efordrocks

I have had my jeep for quite some time now. I recently purchased another daily driver and had been driving that around for a while. I was about to go up to the mountains this weekend to do some snowboarding and was going to take my jeep. I drove it around to block to make sure it was still solid but I couldn't get the temperature to read anything. The check engine light was on to but it was on before as well. When my parents owned it a while back they took it to a mechanic and they told them it was just a cracked exhaust manifold that made it throw the code.

I took it back home and opened the radiator cap to find a dark brown sludge filled to the top of the cap. The sludge was like paste and really thick. I thought it could be oil but i didn't understand how there was like small specks that felt like it was dirt. Not exactly sure what is getting in my radiator.

I also used my scanner and got codes for cylinder 1 and 3 misfire as well as o2 sensors going crazy.

Anybody got any suggestions of what could be going on? Maybe like a blown head gasket causing misfires and the sludge?

nujeepguy

read about 331 head cracks, those symptoms.

mikesignal

if you have a coil rail it's an 0331 head. If you have a distributor and wires you have a 0630 head. Someone said '99 had both, depending on build month.

sounds like the temperature sending unit is toast. That could be why you are not reading anything.

you should flush the coolant system, replace it and have it pressure tested. Look into using "Amway" product to help flush the system

also take a look at your oil, see if it's milky - that is a sure sign of coolant in your oil.....smaller amounts of oil in the radiator will make oil swirls

Fred/N0AZZ

^X2^


I have yet to see or hear of any 99's having the 0331 head, wonder if it's just a XJ myth started by someone and repeated till it stuck?

CCKen

The 1999 Grand and Wrongler 4.0 had the 0331 head/ignition system. The 1999 XJ did not.


Of course, some ******** would look at the decal on the driver's door of a 2000 XJ and see a build date of 1999 - therefore there had to be 0331 heads in 1999.

tjwalker

If it's a 99 XJ (not a Grand Cherokee) you do not have the 0331 head. You have the 0630 head. In 5 minutes with a can of carb cleaner and a rag, you can confirm this by thoroughly cleaning the lip of the head and right next to the valve cover on the drivers side about mid-way, the casting number of the head is etched in.

Please post each and every code (not just a description) and we can go from there. With OBD codes, the devil is definitely in the details!

You can do a "block test" (kits available at Napa, etc) where the coolant is sniffed for the presence of hydrocarbons; a positive and you may have a head gasket leak or something else internal. Any shop can do this test for you as well. It's simple.

What is the history of routine cooling system maintenance? Cooling system flush, new 195 degree thermostat and radiator cap for starters. Consider doing a wholesale replacement of radiator and water pump as well while you are at it. Parts are not that expensive if you do the work yourself. Possibly the best money you can spend on your XJ is on the cooling system.