my temp gauge on gets right at the red line after i drive for 20 minutes or so.
has never had problem before and water pump and coolant has been changed,and the gas mpg has dropped big time.wandering if problem might be with the cat and exhaust....


its 1994 22re 5sp. any ideas would help alot

 

are u losing coolant? probably a blown headgasket

 

first thing to check is does the temp get that high at idle or only when driving. if both then start by changing t-stat. if only at freeway speed probable plugged rad. u didnt specify if u had rough idle on startup or lack of power hissing fropm exhaust . def. need more info on this

 

blown hg

 

temp only gets high after about 20mins at hwy speed.no rough idle but big loss in mpg and a little loss of power.ill check again but dont seem to be lossing coolant.

 

First thing I'd check is the thermostat. If it's sticking closed, or partially closed, it will restrict coolant flow and cause the temp to rise. they're cheap so a new one isn't a bad thing. If a new thermostat doesn't fix the problem, then we have to think about the driving conditions.
If it doesn't overheat at extended idle periods and only overheats at highway speeds, not overheating at idle suggests the fan and fan clutch are most likely working. This makes it seem more like a clogged radiator (most likely), failing lower radiator hose(s) (22r/re have 2 lower hoses: one from the radiator to a hard pipe, then from the hard pipe to the water pump).