Hey all, I've got a 2000 XJ 4.0 with ongoing radiator issues. I had the stock radiator blow on me two weeks ago, but before it went I noticed a continual loss in coolant and no visible leak. The overflow tank kept trending went toward empty and I noticed a 'rushing' sound of water after starting.

Fast forward two-weeks and I've got the new radiator installed but still seem to be losing fluid, and again with no visible leak. I put in just under 2 gallons in the radiator when filling it and the overflow tank is on empty again. Can't figure it out.. it's almost like it's drinking the stuff because I don't see any spot on the driveway.

Any thoughts would be a big help. Thanks

 

I'm so sorry to tell you this, but you have a cracked head. Now it could be some thing else but all your symptoms point to a cracked head. Do not drive it. Check your oil. Post a pic of its color. It seems you have had this problem awhile and lost a lot of coolant. Your motor may be on its last legs. How mechanically inclined are you? You could rent a pressure tester and check for sure.

 

just curious how many miles are on it?

get it pressure tested as Martlor said. if the oil looks ok you can have an oil analysis done for around $30 and it will tell you if there is coolant mixing in that cannot be seen with the naked eye, but I do think the pressure test will be definitive. With as much coolant as you are loosing it sounds like you should be able to see it in the oil, but some people say the oil can look good and the head still be bad.

What is the operating temperature? I would not trust the dash temperature gauge. I would get the running temps on a scanner or IR thermometer. My gauge was reading fine and it was really running about 30 degrees higher.

http://www.blackstone-labs.com/free-test-kits.php

 

google 0331 head

sorry.

 

The oil is clear.. no milky white color. I also haven't had any overheating issues, and the oil pressure seems fine (goes between 30 and 50 most of the time).

Does it still sound like a cracked head?

 

It does. As stated above modern oils don't really show up as milky. They could and that's why you look. But if you are losing that much, and it's not on the ground, we'll that means it's internal. Hopefully you have another vehicle because the jeep should stay on the shelf until you do some testing

 

2000 XJ

you bet it does

 

Martlor is giving you some good advice. That much coolant mixed in the oil will damage the motor (if it is getting in the oil)

also I cannot state this enough--do not go by the dashboard temperature gauge. The sending unit can fail giving you a false good reading. If you do not have a scanner or access to one you can get the torque app or dashcommand app, and a wifi or bluetooth obd2 adapter

https://www.amazon.com/ieGeek-Wirele.../dp/B00B3K2X4M

 

If losing that much coolant and oil is not milky, wouldn't it at least read over full on the dipstick? Also look for white smoke from exhaust with a sweet smell and check that the passenger footwell isn't wet with coolant. If it's not in the oil or on the ground it must be somewhere.

 

Send off an oil sample to Blackstone as noted above. That will tell you definitively whether it's going into your oil.

Shine a light down into the oil filler hole and look for a crack between the #3 and #4 cylinders. Sometimes you can even see coolant weeping up from the crack there.

A compression test will also indicate whether you have a head problem.

Have you noticed any brown crap in your coolant or in the overflow bottle? Has the overflow bottle ever bubbled at all? If so, you can also test for the presence of exhaust gases in the coolant using a combustion leak tester kit. You can buy one for $50, but apparently some of the auto parts store also loan them out.

If you catch it early enough before you do serious damage to the short block, you can replace a cracked head with an aftermarket 0331 from Clearwater Cylinder Head for around $500. It comes to you ready to bolt on and takes an afternoon to swap in.

Alternately, you can swap in a TUPY 0331 head from 2002 on or a '99 or earlier 0630 head. The TUPY 0331 will bolt right in, but they're not that easy to find and sometimes need machine work. The 0630 is fairly easy to find but requires a little bit of fabrication to make the coil rail work on it. The Clearwater head is by far the easiest solution.

If you do determine you have a cracked head, stop driving it until you fix it. Continuing to drive it will damage the bearings in the motor and lead to failure. If you just ignore it, it could mean the difference between a fairly easy $500 head swap one Saturday afternoon and an entire engine swap.

 

Good luck finding a TUPY head. They are difficult to find unless you have some jeeps at a local junk yard.

The Clearwater head does NOT come 100% ready to bolt on. You will need to transfer two exhaust manifold studs and two dowel pins to the new head. Mine are rusted in so I had to get new ones.

I'm going through the process of the head swap right now. It's very time consuming if you're an amateur like me. A shop will likely charge you over $1000 for this kind of work.

 

this is kinda common

is there a sticky or a well laid out thread telling owners what to do in this situation?

 

I am going to replace mine soon. I thought that the Clearwater heads were ready to bolt on too. I am going to rethink my options. Oreilly's has a re-manufactured one for $450 plus core.

http://www.oreillyauto.com/site/c/de...cylinder+head+

 

Reman non-TUPY 0331 head won't help. It's going to crack, too. Might already be cracked and the reman place didn't catch it. These have a factory casting flaw that can't be repaired or machined out.

Your coolant is probably being burned in the combustion chamber.

Clearwater. A couple of studs swapped or replaced is no big deal in comparison to what you're fixing to go through.

Or sell it now.

 

They are ready to bolt on in the sense that you get a (nearly) complete head that doesn't have to be built out. A couple of studs and a couple of dowel pins really don't rise to the level of assembling a valve train.

That head is not any more "complete" than the Clearwater head.

The ONLY way I would even consider buying that is if O'Reilly could confirm that it's actually a TUPY 0331 that has been rebuilt and not an original casting 0331. The Clearwater heads are a known quantity, and I wouldn't gamble that $100 difference on a used head that might have the exact same problem I'm trying to remedy.