Turbo X_J

Looks like someone bottomed a flex plate bolt in to it. What doe this have to do with the ever elusive cracked cylinder head issue?

Kap

(possible repeat due to connectivity probs)My 2000 Sport Cherokee XJ with 175,000 mi. overheated badly twice two years ago. Turned out radiator was full of gunk and rust despite garage -- it was in storage for six months -- promise that they had done a reverse flush and used rad cleaner. Replaced rad, held my breath, and what do you know? All okay.Lucky me.
Also looking at the stats it seems if no problem, leave well enough alone...
Great vehicle. Good luck to us all
-0-
Great question / great post. Very useful.

CCKen

Crankshaft.


Probably excessive fore and aft play in the thrust bearing.

PawPaw032101

2001 XJ with 224,500 and still going. But, something is in the process of failing. Can't decide if it is a rod bearing or a lifter or what. Usually on cold start it is knocking pretty bad for about 15-30 seconds. Sometimes it doesn't knock at all on cold start. Never does it once warmed up. But, always has a little bit of a knocking sound going on that you have to pop the hood to really hear. Wish I were smart enough to figure out what it is. Fixing to go ahead and get a new long block I think. Love the vehicle, no rust, very solid besides this noise. What is it about these XJs that make them so fun? I have a nice new truck, a very nice little mustang with 500+hp, and I ALWAYS get in the XJ unless I'm towing something or showing some smug a#$#ole how fast his corvette AIN'T..

Rambler65

Mine is a pretty late-build 1999 model with a manufacture date in June 1999. (I'm not sure when 2000 production started.) I just checked the casting number on the head - it's 0630. One less thing to worry about. (It's been running great but I a got a bit concerned reading that late 1999 models might have the 0331 cylinder head.)

Ralph77

'00 155K and as best I can tell my 0331 head is OK. Did a valve cover gasket a year ago and everything in there looked clean and OK. Is not a TUPY head. Still could be a 0331 head that was replaced at some point by one of the 2 previous owners.

RubenZ

I think my head is cracked. i am just shy of 90K But I seem to be losing Coolant from reservoir tank. I'm not exactly sure how the reservoir tank should function. Sometimes I noticed it on the LOW mark, then after engine heats I think it GOES UP to almost the FULL mark. But then other times it will go below the Low mark. i'm probably in need of a new radiator cap. Other than that my Oil Pressure is good around 40-60 depending on how i drive, but its usually at the 40 mark. Is that normal? I may try to find me a newer Cylinder Head that is of the TUPY mark just to be sure but I'm kinda low on funds now.

JeepWoman

There is no coolant on the top of the head, valve cover removed. Oil is also free of coolant, and no coolant trails down engine sides. But have to refill the overflow bottom at least every weeks. Temp gauge sits just to the left of 210, and hasn't gone past it since I've owned it. Thermostat and water pump were changed by po prior to me buying it. Did a pressure test (cold) and it held 16lbs for over an hour. I'm stumped.

Rambler65

A small leak in the plastic overflow tank? Seepage at a coolant hose? (Check that all clamps are tight.) Pinhole leak in a hose or the radiator? Defective water pump seal or gasket? (New parts are sometimes bad.) Small leak from a core plug? (There's one at the back of the head that you can't really get to without pulling the head.) If it was the heater core you'd smell it inside even if it's a very small leak. The coolant has to be going somewhere!

JeepWoman

I've even got out the mirror looking behind the manifolds, and head found nothing. Been told that some of the replacement rads leak at the seams. But I find no trace. The rad looks kinda new. But wouldn't drop during a pressure test?

nujeepguy

my 2000 good at 168000, but has cold start piston slap for a few min the noise the other guy was talking about.,

Rambler65

I guess that depends on how bad the leak is. You might try the pressure test for a longer period of time, see if pressure still holds and look for any seepage. From your description it seems to be a real head-scratcher. There's also the transmission cooler in the radiator (if you have automatic trans) but you probably would be having transmission problems by now if it were leaking coolant in there.

I wonder if anyone makes a fluorescent dye for checking coolant leaks similar to what is used for air conditioning?

CCKen

The '99 XJ did not have the 0331 head. The Grand Cherokee used the 0331 head in '99.

lfhoward

I'm the original poster from like 6 years ago. Amazing that this thread is still going!

I do do have some recommendations if your coolant is disappearing seemingly without a trace. Do an oil test with a company like Blackstone Labs. If there is coolant in your oil (even if you can't detect it by eye), they will be able to tell you. It will silently and quickly kill your engine bearings if mixed in with your oil. If you are adding coolant semi-weekly and can't tell where it is going, this is likely the case.

Good luck!

extrashaky

Oil used to turn milky when it got coolant in it, but now the detergent packages are so good that the oil can bond a lot more moisture before it changes color. I was using Mobil 1, and mine never turned milky at all.

The only way to rule out coolant in your oil is to send a sample off to a company like Blackstone for analysis. They'll send you a test kit for free. The test itself costs $28. Then they send you the analysis results via email. I had problems sending my sample via USPS, so I always use UPS instead. You will also have fewer shipping issues if you put the entire mailer bottle inside a padded envelope. Since my head crack adventure, I send off samples for all my vehicles at every oil change, just for cheap peace of mind.

You could also be burning coolant instead. If you are, you'll have exhaust gas leaking into your coolant. You can test for that with a combustion leak tester. You can buy one for $50 or rent one from a parts store.