Blown Head Gasket!

[Mudderoy]

As I suspected for some time now I have a blown head gasket on the 1998. I ordered the exhaust leak test kit from Amazon the other day and didn't get around testing the Jeeps until today.

I tested the 1998 after driving it an hour home. It turned yellow pretty fast. I have the two chamber kit that is supposed to help resolve the false positives.

I also tested the 1999 but it had not been driven today. I took the cap off the radiator and ran it about 15 minutes then tested it, only once because I wasn't too sure that I was testing it correctly, it being cold and all.

It did NOT turn yellow. It stayed blue. I'll test it again after it's been driven and the system is hot.

[Mudderoy]

So I'm considering my options.

I can pull the head off check to see if it is warped, and if so, take it to a machine shop and have the head tested for cracks and shaved so it will be flat again.

The Jeep will be done for several days and there is a possibility that the head will have to be replaced. I guess there's even a change that the block would have a problem, but I understand that would be unlikely.

Or I can buy a rebuilt head, new valves etc... and pull the current head off and put the new head on. Then I could take that head to the machine shop and all the work done to it. I'd have a spare for two Jeeps!

Or with 170k miles on my 1998 4.0L I could purchase a long block. I would keep my current engine and rebuild it myself. I could then put it in the 1999 XJ (when I felt like it). Most likely I would just sit on it until I thought the 99 4.0L was having an issue then do the rebuild.

Does anyone have a suggestion as to a good place to deal with for rebuilt heads and short or long blocks?

[4.3LXJ]

Tony

I am a little leery of production rebuilds. There are a lot if times they cut corners or do something they shouldn't so they don't have to throw away a core. But that is just me.

[msmoorenburg]

ok here's my 2cents :rolleyes: search for the good head (the desired casting numbers) at the jyard and have it reworked. I've priced the machine work local and its about 100+ parts

[bigjim350]

I am a firm beliver that if you test 10 xj's, 9 will show positive for a blown head gasket. Also I agree with Matt. Now if you saw ridges on the cylender walls when you have the head, then I would think about a rebuild

[Mudderoy]

ok here's my 2cents :rolleyes: search for the good head (the desired casting numbers) at the jyard and have it reworked. I've priced the machine work local and its about 100+ parts

Oh I like that, just won't know if it's cracked until the the machine shop gets it.

It would need a value job though wouldn't it?

[msmoorenburg]

Oh I like that, just won't know if it's cracked until the the machine shop gets it.

true but they do offer a 30 warranty :)

[XJ4IV]

this is interesting... I always thought a blown head gasket will give tell tale signs like smoking like crazy and TOTAL lack of power and obviously seizing ... Id put 100 bucks that mine is blown as well LOL so I guess the 4.6 stroker is up on the chopping block this winter YAY!!!

[4.3LXJ]

Blown head gaskets can have a number of symptoms, depending on where it it is blown. I have had them put out a cloud of steam with a miss. Or hitting on all cylinders and literally pouring out the side. Ten miles to a gallon of water. Or just a tell tale miss that wouldn't let me pass smog, like the last time it happened. They can only let loose in the exhaust and never miss, only get the pressure in the water jacket. It can be highly variable.

[Mudderoy]

Well to be accurate I should say I have evidence of exhaust gasses in my coolant system. How it got there I cannot say. The most likely cause is a blown head gasket, a crack in the head or block, or a warp in the head or block. I think the block being warped is nearly impossible.

[bigjim350]

Yeah I have never seen a warped block. Seen plenty of cacked ones though. Hell I cracked a 5.0 in half one time do to a nitrous hicup. But I doubt you have a cracked block

[4.3LXJ]

My son the destroyer can go you one better, he broke the back off his 351 doing burn outs.

Gaskets let go before heads warp.

[bluedragon436]

I am planning on picking up another long block, then rebuilding my current 4.0 into a budget stroker and then swapping the stroker back into the 98.. then maybe if I really want too I'll rebuild the other long block into a budget stroker for another project or for a spare... heck.. take your head and have it checked at the machine shop, and have it ported and polished while it's there..

[msmoorenburg]

Yeah I have never seen a warped block. Seen plenty of cacked ones though. Hell I cracked a 5.0 in half one time do to a nitrous hicup. But I doubt you have a cracked block

pssst jim it's time to grow up and stop wanting to be bottle fed :thumbsup:

[default83]

just pull it, check for cracks, have it rebuilt at a local shop, if you need a number i have some guys that my dad uses all the time, good guys, and throw it back on.

you can check the cylinders/block, but i seriously doubt there is going to be any problems there, to replace the whole engine would be alot of work just for a head gasket.

[Mudderoy]

Thanks guys, but it's not a pull it and see situation. Remember this is a daily driver so down time is critical. I'll get to it but with the coolant temp situation cured for the moment I'll run it until I can have it down for a week, or longer.

[bluedragon436]

Well I was pretty much thinking pick up a working long block with good compression to throw in there while you are tearing into your current engine.. then have it checked (possibly ported/polished and gasket matched) while it is at the shop getting checked.. then get it all back together while rebuilding whatever part you want too.. then swap it back into your 98.. then you'll only be down for as long as it takes you and whoever you get to help swap the engine..

[Mudderoy]

Well I was pretty much thinking pick up a working long block with good compression to throw in there while you are tearing into your current engine.. then have it checked (possibly ported/polished and gasket matched) while it is at the shop getting checked.. then get it all back together while rebuilding whatever part you want too.. then swap it back into your 98.. then you'll only be down for as long as it takes you and whoever you get to help swap the engine..

Well I need to get the shed up in the back yard. Move the crap in the garage out there then get an engine stand and a block. Once I have that then I can start working on it and collecting parts. I need to do some reading on it, but my first choice will be a stroker. I need to make sure there isn't some ECM programming that has to be done for it to work correctly.

All new parts with a 99 intake and probably a larger throttle body. Larger injectors I already know.

[4.3LXJ]

If you are going to do that Tony you might want to use the pre 99 HO head. It will give you more horsepower.

[Mudderoy]

If you are going to do that Tony you might want to use the pre 99 HO head. It will give you more horsepower.

Yeah more of what I have to research. I mean I know I didn't want a 2000/2001 head because of their issues.

[4.3LXJ]

The hot deal for more hp is to combine the HO head with the 99-00 intake. It makes the engine breath much better. After you get that one under your belt, then you can do it to your 98

[Mudderoy]

The hot deal for more hp is to combine the HO head with the 99-00 intake. It makes the engine breath much better. After you get that one under your belt, then you can do it to your 98

How far do you think I can have it bored without running into a cooling problem?

[4.3LXJ]

You can usually go .030 over. But I don't think you will have to worry about that. A head gasket is a simple matter. Also, I think if you had a crack you would be seeing consistent problems, not intermittent.

[Mudderoy]

You can usually go .030 over. But I don't think you will have to worry about that. A head gasket is a simple matter. Also, I think if you had a crack you would be seeing consistent problems, not intermittent.

Oh it was in the post above. I'm going to get another block build a stroker and then rebuild the 4.0L I have in the 98 now, later.

So for the stroker I was going to have it bored for more cubes.

[bigjim350]

You would be fine cooling wise with a .030 over bore. .060 over would be problematic most likely. Although Titan sales a 4.9 stroker, not sure how they keep that thing cool.

[Mudderoy]

You would be fine cooling wise with a .030 over bore. .060 over would be problematic most likely. Although Titan sales a 4.9 stroker, not sure how they keep that thing cool.

what about .040?

[bigjim350]

.040 would probably be okay. But why chance it. You wont "feel" any difference between .030 and .040

[4.3LXJ]

Tony, you will get the biggest gains from the stroke, and good head work. And if you can, get that crank balanced instead of trying to balance it with different weight pistons.

[Mudderoy]

There's no replacement for displacement, so if you want even more torque, you need a bigger engine.

The 4.0L engine has a 3.411" stroke, 3.875" bore, 6 cylinders, and a displacement of 241.5ci (3956cc). You can increase the displacement of your 4.0L engine by installing a stroker kit. At the heart of the kit is the 3.895" stroke crankshaft that was used in the AMC/Jeep 258ci (4.2L) I6 engine.

On an engine with the stock 3.875" bore, the stroker crank increases displacement to 276ci (4517cc or 4.5L). Add 30 thousandths or 60 thousandths overbored pistons, and displacement is increased to 280ci (4587cc or 4.6L) and 284ci (4657cc or 4.7L) respectively.

If you're feeling really brave, you can overbore your engine to 4.00" and use custom forged pistons. The block must be sonic-tested to ensure that there's adequate cylinder wall thickness before overboring this far, though. Displacement with the 3.895" stroker crank is increased to 294ci (4812cc or 4.8L). The next step up the ladder includes an offset-ground 3.98" stroker crank that increases displacement to 300.1ci (4917cc or 4.9L). The ultimate stroker includes an offset-ground 4.06" stroker crank producing a displacement of 306.1ci (5016cc or 5.0L).

:link: (http://www.ajeepthing.com/stroker-motor.html)

[jeepxj95]

also try jeepstrokers.com good fourm and lots of info

[bluedragon436]

Yeah I am looking at doing either the 4.5L Low-Buck simple stroker.. or the 4.6L Low-Buck stroker when I do my stroker build on this site (http://www.ajeepthing.com/stroker-motor.html). Another three sites that I am using to help me collect the correct parts for the low-buck stroker is snowtracks (http://www.snowtracks.com/snowtalk/ForumID34/4006.html), LungHD (http://www.lunghd.com/Tech_Articles/Stroker/Stroker.htm), Pirate 4x4 (http://www.pirate4x4.com/forum/showthread.php?t=450927).

[XJ Rat]

Wonder if this is related to your cooling issue?

[Mudderoy]

Wonder if this is related to your cooling issue?

Well that is why I thought I had the cooling problem for a long time, so that is why I suspected it was an issue. I read another post on another site where the guy had running hot problems, tested for exhaust gas in the coolant, found he had a head gasket leak, replaced the head gasket, and still had the running hot problem. Finally he replaced the copper/brass radiator with an aluminum core and the running hot problem went away.

I would hate HATE to have gone through all the trouble of replacing the head gasket only to find that wasn't the "complete" solution.