Blown head gasket? Need second opinion

[Ecomike]

I was seeing some light brown to yellow stuff that looked like water induced rust. That added to the clean pistons made me think of steam cleaned pistons. I guess the gas could have done it too. Hard to say which it was for sure.

I would be a little worried about bearings now. If I were you, I would drop the oil pan, clean and inspect the oil pump, screen, and crank bearings, replace the lower end pan gaskets and CS main seals. Might even check the cylinder walls on those 2 washed cylinders!

Do it before the JY gets any more time past the warranty issue. Hang on to those pics, you might need them later!

 

[TerraWombat]

I was seeing some light brown to yellow stuff that looked like water induced rust. That added to the clean pistons made me think of steam cleaned pistons. I guess the gas could have done it too. Hard to say which it was for sure.

I would be a little worried about bearings now. If I were you, I would drop the oil pan, clean and inspect the oil pump, screen, and crank bearings, replace the lower end pan gaskets and CS main seals. Might even check the cylinder walls on those 2 washed cylinders!

Do it before the JY gets any more time past the warranty issue. Hang on to those pics, you might need them later!

When I had the engine on the stand (and was completely unaware of the head gasket issue), I had the pan off and replaced the rear main seal. I took all of the main bearing caps off and did a visual inspection on all of them and I didn't see anything strange.

While this engine was running (although poorly), I did make note of the oil pressure and it was around 40-45 on a cold start up and dipped to 20 or so with the engine around 220*F and idling, but I really didn't run the engine long enough and put the car through normal operating conditions...

 

[TerraWombat]

The machine shop called me up and the head was out 0.008". They're going to clean it, mag check it, deck the surface, and do a valve job on it. Price is about $100 less than what rebuilt heads are going for at my local auto parts stores so I decided to get it done. I've used this particular machine shop in the past and they did great work. Completely rebuilt the cylinder heads on a 3.0L V6 - I've put at least 30K miles on those with zero issues.

 

[JNickel101]

I'm interested in hearing how this 0331 head holds up for you.....keep us in the loop! Great pictures by the way!

 

[TerraWombat]

I'm interested in hearing how this 0331 head holds up for you.....keep us in the loop! Great pictures by the way!

No 0331 head being used here. The one that originally came out of this truck is the 0331 head, but that's currently sitting on a shelf as a paperweight. I am rebuilding a 0630 cylinder head as the failure rate seems to be much lower on those.

 

[JNickel101]

Ah, ok, re-read your original post - So you're just going to use the '98 engine as a whole, keeping the block from the 01 as a "just in case" sort of thing?

Either way, keep up the posting, I want to see how this turns out for you. Any major issues fitting the 98 engine with the 01 wiring harness?

 

[TerraWombat]

The '01 engine will eventually be rebuilt when I get the time and I'll keep it around for a spare.

As far as the wiring harness is concerned, I had zero issues with fitment since I kept all of the sensors from the '01 engine. The exhaust manifolds are completely different between the '98 and '01 engine, but there is a member on this board that makes an adapter plate so that the old '98 head mates up with the new '01 exhaust manifold - I got one of those for this engine.

 

[TerraWombat]

I got the 0630 head back from the machine shop today. It's a thing of beauty - I'd almost rather put it on my mantle I'm just waiting on new head bolts and a head gasket from Rockauto and I'll get this thing back together and running.

 

[JNickel101]

Wow, very nice

 

[old_man]

Make sure and coat the head gasket with spray CopperKote before installing. I have used it for 40 years and have yet to have a head gasket fail.

I have even used it on heads that were warped when I was out of money and got them to work OK.

 

[TerraWombat]

I installed the rebuilt cylinder head last night and I did NOT use the spray-on copper coating (although I do have it) as the Fel-Pro gasket I bought specifically says NOT to. One of the gaskets other "features" is that it has some sort of coating on it already that fills up small imperfections in the cylinder head and block - so I'm thinking that may be similar to the copper coat.

The install went pretty smooth - I bolted the exhaust and intake manifold to the head prior to dropping it in. I used an engine hoist to lower it all down since it was heavy with the extra junk on it. Got it seated on the dowel pins and started tightening it down. Needed to modify a 12-point 1/2" socket to fit under the firewall ledge on the rear of the head, but other than that it went very well. Buttoned up the engine bay, topped off the coolant, added about five quarts of oil and it fired up on the first crank. Oil pressure is around 60psi at cold idle and drops to 20-25psi at hot idle. While cruising at 45MPH, it's around 40-50psi so I'm happy about that. Temperature coasts up to 210*F while idling and is a little below that when cruising at 45MPH - Seems to be about right, although seems a little warm at idle, but I know Jeep are notorious for running hot.

There are still a couple things I need to address, though.

The new oil slinger on my transfer case seems to be rubbing on the rear extension housing. I must have installed it a bit to far down the shaft. I'll see if I can slide it back up a bit.

My steering feels REALLY loose (almost like I have super power steering). I replaced the steering stabilizer and that made a small difference, but I'm thinking my steering box is shot. I may try making small adjustments to that bolt on the top and see where I wind up with that.

My exhaust seems to be rattling against something near the rear of the vehicle. I also noticed that my exhaust header downpipe and the intermediate pipe really didn't line up all that well and I had to use a crowbar to get the two flanges to meet so I could get bolts through. I also have a leak (not surprised) at those two flanges. I think I may just unbolt the intermediate pipe from the downpipe and cat and start again.

Even though I replaced the RMS when the engine was on the stand and I was very diligent, I think it may be leaking some as I'm getting a very, very small buildup of oil on the bottom of the transmission case. I might also just be fluids that spilled over when I was filling the engine and transmission, so I won't say all is lost yet.

 

[Talyn]

Did you put thread sealant on the #11 head bolt (front driver's side)?

As for the copper I haven't seen a Jeep head gasket that is recommended to use on. They all go on dry. I know some gaskets in other engines call for it, but I haven't seen any for the 4.0L.

 

[TerraWombat]

I saw your original message in my e-mail. Again, no 0331 head was used in this process. The engine that had the blown head gasket was from a '98 XJ with a 0630 head - which is the one I rebuilt and the one I installed.

I DO have a spare 0331 head with 157K miles on it and NO cracking, but I'll use that as a paperweight instead

 

[Talyn]

They also make good practice for polishing and porting.

 

[kastein]

You must have some really big papers...

Personally, I'd sandblast an old worthless long block, bolt it up (probably upside down with some spacers, valve springs get boring), attach a piece of 1/2" tempered glass to the top, and stick it in my living room as a coffee table.

New head looks great! Hope the RMS isn't leaking on you.

 

[TerraWombat]

Did you put thread sealant on the #11 head bolt (front driver's side)?

As for the copper I haven't seen a Jeep head gasket that is recommended to use on. They all go on dry. I know some gaskets in other engines call for it, but I haven't seen any for the 4.0L.

Yea, plenty of thread sealant was used on the #11 head bolt. The torque step sequence and pattern from the field service manual was used, with the exception that I did not jump from 45 ft-lbs to 110 ft-lbs (and 100 ft-lbs on bolt 11), but did a step in between.

 

[TerraWombat]

Personally, I'd sandblast an old worthless long block, bolt it up (probably upside down with some spacers, valve springs get boring), attach a piece of 1/2" tempered glass to the top, and stick it in my living room as a coffee table.

Well, I did just move into a new house and am in need of some furniture....hmmmmmm.....

 

[Ecomike]

Did you put thread sealant on the #11 head bolt (front driver's side)?

As for the copper I haven't seen a Jeep head gasket that is recommended to use on. They all go on dry. I know some gaskets in other engines call for it, but I haven't seen any for the 4.0L.

I used Indian head gasket shellac on the 89 XJ head gasket 18 months ago. About 25,000 miles on it with no problems.

 

[TerraWombat]

So it has been 3 weeks and approximately 1500 miles and the rebuilt head seems to be doing it's job. I have a very odd knocking sound at idle that I cannot seem to pinpoint. It's very faint and I should probably just write it off as nothing important enough to worry about, but my perfectionist tendencies have me searching all over for this noise. It happens in any gear (P, R, N, or D) and seems to be RPM dependent. I have yet to check the flexplate bolts, but I've read that those like to come loose.

Other than that, I'm really enjoying the Jeep other than the lower-than-expected MPG (about 16-17 no matter how I drive). I suspect the O2 sensors are the originals and could just a replacement (Jeep now has 158.5K miles on it)...just dreading having to pay for FOUR O2 sensors...

 

[joe_peters]

So it has been 3 weeks and approximately 1500 miles and the rebuilt head seems to be doing it's job. I have a very odd knocking sound at idle that I cannot seem to pinpoint. It's very faint and I should probably just write it off as nothing important enough to worry about, but my perfectionist tendencies have me searching all over for this noise. It happens in any gear (P, R, N, or D) and seems to be RPM dependent. I have yet to check the flexplate bolts, but I've read that those like to come loose.

Other than that, I'm really enjoying the Jeep other than the lower-than-expected MPG (about 16-17 no matter how I drive). I suspect the O2 sensors are the originals and could just a replacement (Jeep now has 158.5K miles on it)...just dreading having to pay for FOUR O2 sensors...

Replace them one at a time, starting with the one closest to the engine. When (if?) you get improvement in MPG stop replacing them.

JP Magazine three part article on XJ mileage:

MPG:


http://www.jpmagazine.com/projectbuild/154_0808_building_a_fuel_efficient_jeep/index.html


http://www.jpmagazine.com/projectbuild/154_0810_building_a_fuel_efficient_jeep_part_2/index.html


http://www.jpmagazine.com/projectbu...cherokee_xj_project_mileage_master/index.html