doctorbaxter

Hey guys,

My coolant gradually becomes brown over a period of a month. When I first bought the '99 XJ the coolant was like sludge. My guess was the PO accidentally mixed dexcool with your average green coolant, causing sludge to appear. Since buying the rig I have done appx 5 coolant flushes with cleaner. One month ago my coolant was clean/green which made me happy as the last time the coolant was flushed was a month before that. However since that time the coolant has again become brown and nasty. I do not have the 0331 head however I am concerned I may have a head gasket issue. However my oil is beautifully clean, which is surprising for a rig with <200,000 on the odometer.
Anyone have any ideas as to why this is occurring? I just flushed again today and will update if the coolant again begins to brown.

-Thanks

JstGtnStrtd85

I also have the same issue with my 97 ZJ with 265k oil clean as a whistle, vehicle runs good and heats good just brown coolant... Tho in my case its been a while since its been flushed and changed

rackem

the privious owner probably didnt keep a proper 50/50 mix in the system causing rust.

do a two fold flush and keep an eye on the water coming out.

also, pull your thermostat and check in there to check for rust if you want to double check.

Ye Ol' Cherokee

First of all, do a leakdown test. That should tell you whether or not your head gasket is leaking.

If it is not, i would advise you to replace the radiator (Only if the leakdown test comes back good). I had a chrysler sebring that did the same exact thing. Repeated coolant flushes only to have it brown and gruddy again not long after. That engine was junk anyway, but it wasnt the headgasket. My radiator had so much crud built up in it. After one of many flushes, the stuff came loose and coolant was spewing everywhere. I replaced the radiator, and flushed the system, and put fresh fluid, and guess what? The coolant stayed green til i sold the thing. (It still ran like crap, but thats another story)

So 1.) Leakdown Test (in addition to any other head gasket check)
and 2.) Replace radiator

Ye Ol' Cherokee

Yea there could also be rust anywhere in the cooling system, so rackem is definitely right about that. So keep that in mind too.

JstGtnStrtd85

From my knowledge my radiator was replaced a year or so ago... ( father was using it while i was in stl ) im just hoping it just needs to be flushed and refilled

doctorbaxter

Yeah I also wondered about rust being the culprit. What do you mean by "two fold flush?" I may check the thermostat in the future if I cannot resolve the problem.

Turbo X_J

The main problem is you can't find a "cleaner" to cut the crud that will not permanently harm everything in the cooling system. Only real solution is to pull the engine, tear it down, and boil out the head & block in caustic soda. Then use all new parts (radiator, heater core, hoses, etc.) Sorry to say but once the crud appears, it's foreva.......

doctorbaxter

Thats a bummer. I am tossing the idea around of rebuilding the engine during the summer. I would, however, like to keep the fluid clean as a rebuild may not happen for another year or two. I guess I'll just keep flushing and see what happens. Thanks for the reply!