Proper Engine Operation Temperature when warm? 5.7 Vortech

My 1998 Chevrolet 2 Door Z-71 Tahoe 5.7L Vortech runs when warm (30 minutes at 70mph) at about 155F. Does this seem low considering other 5.7 Vortechs that I have come across operate at or around 210F? If so, what steps should I take in diagnosing this issue?

My 1998 Chevrolet 2 Door Z-71 Tahoe 5.7L Vortech runs when warm (30 minutes at 70mph) at about 155F. Does this seem low considering other 5.7 Vortechs that I have come across operate at or around 210F? If so, what steps should I take in diagnosing this issue?

your engine is designed to operate at 190 deg f....check for the exact temp and use a high quality thermostat...

the 155 deg temp with the heater not putting out a very hot air flow means the thermostat is stuck open...


this if required can be verified by removing and testing in boiling water...with the new replacement... I do this to ensure these work correctly and I don't have to repeat all of this work..


these thermostats should be replaced every time the dexcool is serviced at the 4 year time...approx.


the cost for this is much cheaper than engine damage..

I don't believe it's accurate. How's the heat?

Check the temp of the heater core input hose, and output hose also...

Replace the t-stat. I wouldn't be surprised if the old one is physically broken!

The heat works great. I had it on this morning and I was almost too warm with the system on low. The outside temp was 43F and the truck was running right at 150-155f. (30minutes @ 70mph)

What goes into replacing my thermostat?

Remove the upper hose, remove the 2 bolts that holt the t stat housing to the intake manifold, remove old stat, clean surfaces, install new stat/gasket, install housing, install upper hose, add coolant, and burp.

Sending unit may need to be replaced if the thermostat don't fix it.

I replaced the T-stat and it was a piece of cake. The old part was most definately stuck open. It took me less that ten minutes to complete the repair and that was with a cold one in my hand. The truck seems to be idling much better and my gas mileage has improved by about 1.5mpg. Thanks for the help.

I replaced the T-stat and it was a piece of cake. The old part was most definately stuck open. It took me less that ten minutes to complete the repair and that was with a cold one in my hand. The truck seems to be idling much better and my gas mileage has improved by about 1.5mpg. Thanks for the help.

so now winter has forced you to do this thermostat....I bet the engine will work much better...and you feet will be niece and warm...