milehilonewolf said:
I'm looking for any tips or solutions for an overheating issue...What I've been troubleshooting for the past year or so is a stubborn overheating issue. The first time I overheated was last year climbing over Monarch Pass, near Gunnison, Colorado. By the time I reached the summit I was badly overheating. The color of the coolant was that of RUST. Since that incident, I have had continued problems. I have replaced the radiator, thermostat, all cooling hoses, heater core and water pump (4.0L. with 140,000 miles) The coolant color still looks like rust after about 2 months. So it seems as though I have a rusted engine block at the very least, but has anyone had a similar experience and if so what did you do to remedy the problem? Is replacing the block the next step? I've already tried coolant flushing products, regular visits to the shop to have the block fully flushed, but without fail, the coolant is back to rust colored and I'm close to overheating again.
This is my first time using a forum online, I hope that there is someone out there with some advice...
Thanx
Milehilonewolf
What is the year of your XJ?
Do check to see if your auxiliary electric fan is working, however if your air conditioning is off, the fan should not turn itself on until the coolant temp reaches around 220 degrees and shouldn't turn off again until the temp reaches 200. If you have the a/c on, the fan should cycle on and off with the a/c compressor. Check to make sure this is functioning (although I do realize this has little to do with your coolant).
Have you checked the head gasket for leaks? It isn't a definitive method for checking but if you have a milky, whitish residue on the oil cap you could be leaking antifreeze into your oil and vice versa... oil leaking into the coolant would tint it, however it would seem as though you would need a substantial leak in order to turn all of the coolant brown. Other classic head gasket symptoms would be white exhaust (with a sweetish smell) and/or constant air bubbles in the coolant due to engine exhaust gases) Worth a look.
With all the flushing you have been doing, it would seem as though you would be at least removing the majority of the loose rust in the block, or at least enough to slow the process of the color change. I remember the first time I took my jeep into the shop when I was probably only 17 or 18 years old and asked for a coolant flush (thinking they would hook it up to a machine) and all they did was drain and fill it. I was so disgusted, that didn't do ANYTHING to clean stuff out.
I couldn't tell from your first post, but if you have only used the 15 minute idle/drain flushes, I would try using the 6 hour flushes (or 2+ at the same time). You drain out all your coolant, dump the flushes in with water, and run the car normally for about 6-8 hours worth of driving. These probably won't unclog a restriction, but will dissolve a lot of rust.
Make sure you COMPLETELY drain out the flush when done, and refill with the proper 50/50 mixture of water/antifreeze (USING DISTILLED WATER OR A PREMIX ONLY, NO TAP WATER!!!!). Again, maybe you have possibly already done this procedure, but worth mentioning.
Let us know if you've tried any of the above, if not it's worth a shot, if you have we'll try some other suggestions.
Crap, and I should add it would really help to fill us in with some more details about your overheating. Does it overheat in the city/idling, on the highway, or both? (or randomly?). If it overheats in the city/idling and does fine on the highway, your fan clutch/e-fan probably aren't functioning properly. It could also be a bad, eroded water pump but I see you recently replaced that. If it overheats more on the highway, unfortunately your chances are better that your relatively new radiator is clogged and can't keep up. Does turning on the heat stop the overheating, or at least slow it down? Also make sure that the exterior of the radiator is free from dirt, bugs, grass, whatever. Spray some degreaser on there, let it soak, then hose it out. Also use a fin comb or another very thin tool to straighten bent fins. I know you mention a new radiator, but that wouldn't be the first time a new radiator was bad.
New 16# pressure cap???
Can you tell I've been through this same problem before (well, not the rusty coolant..)?