Blogs Car Info Our Show Deals Mechanics Files Vehicle Donation

2005 jeep liberty misfiring/knocking. Can this really be piston ring?

Our 2005 jeep liberty sport has 69k miles- my husband mentioned it wasn’t running well months ago and then I had to drive it and I got it to the shop right away. The shop initially quoted $250 to replace 2 spark plugs but the next day stated $500 for a valve or $2800 if it was a piston ring but that they needed to call an affiliate shop as they didn’t have tools for this repair. Fast forward 3 days later and was just told $3k minimum for piston ring repair or we could have a rebuilt engine placed for $5k. I honestly don’t know that last time he took the jeep for an oil change or any other type of maintenance. The car runs but sounds like a misfire and some days is worse than others (i’m told). I suppose it could actually be a knocking but shrug, I’m not a car person. I’m told the problem hasn’t gotten worse over the past number of months but just some days better than others. If you try to go highway speeds it is HORRIBLE but in town gets him around. So higher speeds definitely make the issue worse. Does the car dx make sense. I"m also a little concerned that his poor maintenance led to this problem and wondering if a new engine with a good warranty be a safe bet if this is the route we go. This repair recommended by Chrysler dealer we always use as I got my van there.

In my opinion at 69,000 miles your engine shouldn’t need replaced or major work . I repeat shouldn’t . Anything can happen to an engine at any time so anythings possible . Your statement about the vehicle not having maintenance , even oil changes , is concerning .
I would take it to a good independent shop & have its problems properly diagnosed before deciding on what step to take next .
It could be that it just needs minor repair . If it has the 3.7 V6 engine sometimes a rocker arm will jump out of its proper place & cause a lot of noise & poor running . These engines are also known to drop valve seats which would be an expensive repair . It could be something as simple as bad spark plugs , bad injectors or coils but if it’s making loud knocking noises its probably a more serious problem .
As I stated before a proper diagnosis is your definite first step . I also own a 2005 Liberty .

It is always prudent when advised that you need an expensive repair to get a second opinion.
However, like Sloepoke, I fear that hubby’s neglect may be coming home to roost. My condolences.

For future use, perhaps it would be a good idea to learn how to check fluids, and to become familiar with your hubby’s vehicle maintenance schedule, and check the fluids and take over the maintenance on your hubby’s future cars. It may not be fair, but you’re probably unlikely to get him to change his ways.

Oh, yeah, and if I were to make a wind guess I’d guess a spun bearing… from oil depletion (neglect).

Reading the starting post I suspect there are several communication problems. Service history is sketchy , repair recommendations not fully understood and maybe the OP has not asked for a written estimate of what is needed.

You present comments about not knowing when the oil was last changed and poor maintenance.
It’s entirely possible the engine could be trashed at 69k miles. Some don’t even make it that long if maintenance is neglected.

What you need to do is clarify whether this diagnosis was done with a compression or leakdown test. If so and if the compression is down then a reman engine is needed.

Ten years of age, low miles, and few if any oil changes during that time can lead to engine oil sludging and coking. That in turn leads to oil consumption, oil pressure issues, and serious mechanical problems.

Offhand it sounds like they thought a tune-up so to speak would cure the problem and then discovered a compression issue when it did not.

Wow! $250 to replace 2 spark plugs. I wish I could have charged that in 1977. !972 Chevy van 350cu in. R&R 6 plugs was “normally” difficult for that vintage GM V8 with the expected exhaust manifold and heat shield obstructions. 2 plugs possibly #s 3 and 4 were nearly impossible! Vehicle on lift. Excessive knuckle cutting and scraping. I finally got the $!%#s R&Rd with a 12 point box wrench but used up all of my expletives in the process! We based our tune-up parts and labor on 4,6, or 8 cylinder. Fortunately I enlisted in the military less than a year later and was able to replace my used up expletives with many new ones.

Updated word is he was past due on Oil change but he said he was only past due, that he’s ben changing oil but that he HAS been getting in done. I don’t think there was 100% lack of maintenance but more like every 5k oil changes. I do really appreciate the input so far.

I am wondering if the Check engine light has illuminated and what codes are present. There are MANY causes of an engine misfire. Most will post an engine code to help track down the culprit.

PLEASE DO NOT listen to any nonsense that the piston rings should be suspect as a first guess…that is Preposterous. There are many many areas to check before suspecting a piston ring. Besides anything ring related would be a steady issue…always there and never going away. Piston ring problems on an engine with normal oil change intervals are rare if not non-existant entirely.

No shop should utter anything about piston rings until after exhausting many other possible causes of the misfire.

Most common causes of an engine misfire? Tune up stuff…plugs, wires (if used), ignition coil over plug systems… OIL that leaks into spark plug wells and makes the coil ground out and not spark the spark plug again…this is in coil over plug systems. Other items…like intake manifold gaskets…the manifold itself especially plastic intake manifolds…etc In other words there are MANY areas to check prior than EVER uttering anything about piston rings…and even rings can be checked for and verified good or bad.

Lots of info here. If the engine light is on…what are the codes? You can have them pulled at Autozone or Pepboys. Don not let some shop scare you like this right off the bat, that is poor form IMHO. Misfires are as common as colds. Their solutions do not always break the bank and usually do NOT. Many can be simple, cheap and easy to repair…no big deal.

There are plenty of areas to check before anyone mentions a piston ring and what that entails (low compression misfiring).


we will check the code again when we pick it up. Have to wait till tuesday before we can get in any other shop for a look but we’ve driven it this long… will post a code as soon as we get it back from shop number 1.

Thats a great first step. Piston Rings be damned. LOL We LOVE codes here…they are like a treasure map…


If this is the V6, that engine is very well known for having valvetrain problems

Yes, that dx makes sense. A good shop can easily determine if there’s a compression problem and narrow it down to valves or piston rings with a lot of confidence. If you trust their skill and workmanship, then I expect the shop is correct and there’s a piston ring problem. That would definitely cause the engine to perform poorly. Ask them to check the customer interest and technical service bulletins for the vehicle to see per chance if this problem has already been reported; i.e. it’s a known problem. If I recall correctly, there was some kind of systematic ring problem on certain Toyota engines a while back that was due to the opening segments of the rings lining up with the ones below and above, when they are supposed to stay a certain number of degrees from each other. Maybe some problem like that is known for this engine too. But I expect whatever the reason, you are looking at a major rebuild or a replacement engine.

Whoa…we just leaped over the river of fire… With no codes or assessment yet. Steady…steady. Valvetrain does not beget piston rings.

Slow down…get codes, perhaps a precursory exam…then make a diagnosis.


Since I have the same vehicle I have done a lot of reading about the 3.7 engine . It is not uncommon for this engine to spit out a rocker arm which will lead to noise & a poor running engine . This engines big brother the 4.7 is plagued with the same problem which from what I’ve read isn’t a terribly expensive repair .
I posted this before but the 3.7 is also plagued with dropping valve seats which is an expensive repair . I’d definitely get a proper diagnosis .
Liberty’s were also available with a diesel engine which is a whole different animal .

Problems like these in an vehicle newer than 00’ are actually a little laughable and the mfg’s should be hiding in shame. Especially with the competition from Japan and other areas in Europe. You wont hear stories like this coming from Japan in regards to engines. Suppliers can let down any car mfg for ancillary parts. The engines themselves most always retain their designed in reliability and for the most part are almost always WAY over engineered.

In this time…its almost funny to hear the words “Rocker Arms” talk about cheaping out and making money. The Rocker Arm served its purpose and did a good LONG run without too many problems. But this tech is way beyond old at this point and I’m surprised they show up under any hoods these days. Exception given to the latest crop of the LS platform from GM…they get a free pass because they are basically pretty Badass and about as ultimate in form as they are going to get really.


1 Like

Ok so I didn’t get the code (husband doest know which is was but it was a misfire code) but I did feel the second opinion and it made much more sense. The current mechanic said he did the compression test and our jeep passed just fine. He has seen several engines that have the rocker arm come off. He will have to take engine apart to some extent but is hoping he can just put back and change the oil and that will be it. He has had an engine with rocker arm fall off and then have more damage but it didn’t pass compression test. I really appreciate all the input and will let you know what the final verdict is, hopefully, early next week. Feeling much better about it at this point :slight_smile: