olds overheating only when pulling

We recently replaced the raditor,hoses, therostat,overflow tank and cap.
car overheats only when pulling uphill and blows coolant out of the overflow tank. What else could the promblem be????:banghead:

OH YEAH, fans are coming on.

Checking to see if you had a fix. Mine is doing the same thing. Replaced w/p. rad, therm, seals around cond,rad, checked for HC in bubbles out of overflow tank. No dice! Any help?:screwy:

haven't solved yet, mechanic seems to think motor may be clog up with junk from old hoses that were on the rad. So I bought some rad flush and am going to keep flushing the rad out the first time after the flush seemed to help a little got my fingers crossed that the 2nd time will make a big improv. let me know if you fix your prom. I will let you know if this works for me.

head gasket blown that is the promblem:banghead: anyone got a time-sert kit 4 sale???