Gents: I have a '48 Buick Super w/248 straight 8, 3 speed manual. I have been having overheating problems lately, and was hoping to get some tips from you. After driving the car about 20 mins, the rad begins to overheat and send steam and coolant shooting out the overflow tube. The weather is not hot here...only about 35F-40F. I had the car out for about 90 mins. straight the week before, and it overheated when I pulled off the freeway. Last week it happened even faster...after about 20 mins. of highway driving. So, it seems to be getting worse. One obvious complication is that my temp gauge is not working(!). In any event, I'd like to know what to check next. I had a 4 lb rad cap on it; replaced it with a 7 lb. cap from Bob's the other day. (btw: do rad caps have a life expectancy?) I also have a new 180 thermostat from Bob's I'll be putting on asap. I can't see any leaks from the hoses or the rad itself. Installed a new water pump about a year ago. Engine has been recently tuned up. Coolant changed about a year ago...haven't driven the car much since then (been working on other things). I suspect the rad may be plugged...this car sat for years before I got in 2007. I am leery of taking it to a rad shop as a pressure test and kids that know little about working on old cars may make it even worse. Fan belt seems to be a little loose-could that alone account for overheating? If I press it with my thumb hard it goes in about an 1"; according to my shop manual it should only depress 1/2". Any other advice, esp. from those with straight 8's? Thanks a lot!