2002 dropped valve

[Roberte]

Hello everyone
I'm new to the jeep liberty line although I did have a 2000 jeep cherokee 4.0l that I loved to drive. Anyways I just purchased a 2002 liberty sport with 179,000 miles and* a bad miss in #2 cylinder thinking it was a plug or a coil. The body is the selling point because it's pretty nice shape. After replacing all coils,plugs and cam sensor it did help it to start and idler better but the miss was still there. So I took it to a very good* repair shop that I use and after he put it on a scope ,compression test he pulled the valve cover . The rocker was off the valve lash adjuster so he put a new adjuster on and the rocker fell off again.
He said the valve seat had fallen down enough to where the lash adjuster couldn't hold the rocker on.
So I decided i will replace both heads seeing all the remarks after googling my problem that this is a known problem with these heads.
I did get the numbers off the right head and it is 53020984 and from all I've read the left side should be a 53020983.
My question is will other heads work ?
And is the passenger side or right side the problem child that everyone has trouble with? ?
I am thinking of doing it myself but I know the timing is the critical part of this job. So I'll refer to the manual I have for that (hopefully it has good instructions )

 

[ltd02]

Wow it's actually good you caught it before the valve seat completely fell. That would have potentially trashed the piston too. So as a previous owner of an 02, yes it seems like the number 2 or 4 cylinder is the problem child most times. My 02 dropped a rocker on the #2 exhaust twice then I changed the lash adjuster and it was good til I got rid of it. I also had a headgasket failure at one point and pulled both heads to fix that. So while setting the timing sounds scary, I managed and I'm not a mechanic or particularly talented with a wrench. The factory service manual is very good.

It sounds like you will change both heads as you should. They should really be matched for the year just to be safe since there have been minor changes over the years. Most importantly, anything 05 and newer will have a different Cam reluctor ring on the right side head. This is what the cam sensor reads and will have to be changed to an 02-04 ring. Sometime in 04 they changed from the JTEC computer (that you have) to the newer NGC. If the ring doesn't match what the computer needs, the thing won't run.

Hopefully others will add any detail that I forgot, like I said I'm not much of a mechanic. :emotions34:

 

[Roberte]

Thank you ltd02
I'm going to start tomorrow pulling head to see what a dropped valve seat looks like. I'm very mechanical and I read a lot when I have a problem with something. I have a place that rebuilds heads and may go that route. I'm also 70 years old so it will be slow going.

 

[sota]

I would think if the seat hasn't fallen out completely and nothing else is trashed, replacing the seat should be a viable repair option in place of replacing both heads.
but then I've never dealt with a head with a dropped seat. Come on down, TJKJ2002! We need some of your expertise in here!

 

[Aceofspades]

News to me. I’ve cut and lapped seats before. I didn’t know they could fall out ? Do we use an insert of some sort thst is pressed into the head?

 

[ltd02]

I would think if the seat hasn't fallen out completely and nothing else is trashed, replacing the seat should be a viable repair option in place of replacing both heads.

Might be easier and cheaper to just buy upgraded heads. Most places that do head rebuilds know about the valve seat defect and correct this on older heads. Seemed to be mainly the early KJs like 02 maybe 03s.

News to me. I’ve cut and lapped seats before. I didn’t know they could fall out ? Do we use an insert of some sort thst is pressed into the head?

Yes, allegedly hardened seat pressed into aluminum head. Not too uncommon for them to fall especially if you overheat an early KJ.

 

[Aceofspades]

Damn. That ***** and good to know as well

 

[TomB985]

Interesting, this is something I hadn’t heard of before buying mine. Would my ‘04 be susceptible to this as well?

 

[sota]

I can't speak to specific statistical information, but it seems like only 02's and some early 03's have had the dropped seat problem, based on postings in various places. That's not to say it hasn't happened to other years, I just can't remember reading about one.

 

[Roberte]

I ordered 2 rebuilt heads that they say has the valves seats corrected in them.
This problem on the earlier 2002 thru 2004 3.7l is a known problem. Every one I tried to rebuild my heads said this is a problem that can be corrected with a larger valve seat. But they wanted more to rebuild 1 head then I spent for 2 rebuilt heads.
There is a place in Florida that sells both rebuilt heads for $600.00 shipped.
I got 2 different causes for the valve dropping and both are heat related. Some said low water or water pump or radiator caused engine to get to hot.
But I talked to a guy that works only on jeeps, mostly liberty's and he said the catalitic converter is the biggest problem. If they get pluged this is the biggest problem of heat and that there located to close to the heads.
Thank you all for the reply's and I'll post again when I get them out and new ones on.

 

[uss2defiant]

clearwater cylinder head in FL?

 

[Roberte]

clearwater cylinder head in FL?

Yes Clearwater heads.

 

[Roberte]

Well I finally got everything back together.
I installed both heads,the timing chain kit,new plugs,new coil on plugs and cam sensor.
It's runs great. New filter and oil. It's in the shop now having trans fluid changed,Rear pinion seal and 4 wheel transfer case oil changed.and g-05 antifreeze hoat type.
The number 2 valve seat was hanging by the valve. I wish I could post a pic but I need to resize it

 

[TomB985]

Glad to hear you got it all up and running!

The number 2 valve seat was hanging by the valve. I wish I could post a pic but I need to resize it

I'm happy to post it for you if you want to send it to me. [email protected]