If you can feel a lip on it, that's not good. One side higher than the other. Don't take me as gospel but in my unofficial guess I would say this is ...consistent..with what you might see when a cylinder wall cracks.
Walk us through how this happened to come about? It was driving fine one day and then bang you had a misfire? or what...

 

It was driving mostly fine. Fine for a car with 136k+ of unknown origin: some ticks like the lifter tick, a whistling that sounded like an exhaust manifold leak, some minor intermittent knocking. We’ve been driving this Jeep daily since 12/17, usually about 60 miles a day. After a water pump replacement 3 or 4 months ago we’d been keeping an eye on the antifreeze and didn’t see any noticeable loss.

One day it started running a little rougher than typical. My partner was driving it on a parkway, started misfiring and bucking. He pulled over immediately and we towed it home. We pulled the plugs and found oil on a few of them, then noticed the coolant overflow was almost empty. Found antifreeze in the oil and started on this journey.

 

Very sorry to hear about this. That sure looks like a crack. If you have cleaned that area and you can catch a fingernail on it that is a reasonable confirmation. You did a good job paying attention to details to find this and save the work of putting everything back together only to have more problems. I don’t think you did anything during your ownership to initiate the problem. We know that whoever worked on it prior did a dreadful job, RTV and all.

This is a bit outside of my area of experience but I think a cost effective repair of this block would not make sense. Once a crack starts is tend to continue to expand. This block may have had a crack for some time that grew until the point it caused the symptoms you encountered. Even if the cylinder could be sleeved the crack is still an issue.

Cast iron has some unique properties that make it much more difficult to successfully weld. To weld properly the entire block would be removed, disassembled, preheated in an oven to a high temperature (600 degrees or higher), brazed or welded by a welder experienced with cast iron and properties of the Jeep block, then cooled down in a controlled manner to prevent over hardening of the metal. There are other repair methods for cast iron but I doubt they are a good choice for a cracked cylinder surface. For a common engine block as is the 4.0 a quality crack repair is likely cost prohibitive and risks future cracking.

If it’s fairly certain there is a crack in the block I believe to save this Jeep it will need a different engine. There is likely other engine wear and damage that work against the practicality of a repair of this block. I don’t recall that it has been discussed what condition the Jeep is in otherwise. That could help determine the go forward path. If it has more than minor surface rust in the typical areas it is a consideration. Even though you have put a lot into this Jeep it may not make sense to invest more only to lose more. Thoughts for additional discussion.

What initiated the crack we will never know. There are many potential causes. For those interested in the basic science, a crack is a result of excessive mechanical stresses. A crack occurs to relieve the resulting strain in the metal. Cast iron is unusual as it typically has a limited yield point, or ability to stretch, until it reaches the point of a crack forming (tensile point). Excessive loads could have been due to freezing of the coolant in the block in the past or excessive overheating. Maybe a failed head or head gasket introduced enough coolant into the cylinder such that the compression went way up in cylinder 6, exceeded the capability of the cylinder wall. If the crack is near one of the head bolts maybe over tightening initiated the crack. Issues during the casting process or metallurgical impurities could have been the origin.

 

People have been tiptoeing around this thing trying to not upset you too much, but if you will let me be blunt, what you've got there is an expensive boat anchor! I don't hold much hope of installing a sleeve either. If the body and running gear are in good shape, your best bet is to find another engine. A good used engine is a possibility if it has low mileage and a short guarantee, like 30 days. If you can hook up with a shop, you can get better options in finding one if you're willing to have them install it. When my rear axle blew up, it damaged the transfer case at the same time. My mechanic found me a good deal on used parts and installed them for me at a very reasonable price. That was 50K miles ago and everything is still working fine. Since you already have the head, all you need is the short block.

It's your decision if you want to invest the money to fix it or get rid of it. It depends on how much it will cost compared to how much you'll lose by selling it with a bad engine. I get the impression you really love this jeep and want to fix it. Good luck. The NYC area is not an ideal place to have this happen. Vince's Auto Parts in Marcy, NY is one of the largest salvage yards in the state and has a ton of jeeps. A good source for engines and other stuff. Give them a call. (315) 768-9255. It's a U-Pull-it yard, but they may ship parts as well. OR go get it!

 

Aside from the engine (LOL I feel stupid typing that) it's in good shape - tailpipe fell off but we can throw that back on whenever. This thing was jury rigged beyond belief when I bought it, and I didn't catch ANY of it. Which is understandable because while I'm not a novice, I'm no expert and wouldn't know what to look for anyway. We had addressed small issues as they came up - brakes and rotors, a cross threaded lug, new water pump, something about the axles and tie rod (mechanic did that, I didn't touch it - I'd have to pull the paperwork to figure out exactly what he did). The clear coat is shot but there is very minimal rust, the body is in good shape.

I'm into this truck for about $4600 over almost two years, including purchase price, and as is I'd be lucky to get $800 for it - not even enough to buy a replacement car that isn't a complete POS. None of the salvage yards are open today but I'm off tomorrow and going to make a few calls. We're thinking of getting a salvage engine and dumping it in and see how she runs. Since I have a non-returnable head sitting here, even if I get an engine with the 0331 head, we can always tear it down and replace the head, etc. Emotionally I'm ready to set the Jeep on fire and get a new truck - financially, that's another thing. My partner is now a Jeep guy and I know even if we got rid of this Jeep, he'd likely buy another 4.0, so the fancy parts we have wouldn't really go to waste.

I appreciate everyone's helpful advice, opinions, and honesty - I learned a lot being married to a mechanic for 15+ years, but I got in over my head with this. I keep telling myself that there was no way we would have found the crack until we got down this far anyway, but it still feels like I bit off way more than I could chew. This board and its members have been a huge help! I'm going to call salvage yards tomorrow and look for local 4.0s for sale, then figure out what we might want to do.

 

Okay, keep in mind the engine has got to be from a 99-04 Grand Cherokee because the block is different from the older ones. The way to tell by looking at them is the oil filter is screwed directly into the block rather than into a 90* adapter near the oil pan. The Cherokee (XJ) and the Wrangler still use the old block with the 0331 head up until 06 for the Wrangler and 01 for the XJ. After 02-and-a-half, it was the 0331 TUPY head.

The difference in the blocks, other than the oil filter location, is the location of the motor mounting bolt bosses. They moved them rearward to make the 4.0 fit in the same mounting locations as the 4.7 V8. People are telling me they make conversion mounts, but as far as I know, that's hearsay. I don't know for sure not having ever seen them.

I agree you never would have known about that crack until you pulled it apart and I firmly believe the seller was trying to hide the fact that something was wrong with it. Look for a private message.

 

In looking for a salvage engine it would be nice to have some reassurance that the engine was in good running condition when it went to salvage. If it is in a Jeep that had collision damage that would be a plus as you know it was running. If the vehicle was sold by an insurance company that is a good indication it was a collision claim. It does not take much damage on an older vehicle to be classified as a total loss. If it was from an insurance auction there will typically be a sheet stuck on the windshield identifying the insurance company that sold it.

 

Yeah, I had $1000 deductible collision on my 2000 WJ, then realized Kelly Redbook only had it listed for $1000 in perfect condition! D'oh! Cancelled collision.

 

Okay, I called a couple of salvage yards and found one that has an engine from an '04 that has valve issues, but the block is solid. He's selling it to me for $150 so I'm happy with that. He also had an '04 engine from a wreck with 100k for $600 (engine wasn't damaged). I'm taking a half day on Wednesday to drive out to Southampton to pick it up. Hopefully it will fit in my little hybrid lol!

ETA: Now I'm thinking I should by the one for $600, drop it in the way it is, and see what happens. The yard has a 101 day warranty. I'm not good at decisions like this.

 

Do it Stephanie! Don't mess around fixing the valve problem.

 

I agree with Dave. Probably not worth the risk for the one with reported valve issues. I would wonder: how do they know it has just a valve problem, and exactly what does that mean? Could be other issues also. If you go with the more expensive one and all is good you should be able to sell your rebuilt head for close to what you paid for it and make up for much of the additional cost of the “better” engine.

It would be great if they can show you the Jeep that the engine came out of to verify year, mileage and that it was really a collision total. I would try to bargain for a little lower price, especially if they can’t show you the vehicle. Make sure you know what comes with the engine ahead of purchase: any accessories such as starter, alternator, power steering pump. The more the better.

FYI, a 4.0 engine weighs around 500 pounds. You might think about borrowing, renting or stealing a pickup truck for a day if you can. It's a good idea to have some cardboard and plastic to put the engine on as it is likely to leak some fluids along the way.

 

Good advice - I’ll take it and use it when I call the yard today to ask for the $600 engine. I’ll ask specifically what comes with it and ask if we can see the vehicle - they pull the part for us and it will be ready for pick up. We think the engine will fit in my Ford CMax hybrid based on the dimensions, but I might be able to see if we can borrow someone’s huge SUV. No one we know has a pickup. The yard is about 45 minutes away and we’re putting down a tarp and cardboard and bringind some old moving blankets to make sure we can keep it as upright as possible. We’re picking up a hoist from Harbor Freight today and pulling the old block tonight, then we’ll be ready to drop this new old engine in tomorrow. The hope is that we can get it fully situated this weekend.

I wish we we had known this would be the outcome. Would have saved us a lot of time! But we learned a lot about the engine and my parter has been converted to a Jeep guy.

 

It makes me very happy to see you are not going to be giving up.. Picking right back up like this is very impressive!

 

x2 on what the others have said. So sorry! I was emotionally invested in helping on this one LOL! Now, my two cents going forward, ..looking backward, ...That thing cracked for a reason, and I think it had to do with the head problem that these are known for in the first place. If you leaked enough coolant through a cracked head to where the coolant got down below the point where the cylinder wall cracked, there you go. Of maybe added water to a dry smoking hot engine and that did it.
So, beware of these years engines...because of the head problem..Thats all I can say.
Now as far as the $600 one, maybe, thats a tough call to make because used is used, .. unless you have some indications that this one is a better bet. I wouldn't rely on a guarantee or warranty, all that means is you're once again stuck pulling and replacing it, they may not cover labor especially if you do it yourself.

By the way, no reason you can't try to haggle a better price either, no harm in trying. Show up with cash and tell him that's all your willing to risk. These guys love cash and most of them love to haggle.

 

Stephanie: maybe you have seen this thread but if not it may contain some useful info and lessons on an engine swap. It was for a Cherokee, not a Grand, so there will likely be differences. If nothing else it is an interesting story. https://www.cherokeeforum.com/f2/bro...e-swap-249948/