Disappearing Coolant?

[Kingkong0192]

If the leak was slow enough, it may have boiled out before doing any real damage. I would do the compression test now, yes you cab still do the compression test, just disconnect the CPS sensor so the computer kills the spark and fuel feeds, and skip the leak down test as it is a waste of time if you are replacing the head anyway, and if the compression test was good. If the compression is good, it confirms good pistons and rings and cylinder walls. If compression is bad, it does not confirm where the leak is!!! But wasn't this engine still running smoothly??

If the compression test is bad, a leak down test might help collect data on the leak source, ie rings, head gasket or valves, or might not.

You can drop the oil pan and pull the crank bearings, inspect them and the crank bearing surfaces and install new bearings, with out pulling the engine.

How was the oil pressure???????????? If it was still good, that is a great sign!!!

Most of us get a JY core ( I let the machine shop get mine), and have a machine shop test (full inspection) it and rebuild it. New head, if they even make them won't be cheap!

Alright i'll go disconnect the CPS from the engine, and begin doing a compression test on it. Yes, the engine was running perfectly before i took it apart tonight. The only thing it didn't do was go above 3,000 RPMs in like 3rd or 4th gear. I never figured out why, and am still unsure if it was related to the engine.

Can i have a cracked head and still have good compression? I don't really want to replace the head if there is nothing wrong with it. I kind of want a way to confirm that there is actually something wrong with my head.

If i get a bad compression reading, i'll do a leakdown test.

So if i cooked the engine bearings, i can replace those? That would be the only thing that would wear out on the bottom end that would need replacement?

The oil pressure seemed to fluctuate, but it never seemed low. It normally was right around 40. Is there any way to confirm my oil pressure at this point?

When you say you get a machine shop to get them, you mean like a manufucating company? You call them to get the head, and then they rebuild it? What do you mean rebuild it? What do they do to it?

I know clearwater cylinder head makes a replacement 0331 head for like $400. That head won't fit on my XJ?

 

[Ecomike]

Can i have a cracked head and still have good compression?

YES!!!

So if i cooked the engine bearings, i can replace those? That would be the only thing that would wear out on the bottom end that would need replacement?

YES,....NO. But your oil pressure and smooth running engine means the bearings, lifters, pistons, rings, .....are all probably still good, and you just need to replace the cracked head. Heads can crack and fail in many places, and the symptoms are different!! If the bearings were wiped out you would have seen 0-10 psi oil pressure and a white emulsion in the oil pan.

The oil pressure seemed to fluctuate, but it never seemed low. It normally was right around 40. Is there any way to confirm my oil pressure at this point?

Hot idle oil pressure versus cold oil pressure will vary. 40 psi is GREAT!!!!

When you say you get a machine shop to get them, you mean like a manufucating company? You call them to get the head, and then they rebuild it? What do you mean rebuild it? What do they do to it?

My local engine machine shop has a deal with local junk yards, they get a used head(s) from them at a discount, clean, and inspect the head for any cracks, then they rebuild the head. I paid $120 for the clean rebuild (new valve seals installed) and inspection on mine, when I replaced a head gasket. And about $40 for the head gasket and new valve seals from Auto zone. They can do just about anything, but a good reusable JY head, they usually just clean, make sure the block face is flat, so it will seal, and replace the valve stem seals. I got the two 3 cylinder heads for my son's V-6 (ford) from them ready to install for about $120 each. They were good JY pulls, but they cleaned, inspected and replaced the valves seals, and if needed machined the head face to make sure it was flat. It was cheaper than buying rebuilts from the auto stores.

 

[Gonepostal]

Thanks for that. I know that the 0331 head is prone to cracking, and that Clearwater Cylinder Head makes a replacement 0331 head. Would that head fit onto a 99 XJ or no? I think if my problem lies within the head, instead of trying to "patch it up" i'd be better off just buying a new head and dropping it in.

I just realized i made a thread on this last week, (more along the lines of me thinking i had a head crack) and i should of posted all of this in THAT thread, but i forgot about it. I apologize for double threading.

Anyways, my oil cap does have that milky stuff on it, but my dip stick does not. I will drain the oil today and see how it looks.





Alright. I think you missed what i was saying. The coolant isn't coming out of the overflow on the bottle. When i took the radiator cap off to use the combustion leak tester, coolant just kept coming up and going over onto the ground.

I'm going to go perform a leak down test on the jeep now and see what it's looking like.

Here's a picture of my oil fill cap and my spark plugs.

I had exactly this condition, milky oil cap and disappearing coolant on a 88 Ford Bronco II with a 2.9. The crack in the head was through the water jacket on the head and located in the rocker galley so the thing ran like a watch. It just ate coolant. I caught it too late and the contaminated oil had ruined my main and rod bearings. Luckily my crank and rods were OK. Your probelm is similar. I would not drive it any further until you get the head off and the problem fixed. I would also check your crank and rods closely for abnormal bearing surface wear.

 

[Kingkong0192]

Double Post.

 

[Kingkong0192]

YES!!!



YES,....NO. But your oil pressure and smooth running engine means the bearings, lifters, pistons, rings, .....are all probably still good, and you just need to replace the cracked head. Heads can crack and fail in many places, and the symptoms are different!! If the bearings were wiped out you would have seen 0-10 psi oil pressure and a white emulsion in the oil pan.



Hot idle oil pressure versus cold oil pressure will vary. 40 psi is GREAT!!!!



My local engine machine shop has a deal with local junk yards, they get a used head(s) from them at a discount, clean, and inspect the head for any cracks, then they rebuild the head. I paid $120 for the clean rebuild (new valve seals installed) and inspection on mine, when I replaced a head gasket. And about $40 for the head gasket and new valve seals from Auto zone. They can do just about anything, but a good reusable JY head, they usually just clean, make sure the block face is flat, so it will seal, and replace the valve stem seals. I got the two 3 cylinder heads for my son's V-6 (ford) from them ready to install for about $120 each. They were good JY pulls, but they cleaned, inspected and replaced the valves seals, and if needed machined the head face to make sure it was flat. It was cheaper than buying rebuilts from the auto stores.

That's good to hear. I still haven't gotten to draining the oil. As soon as i finish this sandwich, i'm going to drain it. I'll have pictures up tonight of the oil.

I'm not sure if the 40PSI was accurate though.

I'll call around and see if i can find a shop that has a 4.0 head. I don't even know of any shops off the top of my head. I was expecting to pay like $400 for a head.

I had exactly this condition, milky oil cap and disappearing coolant on a 88 Ford Bronco II with a 2.9. The crack in the head was through the water jacket on the head and located in the rocker galley so the thing ran like a watch. It just ate coolant. I caught it too late and the contaminated oil had ruined my main and rod bearings. Luckily my crank and rods were OK. Your probelm is similar. I would not drive it any further until you get the head off and the problem fixed. I would also check your crank and rods closely for abnormal bearing surface wear.

I honestly have no clue what you're talking about. I'm going to go pull the automotive textbook out of my closet and begin reading up. I'm oblivious to everything inside an engine. It's all over my head and i'm trying to learn it all as fast as i can to figure this out. No clue what anything inside of an engine does or how it works. I have no glue how to check my crank and rods closely for abnormal bearing surface wear. Don't even know where any of that is.

Time to read up.

I also need to figure out which heads are 100% compatible with my jeep.

I want to stay away from the 0331 head in the 00-01 XJs. I want to stay on the somewhat cheap route while getting quality. Like the $400 mark (just for the head.)

While i have the head out is there anything else i should do?

Also, if i could find an entire engine already running for cheap, i'd like to go that route instead. If it's an easy answer as well, what 4.0s are a direct swap into a 1999 Jeep XJ?

Is there a reason i can't edit my posts? It's not letting me. I tried to update the pictures because i screwed a 300W bulb into the overhead socket and my pictures have much more light. Here are the new pictures.

 

[ChiXJeff]

Is there a reason i can't edit my posts?

Yes, there's a reason. Short edit time due to problems in other areas of the site, and it's a global configuration setting.

 

[Kingkong0192]

Yes, there's a reason. Short edit time due to problems in other areas of the site, and it's a global configuration setting.

Thanks for the clarification. I did notice i could edit right after i posted, but like 20 minutes later the option just disappeared.

Just drained the oil out. Here's a picture of it. Sorry for all the pictures, but i feel like if you can actually see what everything looks like, you can judge it better.

 

[SRT41320]

You can take the serpentine belt off. These engines use internal timing chains. An easy way to see if you're on the compression stroke, is to stick a little wad of paper towel in the spark plug hole. It will get shot out when the piston hits tdc on the compression stroke.

 

[Ecomike]

That oil looks fine. Did you see any white or coolant green at all as the oil drained out????

So far all I see and hear, says you just need to replace the head. Be sure to use new head bolts, new gasket and new valve stem seals and if you get one from a junk yard pay a local engine machine shop to check the head.

headbolts.com is where I got the bolts.

 

[Kingkong0192]

You can take the serpentine belt off. These engines use internal timing chains. An easy way to see if you're on the compression stroke, is to stick a little wad of paper towel in the spark plug hole. It will get shot out when the piston hits tdc on the compression stroke.

Thank you! I'm going to start pulling some parts off because i don't plan on starting the jeep until i remove the head and check the HG and see what's actually wrong.

Will go use the towel trick.

That oil looks fine. Did you see any white or coolant green at all as the oil drained out????

So far all I see and hear, says you just need to replace the head. Be sure to use new head bolts, new gasket and new valve stem seals and if you get one from a junk yard pay a local engine machine shop to check the head.

headbolts.com is where I got the bolts.

No i did not. All engine oil came out looking like that picture. Nothing green or anything like that came out of the drain hole. I'm pretty happy the milkshake affect didn't spread down into my engine.

I just want to make sure the head is actually cracked. I'll send it out to a machine shop to be checked out if i don't see visible parts missing from the head-gasket. (Or would a headgasket not let the milkshake affect happen up in the valves and valve cover?)

Is there any way to tell a difference between a HG failure and a head crack? (without pulling it all apart.)

I don't know what a valve stem seal is, but i will google it and figure it out.

Thanks for all your help and patience. Really appreciate it.

 

[Ecomike]

It is pretty obvious that there is a tiny hairline crack in the top side of the head that is spraying coolant at some point onto the valve cover IMHO.

A head gasket (bottom side of the head) leak of coolant would put coolant into the combustion chamber and out the tail pipe, or into the oil sump.

IIRC a top side hairline crack between 3 & 4 cylinders is common on the later 0331 head. Are you sure the dealer did not put an 0331 head on it?

You could rent a radiator presssure tester and run the cooling system pressure up to 16 psi and look for a leak, but the leaks can come and go with heating and cooling cycling, until they get real large, and thus at your stage be hard to locate.

But there is no mistaking that green coolant on top of that one rocker arm bolt in your photos!!!

Have you completed the compression tests? DO NOT crank the engine with out oil in it!!!!!

 

[Kingkong0192]

It is pretty obvious that there is a tiny hairline crack in the top side of the head that is spraying coolant at some point onto the valve cover IMHO.

A head gasket (bottom side of the head) leak of coolant would put coolant into the combustion chamber and out the tail pipe, or into the oil sump.

IIRC a top side hairline crack between 3 & 4 cylinders is common on the later 0331 head. Are you sure the dealer did not put an 0331 head on it?

You could rent a radiator presssure tester and run the cooling system pressure up to 16 psi and look for a leak, but the leaks can come and go with heating and cooling cycling, until they get real large, and thus at your stage be hard to locate.

But there is no mistaking that green coolant on top of that one rocker arm bolt in your photos!!!

Have you completed the compression tests? DO NOT crank the engine with out oil in it!!!!!

If this was your jeep, would you bother sending my head out to a machine shop to check out, or just bite the bullet and begin shopping for a new head?

Yeah i know the 00s and 01s have the 0331 head in them which is notorious for cracking when it overheats. I have a 1999 though, and there is no reason there should be a 0331 head in it. The dealer said they did a HG, not a head. Is there a way to identify a head by looking at it?

I see that hint of green in the picture too. The only thing i can think of is maybe when i pulled the valve cover i managed to somehow get coolant under there from the thermostat housing or one of the hoses i removed. I'm probably just not wanting to face the fact that my head is cracked.

No, i was going to do the compression test today, but my compression tester will not screw into the jeep spark hole for some reason. Maybe it was the jeep god warning me not to crank it without oil in it, because i was going to if it screwed in. I guess i got lucky.

Would you bother pouring the oil back in so i can compression test it or no?

What's the best replacement head for a 1999 4.0?

 

[Ecomike]

You could put the oil back in to do the compression tests.

The 0331 is cast into the side of the head, passenger side I think.

I would take the head to a machine shop while shopping for a new head.

BUT, I would also fire it up one more time, valve cover loose, and while cold, and then while hot, lift the cover off and look for steam or green coolant and a crack. I would probably use the radiator tester first to see if pressure alone reveals the crack. Then I would pull the head and take it to an engine machine shop for final verification of the problem.

Some else needs to answer the best replacement head to use question.

 

[dryad001]

The 0331 is cast into the side of the head, passenger side I think.

Some else needs to answer the best replacement head to use question.

The head stamp is on the drivers side around #4 cyl.

As to what the best head is. Mine was something that I already had. I replaced a 0331 head with a 7120 casting. Finished it up today and it actually runs pretty nice.

I think the best head to use is whatever one comes around at a price that your willing to pay.

 

[Kingkong0192]

You could put the oil back in to do the compression tests.

The 0331 is cast into the side of the head, passenger side I think.

I would take the head to a machine shop while shopping for a new head.

BUT, I would also fire it up one more time, valve cover loose, and while cold, and then while hot, lift the cover off and look for steam or green coolant and a crack. I would probably use the radiator tester first to see if pressure alone reveals the crack. Then I would pull the head and take it to an engine machine shop for final verification of the problem.

Some else needs to answer the best replacement head to use question.

I just went out and looked at the head. I think i can actually see the crack in it.

If i'm not seeing the crack, then i will take your advice.

The head stamp is on the drivers side around #4 cyl.

As to what the best head is. Mine was something that I already had. I replaced a 0331 head with a 7120 casting. Finished it up today and it actually runs pretty nice.

I think the best head to use is whatever one comes around at a price that your willing to pay.

Just went out and checked. It's a 0630 head. Never heard of those cracking.

I'm going to try to shop around and see what i can find.

 

[ihscoutlover]

Ok i just read through this entire post. My XJ was built 09/99. It has a 0331 head. I had a compression test done, checked for coolant in the oil, none. Checked for compression across all cylinders, and the #3 was lower than the rest, but the mechanic believed it was his equipment. No exhaust gasses in the coolant. I am seeing a similar fill cap sight. I just drove to Louisville, from St. Louis. The overflow was full before I started, and at my fillup stop, it was pretty much empty. I have had some leaky hoses, but nothing out of the ordinary. The heat is pretty much non existent. I have put the system under some pressure and found the leaky hoses. At my last oil change, I added some lucas oil stabilizer, and used Rotella 15W 40 oil. The oil pressure has been all over the place when cold at times being around 80 psi, then other times around 60. Oil still appears fine, but I get the gumption that the head is cracked. Question, are there aftermarket replacment heads to fix the dreaded head issue, or should I get a head from an earlier model?? I want to keep the unit as stock. Its a DD/Weekend warrior. I was getting 20mpg when I first got it, ive put over 8k on it in less than 4 months, and its pretty much just driven highway. Thoughts or suggestions here?? I just want to do this once and be done with it, but I want to make sure that I don't have other issues. The radiator, thermostat, water pump and upper and lower hoses have all been replaced. I will try and post up the actual numbers on the compression check and let you all know tommorrow what those results were. Pick me apart as needed. I also still have my '94 apart in the driveway, that may have to go back together so that I can get this one repaired right. Can the heads be repaired? I plan on letting this sit while I am here, but it will have to make the jaunt back home. I want some thoughts and input from those of you that have completed this task. I just want suggestions or ideas since I did the search and found the information that you guys have just posted and I want to make sure I don't cause any further damage than what may already be lurking. Thanks in advance.

Jeff

 

[Ecomike]

There are other good heads you can use. They are mentioned in dozens of other threads all over this forum already with the advantages and mounting issues (If any) of each.

 

[Kingkong0192]

Ok i just read through this entire post. My XJ was built 09/99. It has a 0331 head. I had a compression test done, checked for coolant in the oil, none. Checked for compression across all cylinders, and the #3 was lower than the rest, but the mechanic believed it was his equipment. No exhaust gasses in the coolant. I am seeing a similar fill cap sight. I just drove to Louisville, from St. Louis. The overflow was full before I started, and at my fillup stop, it was pretty much empty. I have had some leaky hoses, but nothing out of the ordinary. The heat is pretty much non existent. I have put the system under some pressure and found the leaky hoses. At my last oil change, I added some lucas oil stabilizer, and used Rotella 15W 40 oil. The oil pressure has been all over the place when cold at times being around 80 psi, then other times around 60. Oil still appears fine, but I get the gumption that the head is cracked. Question, are there aftermarket replacment heads to fix the dreaded head issue, or should I get a head from an earlier model?? I want to keep the unit as stock. Its a DD/Weekend warrior. I was getting 20mpg when I first got it, ive put over 8k on it in less than 4 months, and its pretty much just driven highway. Thoughts or suggestions here?? I just want to do this once and be done with it, but I want to make sure that I don't have other issues. The radiator, thermostat, water pump and upper and lower hoses have all been replaced. I will try and post up the actual numbers on the compression check and let you all know tommorrow what those results were. Pick me apart as needed. I also still have my '94 apart in the driveway, that may have to go back together so that I can get this one repaired right. Can the heads be repaired? I plan on letting this sit while I am here, but it will have to make the jaunt back home. I want some thoughts and input from those of you that have completed this task. I just want suggestions or ideas since I did the search and found the information that you guys have just posted and I want to make sure I don't cause any further damage than what may already be lurking. Thanks in advance.

Jeff

Do the job yourself man. I'm 17. I thought i was going to be in WAY over my head. Job was so easy. (granted i only have it apart.) If i can do it, anyone can.

Just get a can of PB Blaster or Kroil (I prefer Kroil) and spray the intake manifold and exhaust manifold religiously for days. Those bolts came out so easy for me. Everyone makes a fuss about the lower intake bolts, but honestly those weren't bad either.

Get two extensions, a swivel, and a short 9/16" socket with a 3/8" ratchet on it. Reach under the intake and feel for the bolt heads. Once you locate them place the socket on it, move the extensions out to the open, use the ratchet to break them loose, and then i used an air ratchet to spin them out.

Was super simple and not complicated at all. Be sure to label everything. I put everything into ziplog bags and labeled it all.

Just got the exhaust manifold and intake off tonight. The exhaust manifold bolts that hold it to the rest of the exhaust get so hot it basically welds them together. They were way too tight to loosen. I used a cut off wheel to cut them apart so i could pull the entire manifold out. (not necessary but i wanted to check for cracks.)

Turns out my exhaust manifold was indeed cracked. I will be replacing that.

Going back to my garage momentarily to pull the head off and look at the head gasket.

 

[ss427ci]

Nothing like working on your own Jeep, that way you know exactly how it's done. Nice job on taking this on yourself. You will gain tons of knowledge by the end and be an asset to others in the future. :thumbsup:

BTW: I went through this whole ordeal with my 2001 with the 0331 head a while back. Never underestimate the importance of cooling system maintenance on the XJ.

 

[Kingkong0192]

Nothing like working on your own Jeep, that way you know exactly how it's done. Nice job on taking this on yourself. You will gain tons of knowledge by the end and be an asset to others in the future. :thumbsup:

BTW: I went through this whole ordeal with my 2001 with the 0331 head a while back. Never underestimate the importance of cooling system maintenance on the XJ.

I like it. Kills time and keeps me from doing things I might regret later. You learn a lot too. At this point I honestly don't even trust mechanics. I trust the words of people on offroading forums way before I'd even think about trusting a mechanic.

Tell me about it. It's quite an ordeal.

Anyways.

Pulled the head off.

Head gasket looks fine. At least from what i can tell. I don't see any huge parts of it missing.

I'm assuming it's normal for coolant to be in the lower end of the engine. I set it on my bench, and am going to degrease it to hell and back looking for cracks.

If i don't see any cracks, and my headgakset looks fine, i'm going to be super confused as to how all that milkshake stuff got on my valve cover and even more confused on where all my coolant is going.

Just went back out there and spun my crankshaft some more. The 3rd and 4th cylinders literally go together in pattern. They would fire at the same time. Is this normal? I don't know. I made a video of it, and it's uploading to youtube now. You can see in the first picture that they're both at the top, and then when i crank the shaft, they both go down at the same speed, come back up at the same time, etc etc. All the others go at different speeds.

Here's a video so i don't clog this thread up with pictures. Shows everything.

http://www.youtube.com/watch?v=q0a4sHSk18s