99 5.3 z71 overheating?

Hey all,
I have a 99 chevy z71 with the 5.3. Whenever i get over about 65, it used to spike from around 175-180, to almost 210 on the gauge. Anyway, i
replaced the thermostat with a duralast thermostat from autozone and flushed the radiatior, put new anti freeze in it. It used to only run hot when i got up to those speeds, but with the radiator flushed and new thermostat, it's running at about 208 or so after i just let it idle up. I haven't driven it since i replaced it and did the work, i just let it run 10-15 minutes when i saw it jump like that. is this a normal temp for a 99 5.3? is the thermostat ok? it said it was a 194 degree, but the guy said that's what it needed to make the computer still work correctly. any input would be really appreciated.
thanks TB
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99 5.3 z71 overheating? Group: alt.autos.4x4.chevy-trucks Date: Mon, May 30, 2005, 2:28pm From: snipped-for-privacy@yourbusiness.net (Trailblazer) Hey all, I have a 99 chevy z71 with the 5.3. Whenever i get over about 65, it used to spike from around 175-180, to almost 210 on the gauge. Anyway, i replaced the thermostat with a duralast thermostat from autozone and flushed the radiatior, put new anti freeze in it. It used to only run hot when i got up to those speeds, but with the radiator flushed and new thermostat, it's running at about 208 or so after i just let it idle up. I haven't driven it since i replaced it and did the work, i just let it run 10-15 minutes when i saw it jump like that. is this a normal temp for a 99 5.3? is the thermostat ok? it said it was a 194 degree, but the guy said that's what it needed to make the computer still work correctly. any input would be really appreciated. thanks TB
..Sounds more like your getting air .Or you didnt get all the air out when you flushed it.....What does your intake look like? Did you pressure test the system? Also should check your cap seal.... The T stat doesnt do anything for your computer...You can run your truck without out it and your truck will still run...Your ECT Sensor is the one which sends the information not your T-Stat...Probly just need to burp your system...
S Cook
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Trailblazer wrote:

My input would be....get an original GM thermostat and stick that in there before you do anything else. Obviously, you need to make sure there is no air in the system, but frankly, the new generation v-8 doesn't have any real problems with that. You fill the overflow tank while you run the engine, and it will pretty much autobleed itself.
Ian
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Re: 99 5.3 z71 overheating? Group: alt.autos.4x4.chevy-trucks Date: Mon, May 30, 2005, 10:32pm (CDT+5) From: snipped-for-privacy@hotmail.com (shiden_kai) Trailblazer wrote: I have a 99 chevy z71 with the 5.3. Whenever i get over about 65, it used to spike from around 175-180, to almost 210 on the gauge. Anyway, i replaced the thermostat with a duralast thermostat from autozone and flushed the radiatior, put new anti freeze in it. It used to only run hot when i got up to those speeds, but with the radiator flushed and new thermostat, it's running at about 208 or so after i just let it idle up. I haven't driven it since i replaced it and did the work, i just let it run 10-15 minutes when i saw it jump like that. is this a normal temp for a 99 5.3? is the thermostat ok? it said it was a 194 degree, but the guy said that's what it needed to make the computer still work correctly. any input would be really appreciated. My input would be....get an original GM thermostat and stick that in there before you do anything else. Obviously, you need to make sure there is no air in the system, but frankly, the new generation v-8 doesn't have any real problems with that. You fill the overflow tank while you run the engine, and it will pretty much autobleed itself. Ian
True ....After you let it sit was it low on coolant? If he just filled it up and put the cap on the first time you ran it it wld spike unless you let it run with the cap off to burp it...But your right they do autobleed them selfs...By now he sholuld be low on coolant if it was air... S Cook
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When I filled it, i left the cap off for the first 5-10 minutes to let it cycle in. I then tightened up the cap and let it run, and it kept going up until it hit 210. I guess my next move is replace the tstat with a GM one, i still have the receipt from the autozone tstat. I didn't figure it should run this hot, and it's pissin me off. I guess I'll drive it to autozone and back and see how it runs and check on a new tstat. Does anyone know what it the engine should run typically?
thanks TB
(shiden_kai)

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Trailblazer wrote:

If it's a 195 thermostat, then it will run at 195 all day long if you have sufficient air going thru the radiator, and the radiator is not plugged. Don't take the dash guage reading as gospel. I always check these types of concerns with a scan tool, you get the exact reading with a scan tool.
Ian
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"shiden_kai" wrote: > Trailblazer wrote: > > > When I filled it, i left the cap off for the first 5-10 > minutes to > > let it cycle in. I then tightened up the cap and let it > run, and it > > kept going up until it hit 210. I guess my next move is > replace the > > tstat with a GM one, i still have the receipt from the > autozone > > tstat. I didn't figure it should run this hot, and it's > pissin me > > off. I guess I'll drive it to autozone and back and see how > it runs > > and check on a new tstat. Does anyone know what it the > engine should > > run typically? > > If it's a 195 thermostat, then it will run at 195 all day long > if you have sufficient air going thru the radiator, and the > radiator is not plugged. Don't take the dash guage reading > as gospel. I always check these types of concerns with > a scan tool, you get the exact reading with a scan tool. > > Ian
Actually a 195 will run closer to 200 to 205 in warmer weather because the stat just starts to open at 195 and is not open enough to cool in warmer weather until another 5 or 10 degrees beyond that. A 190 is usually the warmest stat I will use and I never use one colder than a 180 either.
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SnoMan wrote:

No doubt you are going by what you seen on the dash. Try hooking up a scan tool. A good "oem" t/stat will open right up at the temp it's designed to open up at. On a lot of cars with electric cooling fans, it makes little difference, as in stop and go traffic, the temps will spike quite a ways above the t/stat temperature. This doesn't do any harm to the engines.
Ian
Ian
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"shiden_kai" wrote:

Done better than that with remote thermaster sensor and IR sensor too. I have even boiled a few in water to check actula operation vs temp. BTW my obsevations on operating temp of a 195 is based on actual temps, not dash gauge.
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"Trailblazer4" wrote: > When I filled it, i left the cap off for the first 5-10 > minutes to let it > cycle in. I then tightened up the cap and let it run, and it > kept going up > until it hit 210. I guess my next move is replace the tstat > with a GM one, > i still have the receipt from the autozone tstat. I didn't > figure it should > run this hot, and it's pissin me off. I guess I'll drive it > to autozone and > back and see how it runs and check on a new tstat. Does > anyone know what it > the engine should run typically? > > thanks > TB >
> (shiden_kai) > > Trailblazer wrote: > > I have a 99 chevy z71 with the 5.3. Whenever i get over > about 65, it > > used to spike from around 175-180, to almost 210 on the > gauge. Anyway, i > > replaced the thermostat with a duralast thermostat from > autozone and > > flushed the radiatior, put new anti freeze in it. It used to > only run > > hot when i got up to those speeds, but with the radiator > flushed and new > > thermostat, it's running at about 208 or so after i just let > it idle up. > > I haven't driven it since i replaced it and did the work, i > just let it > > run 10-15 minutes when i saw it jump like that. is this a > normal temp > > for a 99 5.3? is the thermostat ok? it said it was a 194 > degree, but the > > guy said that's what it needed to make the computer still > work > > correctly. any input would be really appreciated. > > My input would be....get an original GM thermostat and stick > that in > > there before you do anything else. Obviously, you need to > make sure > > there is no air in the system, but frankly, the new > generation v-8 > > doesn't have any real problems with that. You fill the > overflow tank > > while you run the engine, and it will pretty much autobleed > itself. > > Ian > > > > True ....After you let it sit was it low on coolant? > > If he just filled it up and put the cap on the first time > you ran it it > > wld spike unless you let it run with the cap off to burp > it...But your > > right they do autobleed them selfs...By now he sholuld be > low on coolant > > if it was air... > > S Cook > >
What temp stat did you put in it? (It is stamped on stat as well as package)
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"shiden_kai" wrote:

You do not need a GM thermostat becuase even GM does not make them anymore and outsources them too. You may have a air locked system that will need to be purged of air and you might alos check for proper operation of clutch fan and if consensor and radiator core are free of chaff and blockage in path of airflow through them that cools them.
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SnoMan wrote:

The term "GM thermostat" has little to do with whether GM "actually" makes the t/stat themselves. It has to do with picking up an "OEM" thermostat. Too many problems with a lot of the aftermarket stuff. In 25 years of working on GM vehicles, I've yet to see any aftermarket thermostats that work any better then the oem ones....and plenty of them that worked far worse.
Ian
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