byrns149

Here is my story, it is a bit to read, but any help would be greatly appreciated.

So i bought my 2001 4.0 XJ about 6 months ago, being completely clueless on this whole 0331 cracked head scenario. Im fairly new to cars in general but i have been doing as much reading as i can in the last few months. I pretty much caught the jeep bug.

My jeep was built in May of 2001 and currently has 169k miles on it. The body is in great condition, as well as most of the undercarriage, including virtually no rust on the frame at all. I got my jeep for a great price that i couldnt pass up and everything seemed to be in good order.Interior and paint in great condition. Coolant looking nice and green, running smoothly, shifting well.

2 months went by with no problems besides a leaky Power Steering unit which i replaced.

About a month later i started to have trouble with a rough and stumbling idle followed by a stall when starting my car between 190 and 210 degrees. I got a check engine light for Cylinder 3 misfire as well as Catalyst below minimum and a MAF/MAP which i believed to be all connected to the misfire.

I read about the recall involving the area around injector 3 becoming too hot, and was told to replace my current injectors with upgraded 4 hole injectors. A few weeks later this problem went away with the weather becoming much warmer in my part of the country so i decided to leave the stock injectors alone for now.

It recently came to my attention that my car was built with the dreaded 0331 cylinder head. I began to watch my cooling system, running temp, and oil pressure.

My running temp never goes above 210, and i have taken my car on 50 mile excursions with no problem. My oil pressure is around 30 at idle when at running temp and gets to around 60 when accelerating.

This is whats really scaring me.....
About 3 weeks ago i topped off my cooling system with coolant and some water. Today i opened my reservoir, and it is down to the add marker. There are no visible leaks. I then checked my radiator cap to see thick brown chocolate milkshake looking coolant.


My father thinks im overreacting but i keep trying to tell him about this 0331 head. Could all of my symptoms be connected? Is it possible the cylinder head is cracked? Is the chocolate milk coolant a dead giveaway? or could it be something else? I plan on completely flushing my system this weekend.

Ill really be angry if i gotta replace a head or even better a whole engine....



HELP PLEASE

Klutch

I too bought an XJ six months ago. Mine is a 2000. Shortly after I bought it, I discovered it had the dreaded cracked 0331 cylinder head. I'm sorry to report your symptoms point directly to a cracked cylinder head.

To be sure, you can borrow/rent a coolant system pressure tester from a chain auto parts store. It fits on the radiator where the radiator cap goes. You pump it up and check to see if the pressure drops. Likely, your pressure will drop and you'll see oozing from below the oil fill cap.

When you look through the hole in the valve cover while the engine is warm and running, can you see small amounts of coolant coming out?

Also, there should be an insulator around your number three injector to prevent it from vapor locking. You can buy it at a Jeep dealer. I had this problem as well. My number three injector had the insulator, but it wasn't fastened in any way. Two tie wraps solved that problem.

I went with a new cylinder head from Clearwater. It was $440 shipped to my door. It's designed to eliminate the cracking problem. Be careful of remanufactured 4.0 cylinder heads. Many of them are cracked cylinder heads which were "repaired". The repair is temporary at best. Some are pinned. Some are welded. Don't bother with either scenario. If your head is indeed cracked, replace it with a new casting from Clearwater or another vendor and don't look back.

justin92xj

Sounds like a cracked head. They're pretty easy to replace and there's a bunch of video's on YouTube that walk you through it.

byrns149

i havent experienced any other symptoms besides the gross coolant. My oil seems fine and doesnt get low or anything. My oil pressure is fine and i have never overheated. Im thinking it might just be cooling system neglect?

Klutch

The goop on your finger in the pic looks like radiator stop leak. It's possible, maybe even likely, the previous owner dumped in a bunch of stop leak to hide a cracked cylinder head.

If your cylinder head is cracked and leaking, you'll see the oil level go UP and the coolant level go DOWN. This problem leaks a tiny amount of coolant very slowly. Thus, the oil on the dipstick may not appear milky, but you will see milky residue under the oil filler cap.

Hopefully, what you need is a new radiator and not a new cylinder head. In my case, I needed both. The factory XJ radiator is notorious for leaking around the tank seams and this cannot be repaired. That could also explain why the PO dumped in stop leak. I really hate that stuff. It's a temporary solution at best and it gunks up the cooling system.

XJ-kee

edit to say: Take everything that we say with a grain of salt. We all have had different experiences, irritations, and triumphs with these issues. The absolute best thing you can do is go through your coolant system top to bottom, front to back, and make sure it's all in working order. Then open the oil cap and start it up and watch for some coolant with a bright flashlight. If you dont see any, fill your coolant back up to normal and watch it every single day. Take your oil dipstick out, note where it's at on the stick. If your coolant goes down, oil goes up, it's a sign of the head issue.

Yeah all of the symptoms point to it. Odds are the previous owner saw his coolant dropping and threw stop leak in there. That's what the brown stuff looks like that's on your finger and in the rad cap. Coolant in the radiator there should be green green..not that color. Klutch is definitely correct in what he's talking about.

1. Did you check your oil? Does it look good or ? Chocolate milk OIL is a giveaway, not the coolant
2. From what I've read, the crack can happen in a couple different places but by far the most common is between cylinder 3 and 4 which you can see under the oil filler cap. See the pic for what it would look like (this is engine on and running, cap off, looking down to see the coolant seep through as was mentioned -- right hand side of the picture is towards the front of the car)
3. It's the most worrisome that you filled up the coolant and came 3 weeks later and had it at the add marker...this would be your biggest signal IF you know the rest of your cooling system is in good order.
4. Always check the obvious first - No leaks in your radiator? Nothing sprayed up against the inside wall of your tires? Coolant hoses are all not leaking? Water pump and its gasket aren't leaking? Rad cap isn't bad and leaking?

See my post (#27 if it doesn't link correctly) HERE

My head cracked at 162k miles and I caught it early. Not even bad enough that the oil got milky and didn't even go through a lot of coolant. I'm hyper sensitive to parts on my cars, so I replaced everything that I touched + a little bit more. I spent about $1k on parts doing everything. If you just want to plop a new head and change the oil and coolant, you can do it for $650 or so plus a saturday. The basic parts you would need is a head gasket, manifold gasket, cylinder head from clearwater, new oil and new coolant.

There's a lot of writeups out there, friend. Don't let the bad cylinder head put you off to a jeep! It's worth it to fix it! Once you do, you're sitting on a long lasting engine.

RTorrez1

Listen to what others have mentioned. One of the things I would do is drain the oil and make sure there isn't any coolant in the oil. If there is stop running the engine! If you keep running it with any water/coolant in the oil you have a good chance of destroying your bearings and then you will be in a bigger mess then you may be in, instead of having to replace the head you will be having to rebuild your engine. Let us know what you find.

extrashaky

FYI, you can't always tell whether there's coolant in the oil by looking at it. To be certain, you need to send an oil sample off to a lab like Blackstone. The test costs $25. They send you the oil report in PDF form via email.

The sample will get there a lot faster if you spend the extra money for UPS Ground, because the Postal Service has it's collective head up its **** and will hold onto it for a month trying to figure out whether to deliver it.

RTorrez1

This is very true!
But, my point was that he shouldn't keep running the engine until he can verify his situation.

md21722

The normal 0331 cracked head does not contaminate the cooling system with engine oil. It contaminates the engine oil with coolant. The only way to get oil into the coolant is to have a cracked head or a blown head gasket, or both. When you pull the head, change it to something other than the factory 0331 non-TUPY head. In some cases oil in the cooling system may even be ATF if the transmission cooler is leaking. Dexcool mixed with conventional green will turn to brown poop.

andrewmp6

A compression test can show if you have a head problem or not with out pulling the head.

travs2448

Its also worth mentioning that the cooling system is under pressure and not the oil at the point of the cylinder head in the valve train. so the coolant would mix with oil but its next to impossible for oil to get into the coolant like that. also my coolant has always had an orangeish tinge to it since i got it and thats after two flushes. ive chalked it up the the cast iron block

However i also bought an 01 an and right after got the 0331 head issue. good thing i knew about. First things first always check your coolant level when the engine is cold and i mean sitting for a while. because checking it while its warm will give you false readings.

The best way to see if your head is really cracked is after a long hot drive. pop the hood and open the oil filler cap on the valve cover. look down in there with a flashlight. if there is a crack you will be able to see coolant weeping out of it clear as day.


heres an example of what mine looked like. hope i helped you out a bit