Looks like someone used a crapload of RTV on the head gasket. Why? I haven't a clue. Gently pick out what you can and use a shop vacuum on the rest. Those big open areas are clearance for the pushrods and the lifters are below that. Once you get the cavities clean, stuff rags into them before you clean off the block surface and vacuum after cleaning. Turn the crank over to bring each piston to the top for cleaning. Try not to scratch the pistons because they will make hot spots that might cause detonation. I'm talking about deep scratches, not minor ones. You can tape around a piece of hose in the vacuum hose to get down inside for the stuff that fell inside the lifter area. If you want to, you can pour some kerosene in there to displace any antifreeze that may have gotten inside. It will allow it to drain out thru the drain plug. Those small triangular openings are the water jacket which you can flush after the head is on to get the junk out. You don't want that stuff in your radiator or heater core. You can use a razor blade on the block surface to make sure all foreign matter has been removed. Just keep it flat as possible so it doesn't make scratches.

Sorry I was thinking while typing so the order of things might be a little out of order, you know, what to do first? I hope this helps.

 

This definitely does help! Thanks There is/was a ton of RTV on there. That is not something that's done at the factory, am I correct? We think someone has been in here before (we have no idea how many people owned it before us, at least three) based on some weird things, like a bunch of washers on one of the manifold bolts and the head bolts do not match. There's just so much carbon buildup and gunk everywhere and I feel like if we're in there, we should get it as clean as possible before putting the head on.

The kerosene trick - after cleaning everything else up, just pour some kerosene in there and pull the drain plug and everything will come out? Should I just live with the fact that there will still be gunk down there and do the best I can?

Third coast mentioned using Gumout Carb and Parts cleaner for cleaning the mating surface - can we use that to clean the tops of the pistons and the edges of the cylinders too? Cylinder walls all look smooth, just a little gunky at the top.

 

You made excellent progress. I hate to see what sure looks like blue RTV on the head sealing surfaces. If that’s what it is it tells me that whoever did that either did not know what they were doing or did not care. No excuse for anyone to ever do this. Washers on manifold bolts is another bad sign. (You will want to find replacement cup washers if any are missing) Curious how many miles it might have been driven like that. Blue RTV is not good for the temperatures or pressures involved and absolutely nothing like that should be used as part of a proper head gasket replacement task.

When you remove the head some coolant can be expected to go everywhere. Wipe up all the coolant with rags. Then vacuum crud as mentioned above. Afterwards you might spray things down with WD-40 as it displaces moisture. I don’t see any harm in using kerosene to clean things. It will not be as effective as carb cleaner on carbon. Don’t vacuum up any solvent as you risk generating an explosive mixture. Yes, you can use carb cleaner on the piston tops and to remove the carbon ring at the very top of the cylinder. (some buildup there can be expected). Before you crank/rotate engine be sure gunk is removed at the piston to cylinder area and add a small amount of oil there.

It is a concern if a lot of antifreeze has mixed with the oil over a long period. When they mix hard particles form that can excessively wear close clearance, high load interfaces such as cam lobes to lifter and piston rod bearings. Had you noticed ongoing coolant loss? Unusual engine noise? Draining the oil and taking a sample mid drain would be one easy way to get an idea if very high wear has occurred. Dropping the oil pan to inspect main bearings could be another approach but it can be difficult. A lab such as Blackstone will give you an idea of how the metal content compares to averages and what the likely source is. If it was me I would wait to order a head until I knew if there was a good chance the engine is reasonably sound. No point in putting a good head on an engine that is near death.

I suggest using a steel ruler or equivalent to check flatness of the engine block front to back and across each cylinder opening. There are specs on flatness that is indicated by the dimension of any gaps between the ruler and block. A feeler gauge or even a sheet of copy paper can be used to determine gap dimension. This helps determine that the block is suitable to seal against a new head/head gasket. Hoping for the best.

 

I don't want to add more bad news but while I am thinking about it - whatever was used on the head gasket likely was not good for the catalytic converter and O2 sensor, especially if it contained silicone (RTV).

 

I'm kinda thinking whoever used the RTV probably reused an old gasket! That's probably the dumbest thing you could ever do! I only used an old gasket once in my life just to see of an old flathead Plymouth we found in a barn would still run. The valves were all stuck open when we first turned it over so we had to lube them until they worked the way they were supposed to, then stuck the head back on and it fired right up! Good! Now it's worth working on.

 

Thanks third coast! You all have been so helpful. I truly do appreciate it.

We hadn't noticed any coolant loss. Water pump went a few months ago so my partner (who typically drives this Jeep) was watching the coolant levels pretty closely. Unusual engine noise is what started us on this path. Aside from the more typical noises this engine is known for making, we started hearing more of a knock and started trying to diagnose. While he was driving it home one day, the CEL started flashing and he lost power, so he pulled over and we had it towed home. It hadn't overheated but we saw the coolant overflow was very low. We saw coolant and oil on spark plug 6, oil dipstick looked normal, but when we opened the oil cap on the valve cover, we could see antifreeze in there. We started digging and researching and realized there were a lot of symptoms of a blown head gasket and/or cracked head. So as far as we are concerned, it was not driven a significant amount of time with these issues, probably less than 100 miles. When we drained the oil, a significant amount of antifreeze came out before the oil started coming out. The mixture filled up our big oil drain container.

I'm still leaning towards a Clearwater head. It's a new head cast with remanned valves. Other choice I found is a remanned TUPY head with remanned valves. Our Jeep has the original 0331 and i'm seriously not interested in putting it back with the rate these things seem to crack at. Jeep has 168k on her, and it's obvious someone has been in here before, but I don't know what they did. I don't *really* have the money for the head, but we also don't *really* have the money to have the Jeep out of commission for another couple of weeks if this head cracks. I can find the money and just not eat a lot for a couple of weeks

 

The only other option I can suggest is finding a TUPY head on and engine in a junkyard and testing the valves for sealing by pouring something light (like kerosene or mineral oil) into the chambers and seeing if it comes out the valve passages. If it only seeps slightly, slap that kid on your engine and be done with it. OR reseat the valves. Either way, you'll have a TUPY head for cheap and you can do whatever it needs done to it. You can find a TUPY head with a flashlight looking down the oil filler hole.

 

I pulled the trigger on the new cast head with remanned valves from Clearwater for $455. I found a couple of remanned TUPY heads with valves but they were only a few bucks cheaper. We thought about going to a junkyard but if we did that, we'd likely bring it to a machine shop anyway just in case because I would like to avoid EVER pulling this much of the engine apart again! Our time is worth something. I'm just hoping Clearwater ships out quick! Now we're going to focus on cleaning up the block and waiting for all the stuff from Rock Auto to come in - we ordered some new hoses, thermostat housing, stuff like that.

 

Here are the block flatness specs that I located in my notes from when I replaced the head on my 2000: I don't recall if I got this out of the factory service manual or elsewhere so it would be a good idea to verify. Check the block after it is cleaned of carbon, old head gasket remnants and the apparent RTV. It is not likely to be off much on the 4.0 engine but if it is a new head gasket may not last long.


Flatness . . . . . . . . . . . . . . . . 0.03 mm per 25 mm (0.001 in. per 1 in.)
Flatness . . . . . . . . . . . . . . . 0.05 mm per 152 mm (0.002 in. per 6 in.)
Flatness Max. . . . 0.20 mm - max. for total length (0.008 in. max. for total length)

 

I got mine in 3 days because they have a warehouse in Kingston or somewhere near there. It's interesting that yours was $455 because that's what mine cost 5 years ago but had NEW valves . I've recently seen them advertised on other websites for $525 from other sources, probably trying to make a profit on Clearwater's good name. I know for a while Clearwater couldn't keep up with the demand and sold thru other jobbers to devote more time to building rather than marketing. They give you 30 days to return the core or then send you a bill for an additional $100. Save the box and wrappings because you'll need it for the return. The return shipping tag says "Scrap iron."

 

Dave, I'm on Long Island. Not holding my breath, but I'd love to see this head in three days!!

 

That's why I mentioned it! That was 5 years ago for me. It came Fedex and because it was 90 lbs, the guy dropped it on my front lawn! He didn't ever get to the porch. They give you a prepaid return shipping label for USPS as scrap metal. The old one weighs 78 lbs so you can see how much more metal is in it.

 

UPS tracking said it will be here Saturday!! Faster than I expected. And since it's a three day weekend, who knows - maybe we'll get this thing back together this weekend. That would be nice - my partner really misses his Jeep!

 

Don't we all? Funny, you may have other cars, but the world isn't the same when your jeep is busted. I'm now driving my XJ while my WJ is waiting for litigation involving who is going to pay for my destroyed brand new engine because the oil pump failed.

 

Did you get the new head?

As you prepare to put things back together here are some items to consider. When I was researching replacement head options I ran across info that indicated that new replacement heads typically do not come with dowel pins that are essential for precisely locating the head to block and manifolds to head. You will want to compare a new head to the one you took off. If the dowel pins remained in the old head you should obtain new pins to install in the new head. Removing pressed in pins is very difficult without damaging/marring the surface. New pins may be available from a Chrysler parts department.

Manifold pins - Chrysler part: Dowel, cylinder to intake p/n J3172318, 2 reqd

Block pins: Cylinder head to block, .620D x .50, J4005149; 53040018; J3197511; J3173090; Verify quantity 2 needed

Also, the two exhaust manifold studs, one at each end of the head, may not come with a new head. I provided a part number in post #18. Alternately you might be able to transfer from the old head if they are correct and in good shape.

When reassembling be certain to torque all fasteners to spec. This is especially important on head bolts and manifold bolts and studs. I found that some manifold bolts and head bolts could not be reached with any socket I had. In that case you must use a wrench type “torque adapter” on a torque wrench. The torque value you set on the torque wrench (indicated value) must be adjusted to compensate for the added lever length – torque wrench plus torque adapter. A calculator to adjust the indicated value to achieve an accurate applied torque value can be found here: https://www.engineersedge.com/manufa..._extension.htm