My '00 has the 0331 head so I'm paranoid that it might be cracked, but I'm thinking there might be another issue. When I bought the truck in January I had the coolant flushed because it was pretty murky. Then the water pump went in March so I had that replaced. I noticed a few weeks ago that my coolant was low and pretty brown, so I added about a quart, and I've lost about an inch of fluid from the overflow reservoir in the last three days.

My oil pressure is on the low side, but still within spec at 13 psi, even with 5W-30, and it doesn't appear to be milky or frothy at all. There is no residue under the oil filler cap, and my exhaust appears normal.

I'm thinking that maybe my radiator is on its way out, and maybe it's leaking fluid out somewhere when it's hot (so it's evaporating), and maybe tranny fluid is also leaking into the cooling system, causing it to turn brown.

I might just send out an oil sample as well, to be sure that there's no coolant in the engine from a cracked head. Anyone else have suggestions or other things to look at? I'm pretty stumped at this point. I'm not sure why my level is decreasing, or why the coolant is so brown and silty.

 

Could be that a part of your system, like the radiator, just didn't get flushed well enough the first time thru. Just how well did it get flushed? And was it backflushed?

 

To be honest, since I didn't do the flush, I'm not sure how effective it was, so this sludge could very well have been there before.

But how could the coolant get this gross to begin with? My water pump was totally rusted, so maybe some of this is rust, but it seems like it's too dark and "silty" for it to just be a little rust. Looks like some other type of fluid is mixed. That why I was thinking the radiator might be leaking and tranny fluid is getting in. Also confused as to where the coolant loss is coming from. I think it might be my upper hose near the battery, because it looks like it might be compromised.

 

My coolant disappears too! Im not sure where from, but i know that i have to out a gallon in it every couple weeks. Never have any spots on the ground, oil isnt mixed with coolant, and it doesnt smoke at all.... My coolant is also very dirty, but mine is more of a rusty color, probably needs a flush done. And its smells like coolant when it gets warm.

I also have a 0331 head, maybe my head is cracked on the outside of the water jacket, leaking onto the outside of block and evaporating.

 

Required reading for anyone that owns the 00-01 XJ with the 0331 cylinder head.

http://www.jeepsunlimited.com/forums...d.php?t=391831

 

Trust me, I've scoured that thread. Other than the loss of coolant I don't have any other symptoms. Also, no one in that thread described rusty/brown coolant, so I'm hoping this is unrelated.

 

The XJ motor is cast iron and cast iron rusts, if a sufficient amount of corrosion/rust inhibitor (antifreeze/coolant) is not constantly maintained in the system. It doesn't rust overnight but does so gradually as the antifreeze/coolant degrades. That's why it's important to check the coolant level and color frequently. Drain it, flush it and refill it with at least 50/50 mix and check it frequently. At the 1st sign of changing from green/clear, drain it, flush it and refill it with the proper mix. The more u stay on top of it (preventative maintenance), the drain/refill intervals will become longer before color starts to change.

 

first, put 10w30 in it. that is what it says to put in, and to hell with all that "change it with the weather" crap. run the same thing year round, let the engine warm up on cold days.


second, it could be that it didn't get flushed properly....but is more likely that the cylinder head has a crack between cyl 3 and 4 or 4 and 5.