Leaking Head Gasket.

[JeepinAudiophile]

My head gasket is leaking, I have a few questions. One, how long would this take to change? But the major thing is that while i have to take my head off, what if any mods should I do? I am extremely limited $$ wise right now. Also, any regular maintenence or anything I should check while it's off? I'm going to round 100K miles this week.
BTW: It's a 2000 4.0

 

[jeepguy97]

Depends on your mechanical ability....most time consuming part is getting the intake and exhaust manifolds off. Then its pretty straight foreward. While its off be sure to get it checked for cracks, if you want you could do some valve work, check cylinder walls for scoring, etc. Check it while its off saves time should you happen top notice something.

 

[JeepinAudiophile]

err... man it sucked getting my Banks header on... some of the clearances to get hands on and bolts in are friggin tiny. For some reason when i was thinking about it, I had completely ignored the fact that the intake and exhaust manifold will have to come off.Maybe a freudian slip because that WILL suck, but i guess it gives me a chance to re-do a few things I wanted to do in the area anyways. Maybe i'll just keep an eye on it for a while and get another head in the meantime to work on it outside the XJ and then be able to slap it in. Ewww... this is gonna suck.

 

[5-90]

First question - how do you know it's your head gasket that's leaking? Since you didn't mention, I thought it prudent to ask...

Unless it's a coolant leak into the cylinder, there are a few other things to check - depends on symptoms. Please edify us...

Another note - I've had the heads off of my 87 and my 89 (different reasons, but wound up changing lifters both times for good reason,) and it was quite possible to remove the manifolds still bolted to the heads. This allowed me to service the manifold gasket with room to spare, and install the manifolds and head as a unit. This is far easier than wrestling with the manifolds in the engine bay and fighting with the lower rear manifold bolts... I see no reason why this should not work on your 2000 as well as it did on my 87 and my 89 - the basic parts are the same, even if they were improved in the time between.

Also, make sure to label all the wiring. I just pull the head with manifolds, sensors, fuel rail, and all still attached - simply to put it on the workbench. I do what needs doing in the shortblock, then I turn around and service the cylinder head and associated parts as well. The only sensor I remove prior to pulling the head assembly is the oxygen sensor - it's in a bad place for hanging up on things.

Anyhow, why not tell us what's going on so we can make sure it's your head gasket that's leaking and not something potentially far simpler to work on. If you do end up pulling the head, plan on a day for the engine to be DEAD COLD before you start working (24 hours cool-down) and a day to do the job. I can have the head R&I done in a long afternoon, barring problems, so it's not that difficult.

5-90

 

[Dr. Dyno]

Depends on your mechanical ability....most time consuming part is getting the intake and exhaust manifolds off. Then its pretty straight foreward. While its off be sure to get it checked for cracks, if you want you could do some valve work,

Yeah, you definitely want to check the head for cracks. How do you know your head gasket is leaking? Coolant in the oil? Steam from the exhaust? Did the engine overheat?
You said you have a 2000 model and the '99+ WJ 0331 heads have been known to crack down the middle between the no.3 and no.4 exhaust ports (where the head is hottest). I hope that's not what happened to yours 'cause that would really suck.
This might be an opportunity to get hold of a '91-'95 head, mill it for flatness (if needed), do an a la Dino home port job on it, and get the valve seats reground. Might as well get some more performance since your head's gonna come off anyway.

 

[old_man]

When reassembling the engine, get a spray can of CopperKote from Permatex and spray the gasket before assembly. It really cuts down on head gasket leaks.

 

[JeepinAudiophile]

First question - how do you know it's your head gasket that's leaking? Since you didn't mention, I thought it prudent to ask...

Unless it's a coolant leak into the cylinder, there are a few other things to check - depends on symptoms. Please edify us...

5-90

Well, the only problem(that I know of) is that the oil is leaking outside the engine. I have cleaned the engine multiple times and have figured out that it is leaking at that point. I do not like this problem, but I also realize that it is nowhere near the end of the world. I may use it as an excuse to begin working on a stroker, but that is still a long shot because of how tight money is.

 

[5-90]

Weird. Fortunately for you, there is no pressurised oil in the head gasket...

If you don't mind it looking hokey for a little while, smear some RTV Black or Red into the leak with your thumb, and try to give it anywhere between six and ten hours to cure. Like I said, it will look hokey, but should help with the leak. Standard preparation instructions apply...

5-90

 

[Dr. Dyno]

Well, the only problem(that I know of) is that the oil is leaking outside the engine. I have cleaned the engine multiple times and have figured out that it is leaking at that point.

It's normal for high mileage 4.0's to form "oil sweat" on the passenger side of the block below the level of the head gasket and it's nothing to worry about. The oil galleries are on that side of the engine so it's not unusual for the gasket to seep a little. The oil isn't under pressure so it won't cause any problem. Just smear some RTV over the area as 5-90 said if it bothers you.

 

[Bloose]

When reassembling the engine, get a spray can of CopperKote from Permatex and spray the gasket before assembly. It really cuts down on head gasket leaks.

Bad idea. Most if not all composite head gaskets recommend no sealant of any kind be used with a head gasket. If your head and block are flat when assembled and you use a high quality head gasket there should be no problems with leakage. If there is a problem sealant won't help.

Copper head gaskets are another story but I don't know if there is one made for the 4.0L anyway.

Here is a link to Felpro's web site explaining why this is a bad idea.
http://www.federal-mogul.com/fmeconnect/technicalservices/downloads/1403.pdf

B-loose

 

[YELLAHEEP]

Ditto to what Bob said.

When I went thru Auto Tech school to get my ASE certs, the instructor gave his schpeal about using Coppercoat too. When we were rebuilding our engines, the head gasket information specifically said not to use any sealant of any kind.

Most head gaskets are so much thicker now than in the past. Mostly because of new materials being used that are designed to compress more evenly than metal gaskets.

Coppercoat is kind of an "old school" thing. As far as head gaskets are concerned anyways.

My .02 anyways.

 

[JeepinAudiophile]

Thank You for the suggestions, and just to add a bit of information: It is leaking steady enough for small (1"-2" dia.) puddles to form over the course of an 8 hour work day at work. Oh well, i think i'll just wait until i re-do the engine. Thanks.