Hello,
I purchased a 740 turbo wagon yesterday and while looking under the hood I went to unscrew the coolant overflow cap and look in the resevoir. A small amount of coolant bubbled out as the system seemed to be under pressure. This is new to me as my old '87 240 I guess didn't have a pressurized cooling system. So, I drove the car home without incident (other than some stumbling and dieing on a couple occasions - separate problem(?) I knew about already). When I parked the car and turned it off, coolant began boiling out of the resevoir by itself. I tightened the cap thinking that I hadn't tightened it enough before. The temp gauge by the way stayed in the middle of the range the entire drive home. I started the car up and drove it again about 45 minutes later and again once I got home and parked it I noticed it bubbling out at an extreme rate again. Apparently maybe most of the coolant boiled out during these two or three instances. There were absolutely no signs of head gasket damage before all this happened and so I'm wondering if the thermostat is stuck and is allowing the coolant to boil to a much higher temp than it should and thus the cap is letting it all escape? Of course I know the gauge in the dash is not to be trusted as they're designed to not show normal temperature flucutations. Any suggestions on what to troubleshoot on this problem?
Thanks,
Matt Campbell