless it blew the rear freeze plug.
It would commonly run 215 even on a cool day.
On a hot day, about 230 especially after running on the freeway and then coming to a stop on an off ramp.
My dash gauge is accurate as any, I believe.
09-03-2012, 11:00 AM
#67
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At least the way his describes his symptoms they're not exactly like your but I'm still thinking an engine problem. And of course it's less costly to start with the head.
Makes sense. "I think if I had to do it all over again, I would buy a brand new head from Carolina head suppliers. The possible hassle of a used head is just not worth it."
As far as dash gauges go mine at times is reading less than 195 so.......
I've got a GOOD mechanical gauge set I'm thinking of installing.
Makes sense. "I think if I had to do it all over again, I would buy a brand new head from Carolina head suppliers. The possible hassle of a used head is just not worth it."
As far as dash gauges go mine at times is reading less than 195 so.......
I've got a GOOD mechanical gauge set I'm thinking of installing.
09-03-2012, 11:05 AM
#68
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Originally Posted by freegdr
system being pressure checked eliminates cracked head ? unless there not letting pressure stay in long enough. do air bubbles show up in overflo bottle when running ?
09-03-2012, 11:13 AM
#69
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Ok I'm going to buy a rebuilt cylinder head from ebay a powerseller who has excellent feedback (most say best cylinder head they ever bought). They are complete remans and they look brand New. 300 bucks and free shIpping. Which cast # do you recommend? 2686, 7120,or 0630?
09-03-2012, 11:36 AM
#70
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I just don't know where to go from here other than the engine itself. Just to give you a different point of view I posted this on the "oil" thread. It's from a Volvo site.
[Friction, heat and oil
Engine oil has four main functions in your car engine:
2. Remove heat from the engine to the cooling system.]
So if abnormally high heat from an internal engine problem causes the oil not to be able remove the heat it stands to reason the coolant is going to get too hot also. May not happen on short drives. So I'm guessing that cracks in the head,even though undetectable such as firestorm encountered,could be something to consider.
I don't know enough about casting #'s to answer that.
[Friction, heat and oil
Engine oil has four main functions in your car engine:
2. Remove heat from the engine to the cooling system.]
So if abnormally high heat from an internal engine problem causes the oil not to be able remove the heat it stands to reason the coolant is going to get too hot also. May not happen on short drives. So I'm guessing that cracks in the head,even though undetectable such as firestorm encountered,could be something to consider.
I don't know enough about casting #'s to answer that.
09-03-2012, 11:46 AM
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I just don't know where to go from here other than the engine itself. Just to give you a different point of view I posted this on the "oil" thread. It's from a Volvo site.
[Friction, heat and oil
Engine oil has four main functions in your car engine:
2. Remove heat from the engine to the cooling system.]
So if abnormally high heat from an internal engine problem causes the oil not to be able remove the heat it stands to reason the coolant is going to get too hot also. May not happen on short drives. So I'm guessing that cracks in the head,even though undetectable such as firestorm encountered,could be something to consider.
I don't know enough about casting #'s to answer that.
[Friction, heat and oil
Engine oil has four main functions in your car engine:
2. Remove heat from the engine to the cooling system.]
So if abnormally high heat from an internal engine problem causes the oil not to be able remove the heat it stands to reason the coolant is going to get too hot also. May not happen on short drives. So I'm guessing that cracks in the head,even though undetectable such as firestorm encountered,could be something to consider.
I don't know enough about casting #'s to answer that.
Ok I'm going to buy a rebuilt cylinder head from ebay a powerseller who has excellent feedback (most say best cylinder head they ever bought). They are complete remans and they look brand New. 300 bucks and free shIpping. Which cast # do you recommend? 2686, 7120,or 0630?
09-03-2012, 12:43 PM
#72
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I wasn't suggesting you change your oil. Just that if the engine is producing an extreme amount of heat the oil and coolant won't be able to stop an overheating issue.
Found this:
Year............Casting No
1987-90......2686
1991-95......7120
1996-98......0630
1999-04......0331
The early '87-'90 non-HO heads have low intake ports that flow rather poorly. The later HO heads have higher intake ports that flow more air by allowing a straighter shot into the cylinders. The '91-'95 HO heads with casting no. 7120 have the highest intake and exhaust port airflows, especially at lower valve lifts where it is most important, and are the best for performance. The '96-'98 0630 heads are almost identical except that they don't have a port for the coolant temp. gauge sending unit. The '99 and later WJ heads with casting no. 0331 have smaller exhaust ports to produce a faster warm-up of the catalytic converter and improve emissions, but performance also suffers because the ports don't flow as well as those of the 7120 and 0630 castings.
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Found this:
Year............Casting No
1987-90......2686
1991-95......7120
1996-98......0630
1999-04......0331
The early '87-'90 non-HO heads have low intake ports that flow rather poorly. The later HO heads have higher intake ports that flow more air by allowing a straighter shot into the cylinders. The '91-'95 HO heads with casting no. 7120 have the highest intake and exhaust port airflows, especially at lower valve lifts where it is most important, and are the best for performance. The '96-'98 0630 heads are almost identical except that they don't have a port for the coolant temp. gauge sending unit. The '99 and later WJ heads with casting no. 0331 have smaller exhaust ports to produce a faster warm-up of the catalytic converter and improve emissions, but performance also suffers because the ports don't flow as well as those of the 7120 and 0630 castings.
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09-03-2012, 12:45 PM
#73
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I wasn't suggesting you change your oil. Just that if the engine is producing an extreme amount of heat the oil and coolant won't be able to stop an overheating issue.
Found this:
Year............Casting No
1987-90......2686
1991-95......7120
1996-98......0630
1999-04......0331
The early '87-'90 non-HO heads have low intake ports that flow rather poorly. The later HO heads have higher intake ports that flow more air by allowing a straighter shot into the cylinders. The '91-'95 HO heads with casting no. 7120 have the highest intake and exhaust port airflows, especially at lower valve lifts where it is most important, and are the best for performance. The '96-'98 0630 heads are almost identical except that they don't have a port for the coolant temp. gauge sending unit. The '99 and later WJ heads with casting no. 0331 have smaller exhaust ports to produce a faster warm-up of the catalytic converter and improve emissions, but performance also suffers because the ports don't flow as well as those of the 7120 and 0630 castings.
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Found this:
Year............Casting No
1987-90......2686
1991-95......7120
1996-98......0630
1999-04......0331
The early '87-'90 non-HO heads have low intake ports that flow rather poorly. The later HO heads have higher intake ports that flow more air by allowing a straighter shot into the cylinders. The '91-'95 HO heads with casting no. 7120 have the highest intake and exhaust port airflows, especially at lower valve lifts where it is most important, and are the best for performance. The '96-'98 0630 heads are almost identical except that they don't have a port for the coolant temp. gauge sending unit. The '99 and later WJ heads with casting no. 0331 have smaller exhaust ports to produce a faster warm-up of the catalytic converter and improve emissions, but performance also suffers because the ports don't flow as well as those of the 7120 and 0630 castings.
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So if i get the 0630, my temp gauge won't work? I heard something about casting 7120 don't have dowels or something that my block has?
09-03-2012, 12:58 PM
#75
CF Veteran
Not sure about the dowel situation. My '96 has the sending unit on the back left hand side of the head. '96 being a change over yr maybe I have a 7120. I'll see what I can find out.