recently was drivin along and notice my water temp in the red and reading 130 and my commander so pulled over and call the aa thinking it was buggered he pointed out the rad was leaking put some stuff in to get me home and did a check on the head gasket all fine then driving it again and the same happened so when and got a rad off a mate swapped them over and put coolent in there but this one seems to be running hotter

my old one fan cut in at 91 and brought it down to 87-86 but this one cuts in at 91 but only brings it down to 88 and the missis drove it today and said it went up to 94 and then dropped tto 91 and got home and it was on 89 thought there mite be a air lock in there so took the cap off heater on full it when up to 91 and dropped to 86 but as soon as cap was on and heated was turned off back to 88 she went any idears what it could be or is it just the way this rad is

 

you may have faulty thermostat

 

ok how would i check thatalso drove the car today and was fine on the way but on the way back temp was slowly going up to 91 (fan cut in)then dropping to 87 while cruzing at town speeds and going up and down like so

 

if its an airlock, leave the cap off while running it on tick over for around 5-10 mins, that always does the the trick for me.