Coolant temps

[farmerpatrick]

I recently picked up a 91 Blazer with a 6.2L Never Had a diesel before.. Anyways, at first it was running extremely cold. Never getting over 100 degrees. The thermostat was stuck open and now with a new 195 degree thermostat the thing is always running between 215 at idle and 240 on the highway. This seems a little high to me. I am worried this maybe a little hot. Please let me know what normal operating temp should be before I go pulling the radiator for a flow test. I also recently replaced the gauge sensor and the ECT sensor. I haven't run it for more than a half hour so far, but my wife needs to drive 3 hours round trip every day in this thing. So I want to make sure it's not overheating on her.
Thanks
Patrick

[NH2112]

I'd recommend checking it with a good mechanical or electrical temp gauge and sender before tearing anything apart. GM factory gauges aren't known for being all that accurate.

[ueckebes]

patrick , dont mean to be rude but double check the t,stat for prop installation you have gone from one extreme to another,something aint right.gm gauges have been known to be a little inacurate but not as bad as in your case .however after market mech gauges are a good cheap investment.i have 5 80's 6.2 equipped gm trucks all use 180 t,stats all idle in the 170 to 185 degree range even in 90 degree heat with the a/c on . when traveling on the highway in the same conditions with a 8000 lb trailer the temps seldom exceed 195 automatic equipped trucks about [200 to 205] . anyway if your t,stat isnt the problem and a mech gauge also reads high try the fan clutch or cleaning the radiator in and out, also a head gasket is a remote possibility if all else fails , these are the only reasons my 6.2's have ever ran excess temps [220,240] and summer temps hit 100 here in texas fairly often good luck and let here what you find. jim

[farmerpatrick]

I'm putting a mech gauge in now. Hopefully.. the guage is off. I also special ordered a 180 degree thremostat It'll be in tomorrow morning. If still no luck, I'll pull the radiator and have it flow-tested, rodded and flushed.
Thanks for the input. From what I can tell, my 6.2 should never be up around 240 degrees.