My 86 560 SEL has up until now been running just fine at a steady 82 to 85 degrees whether or not the a/c is on unless its about 90 outside and I'm standing still in which it climbs to fluctuate just above/below 100 degrees. At that time the car just had distilled water in her system (because I was waiting for MB coolant to arrive) I recall that when I did replace with the MB coolant, she'd spit it up through the radiator cap and that was why I just put the water in it as a temporary fix.
I just replaced the coolant system with PEAK 50/50 pre-mixed antifreeze (which is also orange in color like the MB fluid) and ever since, she's been running at 100+ regardless of cruising at speed and almost 110 when stopping in traffic. She's been sitting since last Thurs because we left town and upon leaving for work this morning, I noticed that the radiator light came on/off and when I went to fill the car with gas, topped her up with water (again) but when on the highway,the temp shot up to 110+ and as I parked her, went up to damn near 120 and the aux fan kicked in.
Once parked I left her on (because the aux fan STOPS when you remove the key) but noticed the orange fluid bubbling out from the expansion tank area (leaking from the cap). This only happens when I've put antifreeze in her but she ran just fine with water. Any suggestions or advice how to get her back down to normal? I'm wondering if air is in the system. How do I check this and should I just go back to the distilled water? It has a new radiator and cap that have only been installed within the last six months. I'm paranoid that something is screwed with running her with such high temps if this is the case. I've been told that the 560's are supposed to run between 95 and 105 anyway but I've seen on threads that some run just above 80 (which mine did before now- with the water). Need suggestions as quick as you guys can get it to me before I leave here. I'm tempted to tow her home I'm so nervous. Thanks in advance and wish me luck!