temp. gauge

i have a 93 s-10 with 4.3 and a 91 s-10 with a 2.8 both have same problem. temp gauge rises up to 230 then will drop if i put in nuetral drive a little will rise again this will happen two or three times then will stay running at 180,i've replaced the radiator and hoses any ideas??

i have a 93 s-10 with 4.3 and a 91 s-10 with a 2.8 both have same problem. temp gauge rises up to 230 then will drop if i put in nuetral drive a little will rise again this will happen two or three times then will stay running at 180,i've replaced the radiator and hoses any ideas??


A thermostat will cycle (open and close) in response to the coolant temp. You might have some bad ones here; have you replaced them lately? Also, do your trucks have fan clutches? If you have factory A/C you will definitey have a fan clutch. Can you spin the fan without the engine running? If you can, you have a fan clutch. These things go sour after awhile and when they begin to fail, it's not a real noticeable problem... but it can be manifested in wacky coolant temps. Are they original? ... a '93 and a '91... probably well over 100K on the odo....If they are originals, it's time to replace them.


Mike