Hey Y'all,
I've got a 2000 Zr2 Blazer I've had a ton of work done to it. Most recently I have replaced the radiator, fan clutch, and thermostat. Fan clutch is ac Delco, stat is 195° duralast. MPG is right around 13 mpg even with these changes. The temp gauge is showing around 180 which isn't what it should be I know. Before the stat change temp was staying around 160°. From some of the posts I've read on this forum this far I'm seeing that the operating temp should be about 200°. My question is, how much if a difference would the extra 20° of temperature make if any as far as MPG and overall performance? Oh and tires are OE size but less aggressive tread pattern than the BFGs that it came with. I never drive faster than 70 and I usually keep it around 65 on the highway which is where the majority of my driving is done. Thanks in advance.

 

Welcome aboard! I wouldn't think the temp would affect your mpg??? Don't hold me too it though I am not familiar with the ZR2s though, but your mpg seems lower than I would think...

 

Hey go Chevy... But yes the temp affects viscosity of fluids. Below a certain temp and the system will stay in open loop enriching the fuel. Until a certain temp is reached.

 

That makes sense... I would honestly never had really thought about it lol! Learn something new every day

 

The engine temperature definitely affect whether the ECM will have the engine operating in open or closed loop. If it's continuously operating in open-loop because the engine is too cool it will be running rich and result in poor economy.

Not entirely sure what to suggest to fix your problem, but I believe these engine's normal operating temperature range is between 185°F-205°F. Are you sure that you do not have any air pockets in the cooling system? This can affect how it pressurizes and cycles coolant through the system. Maybe try burping the system?

 

Burping the system is not something that I've tried yet, but it's worth a try. Also I've ordered and AC Delco thermostat to eliminate one possibility.

 

That is 1 thing I definately have learned about these trucks, they are picky picky picky I use AC Delco parts whenever possible Usually costs more compared to Duralast, ect...

 

 

Burping couldn't hurt, but if there was an air bubble it would be overheating, not running cool.

A sticking/malfunctioning thermostat is probably a pretty good guess. I've never had much luck with anything Duralast. For parts that are important and/or a pain to have to re-replace ACDelco is usually a better choice in my opinion especially if it's only a $3-4 difference.

 

Rock18... Yeah I gave the Duralast a shot.. but the temp won't exceed about 180 just got the AC Delco stat in today. I'm going to put it in tomorrow, fill up the tank and drive down to the beach to go surf fishing tomorrow. Hopefully I'll see a noticeable difference.