Jeep XJ 4.0l heads question

[mtulett1]

I have a 2001 XJ 4.0l . If i need to replace the heads do i need the head that i put on, to be machine or anything.

thanks

[rhandwor]

If buying a used head I would have it pressure tested and checked for straightness at a machine shop. If slightly warped they can shave it slightly for you. You can do it without doing this but always run a risk of it leaking.
A lot of machine shops will sell a rebuilt head. They will go through yours when business is slow.
A lot depends on what you buy if buying a used head from a running engine without leaks you probably can get away with it.

[fredjacksonsan]

I've recently come across some info about the "0331" head developing cracks, and it was used in the 2001 model year.

The # of the head can be found on the driver's side, just under the valve cover...I haven't looked, but there's a thin metallic plate that might cover it.

Were you losing coolant?

The info I got was that you can use a head from a pre-99 and you should be good to go with only minor modifications.

Have a look here for a great thread on the head.

[rhandwor]

Anyone wondering if they are having anti freeze leaking out. A radiator shop can do an analysis for combustible gas in the anti freeze. This will tell you for sure you have a head problem or cracked block. Anti freeze in the oil will wipe out bearings. Napa sells a test kit for around $50.00 Napa 700-1006
http://www.arrowheadradiator.com/hea..._leak_test.htm

[fredjacksonsan]

You can also send an oil sample and have it analyzed. I use Blackstone Labs.

That's how I found out my 00 was leaking coolant into the oil. And rhandwor is right, coolant in your oil will much your bearings. Just change the oil every 2500 miles until you find out and it should minimize the damage.

[mtulett1]

it is really starting to sound like i have a cracked head. if i get a pre-99 head, what midifications do i need to do. I would prefer the least amount of mods.

thanks everyone

[rhandwor]

I would call a few machine shops for a rebuilt head. If you find one for the price you want to pay. Go and look at it if your driving your vehicle. Use a flashlight and compare heads. The machine shop is experienced with various heads and will help you out. Business is bad I'm sure they will help you out.
Buying a head from a scrap yard add the price of a valve job and pressure test. All they will do is give you another head. A machine shop should fix the problem plus give you a new head gasket.

[fredjacksonsan]

Originally Posted by mtulett1

it is really starting to sound like i have a cracked head. if i get a pre-99 head, what midifications do i need to do. I would prefer the least amount of mods.

thanks everyone

The way I understand it, the pre-99 doesn't have some of the mounting hardware for the coil packs (since it was cap/rotor prior) but it's easy to transfer over. Check the link I put in for more info.

[mtulett1]

Alright first i want to say thanks very much for all the advice and help from everyone! it is greatly appreciated. It turns out that my heater core was leaking as a result of my over heat a while back. also my oil pump is hot and one of my idler pulleys is shot which is causing a loud whistling noise. No head problem ...at least not with the cherokee...lol and no bearing problems. thanks again everyone!