02 limited 4x4 180k engine or heads

[02silliberty]

I'm the original owner and did routine maintenance and repairs when needed. #1 cylinder has no compression and I can see a valve seat is compromised basically missing. Found some of it in the manifold after tearing it down.
Any chance the cylinder isn't damaged beyond fubr?
If I find another used 02-03 motor what are the dealer proofing replacement parts I need to have a reliable engine?
Of course it's after the fact but sounds like the early liberty's have this problem with the heads. Can the 02-03 heads be rebuilt to correct the problem.
I've read a good bit and learned I can get engines up to 2012 but would have to open the bottom and change a couple gizmos on the crankshaft along with a few other top side items. Just trying to keep cost down to see if its worth going this route. Thanks for any advice

 

[Ksat]

Yes, it's possible the seat didn't damage the cylinder walls. One of the easier ways to determine that is to throw a borescope down the spark plug hole and take a look. I think Autozone rents those out, if you don't own one. You can also buy one pretty cheap these days, as well, esp if you get one that works in tandem with a laptop. Make sure the piston is at bottom dead center you can get a good look around when using.

If there is no damage to the area the valve seat rests in, I imagine a garden variety machine shop would press a new seat in and then peen the aluminum on the head all the way around the area in attempt to secure it in place so that it doesn't come out again. Whether or not that attempt would be successful is hard to say. Other shops may heat the head up in an oven to get the metal to expand, pop the (colder) new seat in, then toss it back in the oven and eventually cool it down.

 

[02silliberty]

I searching for a shop but doesn't appear to be to many. If I find another motor I'd like to have the heads done before the swap. 1st shop I got to said to expect to pay between 1000 to 1300. Seams kinda steep.
Was this problem only on certain year models?

 

[LibertyTC]

Here is the 2002 factory service manual: http://www.colorado4wheel.com/manuals/Jeep/KJ/2002JeepKJServiceManual.pdf
If you remove the heads, you can see into cylinders for inspection. Look for any scoring/ carbon / overall condition.
A good automotive Machine shop can do the restoration of heads.

 

[Ksat]

The price you got from the shop depends on how much work they are planning on doing. The sky really can be the limit when it comes to how good a job you want. If you want them to remove all of the existing valve seats and install tighter-fitting ones, that's an expense (especially if additional machining is required). Milling the "deck" or area of the heads mate to the block to make sure it's flat is another expense. If the valve guides (where the valve stems move up and down in) turn out to be worn/out of spec and need to be corrected, that's more work.

If the cylinder wall on your block turns out to be okay, you may be better off just buying a re-manufactured head from Autozone or somewhere else which comes with a warranty. The price seems to be less than what your shop would charge you, and, keep in mind, your head with the dropped seat might not be repairable anyway. A local boneyard may be an option for you, too, if the price is cheap enough to make it worth your time.

As far as which years are more prone to the dropping seat problem, I found someone who posted this online:

"Though there is a correlation between overheating and seats dropping, there are countless instances of seats dropping without any overheat condition. There are also plenty of instances of overheating without a seat falling. We've been running a "dropped seat" poll on JeepForum for quite a few years and though the most common year reported to have dropped a seat is 2002, there is no consistent reason for the drop."

The main reason for the dropped valve seat issue appears to be that the seats Jeep installed didn't have as good of a press-fit seat as they possibly should have. The best way to keep the problem from occurring seems to be by ensuring the engine runs as cool as possible. In addition to the obvious, this also includes maintaining a clean cooling system (free of rust/scale/etc, lots of flushes, fresh antifreeze of compatible type), possibly installing a thermostat with a lower opening temp and making sure the rad fan(s) are doing their job.

 

[02silliberty]

The price you got from the shop depends on how much work they are planning on doing. The sky really can be the limit when it comes to how good a job you want. If you want them to remove all of the existing valve seats and install tighter-fitting ones, that's an expense (especially if additional machining is required). Milling the "deck" or area of the heads mate to the block to make sure it's flat is another expense. If the valve guides (where the valve stems move up and down in) turn out to be worn/out of spec and need to be corrected, that's more work.

If the cylinder wall on your block turns out to be okay, you may be better off just buying a re-manufactured head from Autozone or somewhere else which comes with a warranty. The price seems to be less than what your shop would charge you, and, keep in mind, your head with the dropped seat might not be repairable anyway. A local boneyard may be an option for you, too, if the price is cheap enough to make it worth your time.

As far as which years are more prone to the dropping seat problem, I found someone who posted this online:

"Though there is a correlation between overheating and seats dropping, there are countless instances of seats dropping without any overheat condition. There are also plenty of instances of overheating without a seat falling. We've been running a "dropped seat" poll on JeepForum for quite a few years and though the most common year reported to have dropped a seat is 2002, there is no consistent reason for the drop."

The main reason for the dropped valve seat issue appears to be that the seats Jeep installed didn't have as good of a press-fit seat as they possibly should have. The best way to keep the problem from occurring seems to be by ensuring the engine runs as cool as possible. In addition to the obvious, this also includes maintaining a clean cooling system (free of rust/scale/etc, lots of flushes, fresh antifreeze of compatible type), possibly installing a thermostat with a lower opening temp and making sure the rad fan(s) are doing their job.

I was thinking of replacing every thing myself with the exception of the seats. I wanted a shop to do that. I don't remember ever having an over heating issue just coolant leaks.
Can a shop test heads off the car for leaks warping and any other perimeters?

 

[Robochop]

I was thinking of replacing every thing myself with the exception of the seats. I wanted a shop to do that. I don't remember ever having an over heating issue just coolant leaks.
Can a shop test heads off the car for leaks warping and any other perimeters?

A local machine shop can do a warp and leak check on the heads. You can also ask to check the rest of the seats, but the more you ask for, the more expensive it gets. I have done several of these repairs and the head is just fine after fixing the bad seat, usually costing about $300 per head. Just remember as already mentioned, overheating is bad! The head is aluminum and expands when heated. The seats are steel, that's why they fall out when the engine gets hot. I have found as long as I'm doing a top end rebuild, you may as well do the timing too. You can get a kit on eBay for about $300 and up, depending on the brands. Which side head is bad? I have found Liberty's are plentiful in most junkyards. Make sure you get the same year as some are not interchangeable. There is a lot of good advice and wisdom on this website. Good luck!

 

[02silliberty]

I think I'd be very lucky if both the head and the block are fine. If so I just want the all seats replaced with what ever prevents this from happening. Buying a set of heads from an auto store or eBay may be a more affordable path.
Can the cylinder compression be checked by turning the crank by hand?

 

[Ksat]

Can a shop test heads off the car for leaks warping and any other perimeters?

A shop can check the flatness of the deck with a special straight edge and a feeler gauge set at the proper thickness. It's very easy to do and they shouldn't charge you much for that. They can also test for any cracks that might be in the head using a Magaflux dye system, which basically is a rattle can dye that that gets sprayed on and wiped off. Any dye that's remaining will have crept into any cracks there may be and should be pretty easy to spot.

Can the cylinder compression be checked by turning the crank by hand?

No.