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09-16-2010, 07:18 PM
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#1
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Registered User
Join Date: Aug 2007
Location: Indiana
Posts: 506
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No compression in ANY cylinder?
On a 99 4.7 that was overheated and now will not start. It turns over but is VERY weak/slow as if the battery is dead. Tried charging the battery and jumping it but that made no difference. Doesn't even begin to fire.
Did a dry compression test on each cylinder and they all showed. I verified the tester is good on my other vehicle. Any ideas?
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1998 Cherokee 4.0L
1999 Grand Cherokee Limited 4.7L
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09-16-2010, 07:22 PM
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#2
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Registered User
Join Date: Feb 2009
Location: macungie
Posts: 575
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Hmmmmm...... Seriously a wild guess here but my first thought is fried the rings? Or valves are stuck open somehow
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[QUOTE=sonoran_Tj
"If we collect data long enough, we may discover the root psychological cause for the "jeep thing".
So far it seems correlated to OCD and the need to look at one's poop."
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09-16-2010, 07:22 PM
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#3
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Registered User
Join Date: Apr 2009
Location: Pennsylvania
Posts: 1,055
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Sounds like a blown head gasket...hard to imagine you toasted both of them at once, but its possible.
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LET'S GO PSU
04 WJ Laredo I6
5.5" IRO CP
32" BFG M/Ts on JK 17's
-Devin
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09-16-2010, 07:34 PM
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#4
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Registered User
Join Date: Aug 2007
Location: Indiana
Posts: 506
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I've confirmed no coolant in the oil and vice versa.
If it is the valves, will the cam turn at all?
__________________
1998 Cherokee 4.0L
1999 Grand Cherokee Limited 4.7L
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09-16-2010, 08:18 PM
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#5
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Moderator
Join Date: Sep 2009
Location: Nitro, WV
Posts: 5,385
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Intake manifold gasket?
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~Aaron
NarnWVs Build Thread
2000WJ 4.7 247->242 swap,
Rough Country X-series 4",
K&N, Flowmaster Super 44,
JK Moabs+32" BFG KM M/Ts, Addco rear,
custom4x4fabrication rear bumper
Hitch-Mount Tire carrier for sale
Quote:
Originally Posted by jeep04
I just drive mine with a helmet on (just in case)
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09-16-2010, 08:25 PM
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#6
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Registered User
Join Date: Aug 2010
Location: Clinton,IA, Iowa
Posts: 146
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Try draining the oil and look for metalic parts. I find it hard to believe all cylinders have no compression. inless ALL valves got bent not allowing them to seat. could be a head gasket but still both sides on ALL cylinders? Good luck and let us know the outcome.
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09-16-2010, 08:34 PM
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#7
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Registered User
Join Date: Aug 2007
Location: Indiana
Posts: 506
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Will be seeing what I can find tomorrow.
One last question - Shouldn't it still turn over quickly regardless of whats wrong? It turns over VERY slowly.
__________________
1998 Cherokee 4.0L
1999 Grand Cherokee Limited 4.7L
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09-16-2010, 08:37 PM
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#8
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Registered User
Join Date: Aug 2010
Location: Clinton,IA, Iowa
Posts: 146
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Depending on the problem. broke a cam, broke rings that a grinding into the cylinders...but I still think that is unlikely. could be the starter itself as it could have hung up causing the overheating problem to begin with.
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09-16-2010, 08:40 PM
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#9
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Registered User
Join Date: Sep 2009
Location: Calgary, Alberta
Posts: 102
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Shoot a few drops of oil in each spark plug hole and try again. It will help it turn over a little better and should give you a bit of an idea on compression issues. Its possible you arent turning it over enough to get any compression reading on the gauge.
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09-16-2010, 08:42 PM
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#10
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Registered User
Join Date: Aug 2010
Location: Clinton,IA, Iowa
Posts: 146
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should turn it over 4 times for the correct compression. make sure the gauge is seated proper in the hole also.
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09-17-2010, 04:52 AM
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#11
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Registered User
Join Date: Feb 2009
Location: macungie
Posts: 575
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Well my 4.0l cranked slow when it had five gallons of coolent and oil, in the oil pan lol. But I doubt that's what your problem is. The cam can still turn even if the valves are bent, because it will push the valves open but then they won't close again. So I would consider checking the valves, pushrods, loggers, cam, and what not.
__________________
[QUOTE=sonoran_Tj
"If we collect data long enough, we may discover the root psychological cause for the "jeep thing".
So far it seems correlated to OCD and the need to look at one's poop."
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09-17-2010, 08:32 AM
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#12
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Registered User
Join Date: Aug 2010
Location: Clinton,IA, Iowa
Posts: 146
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thought about this also..spun bearing binding on the crank. How many miles on the motor?
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09-17-2010, 10:29 AM
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#13
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Registered User
Join Date: Aug 2007
Location: Indiana
Posts: 506
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147k miles
Got the valve covers off. The valves are operating correctly. The chains are intact and look to be in great shape.
Got the battery tested and it tested fine. It has spark. Seems to be getting fuel. What next? Pull the starter and have it tested? Pull the heads?
__________________
1998 Cherokee 4.0L
1999 Grand Cherokee Limited 4.7L
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09-17-2010, 10:56 AM
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#14
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2000 Laredo V8
Join Date: Oct 2003
Location: Raleigh, NC
Posts: 2,855
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Can you turn it over with your hand over the S. Plug tube holes? I'd want a "self diagnosis" before I tore off the head.
How about a bore scope? Borrow one? I would really want to see before tearing into it...
Ok...maybe pull starter too.
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2000 Laredo 4.7L Selec-Trac. 161K miles, Leather, 245 tires, tow package, crappy CD changer, full size spare, roof cross-rails & sunroof.
Changes & fixes: Rear Addco sway bar & greasble bushings, upgraded headlights, upgraded tail lights, new hood struts (replaced 2X), new rear hatchglass struts, new radiator (replaced 3X), new oil pressure sending unit (replaced 2X), 2 new speed sensors, 2 new door lock actuators, new ignition key cylinder, chrome front tow hooks, Mobil 1 Synthetic 5/30, Purolator Pure One oil filter, EBC slotted & dimpled rotors, EBC Greenstuff pads, new front shocks (replaced 3X), new rear shocks (replaced 2X),
new IRO steering stabilizer, new timing chain cover, new water pump, thermostat, new thermostat housing, new high pressure power steering hose, Michelin-X radials, new sunroof assembly, new single-piece lug nuts, new exhaust manifold studs & gasket on driver's side. Jeepforum.com sticker, Visit cobaltboatsforum.com when you can!
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09-17-2010, 12:16 PM
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#15
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Registered User
Join Date: Aug 2010
Location: Clinton,IA, Iowa
Posts: 146
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Id test the starter next. Air,fuel,spark. one is missing. Did you find the cause of the overheating?
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No compression in ANY cylinder?
