Overheated, now running extremely rough. Need advice please

[MKehrman]

My jeep has a new engine in it not more than a year old. Yesterday it overheated and it started driving very roughly. My jeep was shaking as it was running. The code on the ODB said that it is the 6th cylinder is misfiring. Replaced it and Jeep is still running roughly really bad. Does anybody got any opinions or ideas? My husband is working on it next thing I told him to do is replace the plugs. If that doesn't work what could it be? My engine has a warranty on it. I just don't know how long of a warranty. It is a rebuilt engine. My Jeep is a 2003 Jeep Liberty 3.7 engine. I appreciate any help I can get thank you very much for your time.

 

[GitEmSteveDave]

Check compression.

 

[MKehrman]

Check compression.

Doing that now. Thanks. Will update soon

 

[LibertyTC]

Was a new Mopar thermostat used when engine was rebuilt? How hot did it get on temp gauge? Steam from recovery tank or?
Is the oil on dipstick clean or have bubbles or milky substance?
When running is there any rattling from valve train?
Can you take it back to engine shop for warranty and have them check it over?
New spark plugs sure but use the right ones...

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[LibertyTC]

You replaced the coil pack right, try moving one around to see if the code moves?

 

[sota]

probably smoke wagon'ed the head gasket.
good luck getting whatever's wrong repaired under warranty

 

[MKehrman]

Update on my issue. Changed and gapped the new spark plugs. It ran a little better but not good enough to drive. It keeps misfiring. Changed the coil pack. For some reason i think it needs a radiator flush for the overheating. Also when someone buys a refurbished/rebuilt engine, do they just put the old plugs in the new engine as well as other random parts? The plugs looked like they were older than the new motor. I also have been burning through a quart of oil everyday. I'm not sure if the dipstick is the wrong one for this engine or if im really burning thay much oil. Does anyone else's Liberty burn through oil like this.
I APPRECIATE THE KIND FEEDBACK. YOU ALL ARE THE BEST! I will keep updating. Thank you

 

[MKehrman]

Was a new Mopar thermostat used when engine was rebuilt? How hot did it get on temp gauge? Steam from recovery tank or?
Is the oil on dipstick clean or have bubbles or milky substance?
When running is there any rattling from valve train?
Can you take it back to engine shop for warranty and have them check it over?
New spark plugs sure but use the right ones...

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I'm not sure if a Mopar was used. I'm going to call the shop that installed it today. The oil looks fine, I'll have to listen again to hear if there is s rattle. Is there a specific brand of plugs you recommend?

 

[LibertyTC]

The above spark plug image shows the correct NGK ZFR6F-11G plugs for the KJ.
Is that what is now installed into KJ?
The Mopar thermostat has it's own sealing gasket and air bleed hole.
This is what fits correctly into the lower rad hose. engine side.
How many miles on this engine now?

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[MKehrman]

The above spark plug image shows the correct NGK ZFR6F-11G plugs for the KJ.
Is that what is now installed into KJ?
The Mopar thermostat has it's own sealing gasket and air bleed hole.
This is what fits correctly into the lower rad hose. engine side.
How many miles on this engine now?

You must be registered for see images attach

Thank you so much for the info. I have a meeting with the mechanic who put in the engine. The original engine seized on me, thats the reason for the replacement. We use it mostly for out of town drives. So its 90% highway miles. Is have to look at what the new miles are. I will send a pic of what the old plugs looked like. And u will see why I am asking if any mechanic would put in the old plugs in the new engine. They look horrible. The new plugs are the NGK ZFR6F-11G.

 

[Royy]

Do you have an itemized invoice? I would assume that if they used new spark plugs (like they definitely should), they would have charged you for them.

 

[daves06lrenegade]

If the engine was allowed to overheat and it now runs poorly you probably have head/head gasket damage ... A compression check like stated above should be the very first diagnostic... You also said that it is now using oil...The oil may be going into the coolant (antifreeze)... Does the coolant look like chocolate milk? The oil may also be going out of the exhaust from either a bad head gasket or piston ring failures... Do you know that it was a "NEW" engine or was it a used one? The bill of sale should state what it is... Also the oil should not look like chocolate milk and should be at the correct level on the oil dip stick...
With the used plugs I would bet the engine is also used... You need to find out the actual mileage on this "replacement" engine... If it is used the salvage yard they bought it from should have given them the VIN# and mileage from the donor car...
Dave

 

[JasonJ]

If the engine was allowed to overheat and it now runs poorly you probably have head/head gasket damage ... A compression check like stated above should be the very first diagnostic... You also said that it is now using oil...The oil may be going into the coolant (antifreeze)... Does the coolant look like chocolate milk? The oil may also be going out of the exhaust from either a bad head gasket or piston ring failures... Do you know that it was a "NEW" engine or was it a used one? The bill of sale should state what it is... Also the oil should not look like chocolate milk and should be at the correct level on the oil dip stick...
With the used plugs I would bet the engine is also used... You need to find out the actual mileage on this "replacement" engine... If it is used the salvage yard they bought it from should have given them the VIN# and mileage from the donor car...
Dave

You're on fire lately, Dave! Spot on assessment.

And after the dust has cleared, someone should be asking why the "new" engine overheated in the first place. If it was/is a true rebuilt engine, it should have had a new mopar thermostat installed using actual HOAT coolant, a cleaned out or repaired cooling system, new plugs (only the aforementioned NGKs, of course)... a whole host of other new parts. It never should have overheated in the first place and CERTAINLY would not be losing a full quart of oil EVERY DAY. Are you sure? EVERY DAY a full quart? So in 5 days time it would be empty? Wow...

 

[Tarek]

bonjour je suis algerie j'ai une liberte 3.7 j'ai change les cols la sonde de temparatute et le relais et mon ventilateur dès qu'il passe en vitesse hign il n'arrete pas de savoir que la temperature descend a 87 degres et le tuyau ne gonfle pas non merci de m'aider

 

[mrlavalamp]

bonjour je suis algerie j'ai une liberte 3.7 j'ai change les cols la sonde de temparatute et le relais et mon ventilateur dès qu'il passe en vitesse hign il n'arrete pas de savoir que la temperature descend a 87 degres et le tuyau ne gonfle pas non merci de m'aider

Courtesy of google translate:
"hello i am algeria i have a freedom 3.7 i changed the collars the temparatute probe and the relay and my fan as soon as it goes into hign speed it does not stop to know that the temperature drops to 87 degrees and the hose does not swell no thanks for helping me"

So it sounds like once the fan goes into high speed it does not turn off again until the temp drops to 87*(Celsius probably so = 188 F)?