5.9 Running Hot and Pinging - JeepForum.com
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post #1 of 18 Old 06-05-2020, 08:14 AM Thread Starter
spang
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5.9 Running Hot and Pinging

Back with another 5.9 problem! I recently changed my rear main seal, oil pump (now an HV pump), and oil pan gasket, and in the process jacked the engine and trans up and down multiple times (to also do mounts and exhaust). On first start, my engine weirdly came to temperature in less than 5 minutes and felt like it was running super hot, even though the temp gauge said a hair below 220, and there was pretty noticeable pinging. It kept pinging for a few seconds even after the engine shut off. I'm doing a plenum gasket fix today and also a tune-up (plugs, cap, rotor).

Did I knock something loose like a sensor while working on the other stuff that would cause this? Is there anything else that I should look out for that would cause this? Should I go back to thinking about dragging the Heep to the junkyard? 😂

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post #2 of 18 Old 06-05-2020, 08:28 AM
MaintMech
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An infrared thermometer is a good aid for checking temps in a case like this. They don't cost that much and can save you a lot of grief!

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post #3 of 18 Old 06-05-2020, 09:21 AM Thread Starter
spang
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Awesome! Definitely grabbing one today. I'm a bit worried to start the engine again though because of the pinging. Is it normal for pinging to continue for a few seconds even after the engine is turned off?
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post #4 of 18 Old 06-05-2020, 10:48 AM
jeepjeepster
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Explain what you mean by pinging. It cannot ping if the engine isnt running, but Im wondering if it dieseled.

The steps to replace a rear main seal shouldnt cause the Jeep to overheat or ping. Did you do anything else?

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post #5 of 18 Old 06-05-2020, 05:03 PM Thread Starter
spang
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It definitely didn't diesel since I've had that happen before in a different car. It sounds exactly like pinging, that sound from detonation. It happened while the engine was on and then when it stopped it sounded like little pings for about a minute after the engine was turned off. I only replaced the things above: rear main, oil pan gasket, and oil pump (for an HV Melling version). When I pulled the spark plugs for cylinder 1 and 3, they were white, but not coated with that blistery stuff, which still leads me to believe that the engine was overheating. I'm doing the plenum and tune-up today, but should I be looking for any sensors that I knocked loose that would cause this?
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post #6 of 18 Old 06-05-2020, 10:46 PM
Timo_90xj
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There is no way the engine would ping when shut off, and especially not for a minute.
Larger plenum gasket leak will cause pinging when the engine is running. It also causes carbon deposits to accumulate on the piston tops, and form a carbon deposit ring around the top of cylinder wall. Piston TDC on the 5.9 is way down in the cylinder, often as much as .070"- .080". All that increases the chances for ping/ detonation, and if you happen to have one or couple leaky injectors it will make the problem even worse.

As for the engine running hot, look for cooling issues. They are fairly common on ZJs and the cooling system needs to be in good condition to keep engine and transmission cool. Is your e-fan operating properly?


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1990 XJ Limited (4-door), 4.0 I6, AW4, NP242, ***rolled and totalled @ 165k miles***

***Under construction***
1990 XJ (4-door), 4.0 I6, AW4, NP242, PBR 42" tires, Unimog 404 portal axles, 110" WB, full cage + uniframe completely rebuilt, front 3-link + panhard / double triangulated 4-link rear,... ***SOLD***
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post #7 of 18 Old 06-06-2020, 08:12 AM
jeepjeepster
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When are you hearing the pinging? Idle, under throttle, going up a hill?

Your not hearing the coolant boiling after you shut the engine off are you?

1994 ZJ-I6 w/270,000 mi
1998 ZJ 5.9 w/66,000 mi Slate Black
2004 KJ w/108,000 mi
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post #8 of 18 Old 06-06-2020, 02:50 PM Thread Starter
spang
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@Timo_90xj , that's what I thought too.
@jeepjeepster , it sounds like little pops when the engine is on and after the engine is turned off.

I've only had it at idle so far since this happened right after I finished the rear main, etc. I'm working on the plenum now, so I'll let you know if that helps. I'll probably flush the cooking system too. I picked up an infrared thermometer. Anything else, I should be looking for? Would a leaking plenum foul the O2 sensors causing pinging? It seems logical but I'm not 100% sure. Mine are about 7 years old at this point, so maybe it's time for a change anyway.

Last edited by spang; 06-07-2020 at 12:20 AM.
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post #9 of 18 Old 06-06-2020, 09:41 PM
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Quote:
Originally Posted by spang View Post
@Timo_90xj , that's what I thought too.
@jeepjeepster , it sounds like little pops when the engine is on and after the engine is turned off.

I've only had it at idle so far since this happened right after I finished the rear main, etc. I'm working on the plenum now, so I'll let you know if that helps. I'll probably flush the cooking system too. I picked up an interested thermometer. Anything else, I should be looking for? Would a leaking plenum foul the O2 sensors causing pinging? It seems logical but I'm not 100% sure. Mine are about 7 years old at this point, so maybe it's time for a change anyway.
A leaky plenum can cause 92 sensor failure but it certain creates deposits on the cylinder walls which create hot spots that cause the fuel and air to combust before the piston reaches top dead center. That is detonation /ping. Sounds like steel bearings in a can when the engine is under load. It's the piston slapping around.
Clean the intake really well. Run some seafoam or Mopar combustion chamber cleaner through it. It'll take a bit of driving to clear out the crap after it's done. Mine took a couple of weeks to go away completely.

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post #10 of 18 Old 06-09-2020, 01:02 AM Thread Starter
spang
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I dropped my intake off at the machine shop today to go through the parts washer. I should have things back together tomorrow and I'll let you all know how things go. O2 sensors just got delivered today too, so we'll see if that helps.
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post #11 of 18 Old 06-09-2020, 04:57 AM
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What brand 02? Just wondering what heat range are the plugs?
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post #12 of 18 Old 06-11-2020, 08:53 PM Thread Starter
spang
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I got the NTK sensors and AutoLite iridium plugs. Also the machine shop was super slow and I just got my intake back today. Gotta figure out how to pull out a rusted and broken intake bolt, then we can go ahead with the intake install.
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post #13 of 18 Old 06-12-2020, 12:58 AM
Zilliver
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Not good choice of plugs - why put iridiums on a old Mopar?

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post #14 of 18 Old 06-12-2020, 07:03 AM
V8GCZJ
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X2, Plain copper plugs work best. I run Autolites.
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post #15 of 18 Old 06-12-2020, 08:07 AM
Timo_90xj
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X3 on wrong choise of plugs. Use the factory specified Champion copper plugs, or matching NTK/NGK copper plugs.

1998 Grand Cherokee 5.9 LX daily driver, 1.75" BB, 32" KM2s, HPD30 Eaton e-locker/D44a stock LSD, 4.56 gears, custom- fabbed tube bumpers and tube fenders,...


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1990 XJ Limited (4-door), 4.0 I6, AW4, NP242, ***rolled and totalled @ 165k miles***

***Under construction***
1990 XJ (4-door), 4.0 I6, AW4, NP242, PBR 42" tires, Unimog 404 portal axles, 110" WB, full cage + uniframe completely rebuilt, front 3-link + panhard / double triangulated 4-link rear,... ***SOLD***
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