Cracked block or bad oil ring?

[kastein]

I've never done one in-car, but if I had to, I'd probably unbolt the motor mounts and lower the block a couple inches so I could get a wrench on that head bolt.

It's annoying just to get the ground strap nut off of it, so I completely see where you're coming from.

 

[blistovmhz]

I've never done one in-car, but if I had to, I'd probably unbolt the motor mounts and lower the block a couple inches so I could get a wrench on that head bolt.

It's annoying just to get the ground strap nut off of it, so I completely see where you're coming from.

Is exactly what I SHOULD have done. Unfortunately when I did the head, I had very little mechanical experience and thought moving the entire engine forward would be a lot more work than it would've been.

Still a lot of work to remove a head. I don't care what anyone has to say about civics. Their motors are ridiculously well engineered. 15 minute head swap is crazy.

Same issue with the cam. Anyone who's replaced a Cam in the 4.0L, and who's also done the same job on almost any other vehicle, will not want to do it on the 4.0L again. Pull the motor or tear it down in place. Your options are two, and neither are convenient

 

[blistovmhz]

Also @Talyn. I actually mostly agree. I'm just in a bad mood about this now I don't mind spending money on an investment, but ANOTHER busted 4.0L isn't an investment. A stroker might be but is still well beyond my ability to put together well.

 

[xjtrailrider]

I've never done one in-car, but if I had to, I'd probably unbolt the motor mounts and lower the block a couple inches so I could get a wrench on that head bolt.

It's annoying just to get the ground strap nut off of it, so I completely see where you're coming from.

That is how I swap the head on a XJ, drop the engine to the front axle by removing both motor mounts and the brackets. I do this when I pull a 4.0 also, its easy to get to the top bell housing bolts like this.

 

[xjtrailrider]

Same issue with the cam. Anyone who's replaced a Cam in the 4.0L, and who's also done the same job on almost any other vehicle, will not want to do it on the 4.0L again. Pull the motor or tear it down in place. Your options are two, and neither are convenient

I guess I have done a few but I can have a XJ 4.0 out of the Jeep and sitting on the engine stand in 3-4 hours. Its really not bad after ten or so swaps LOL!

 

[Talyn]

Hahahha. It's not that changing a HG SHOULD be a lot of work, it's that the engine is slightly too far back in the engine bay, and the unibody is in the way of the rearmost head bolt, and you have to do a lot of shopping to find a torque wrench that'll fit in there. (I've actually never found one, which may be why my #6 is leaking).

I'm not really sure what the issue is with the rear head bolt. You just need the correct length socket. A cut down deep well. I have a standard length 1/2" drive Craftsman one as well the works. I just don't engage it fully on the drive. I don't even need to mess with the mounts any to pull a head.

 

[blistovmhz]

Okay, so all apart and everything looks unfortunately good. I couldn't find any obvious sign of coolant leak in the head gasket, though the #6 is definitely too clean. Also found #5 and #3 have more carbon build up than any other cylinder. 1,2,4 are all clean, but not suspiciously clean. #6 is suspiciously clean, which we expected.
One of the coolant passages coming off the #6 definitely had some build up in it, so I'm guessing it must the the one that was leaking.

Anything else I should be looking for while it's all apart?

Some shots of the #6

 

[Talyn]

Check for any imperfections in the block deck and head. I would lay a straight edge across both.

What did you use to clean the block deck when you first changed the gasket?

 

[blistovmhz]

Check for any imperfections in the block deck and head. I would lay a straight edge across both.

What did you use to clean the block deck when you first changed the gasket?

Plastic scraper, and I probably did a poor job of it, given this was way before I had any mechanical experience, and I was in a rush.
I'm starting to suspect that the block itself is warped, or as you suggested, there's a flaw in the deck, cause this is the same problem I had to solve last time I swapped the head (5 years ago), and now that I've got it apart, I remember that the #6 was real clean last time as well.
Thing is, if there is anything wrong with the deck, it'll be cheaper to just grab another long block than take mine to a machinist. Service is insanely expensive here. Called 2 shops, and both quoted around $800 to inspect and machine flat.

Any chance the layered metal gasket just didn't seal as good as one of the thicker composites might?

 

[Talyn]

Don't rush cleaning anything. You can use a metal scraper on the block without much fear of damage. Do not use one of those 3M scotch locks on the end of a die grinder. If there is an imperfection in the block you will see it or feel it. Don't forget to torque the bolts correctly either.

That is an excessive amount to check and machine a block. Is this with the bare block or them stripping it down and reassembling it?

MLS gaskets will seal fine.

 

[blistovmhz]

Don't rush cleaning anything. You can use a metal scraper on the block without much fear of damage. Do not use one of those 3M scotch locks on the end of a die grinder. If there is an imperfection in the block you will see it or feel it. Don't forget to torque the bolts correctly either.

That is an excessive amount to check and machine a block. Is this with the bare block or them stripping it down and reassembling it?

MLS gaskets will seal fine.

That's just how stuff works in Canada. Everything is generally between 2 and 10x more expensive, with services being on the higher end. Last year I needed some weld washers put on my lower control arm mounts (axle side), and even with everything stripped and ready to go, it cost me $150 (I'd have done it myself in 15 minutes if I had a welder/shop space handy).

I'll give it another go with a good cleaning and new gasket and see how it goes.

 

[blistovmhz]

Well shit. New HG installed (and installed a new exhaust header and did a tune up while I was at it) and SAME PROBLEM!
Blows a tonne of white-ish smoke until it's hot, then it tapers off. Doesn't smell like coolant. Filled up the Rad with 50/50 mix so the exhaust would sweeten up, but absolutely not smelling sweet.
I'm at a bit of a loss here. The only thing I noticed during HG replacement, is that both old and new HG have most of the water passages blocked off. I think the only ones that go through the HG are at the very back of the block. Any idea's if this is normal and if so, why bother with all the coolant passages?

 

[Talyn]

The coolant passages are normal. How did you torque the head bolts down?

 

[blistovmhz]

regular spiral pattern, 22, 45, 110 (100 for 11).
Maybe head warped recently? Can't think of any reason why. Hasn't been overheated.

Again, this started IMMEDIATELY after disconnecting my downpipe from my cat, and putting it back together. I suppose I proved I had a leak in the HG, but still seems weird with the timing.
I'll go beat on it again tonight and give it a few warm/cool cycles to see what it's doing. Maybe still just burning off some oil or water from cylinders from re-install.

 

[Hypoid]

Could be residue in the exhaust, from the last time you shut it down. Just for grins, drain the coolant before you start up cold. You shoud be OK to run for a minute or two to see what the exhaust does.

Also, I don't buy your pressure theory for coolant leaking into the combustion chamber because the thermostat is closed. Pressure should build as the coolant heats up, raising the boiling point.

It would have been nice to see more pictures of the block, head, and gasket.

 

[blistovmhz]

Well, after installing the new HG, header, distributor cap/rotor, wires, radiator, the problem isn't gone but it doesn't seem as bad? Not making as much smoke for as long at startup. While it used to smoke out the entire driveway for 10 minutes, it's now making.... quite a bit of smoke for about 2-3 minutes and tapering off. I seem to have lost a bit of low range power but gained a bit in the middle (suspect the gain is from header and cap/rotor).
Compression test didn't change at all. Around 160psi across the board. Leakdown also still looks good.
The one thing that definitely changed, is that I don't make smoke when warm, when disconnecting the #6 spark or fuel injector connector. Just runs a bit rough but exhaust stays clean.

When I had the head off, the cylinders all looked pretty clean. A bit of carbon on 3 and 4. Left exposed to air overnight, most of it just peeled up and flaked off. The block/head deck had no obvious scratches.

I did notice that before I changed everything over, the main rad hose from the head would pressure right up once the thermostat opened up. After the change over, it did this for one heat/cooling cycle, but hasn't done it since. Pressure now stays low enough that i can pinch the two walls together with a finger and thumb. I don't know what's normal rad pressure in these as most of my Jeeps had the older pressure bottle system, and rad pressure was always pretty high.

Seems like I have more than one problem, but that all the problems result in white smoke from the exhaust?
Keep in mind, the smoke doesn't appear at all if the Cat is removed from the equation.

 

[kastein]

Did you change the coolant or reuse? Put new coolant in it, do an exhaust gas test on the coolant to set your baseline, then run it for a few days and do another exhaust gas test on it. That'll give you a pretty good answer.

 

[blistovmhz]

Didn't reuse coolant, and brand new rad installed.

Decided to confirm it's water coming out the pipe. The weird thing is that I NEVER get the smoke out the header. Only happens if cat and muffler are connected. So I drilled a few holes. One in the downpipe just before the cat, another inbetween the cat and muffler, and another at the end of the muffler. The "smoke" only comes out the hole in the muffler. So I sprayed some water into the holes after the exhaust had cleaned up, and sure enough, we've got steam, just like on startup.

So now the question. Why is there water in the muffler? Sure, could be coolant, so I turned off the Jeep and let it cool down for a few hours, disconnected the downpipe from the header, and put some paper towel below the header output. Start up the Jeep, no water. Once again, connect the downpipe and within about 10-20 seconds, we have steam coming out the tailpipe again. Disconnect header from downpipe and steam goes away. The water is CLEARLY only in the muffler, and doesn't seem to be coming from the engine.
I did the same test before replacing the HG as well, and got the same results.

I'll do the exhaust/rad test next I guess. Getting pretty close to just buying another Jeep that's already passed emissions

 

[kastein]

Could be condensation. Burning hydrocarbons produces both carbon dioxide and water vapor...

 

[blistovmhz]

This is what's killing me. I wasn't making this vapour before I took the exhaust apart to fix the downpipe. I can't think of anything engine related that I might have broke in the process. If I broke the cat, I should be producing LESS water. I failed emissions right after messing with exhaust, with slightly high HC, slightly high HO, and 5x higher the allowable NOx. It's gotta be a bad cat or extremely lean condition, but neither would result in all this water being produced.