Engine is running rough.

Mopargarage · **Posted:** Sat Jan 23, 2021 12:01 am

So today my wife was driving down the interstate trying to pass a semi when she thought she heard the trucks engine brake. Turns out the noise was from the liberty. Pulled over right away when she realized the noise was coming from her vehicle. Got it towed home. I checked to see if it would start but it was a super rough idle. Only let it run for a few seconds then turned it back off. Any ideas where I should start to diagnose the problem?

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TimmyTurner · **Joined:** Mon Mar 27, 2017 10:34 pm **Posts:** 21

Any other symptoms?
Smoking?
Leaks?

Generally speaking I start with the easy stuff.
Make sure your Air Intake boot isn't cracked (usually breaks where it attaches to the Turbo)
Make sure your Intercooler hoses are attached.

If all that is good, how many miles are on the Jeep, and when was the timing belt last changed?

WWDiesel · **Posted:** Sat Jan 23, 2021 1:49 am

How many miles on the vehicle?
A few higher mileage engines have been known to drop an exhaust valve. Makes a loud knocking sound when it happens.
Short of pulling the head for inspection, an easy way to check is to pull the fuel injectors and examine the ends of the injectors for any visible damage. You also may be able to look down into the cylinder through the injector hole to look for any damage.
I would not keep running it as it could cause further damage.
Report back your findings.

layback40 · **Posted:** Sat Jan 23, 2021 6:24 am

When you try to start it, does it crank normal & then crank fast for a short time (1/2 turn) then normal? When you started it, did it have a knocking sound? If no to these, may not be a dropped valve. You could try disconnecting plug on injectors, one at a time. The problem wil be the cylinder that unplugging has no efect. When you disconnect either of the others it probably wont start. When you know what cylinder is the problem, you can remove the injector for a look.

krb · **Posted:** Sat Jan 23, 2021 8:02 am

Codes?

thesameguy · **Joined:** Sat Oct 01, 2016 8:24 pm **Posts:** 652

What sound made her think the truck was braking?

PZKW108 · **Joined:** Sun Apr 06, 2014 5:23 pm **Posts:** 461

krb wrote:

Codes?

Yes, fist step is too scan it !

Mopargarage · **Posted:** Sat Jan 23, 2021 7:00 pm

TimmyTurner wrote:

Any other symptoms?
Smoking?
Leaks?

Generally speaking I start with the easy stuff.
Make sure your Air Intake boot isn't cracked (usually breaks where it attaches to the Turbo)
Make sure your Intercooler hoses are attached.

If all that is good, how many miles are on the Jeep, and when was the timing belt last changed?

No smoking or leaks. It sounds so rough at ide it was fine until on the interstate and it sounded like an engine brake. Only thing I can compare it to.

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Mopargarage · **Posted:** Sat Jan 23, 2021 7:03 pm

TimmyTurner wrote:

Any other symptoms?
Smoking?
Leaks?

Generally speaking I start with the easy stuff.
Make sure your Air Intake boot isn't cracked (usually breaks where it attaches to the Turbo)
Make sure your Intercooler hoses are attached.

If all that is good, how many miles are on the Jeep, and when was the timing belt last changed?

It has 202,000 miles, I just changed the timing belt on Monday.

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Mopargarage · **Posted:** Sat Jan 23, 2021 7:03 pm

thesameguy wrote:

What sound made her think the truck was braking?

The loud knocking would be my guess

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Mopargarage · **Posted:** Sat Jan 23, 2021 7:04 pm

layback40 wrote:

When you try to start it, does it crank normal & then crank fast for a short time (1/2 turn) then normal? When you started it, did it have a knocking sound? If no to these, may not be a dropped valve. You could try disconnecting plug on injectors, one at a time. The problem wil be the cylinder that unplugging has no efect. When you disconnect either of the others it probably wont start. When you know what cylinder is the problem, you can remove the injector for a look.

It took a few seconds to start and it does have some loud knocking at idle.

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Mopargarage · **Posted:** Sat Jan 23, 2021 7:05 pm

WWDiesel wrote:

How many miles on the vehicle?
A few higher mileage engines have been known to drop an exhaust valve. Makes a loud knocking sound when it happens.
Short of pulling the head for inspection, an easy way to check is to pull the fuel injectors and examine the ends of the injectors for any visible damage. You also may be able to look down into the cylinder through the injector hole to look for any damage.
I would not keep running it as it could cause further damage.
Report back your findings.

It has 202,000 miles. It definitely has a loud knocking at idle. Sounds really rough.

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Mopargarage · **Posted:** Sat Jan 23, 2021 7:10 pm

It was definitely an upstairs knock

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WWDiesel · **Posted:** Sat Jan 23, 2021 9:07 pm

Not good, pull the injectors and examine the ends for any visible damage.
Quit running it! :grim:

Report back.

krb · **Posted:** Sun Jan 24, 2021 9:13 am

Mopargarage wrote:

It has 202,000 miles, I just changed the timing belt on Monday.

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Timing belt changed 5 days ago? Are you experienced at stuff like that? Just wondering if the belt tensioner could have slipped some or another element associated with a TB change? Since all was fine until how many miles after the new belt?

So, no check engine light or codes?

Mopargarage · **Posted:** Mon Jan 25, 2021 1:18 pm

krb wrote:

Mopargarage wrote:

It has 202,000 miles, I just changed the timing belt on Monday.

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Timing belt changed 5 days ago? Are you experienced at stuff like that? Just wondering if the belt tensioner could have slipped some or another element associated with a TB change? Since all was fine until how many miles after the new belt?

So, no check engine light or codes?

I am experienced with our diesel liberty's. We own 3 and do all the work ourselves. Probably done a total of 10 times changing timing belts on all of them. I haven't checked anything yet haven't had time until today. About to go into the garage right now. It probably went about 100 miles after the timing belt change before the issue happened.

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Mopargarage · **Posted:** Mon Jan 25, 2021 1:19 pm

WWDiesel wrote:

Not good, pull the injectors and examine the ends for any visible damage.
Quit running it! :grim:

Report back.

I only started it once after it got home from the tow. Haven't ran it since. Going in the garage to check for codes and pull the injectors so I can check the cylinders.

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Mopargarage · **Posted:** Mon Jan 25, 2021 2:27 pm

Well my father in law beat me to the garage. He started breaking down the front end before pulling the injectors and checked for codes

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Mopargarage · **Posted:** Mon Jan 25, 2021 2:28 pm

Mopargarage wrote:

TimmyTurner wrote:

Any other symptoms?
Smoking?
Leaks?

Generally speaking I start with the easy stuff.
Make sure your Air Intake boot isn't cracked (usually breaks where it attaches to the Turbo)
Make sure your Intercooler hoses are attached.

If all that is good, how many miles are on the Jeep, and when was the timing belt last changed?

It has 202,000 miles, I just changed the timing belt on Monday.

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No smoking or leaks

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Mopargarage · **Posted:** Mon Jan 25, 2021 2:51 pm

He had it broken down to this in a hour

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Engine is running rough.

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