Best brand for new thermostat

[DanD]

Need to change the thermostat on my 03 LTZ with the 4.2. Gauge has been a little low occasionally for a while. Have now gotten the CEL with the code for low operating temperature. Any brands of thermostat that are better quality than others? Was thinking about just getting AC Delco but will ask here first. I also will do the sending unit too I guess since I'm there. And since we're at 13.5 years I guess I might as well put new upper and lower radiator hoses on, too. Maybe that's a waste. Both hoses look great. Can the factory hose clamps be reused? I hate the look of the replacement clamps from the parts store.

 

[Eric04]

Overwhelming consensus here is use the AC Delco thermostat. That said, I had a new AC which was bad out of the box and without a local source I had to go with the AutoZone brand, which has the rig at the proper temp. I know a few guys who use the AutoZone stats in their Duramax diesels without issue so I took a chance due to need.

Definitely do replace the sensor at the same time. Well worth the minimal additional cost.

Many people replace the factory clamps with worm drive equivalent. Yours may be fine but those spring clamps can get weak and are generally more of a PITA anyway.

 

[mrrsm]

And while the subject of the "Spring Clamps" is current... the one thing to remember about them is that they will never fail to hold...but pose an almost impossible amount of time and effort to either move...remove...or reset into place...unless you are lucky enough to get your hands on one of THESE babies... Imagine being able to safely compress these Spring Clamps regardless of their sizing.... Large or Small... MND... (Makes No Difference) and the Cool Part is how these tools HOLD PRESSURE so you can slide the Clamps off and up and down the hose... and reliably replace them without having the problem of Slipping Pliers-To-Blood Blisters while having your hands and fingers available to do the work... without having to count them after the job is done.. I have the OTC 4525 flavor of this tool and I recommend the device at every opportunity... When I got my mine... I wanted to tell my Grandchildren about the guy who suggested the idea!

https://www.amazon.com/s/?ie=UTF8&k...o=&hvqmt=e&hvdev=c&ref=pd_sl_8t0f0ghd9t_e_p14

 

[hockeyman]

+1 on the ACDelco Thermostat
+1 on replacing the sending unit too, since it's easily accessible at the time

I'd definitely recommend replacing the lower radiator hose along with installing all new clamps. The upper hose is easy to get to if needed later on, but the lower is a PITA if done by itself at a later time. Just as the sending unit, replace the lower rad hose while you're servicing the thermostat.

Thermostat, sending unit, lower hose and new clamps = 4 birds, one stone.

 

[hockeyman]

the one thing to remember about them is that they will never fail to hold...but pose an almost impossible amount of time and effort to either move...remove...or reset into place...unless you are lucky enough to get your hands on one of THESE babies... Imagine being able to safely compress these Spring Clamps regardless of their sizing.... Large or Small... MND... (Makes No Difference) and the Cool Part is how these tools HOLD PRESSURE so you can slide the Clamps off and up and down the hose...

Oh I GOTTA get me one of these!...
https://www.amazon.com/dp/B00F3DP2KC/?tag=gmtnation-20

Had no idea they even existed and I'm placing an oder as soon as I'm done typing here!

 

[littleblazer]

I would say change the coolant but you pretty much will be by changing the stat.

I would also say Delco is the way to go, when I got my truck the dealer replaced mine with who knows what. in the winter it never will warm up all the way just sitting and if you merge onto the highway it'll pull the temp from 200 down to 185 and then it'll come back up. and in the summer it runs hot doing nothing. I suspect it is simply stuck and has been since they replaced it.

They way I look at it is like this. was it hard to do and would I want to have to do it again. if the answer is yes I get Delco. if it is no I get whatever.

 

[Mooseman]

Yes, ACDelco. I had a Gates initially and found it ran on the cool side. Put in a Delco and it was up where it should be, running at ~185.

And yes, do the sensor as well while you're there. And since you're in there, change your coolant.

 

[therealsethallen]

My thought is "If the ACDelco part made it 140k miles issue free, might as well use a new ACDelco one" right? So I did. No issues.

 

[AWD V8]

When I did my water pump, rad fan & rad on my 5.3 I bought a Stant thermostat, used them for decades, no issues.

After my repairs the temp was inconsistent. It would run a wee bit hot, then cool down, then jump way up. Thinking that the eBay fan was the problem I spent many hours searching for the cause. After not finding anything conclusive I when with my gut, and bought a dealer thermostat. Fixed the problem, rock solid temps now.

So I guess that's a vote for ACDelco

 

[Mounce]

I used a GM thermostat. I assume ACDelco but labeled as GM. Bought it off of hockeyman. Been golden ever since.

Reused factory spring clamp, but put it in a more manageable orientation. Kinda a pita to get off with how it's turned away from you if you're coming from the front.

 

[DanD]

I got all the parts ordered and have everything off no problem. Last time I drove, the temp gauge was about half way to 210 for most of the drive. On the way home it was a little higher but the check engine light came on again. I've gotten the code for low engine temp and actual engine temp from a scanner was at 170. Strange thing is the old thermostat looks great. Took it apart and the seal is good. Can't blow any air through it. Do they just sometimes stick open a little in use? Maybe the sensor is bad. I have a new one of those to install too. Not much else to cause a low reading besides thermostat or sensor. I guess we'll see when it's back together.

 

[kickass audio]

It could be closing like it should but at the same time the thermostat could be opening up before the temperature is where it is specified to be. It could also be a bad sensor. The only way to test the sensor is to take it out and put it in hot water that you can read the temperature off of and then figure out the resistance range that the temperature of the water would read as off of the temperature sensor. For what it's worth i'd just trash the t-stat and temperature sensor and put an ac-delco one in. I had my shop put a Hayden one in and I was back to them just over a year later as it failed again. I went back and they said it was their problem and they would not use anything other than OEM for the t-stat and temperature sensor as other people came back with the same results. Sadly I was not under their 1 year coverage so I had to foot the cost of the parts and labor but it wasn't that bad. I just didn't feel like hassling with the dumb thing in my driveway.

 

[DanD]

Like I said I have a new AC Delco tstat (made in Mexico)and a new AC Delco sensor(made in China) and new AC Delco hoses(made in USA!) in my garage ready to install...was just surprised I didn't see any problem with the old tstat. Just making small talk I guess. Will report back after installation.

 

[kickass audio]

For what it's worth i'd also suggest flushing out the coolant since you will be replacing the hoses and everything so doing a flush while you're getting everything torn apart wouldn't be a bad idea too unless you already have pretty fresh coolant.

Good luck getting the sensor off, it is known to be a pain in the butt to get loose.

 

[DanD]

Coolant I drained is about a year old and is the third batch that's been in there. Inside of passages look new. Sensor took about 15 seconds to unscrew. It's out already. No problem.

 

[Mooseman]

The T-stat is probably opening earlier than specified. If you want, can take it out, put it in a pot of cold water with a thermometer and heat it up on the stove while observing the temperature it opens at. As stated earlier, you could also check the old sensor if you know the resistances.

 

[DanD]

Well got it all installed. Put in the temp sensor after the pic and filled with Dex cool and don't see any leaks yet. Will finish tomorrow.

 

[DanD]

Well, I have good news and bad news. Finished up with the thermostat job tonight and took the Trailblazer out for a test drive and less than a mile from the house creamed a deer. The good news is that the thermostat seemsto work great.

 

[Mooseman]

Good for you, not so much for the deer. Hope it's easily fixable.

 

[Derrick Rucker]

Sorry about your luck man, but if I was you I'd start at a pull a part place before you go and buy brand new parts, looks like you'll need the front grille, headlight assembly and the headlight for sure from what I can see, so I'd definitely try and at least get the front grille and headlight assembly at a pull a part, good luck to you

 

[DanD]

Those things would be easy to fix. Unfortunately the hood and fender are crumpled too.

 

[littleblazer]

Paying attention to the temp instead of the road? I kid. sorry man, but at least the issue is fixed, hope you get the rest taken care of soon.