Jump to content

- - - - -

Water temp on a 98 5.7 Vortec

This topic has been archived. This means that you cannot reply to this topic.
5 replies to this topic

#1 tfchip1in



  • Newbie
  • 8 posts
  • Location:IL

Posted 06 November 2002 - 05:23 PM

Can anyone tell me what the water temp should run on a 98 GMC K1500 w/ 5.7 vortec



    Senior Enthusiast

  • Member
  • 1,189 posts
  • Location:Kentucky

Posted 06 November 2002 - 05:30 PM

My uncle has a 98 2500 with a 350 and it operates right at 200 with no load..hope it helps

#3 CapnDean



  • Member
  • 323 posts
  • Location:Gulfport, MS

Posted 08 November 2002 - 01:01 PM

Historically we were taught that 180 was "operating temperature".  Anything over that was on the hot side.

GM now installs 195 degree thermostats.  Why?  Well...Physics dictates that the hotter you operate an engine, the more efficient it is, to an extent...overheating is always bad.  The hotter you can run an engine, the more complete the combustion, the less emission, less wasted fuel, more bang per ounce of gasoline etc....

So...if your 98 is showing between 200 & 210...you're okay.  Many folks replace the 195 t-stat with a 180 because (like me) they think YEOW! I am borderline overheating.

But the down side of that is that the computer knows what the engine is supposed to do...and if you don't let it get up to the operating temperature that the computer thinks you are supposed to have...the computer thinks that you are still warming up the motor and chokes the engine etc...

If you are not overheating...leave it alone.  If it scares you, replace the tstat with a 180...and prepare to suffer fuel economy!

2006 LBZ 2500HD Duramax EFI  Live, FASS, PCV Reroute, EGR Block 25 mpg




    Senior Enthusiast

  • Member
  • 3,261 posts
  • Location:Chicago, IL U.S.A.
  • Gender:Male

Posted 08 November 2002 - 02:01 PM

Yup 200-210 stock for the reasons Capn stated above.


Summer toy #1) 2004 Pontiac GTO - Impulse Blue Metallic, M6, lots of mods to create senseless levels of power
Summer toy #2) 2006 Cadillac STS-V - Light Platinum Metallic, A6, also lots of mods to create senseless levels of power
Daily Drivers/Vehicles subject to the wrath of Mother Nature:1) 1999 Chevrolet Suburban LT 4x4. 2) 2007 Chrysler Town & Country Limited 3) 2009 Chevrolet Impala SS

#5 GMCZ71



  • Newbie
  • 32 posts
  • Location:Hamlet, NC

Posted 10 November 2002 - 11:19 AM

I have the same motor and mine runs just below 200 at normal operating temp. If it ever goes above 200 I would worry. But the gage show no overheating until about 250.

#6 Zembonez


    Senior Enthusiast

  • Truck of the Year
  • 18,101 posts
  • Name:Jim
  • Location:Republic of Texas
  • Gender:Male
  • Drives:GMC Sierra

Posted 11 November 2002 - 10:08 PM

Yipper... they are all right here. 195 degree thermo is what you want to use because the ECM will send the system into a "full rich" condition if you go to the 180. Fuel mileage will s**k and the o2 sensor will be shot. Really anything under 220 degrees operating temp is safe but I bet you never see anything over 200 if the rest of the system is operating correctly. Keep in mind that the factory idiot gauge is likely not very accurate too...

Cheers!  :D [B]