Truck 5.3 Thermostat - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Houston Ben · 12-30-2015, 04:36 PM

Hi all,
I have a 2011 5.3 was running it with water for a while with stock thermostat. I recently bought a new thermostat and filled engine and rad with 50/50. Now the engine runs hot, up to 230 if I am going 80 mph. With the old thermostat is stayed between 190-200, does anyone know why this would be?

Also, the new thermostat was a lot longer than the stock one (still fit) but it is supposed to be a direct replacement, anyone else have a problem with this?

Ben

**truckdude239** · 12-30-2015, 06:30 PM

Its probably the wrong thermostat if it was longer i wouodnt have installed it why change it if it worked

BR3W CITY · 12-30-2015, 08:43 PM

Did you bleed the coolant crossover (Steam) lines and make sure the system took all the coolant?

I'd think your reading an air bubble.

Houston Ben · 12-31-2015, 12:36 AM

Hi guys, thanks for the response. I use a digiscan II for my dash which is reading the speed, temp, air temp, and rpm which is reading the high numbers. I also have my stock temp gauge hooked up to the passenger head and that was staying below 210 easily.

I am planning on replacing the new thermostat with the old one to see if that works.

Brew, the steam line it the on that comes from the passenger head to the top coolant hose correct?

Thanks again!

LS short box · 01-01-2016, 03:49 PM

I've had good luck loosening up the temp sensor in the head to bleed the air out. Get the engine warm with the radiator cap on and just loosen till coolant seeps out. You should see a spurt of air along with a little coolant. Be careful it's hot.

homemade87 · 01-01-2016, 04:37 PM

I am like others here . I think you have an air pocket . When you took it apart you did not get all the air out . I see and here it all the time when some one has broke the system apart for one reason or another .

I have had good success with taking the steam line loose and filling the upper radiator hose until it comes out of the steam line and then top off the radiator . If you only fill the thru the radiator cap , it will never get it done .

solidaxel · 01-01-2016, 07:19 PM

Quote:

Originally Posted by homemade87

I am like others here . I think you have an air pocket . When you took it apart you did not get all the air out . I see and here it all the time when some one has broke the system apart for one reason or another .

I have had good success with taking the steam line loose and filling the upper radiator hose until it comes out of the steam line and then top off the radiator . If you only fill the thru the radiator cap , it will never get it done .

That Works for me

XwalkerX · 01-02-2016, 12:36 AM

youre sure its the correct part?

Houston Ben · 01-04-2016, 04:53 PM

Hi all,
I emptied all the coolant, replaced the new thermostat with the old thermostat (looking at it again, the were the same size, but different parts were longer) jacked the front end up and refilled and all is well.

The part I bought was the correct part, I looked it up multiple times to ensure it was.

Thanks for all your help and responses!

12-30-2015, 04:36 PM	#1
Houston Ben Registered User Join Date: May 2013 Location: Houston Texas Posts: 713	Truck 5.3 Thermostat Hi all, I have a 2011 5.3 was running it with water for a while with stock thermostat. I recently bought a new thermostat and filled engine and rad with 50/50. Now the engine runs hot, up to 230 if I am going 80 mph. With the old thermostat is stayed between 190-200, does anyone know why this would be? Also, the new thermostat was a lot longer than the stock one (still fit) but it is supposed to be a direct replacement, anyone else have a problem with this? Ben __________________ 1986 C10, 2011 5.3 w/6L80, 3.42 w/ Detroit TrutTrac Build thread: http://67-72chevytrucks.com/vboard/s...d.php?t=584532

12-30-2015, 06:30 PM	#2
truckdude239 Senior Member Join Date: Sep 2005 Location: Lewisville, Nc Posts: 10,237	Re: Truck 5.3 Thermostat Its probably the wrong thermostat if it was longer i wouodnt have installed it why change it if it worked __________________ David fuller Ase Certified Mechanic Click here to help support our board!! 1971 Chevy c-10 under going a 4.8l LSx swap Build Thread http://67-72chevytrucks.com/vboard/s...d.php?t=421305 2007 Honda Accord my daily 145kmiles 2002 Honda Accord 4 door With 330k(sisters car) 2005 toyota Avalon 228k( brothers car) 2002 Sububran 5.3 245k 2000 Tahoe 5.3l 378 General manager for Marco's Carwash & lube

12-30-2015, 08:43 PM	#3
BR3W CITY meowMEOWmeowMEOW Join Date: Sep 2009 Location: MKE WI Posts: 7,128	Re: Truck 5.3 Thermostat Did you bleed the coolant crossover (Steam) lines and make sure the system took all the coolant? I'd think your reading an air bubble. __________________ *'66 Short Step / SD Tuned / Big Cam LQ4 / Backhalfed /Built 4l80e / #REBUILDEVERYTHING* MY BUILD THE H8RDCPTR //\\ MY YOUTUBE CHANNEL REV J HD

12-31-2015, 12:36 AM	#4
Houston Ben Registered User Join Date: May 2013 Location: Houston Texas Posts: 713	Re: Truck 5.3 Thermostat Hi guys, thanks for the response. I use a digiscan II for my dash which is reading the speed, temp, air temp, and rpm which is reading the high numbers. I also have my stock temp gauge hooked up to the passenger head and that was staying below 210 easily. I am planning on replacing the new thermostat with the old one to see if that works. Brew, the steam line it the on that comes from the passenger head to the top coolant hose correct? Thanks again! __________________ 1986 C10, 2011 5.3 w/6L80, 3.42 w/ Detroit TrutTrac Build thread: http://67-72chevytrucks.com/vboard/s...d.php?t=584532

01-01-2016, 03:49 PM	#5
LS short box Registered User Join Date: Jun 2015 Location: Carlos MN Posts: 2,132	Re: Truck 5.3 Thermostat I've had good luck loosening up the temp sensor in the head to bleed the air out. Get the engine warm with the radiator cap on and just loosen till coolant seeps out. You should see a spurt of air along with a little coolant. Be careful it's hot.

01-01-2016, 04:37 PM	#6
homemade87 Registered User Join Date: Apr 2010 Location: Guntersville Alabama Posts: 1,073	Re: Truck 5.3 Thermostat I am like others here . I think you have an air pocket . When you took it apart you did not get all the air out . I see and here it all the time when some one has broke the system apart for one reason or another . I have had good success with taking the steam line loose and filling the upper radiator hose until it comes out of the steam line and then top off the radiator . If you only fill the thru the radiator cap , it will never get it done .

01-02-2016, 12:36 AM	#8
XwalkerX Registered User Join Date: Sep 2012 Location: SoCal Posts: 529	Re: Truck 5.3 Thermostat youre sure its the correct part?

01-04-2016, 04:53 PM	#9
Houston Ben Registered User Join Date: May 2013 Location: Houston Texas Posts: 713	Re: Truck 5.3 Thermostat Hi all, I emptied all the coolant, replaced the new thermostat with the old thermostat (looking at it again, the were the same size, but different parts were longer) jacked the front end up and refilled and all is well. The part I bought was the correct part, I looked it up multiple times to ensure it was. Thanks for all your help and responses! __________________ 1986 C10, 2011 5.3 w/6L80, 3.42 w/ Detroit TrutTrac Build thread: http://67-72chevytrucks.com/vboard/s...d.php?t=584532

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