I was on the way to work this morning and my coolant temperature gauge went up as high as it can. I was concerned, but I knew that it couldn’t be overheating. I pulled over and checked the thermostat housing and it was blazing hot, however, the upper radiator hose was cold. I knew my thermostat was stuck. It slowly opened and I was able to continue on my way. However, I now knew I had a big issue. I was planning on doing the coolant flush this weekend, so I ended up having to do it today instead. I surmised that my thermostat was stuck due to the coolant being so dirty. After all that’s what cracked my cylinder head.
I used some of the tips you all suggested in this post. The starting coolant is shown below (I don’t have a pic of the coolant now because I didn’t finish till after dark). I started by draining the coolant and using a garden hose to flush out as much crap as possible. After the first flush I thought I had most of the stuff out of the system. I followed a friend’s advice and used 1 part baking soda washed down with 3 parts white vinegar. This worked AWESOME, I couldn't believe how much stuff it got out of the radiator, heater core, and overflow bottle. I pulled the overflow bottle out and flushed it for about an hour and a half. I still don’t think it’s all out. To shorten a long story I ran straight water from there and flushed the system 4 different times. Each flush I filled the system with water, then drove for 10 min after it reached operating temperature. Each time the water came out more clear. Between each operation, I rinsed the system out with the hose. Now my XJ runs a tick under 90 degrees and the heater works better than any time since I’ve owned the vehicle.
Thanks for the help, especially Lay.
