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  #1  
Old March 6th, 2005, 12:38
Talyn Talyn is offline
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Head Gasket replacement questions and upgrade while I have it apart questions

This is really a two part question:

1) I may have to replace the head gasket on my 2000. I am not sure because i have notr ecieved my oil Anaylsis back, but if I do it will have to be over spring break so I ened to gather a list of stuff I will need ahead of time.
So far I have compiled this list of parts:

XJ Head parts:
-Head gasket: maybe Mopar Performance head gasket part no. 4529242
-Head bolts
-Exhaust manifold gasket
-Intake manifold gasket
-Valve cover gasket
-Thermostat gasket
-Goodyear gator back fan belt (needs to be replaced anyhow)
-Loctite 592, thread sealant high temp for head bolt #11-- what is an easily available equilavent for this

What is the best way to clean off the old gaskets? Use one of those gasket removers for a die grinder?

What is the possibility that the head is cracked, what other symptoms would I notice?

2) Since I am going to be in there I am thinking of doing some upgrades. My possible options are:

-Replace current head with older better flowing head. What would I need to modify on my 2000 parts to make the pree 2000 head work? Where/ how much am I looking for a rebuilt or used head?

-Performance exhaust manifold. Any suggestions on who to use for this?

-Chris
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  #2  
Old March 6th, 2005, 12:48
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ChiXJeff ChiXJeff is offline
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Re: Head Gasket replacement questions and upgrade while I have it apart questions

If the head was cracked, you'd notice your coolant dropping, or oil in it, possible coolant in the oil (check the dipstick for milkyness.) Possibly a combination.

I would NOT use a die grinder to remove the old gaskets, a hand scraper works fine. Be careful to not ding the flat surfaces. BTW, intake and exhaust gaskets are one piece.

If you've got any idea that that the head may be cracked, take it in and get it magnafluxed and checked for flatness. I picked up a rebuilt head complete with valves at Autozone a couple of years ago, but it did take a few weeks to get it. If you get a new head, you'll need the manifold alignment studs as well, those may be dealer only.

I haven't heard that earlier heads flow better, I have heard that late model intake manifolds are better.

You can reuse the head bolts ONCE. Dot them with paint as a reminder when they get reinstalled. Locktite 592 is a very commonly available sealant.

Performance exhaust manifold? I'm very happy with my Borla header, and their customer service.
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  #3  
Old March 6th, 2005, 13:46
Talyn Talyn is offline
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Re: Head Gasket replacement questions and upgrade while I have it apart questions

There isn't enough coolant in my oil to produce milkyness, and it doesn't drip coolant. But my last used oil analysis showed a bit of coolant in my oil. I am still waiting for the latest one to come back.

Yes, the late model intake manifolds are better as they have more volume. As for the older heads.. I think it may be something else better than the late heads.. like a larger exhaust port or soemthing. I knwo that the head that is on it now can not be ported as they are already prone to cracking.
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Old March 6th, 2005, 15:38
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5-90 5-90 is offline
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Re: Head Gasket replacement questions and upgrade while I have it apart questions

I like Boral headers as well - I've used dozens (in different vehicles) from regular street-driven to full-out power monsters without trouble. Get 'em, they're worth the bucks.

The studs should be regular 3/8"-16 thread - I made mine out of brass threaded rod (for my 87 and 89) and used loctite 272 to retain. I like brass hardware for exhaust wherever I can get away with it - it holds up better, is more resistant to corrosion, and seems to hold torque better - and it's easier to disassemble when you need to.

You should be able to get all of your gasket by buying a "head set" - it's supposed to be every gasket from the head gasket on up. I have found that a light, even layer of RTV Copper on both sides of the manifold gasket has been helpful as well. Retain the exhaust bolts with LocTite 272 ONLY, and if you don't have the Belleville spring washers (they look like shallow bowls) you can order them from MSC Direct cheaply enough and they're worth having, since they spread the clamp loads of the bolts and help to reduce bending stresses from clamping dissimilar metals while heated. While you're at it, if you have a Fastenal close by, go to the trouble to get silicon bronze bolts in the size you need - they'll hold up better than the steel ones. I've used them for years. With the long sealing surface we have to deal with in the I6, it will l want all the help it can get!

If you replace the head, the consensus is that the #7120 casting is ideal. IIRC, you'll find it on 1991-1995 4.0. This head flows best in OEM trim and is most reponsive to port work and modifications. Taking some time to clean up the cast surface in the port runners will help airflow (and therefore power) but DO NOT change the profile of the runner, nor do you want to significantly increase the volume of the thing. A surface cleaning is all you want.

One of the best things I've found for removing old gasket is Scotch-Brite - for tougher jobs, get the little 2" discs that mount in your drill chuck, and use those. They will also leave just about the ideal finish for head gasket sealing, and are relatively inexpensive. Plus, they effectively remove the risk of gouging a sealing surface - especially in aluminum. It is important to remember that only a little pressure is usually all you need - work up carefullly, and you'll be fine. NEVER let the pad sit in one place and work.

If you can't get LocTite 592 or PST (both of which are common in well-stocked locals) you can use a good Teflon pipe dope - like Harvey's or Christy's - from the hardware store with good results. DO NOT use Teflon tape - it just doesn't do the job there. Use some sort of never-seez on the head bolts after cleaning the threads, and reduce book torque values by 30% or so (to account for the lubrication of the Never-Seez.) If there are not paint marks on the bolt, put them there. If there are, get new ones.

You may be able to find an earlier head in the boneyard - the casting number is under the valve cover. The bolt patterns are the same - you should just be able to swap the head and go to it. If you do, let me know where you are, since I'm trying to collect a set of "research" heads that I can sacrifice to the chop saw to get some internal measurements, and to do some porting experments on. We can work something out...

Have you done a compression check or a cylinder leakdown check? You can note the low compression from the first test, then you do the leakdown on the low cylinders to see where the leak it - the second test uses compressed air in the cylinder to determine the amount of leakage, and you can listen/look for escaping air to see exactly WHERE you're leaking. Always a good idea...

The 99-up inlet manifold is about the best out there - without fabricating something - so you can keep that and use the Borla header. Both should bolt right up to the #7120 head - and that's a pretty common swap for all years of 4.0 and later 258's (1975-up "Wide Deck" blocks accept the 4.0 heads as well...)

Anything else we can help you with?

5-90
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  #5  
Old March 6th, 2005, 21:20
Talyn Talyn is offline
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Re: Head Gasket replacement questions and upgrade while I have it apart questions

Thanx. Thats pretty much all the information i need. Justw ant to clarify a few things though.

1) Use never seize instead of thread locker on the head bolts?


Quote:
The studs should be regular 3/8"-16 thread - I made mine out of brass threaded rod (for my 87 and 89) and used loctite 272 to retain. I like brass hardware for exhaust wherever I can get away with it - it holds up better, is more resistant to corrosion, and seems to hold torque better - and it's easier to disassemble when you need to.
2) Do I need to replace the studs for the exhaust manifold, or is that just if I replace with an after header?

3) For gasket removal, one of those 3M type gasket removal discs (look some what like a sanding disc) for the die grinder/ grill will work fine? I don't wany to use a gasket scraper just because I could gouge the surface. I some times use thouse on diff housings.

4) No sealant for the intake manifold? Not even soemthign like hylomar? I know no sealant type for the head gasket though.

I haven't done a leakdown test or a compression check as I don't have the leakdown tool... I should eventually get one.

This is teh first time I will be replacing a head gasket, so I want to do it right.. I have taken a few engines apart, but never had to put a head back on.. i.e. i have done all the intake manifolds, etc, but no engine parts.

Thanx,
Chris
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  #6  
Old March 8th, 2005, 15:07
Talyn Talyn is offline
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Re: Head Gasket replacement questions and upgrade while I have it apart questions

is it possible to pull the head with the manifolds attached?
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  #7  
Old March 8th, 2005, 23:40
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Dr. Dyno Dr. Dyno is offline
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Re: Head Gasket replacement questions and upgrade while I have it apart questions

Yes. Just make sure that you detach the downpipe from the exhaust manifold flange, detach the fuel lines from the fuel rail, and unbolt the PS pump from the intake manifold. Removing the cylinder head, intake manifold, and exhaust manifold as a unit certainly simplifies the job.
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  #8  
Old March 9th, 2005, 05:05
75SV1 75SV1 is offline
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Re: Head Gasket replacement questions and upgrade while I have it apart questions

The 99+ heads usually crack between the 3 and 4 exhaust ports on the top side. Pull your valve cover and look. I don't know the legalities of swapping on a older year head. I used the scotch brite pads on an air grinder and they worked great. I would look at Dino's site and Standard Abrasives site for good head porting instructions. I bought some additional grinding bits in addition to the SA full kit. I put in SB Chevy SS big valves. 2.020 and 1.6. Looking back 1.94 intake and 1.6 exhuast might have been better. The 99+ heads have a lot smaller exhaust ports. About 2/3 to 1/2. The problem with Chevy valves are that you'd have to come up with springs and spring retainers to match. I used the stock springs and machined down the SB retainers to fit the stock Jeep springs. I put anti-sieze on the head bolts except the front one one the right side(looking from the front). I think its #11 in the torque sequence. I used some type of sealant on it. On the 91-95 heads, there is a temp plug on the intake/exhaust side that you will need to plug. No biggy, one guy I help on line panniced when coolant was leaking after a lot of work. So a heads up.Also, the newer heads are loccated to the block with dowel pins. The older heads (87-95?) are not. You will have to eye the location of the head or use a 96-98 head. I had to file and grind some of the castting to get my 95 head to fit an '03 block. Others did not have this problem.
Tom
Tom
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  #9  
Old March 9th, 2005, 11:53
Tom R. Tom R. is offline
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Re: Head Gasket replacement questions and upgrade while I have it apart questions

The head is quite heavy, so if you're working alone you might want to remove the intake & exhaust manifolds.

The cost to rebuild, magnaflux, and check flatness on the head from my '92 ran about $125.
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