Head Gasket Advice

Hey Ya'all! I'm Chris, and I'm new here. I was referred here from a friend. I'm getting ready to do a headgasket swap on my 87 4.0 tommorow. I realize that there are some easy parts to remove, but I have a few specific questions.

First of all, can anyone tell me after I get the intake, exhaust, fuel ect off, and I take off the valve cover, do I have to loosen the lash before untorquing the head? How do I adjust the lash to make sure that its correct?? I'm used to 2.0L DOHC stuff.

Is there anyone here who has done their own HG swap? Anything I should look for? Any special tools I need besides a Torque Wrench???

Thanks guys!!

Personally I pull the rockers and pushrods before removing the head, but that isn't absolutely necessary. You will need to remove them before you put the head back on, so I go ahead and pull them to start.

Once you get the head off, get some Castrol SuperClean to degrease and clean the head. It will cut the crud in a hurry. Also degrease the inside of the valve cover and pull the pieces that are screwed in and degrease under them as well. This will help with blowby venting and general engine health.

I would also pull the valve seals and replace them. If the valve guides are loose, then sleeving the guides will make the head as good as new. NEVER knurl the guides. It lasts 10-15K and then is radically worse.

Thanks, whats included on removing the rockers and pushrods? And re-installing them? I'm used to HVLA's.

No adjustment required. That is why hydraulics were invented. Just a ratchet and socket.

Ok, and I realize that the head gets torqued down to 110-100 ft/lbs. What about the rockers??

BTW, thank you for your help. Of the 4 different places I have posted this, this is the only one with sound advice.

Here goes...

If you can, pull the head and manifolds as a unit - unless you know how to swear in at least three languages (those lower back manifold bolts will teach you in a real hurry!) It can be done lone-handed if you know how to lift and can lug heavy things while leaning over the fender, get a helper if you can't (preferably somebody pretty beefy.)

Remove the rockers and pushrods before you pull the head - and make sure they're labelled/sorted so they go back right were you found them - don't cross anything! You won't have to worry about lash when you put them back together - the 242 is a "zero lash" engine. I'll give you torque specs in a bit.

When you remove the head gasket, clean the deck and mating surface with Scotch-Brite (either disc or hand pad.) It will remove the old gasket crud nicely, and will leave you a near-idea finish for enabling a head gasket seal (a mirror finish is bad - you should get a surface that looks a little like a freshly machined brake rotor.)

If it's an 87, and you're up over, say 250Kmiles, AND you might have had oil pressure/supply trouble in the past, this might be a good time to change the lifters - you're there anyhow. One design flaw of the 242 is that the head has to come off to change lifters (yech!)

Check all your manifold bolts as they come out - make sure they have the little "dish" shaped washers on them. They can be replaced with Belleville spring washers if they're not there - and you need them. They spread clamp loads and encourage manifold sealing, as well as compensating for the fact that the bolts have to hold a hot aluminum and a hot iron part (aluminum expands due to heat twice as much as iron.)

The fuel rail may be left bolted to the intake manifold (requiring two reseal kits for the "quick connect" fittings) or may be removed from the manifold and tied aside, still connected (requiring new fuel injector orings.) Might as well replace both of them anyhow - and inspect your injectors. It's silly to not do the "little jobs" while you've got so much torn to bits...

Torque Values:
Rocker Arm Pivots - 21 pound-feet
Valve Cover Bolts - 85 pound-inches, about 7 pound-feet. Important to do accurately!
Exhaust Collector Nuts - 20 pound-feet
Combination Manifold Bolts -
#1 (top centre) - 30 pound-feet
#2-9 (clockwise outwards) - 23 pound-feet
#10-11 (end studs) - 17 pound-feet
EGR tube to manifolds (both) - 30 pound-feet
I stronly suggest the use of LocTite 272 for these bolts to keep them tight - nothing else will work. Reduce torque values by 10% when using LocTite

Cylinder Head Bolts -
Except #11 (on driver's side front) - 110 pound-feet
#11 (driver's side front) - 100 pound-feet. Use of LocTite PST or similar (Teflon "pipe dope" also works) is REQUIRED. This bolt hole opens into the cooling jacket.
Cylinder head bolts are torqued in order from passenger side center, working clockwise. Note that cylinder head bolts may only be reused ONCE - if they have paint spots, show any sign of deformation, or you just aren't sure, get another set.
Cylinder head bolts should be torqued in stages -
#1 - Torque all to 22 pound-feet
#2 - Torque all again, to 45 pound-feet
#3 - Verify all torqued to 45 pound-feet
#4 - Torque to final values given above.

German torque ("gudentite") is acceptable for all other bolts.

5-90

I'm so impressed and VERY grateful. I think I'll take pictures for people to use in the future. Thank you for your very helpful post.

You're welcome. All this information (and more!) can be had if you get yourself a copy of the FSM for your year - or at least, the same generation.

My 1989 and 1990 FSM's have come in quite handy for my 1987, 1988, and two 1989 XJ's. I've got a few 91-up books, now I just need to get some 1991-up XJ's to go with them...

(Some of you probably didn't expect me to recommend FSMs, did you? Fooled you - if he's looking for advice on a head gasket job, he's got a little learning to do on stock before he gets into performance 242's... Shouldn't take too long, I'd think...)

5-90

5-90 said:

You're welcome. All this information (and more!) can be had if you get yourself a copy of the FSM for your year - or at least, the same generation.

My 1989 and 1990 FSM's have come in quite handy for my 1987, 1988, and two 1989 XJ's. I've got a few 91-up books, now I just need to get some 1991-up XJ's to go with them...

(Some of you probably didn't expect me to recommend FSMs, did you? Fooled you - if he's looking for advice on a head gasket job, he's got a little learning to do on stock before he gets into performance 242's... Shouldn't take too long, I'd think...)

5-90

Click to expand...

if you want to let a 91 manual go....get ahold of me.

need one.

Actually, I have a 88 FSM, but the parts of it I was looking at didn't have any specific information regarding to what I was looking for. I'm quite used to performance 2.0L Mitsubishi motors. This is just my daily driver, and I'd like it to be somewhat reliable.

I use my engine hoist to pull the head out with manifolds still attached. (makes life easier. I also use it for axle swaps) I've also done the bolts by using a wobbly extension and small diameter socket.

Tractionless2g said:

I'm so impressed and VERY grateful. I think I'll take pictures for people to use in the future. Thank you for your very helpful post.

Click to expand...

Told you they'd be more helpful over here.

Still planning on doing it tomorrow?

Tractionless2g said:

Actually, I have a 88 FSM, but the parts of it I was looking at didn't have any specific information regarding to what I was looking for. I'm quite used to performance 2.0L Mitsubishi motors. This is just my daily driver, and I'd like it to be somewhat reliable.

Click to expand...

Oh - I didn't mean you didn't know anything about mechanics (apart from being crazy enough to want to work on Mitsubishi - yech!) just that you didn't sound like you knew much about the AMC/Jeep inline sixes - yet. Different world, y'know (and usually much easier to work on!)

Red - if I had a spare, I'd be happy to. I'm working on building a full set of FSM's for my own reference and use, but I'd be willing to answer questions (please, allow an appropriate amount of lead time. The FSM's aren't the only Jeep tech literature I have handy - maybe one of these days, I'll list the contents of my bookshelf... I keep everything to the left of my desk - my hand usually knows which book I want without my having to look, so I keep it where my smart hand can get right to it!)

5-90

Well, hopefully soon I'll know enough to answer questions. I have done quite a bit of maintenance on this jeep. And Matt, yeah, today is the day. We're starting around 2 at my buddy's place in Bangor. I'll give ya a call later and see if you want to stop by.

Ok, it took me about 5 hours of work. We ran into a few MINOR problems, but all in all, it came together. The headgasket was burned pretty badly in one spot, but looked pretty well intact throughout the rest of it. The good thing is that all of the pinston walls looked B-E-A-U-T-I-F-U-L. Now, onto the head. I wish I had taken a picture, but while I was scraping the gasket, I noticed that 1 valve in each of the cylinders was covered in white. now, from what I remember, this is a sign of some kind of detonation, or lean condition, but I could be wrong. Now, onto the only other thing bothering me, The problem I did the gasket for is still not resolved. Under load, the car mis-fires. If I floor it, it seems to partially come out of it, but you can still feel it a bit. If the car sits for a couple of days, this problem doesn't start until you drive the car for around a 1/2 mile or so. It ONLY happens under load. Usually its around 30 MPH. I feel like its a fuel issue, but I dont know for sure. I also was thinking Timing, but I dont know much about how the timing is controlled in this thing. This problem was why I originally changed the HG. The problem started at one point last week. I was travelling up a very steep hill, at full throttle, and I was a little low on fuel. I REALLY got on the gas, to make it up the hill, and at one point the jeep just cut out. After that point, it was constantly doing this. PLEASE HELP ME!!

If any of you can give me some advise, I'm VERY open at this point.

The car has:
New Plugs
New Dist. Cap
New Rotor Button
New Spark Plug Wires
New Waterpump
New Radiator
All new brakes all around
New Wheels and Tires
All of the U-Joints are in good shape.
New Fuel Filter

First - was it the smaller valve that had the light-coloured deposits? The smaller valve is the exhaust valve, and some light deposits on the exhaust valve are quite normal. As long as the margin or the sealing faces aren't burned, it should be no trouble - I've seen it on my 87 and my 89 Limited, and on numerous engines - and none of them were having detectable detonation problems. I'd be more worried if there were white deposits all over the plug, and some damage to the insulator.

There is a TSB out there on distributor indexing, but it may or may not be necessary.

You say that you're getting this at around 30mph - have you tried to reproduce it in Neutral, at or near that RPM? That might be helpful.

Might also be worth checking for chain stretch - it's easy to do.

Take the cap off, and get a 3/4" socket on a breaker bar.
Turn the crankshaft nose bolt about 1/6 turn counterclockwise.
Watch the rotor as you turn the crank nose bolt - it should turn almost immediately. If you turn any more than about 2-4 degrees before the rotor moves, then the chain should probably be replaced. If you replace the chain, I'd suggest replacing it with a "roller" chain - which looks like an overbuilt bicycle chain, and has bushings to allow for lower strain on the chain. I like to use them for HP engines, since it extends maintenance schedules...

5-90

I meant to mention that the problem doesn't exist when free-reving. I can put it in Nuetral, or free rev it all day long at that speed, and it will rev like it's supposed too. I'm really lost.

I assume you didn't do a valve job or shave the head while it was off?

fuel injector? and check fuel pressure be sure pump putting out correct vol.and pressure under load

I had an 88 with similar symptoms and it ended up being a fuel pump going bad.