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4.0 Cracked head

27K views 91 replies 21 participants last post by  Moncheche 
#1 ·
Project turned into write up, please refer to page 5 for the necessary steps

I took my 01 XJ into the shop today for what seemed to be a valve/ lifter tap. In the process of trying to determine what is causing the sound (it quit making the nose as soon as i turned into the lot) I mentioned to the tech that I had put coolant in it about a month ago, and it is rather low again, and I have not seen any on the ground. Red flag goes off, I had wondered about the head, but remained optomistic thinking perhaps it was just a leaky head gasket.

Several minutes of pressurizing at the radiator and peering into the valve cover with a flash light we spotted traces of green liquid. CRACK. He happened to have what appears to be a good head from a 4.0, not sure if it is the updated or not (I doubt it).

What are your suggestions?:

1) I was told you can cheap out and buy some expensive royal purple/ slick 50 and run it as is with the additive until it lays down (who knows how long that may be is anyones guess)

2) replace the motor, not shure how long it has been cracked and leaking into the engine ( I dont think too long) but I dont want to replace the head and top end to find that my cam bearings are washed out.

3) hope for the best, machine shop the head he gave me, and go from there.

4) get a reman head $1300-1700

Is this a job I should consider doing at home? I have put on a couple of lifts, brake jobs, and installed lockers, and the routine maintenance, water pump, t stat etc etc, but never engine work. I do not have air tools, only hand tools. I am concerned about the exhaust and manifold bolts with only hand tools.
 
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#2 ·
4) get a reman head $1300-1700

Is this a job I should consider doing at home? I have put on a couple of lifts, brake jobs, and installed lockers, and the routine maintenance, water pump, t stat etc etc, but never engine work. I do not have air tools, only hand tools. I am concerned about the exhaust and manifold bolts with only hand tools.
I got a reman engine with a comp cams cam installed for 1800 shipped to me. There's no way in hell the head alone would be that expensive.

Doing the heads yourself wont be too much trouble. It sounds like you already know your way around your Jeep for the most part. The jeep is one of the easier vehicles to pull the heads on. Just take your time.

EDIT: here is the first link I found with about 15 seconds worth of searching ebay.

http://cgi.ebay.com/ebaymotors/REBUILT-4-0-AMC-CHEROKEE-JEEP-LAREDO-CYLINDER-HEAD-/360290511035?pt=Motors_Car_Truck_Parts_Accessories
 
#3 ·
if you have caught it quick enough and the oil pressure is still good put a replacement head on it.

I would not get a 0331 from a local "Machine shop". It could be the same year casting (00-01) that had the problems to begin with.
When I called locally looking to get a replacement 0331 none of the machine shops I talked to even knew to ck for cracks on the top of the head. Their response was we only ck for cracks in the cylinder chamber.

A updated 0331 from Alabama cyl head or from clearwater cyl head (on ebay) runs about $475 shipped. No way should it be $1300+ to replace one.
 
#4 ·
If you decide to pull the engine, i think you should invest in some air tools. You will thank yourself later when you find out how much a PITA those manifold to downpipe bolts are to get off. There's a reason people put brass nuts on the bolts. Wish they did that from factory. :(

Probably the first question I should of asked was, how many miles does it have? If it's sitting on a lot of mileage and you plan to keep the car until the day you die (like me :p) then you might want to consider jumping straight into a complete reman.

Also for pulling the engine you need to invest in a cherry picker. A engine stand is optional as you can use a tire or something, but I highly recommend investing in a stand. A load equalizer is very handy also (it attaches to the cherry picker) but I have managed to pull and replace several engines without needing it. Remember to catalog all your bolts. Head bolts you want to take a block of foam or a cardboard box and push the bolts into the box in the same configuration as when you pulled them out of the engine, so that when you put the new heads on, the same bolt goes into the same hole.
 
#5 ·
You shouldn't even need to remove the downpipe. You can just unbolt the intake and exhaust manifolds and move the out of the way enough to get the head off no problem. You could tie them back with a ratchet strap or something if they won't stay. It's really an easy job if you decided to do it yourself. The only way I can see it costing $1300- 1700 is if the shop is marking up the price on the head and charging you way too much for labor. Like was said already you can get a whole new motor for that much.
 
#6 ·
it has 98K miles on it. the price of the head i quoted 1700 is a mopar reman, the 1200 figure is my price (former employee of the shop) cost plus 10.

So just let me clarify, the head that I was given by the tech, not sure if its updated or not, is it worth it to take that to a machine shop and try and use that? Or should I go straight for an updated.

what about pulling the head from a JY on a newer engine, say a TJ 02-03?
 
#7 ·
Sure it would be the cheapest thing to get the head he gave you checked if it was free. Make sure they check between cylinders 3 & 4 on the top and bottom of the head for cracks. Getting one from the JY then having that one checked too would probably cost more than buying a new one from the Alabama guys though. I wouldn't just put on a junkyard head with out having to it checked out first.
 
#8 ·
just buy a new cast from clearwater cylinderhead. i got mine in like 4days. cost somewhere in the 400 range. ripped her down...CARFULLY remember where every bolt went. i made bolt holders in the oritntation they were on the egine out of wood. i just used plastic bags to seperate everything and wrote on the bag with a marker. its not a bad job. dont have to remove exhaust manifold. hardest part is gettin the top exhaust/bottom intake manifold bolts back on...but you can do it. took me like 12 hours total. if you get the newly cast head from there, there is a hole that needs to be plugged in the water jacket on the rear driverside corner. plug it with RTV and a bolt. forgot the size. i have had no problems......except i was too late and need to pull my engine and rebuild due to rod bearing wear. have fun.
 
#10 ·
I was wondering about that hole plugging also, sounds a bit odd.

What kind of time frame am I looking at here? I realize the sooner the better and the less it runs before repair the better. I work full time m-f 8-6 and it is my only vehicle. If I order a head you think driving it another week is a horrible idea? If i keep an eye on the coolant level.
 
#11 ·
If it leaking coolant into the oil then I wouldn't drive it at all but that's up to you. Coolant will burn out the engine bearings rather quickly so I wouldn't go it if I was you. You don't even know exactly how long you've been driving it like that already so you got to take that into account.
 
#12 ·
If you plan on keeping the vehicle, I would NOT put another 0331 factory head back on it unless it is an 03 or newer (with the word TUPY on the head). These heads are just too much of a wildcard in my opinion.

Get a head from Clearwater or Alabama Cylinder head, put it on yourself. Couple of oil changes to clean things out and should be good to go. Hopefully, you caught this early enough to save the engine (how is the oil pressure??).

However, I personally wouldn't want to push your luck by continuing to drive it until you get a new head on there........

Your total investment here with a replacement head would be minimal and you would learn a lot!
 
#19 ·
Thats what it is supposed to do. Faster the engine is turning the faster the pump turns. 40-60 is normal highway. Hot idle 13psi to 25 or something like that is considered normal by the FSM.

Edit: From 2001 FSM
Min. Pressure (600 rpm): 89.6 kPa (13 psi)
Min. Pressure at Idle (800 rpm): 172 to 241 kPa (25 to 35 psi)
Min. Pressure at 1600 rpm and Higher: 255 to 517 kPa (37 to 75 psi)
 
#20 ·
thats what I thought.

so looking at these heads on clearwater and alabama. alabama is listed for $495 clearwater has 2 one for $325 and one for $450, not sure what te difference is.

On a side note, do these come with valves in place? or is this going to be a bare head?
 
#21 ·
thats what I thought.

so looking at these heads on clearwater and alabama. alabama is listed for $495 clearwater has 2 one for $325 and one for $450, not sure what te difference is.

On a side note, do these come with valves in place? or is this going to be a bare head?
The 325 is remaned, the other is new. I assume atleast by the part numbers, the second having an N at the end.
And it should have the valves and everything. Alabama has the picture but at work you might not be able to see it. Clearwater isn't showing pics for me.
 
#23 ·
Reman sound reasonable...could just find another engine on craigslist for like 500 bucks if that..
 
#25 ·
Does anyone recommend alabama over clearwater or vise versa? I need to get the ball rolling on this. I'm going to down the Jeep for the week and borrow a car for the time being and plan to do the head job next weekend. Gotta get this ordered.
 
#31 ·
Lol, I have no idea, but I'm glad I picked it up. The stock head has always made me nervous, even though I've got 170K on it(I've noticed most go before 100K), I found an 05 TJ engine with 13K on it, that the block was trashed and gutted it, sold every thing that I could that I didn't want, and have been taking my time porting and polishing the head. still need to have the valves done and get a cam kit, but it's nice to know it's there incase.
 
#33 ·
Sounds like a good project.

I was looking more into heads; NAPA offers a reman 0331 head fot the XJ, anyone used that before?
I think about any of the remanned heads will be good, so long as they have the TUPY casing, thats all you should really check for. Other than that they are all pretty much reconditioned factory heads.
 
#35 ·
Ok cool, thanks guys. I think I will check my local NAPA, it is 5 minutes away and see if they have a TUPY in stock, avoid the shipping costs. If not looks like I'll order a reman from down south. Anyone that has done this procedure have a parts list? I'm sure I'll over look something and have to make multiple trips back to the parts store.
 
#37 ·
-The head bolts you can only reuse once, but I got new ones just to be sure
-Head gasket
-Thermostat housing gasket and Thermostat (while you are in there)
-Valve Cover Gasket
-Intake/Exhaust manifold gaskets

I also read a thread about someone using a shoebox and poking the push rods through it to keep them in order. Thought that was a pretty good idea.
 
#36 ·
I bought a reman from clearwater. Lasted me just over 2 years and then cracked again. They were good about replacement, though. They no longer sell the reman (they said after all the machining going into them, the price they could sell them at just wasn't worth it) so they gave me the new, built-up head at the same price, 400 shipped. I haven't completed my install so I can't say how durable it is, but the thing looks like a beast compared to the other one. I think this one will go the distance.
 
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