Beginner’s DIY Guide to Jeep 4.0 Head Replacement: Draft #1

The Jeep 4.0 engine head 0331 casting is prone to crack over the model years 2000-2002. This crack usually manifests as coolant leakage into the oil. I am not a mechanic, but I was able to successfully replace this head myself. I write this guide for other DIY "non-professionals" who might wish to attempt this head-replacement job in their own home garage. I would not have attempted this project, were it not for others who took time to post thier own experiences in doing so before me. Furthermore, I might not have been able to complete this project without the online help generously offered by others (special thanks to CCKen, Talyn, cruiser54, OnTheOffRoad, and many others). In such thanks, I pay forward, by posting my experience for other DIY newbies, who might be tempted to this job for themselves: You CAN replace that cracked head on your Jeep youself!

You should watch this you-tube video to see the first steps (valve-cover removal):
Pay very close attention to how he gently revomes the throttle-body cables. Each comes off in a different way. I broke one of mine, but I was able to glue it back together at the end.

OK; think you can do the rest?

You will need the following chemicals:
1) Engine degreaser.
2) Carb cleaner: needed to clean caked-on crud off of surfaces.
3) Brake cleaner: needed to degrease gasket-mating surfaces after you clean them with carb cleaner.
4) WD-40: needed on each electrical harness connector to help free it before you disconnect it; use a bit more when you reconnect it. Be gentle with these fragile parts.
5) Thread sealant. You need this for the threads of head bolt #11 to prevent coolant leakage through that bolt. Get the kind that does not harden. I used Permatex Hi-temp Thread Sealant.
6) Engine assembly lube (I used Lucas) for the rocker re-assembly.
7) Anti-sieze lube: for EVERY bolt that screws into the aluminum head (not just spark plugs).
8) 2-cycle oil: to help keep your piston rings clean while you scrape old gasket off the block (see explanation below).

You will need the following special tools:
1) A 12-point deep-socket, either 1/2inch or 13mm to remove and install the “star” head bolts. My Kobalt (Lowes) ½-in 12-point fit VERY tight: it was good for head-bolt removal, but the center hole was not big enough to for the new (non-rusty) head-bolt studs. Craftsman 13mm 12-point deep socket worked great for reassembly. Though it fits the “star” head-bolts looser, I imagine it would work well for head-bolt removal as well, as long as you keep pressure down against the bolt.
2) The fuel-line disconnect “tool”. The fuel line connects to the fuel rail with a “quick connect” (but difficult-disconnect) fitting. The plastic ring “tool kit” from O’Rileys did not work for me; I spent over an hour trying to make it work. The nylon ring kit from Autozone did work for me.
3) Haynes Repair Manual for 2000 Jeep. I regret not getting it sooner. Follow it step-by-step; yet take my advice below.
4) Impact wrench (air gun): you'll need this to get the lower exhaust maifold bolts off the exhaust pipe (or maybe you can find a way to just cut them them off from their middle to remove it from the exhaust pipe). If you try to remove the manifolds before removing the head from the block, then you will instead need: lots of socket extensions of different lengths, along with time and patience. “Luke, use the force!”
5) Shop-vac: you need to vac out the old head gasket shavings out of the cylinders and off the lifters. You will need the narrow “crevice” end-attachment to get down to the lifters. I used the crevice attachment off my home vac, put it down into the engine, and used my hand as a 90-deg-bend to “connect it” onto the shop-vac hose end. Worked great.
6) Harbor Freight sells a flat stone block for sharpening knives (on sale for $1). This big, perfectly-flat, abrasive surface works AWESOME to clean old gasket off all flat aluminum surfaces: intake manifold, thermostat housing, etc. Rinse away all that greasy-stone-sand with water (as you sand), then use carb cleaner, then brake cleaner, before re-assembly.

You will need the following parts:
1) A re-man head. I chose a re-man 0331 casting with the TUPY stamp.
2) Head gasket “set/kit”. This gives you more parts than you need, yet it is cheaper than ordering each gasket part individually. I got the Victor-Reinz head set, and a new set of V-R head-bolts. I suggest RockAuto if you order online. Also consider ordering a new serpentine belt, and new thermostat as well.

So, lets get started: If possible, take your Jeep to the car wash (the kind where you put in quarters, and get the high-pressure spay-gun), hopefully less than 2 miles away, so your exhaust manifold stay reasonably cool. Open the hood, and use a whole can of engine degreaser liberally all over. Let it soak for a few min. Then spray the crap out of your engine with the high-pressure gun on soap setting, and then rinse. This will make everything much cleaner for the rest of the job ahead. Otherwise, do your best with your hose at home (but don’t skip this important step).

Remove your hood from the start. When I finally did, it seemed easiest to cut the wires connecting to the hood light: you’ll see why. I plan to twist them back together at the end.

Be VERY gentle removing the plastic clips that connect the throttle wires to the throttle body. They each come off in a different way. I can promise that you will break the front-most-clip if you fail to pull it forward (towards the driver’s door) before disengaging it. See youtube video.

After you remove the valve cover: check to see that all of you rockers are nice and tight. If any rocker is even a bit loose (if you can wiggle any rocker at all), then you have a problem that must be addressed: look for a bad lifter or bent pushrod. See you-tube video above. Mine were all tight, so I left my lifters alone. Disassemble your rockers very gently and evenly: the bridges can get twisted very easily. Keep all your rocker assemblies and push-rods in their original orientation as you remove them, and store them in that same orientation and order.

Inspect your removed rockers now. If the pivots are worn, order new pivots and rockers now. Or, make plans to pull used ones from the junkyard, like my buddy did for me (these engines are everywhere). This pic shows good pivots (on a twisted bridge, on the right) compared to a bad pivot (on the left):

I re-bent the the twisted bridge (on the right) to lay flat before re-installation.

We used a crow bar to break the bottom of the air-filter-box off the bottom bolts. If the nut-side is rusted, you can’t get to it, and they spin: I’m glad we finally took the crow-bar to break this plastic off these bolts. No real harm done; these breaks are made UNDER the air filter.

Remove as many electrical connector harnesses as you can from the plastic fuel-injector electrical bar, or you will be fighting this plastic bar the whole time. Make sure you remove the connector under the power steering pump to really free it up. Get a flashlight to see it. Finally: you will see 1 thin wire that somehow goes to injector #1 that I could not disconnect. If I had to do this job again, I'd just cut that single wire, and twist it back together at the end of the job.

On my 2000 Grand Cherokee, there was no need to remove the alternator or it’s electrical connections. I just removed 2 bolts to free that connection from the head.

To dismount the steering pump, use the holes in the pulley to get easy deep-socket access to the 3 bolt heads. I also (later) loosened that PS bracket (15mm bolt) to allow better access to the front exhaust bolt. Set the pump aside to where your air-filter box used to be.

I removed the thermostat housing before removing the head. This made it easier to lift out the head, b/c the rigid AC hose is right above this housing on my model year. Closed-end wrench and patience to get that bottom bolt off the thermo housing.

If possible, remove the head, intake, and exhaust manifold as a single unit. This will save you much time. It may be a challenge to get the exhaust bolts off (from under the car, using many extensions on your impact-wrench, hopefully without spinning/crushing the rusted nut-retainers off the exhaust nuts). It is definitely worth it if you can make this happen. Then, just rig ropes over a pole and get some friends to help lift off this heavy assembly. See pic of re-install below for an example of how to rig ropes and pole. If you happen to have an engine hoist, well, that would work too.

Let me be clear on this point: make every effort to remove the head, intake, and exhaust manifold as a single unit, even if you need to cut the lower exhaust mainfold bolts off the exhaust pipe to do so. Otherwise, if you try to remove the manifolds before removing the head, you will need: lots of socket extensions of different lengths, along with time and patience... You cannot see those lower manifold bolts, and they are very difficult to reach... “Luke, use the force!” This is how I did it myself, so it’s not impossible. In this case, a friend with a flashlight and mirror will help a lot.

Harbor Freight sells a flat stone block for sharpening knives (on sale for $1). This big, perfectly-flat, abrasive surface works AWESOME to clean old gasket off all aluminum surfaces: intake manifold, thermostat housing, etc. Rinse away all that greasy-stone-sand with water (as you sand), then use carb cleaner, then brake cleaner, before re-assembly.

For cleaning old gasket off the engine block: I used a razor scraper, then a brass brush wheel on my electric drill. Unlike aluminum, razors and brass power-wheels will not hurt your steel engine block. Of course, powder debris dusted all down into my engine (to protect with 2-cycle oil; see below). I finished the block with carb cleaner and Scotch-Brite (green kitchen scrubbing pads). I did not use the knife-sharpening stone on my engine block, fearing the sand it would shed into my engine. I vaccummed out all the shavings with my shop vac (both the pistons, and the lifters).

If I had to do it over: here’s how to keep your rings clean while you remove the old head-gasket off your block: pour 2-cylce engine oil onto each piston, so that it totally fills the gap around the piston, and lightly covers the piston head. This will protect the rings from falling debris and wheel dust as you scrape old gasket off your head. Keep in mind: 2-cycle oil was designed to be burned in combustion chambers, so I can’t imagine any harm in flooding it over your rings and pistons. Do this BEFORE you start scraping and power-brushing the old gasket off the block. Also pour the thickest oil you have onto the tops of your lifters. The old gasket shavings and dust will then land on top of the oil, and just sit there on top of the oil (which you will shop-vac off soon enough). Now, use compressed air to the blow gasket shavings out the head-bolt threads in your block. If you want to chase out your blocks threads, then do so. NOW, shop-vac that oil off the pistons, rings, and lifters: you will now be removing those shavings and dust before they ever touched your rings or lifters.

OK. If you have made it this far, then I can assure you that re-assembly will be much easier.

Use the head side-bolts with rope and pole to gently lower your new naked head onto your new gasket.
PIC:


My Autozone rental torque-wrench was completely broken: test your torque wrench on your lug-nuts to see it works at both light and heavy settings before you get started on your new bolts on your new head on your new gasket. Follow the Haynes guide for sequential torque specs.

Re-installing the maifolds after the new head is on: Use a freind with a mirror and flashlight to help you get the lower manifold bolts in place. Or, do like I did in advance: Pre-thread all the lower manifold bolts on, with sockets and extensions on each bolt, BEFORE you slip on the intake manifold:
PIC:


Re-installing your new rockers/pivots/bridges onto your new head: My rockers and pivots bearing surfaces were utterly DESTROYED by running coolant in my oil (yet, my lower engine bearings still yield 20 PSI at hot idle). I got shiny junk-yard rockers/pivots/bridges to replace mine. My OEM parts had grooves cut into them (?for oil flow?). Yet, the one new replacement pivot I bought had no groove at all. Therefore, if you get junk-yard parts like I did, I see no need to worry about how these OEM grooves mate. I turned the engine with a wrench to get both pushrods in the "down position" before gently torquing each rocker/pivot/bridge assembly on to each cylinder.

I used no RTV on my therm housing gasket (b/c all surfaces were polished smooth with my stone). It has not leaked since. I did drill a TINY pin-hole into the top of my new thermostat to aid coolant filling/burping (not sure this really matters).

Remember all those electrical harnesses you disconnected: they all just fall back into place at the end.

Hope this helps (draft #1; 3/29/13),
JohnEP

 

Just finished my head job yesterday. Here are three tips i found very useful; (For an XJ.)

1. Install the intake manifold and exhaust manifold on the bench. Makes it a lot easier than trying to fiddle with them once the head is already installed. Use a little bit of copper RTV on the intake manifold and exhaust manifold gasket to get it to seal better.

2. Instead of just dropping the head on the new gasket and risk not getting it on perfect first shot, do this instead;

Take two (or three) of the old head bolts, and take a hacksaw and cut the heads off the bolts. Once the heads are off the bolts, cut a slot about 1/4" or a little bit more into the top of the shaft. Thread these into the block, and when you drop your new head on, these will go right up through the holes when you have the head lined up correctly. This will ensure you drop the head on correctly the first time. Once it's on, screw in your new bolts, and use a flathead screwdriver to take out the custom bolts out.

3. Make sure to drop the #14 bolt (if you're standing in front of the jeep the far right bolt against the firewall) in before you drop the head in the jeep. Drop it about half way in, and use some tape to stop it from dropping all the way in. If you don't do this, it will be impossible to get that bolt in once the head is on.

Well, not impossible. If you forgot, get a drill bit and drill a hole straight through the firewall and drop your bolt straight down and in. Torquing this bolt also proved hard.

 

Nice write up. I have a 98 Cherokee so don't have to worry about the 331 head but I'm sure many will take a look at your info.

 

HA! Don't think the 0630 head will not crack.

I have a 99 Cherokee with the 0630 head (same as yours) and it cracked. Just finished replacing it like two days ago.

This problem doesn't only happen to 00s and 01s.

 

the 99 im doing right now had the 631 and it was cracked.
i got another 631 from the jy and am in the process of putting back together now, just need some torque specs.

 

Thanks John. Do what tweaking you deem necessary and we'll get it in the write-up section.

 

Great write up guys.

 

I'm commenting on this because I've referenced it many many times, along with the FSM and various youtube videos. Yep, I know it's a wrinkly old historical post. Just how I do.

The point about the rearmost driver side head bolt is important. It's super easy to remove/install the head with that bolt taped up. From the look of the lip above my firewall, the mechanic I paid $1100 to service the head the last time wasn't able to figure this out. It looks like they took vice grips and bent the hell out of that lip. Seriously, it looks like something my kid brother would've done if he were replacing the head... and still 12.

Some things that I didn't know that I wish I had known... just because lots of people have a hard time getting to the intake and exhaust manifold bolts, doesn't mean you will. I took this advice initially and ended up spending much of a day torching, beating and cutting up the downpipe on my 2000. By the time I decided enough was enough, I simply snaked my hand between the intake and exhaust manifolds and had the both of them out within 15 minutes. It really was that easy.

MY new clearwater head came without a few bits that needed to be transfered from the old head. The two threaded 'dowels' at the ends of the head need to be transferred over... the dowel pins, however, can probably be left on the old head. I suppose there is a possibility that my intake is off a slight bit now, bit I'm pretty sure it's in the correct place. To be clear, the two intake alignment pins are located centered below the (from front to rear) #2 and 3 intake ports and #4 and 5 intake ports. *not certain what years this applies to. I have a 2000 and it took me a trip to the dealership to figure out what they were.

I learned that there are four (4) bolts holding the ac compressor bracket in place. I discovered this by smacking the thing with a hammer to 'unseat it' after taking out the three most obvious fasteners. Fortunately, the local pick and pull had a spare for me... $5.50 plus tax. Ebay was upwards of $60 shipped for that part.

By and large I followed all the advice in this write-up. It seems to have worked out well.

Once I get the belt driven items and radiator reinstalled, I'll give it a test! *Fingers-crossed*

 

I guess my 91 is a bit different. I did not have to remove the fuel lines. I remove the air box and power steering assembly (and belt) and moved the intake, exhaust and fuel rail assembly off to the side. Also, I bought each gasket individually. The gasket sets I saw are all cork and I prefer rubber.

 

Hi, thanks for the great write up. I need to get my head rebuilt, so I need to remove it. Will the above guide apply to a '97 Wrangler as well? Same engine.

 

Might be a few slight differences but for the most part swapping the head on any 4.0L Jeep engine is about the same. The differences would only be accessories but the bigger important stuff is all the same

 

Great, thanks.

 

Is it a mistake to do a head rebuild only on an older engine like mine at 190k?

Other than my CEL always on caused by bad springs/seats, she runs like a champ.

 

Whaddya driving?

 

'97 Wrangler