Engine light came on tonight

[Ghost]

http://www.dtcsearch.com/P0128/?from=Torque

I'm 8 months or 6k since oil change. Is that the problem ? The thermostat gauge hangs just below the 200mark which I think it usually chills right at 12o clock *200

 

[Mounce]

I thought 12 o'clock was 210.. I can't really remember though, been a few days since I drove it. But P0128 usually means either the thermostat is stuck open or the ECT sensor has became faulty. Most people just change both while they're down there due to the pita it is to get to.

 

[dmanns67]

I typically run 6,000 to 6,500 miles in between oil changes. Have been that way since I bought my TB in 2008. The 12 o'clock position should be 210* on the dash. Do you have TorquePro to see what your actual coolant temps are?

Do you notice the needle move on the temp gauge when you get on the throttle? This past winter my needle would move on the temp from 210 to about half on the highway. Using the TorquePro app I could see my temps would change. Consistently running at around 183* even when my dash gauge was telling me 210*. When accelerating, the temp would drop as low as 165*.

By reading a few threads here I figured my TB was running too cool. Most members see 194*-200* on TorquePro, mine never went above 183*. I replaced the T-stat and ECT sensor and now there is no fluctuation in temperature and I consistently see 195* with TorquePro.

I imagine I could have seen the same results by just changing the t-stat, but I read recommendations to do both at the same time. The 02-05 ECT sensor is easier to change because it is near the t-stat. The 06-09, GM decided to put it on the passenger side of the engine near the firewall

 

[Ghost]

Is my truck going to break if I don't replace the thermostat right away ? Is this code a serious problem. I was 70mi from home when the light came on so I scanned it with my torq app. Don't notice the truck driving funny except the temp gauge being below the 12 o clock spot.


Oil temp gauge moves when I get on it to about 1-2 o clock depending how hard I am on that gas pedal.

 

[dmanns67]

Do you mean the oil pressure gauge on the dash or have you added an additional gauge?

What coolant temps are you seeing with your Torque app?

There are other ramifications that will take place the longer you put off replacing the t-stat. It is a very cheap part. Picked mine up from Rock Auto for $20 and the ECT sensor for $18.

I would not call the t-stat a "serious" problem, but the longer you put off the repair, more issues might arrise. T-stat is cheaper than a clogged cat.

If your only concern is being able to drive your vehicle to get back home, then you should be ok. I would recommend not waiting months to change it out though.

 

[Ghost]

How hard is it to replace this thermostat my self ? What tools are needed ?

 

[KNBlazer]

How hard is it to replace this thermostat my self ? What tools are needed ?

Getting to it the first time can seem like a PITA, the 2nd time it's still a PITA but with experience, lol.... you need to remove alternator in order to have easy access to it... there are threads on the step by step process...

 

[Ghost]

Getting to it the first time can seem like a PITA, the 2nd time it's still a PITA but with experience, lol.... you need to remove alternator in order to have easy access to it... there are threads on the step by step process...

thanks, I have no one nor the $ to pay a mechanic. I guess the worst thing that can happen is I give up.

 

[HARDTRAILZ]

Its really not too hard. Just read the write-up n take your time.

 

[Ghost]

This is the gauge that usually sits on 210 on the spot. But when the light came on and I scoped put each gauge this one was one notch below its normal spot.
Pic taken 3 min after start!

 

[Ghost]

I want add more pics but tapatalk doesn't allow me to. Temp is sitting idle at 85 celceus

 

[Sparky]

3 min isn't enough to get up to full operating temp.

My gauge sits 1 tick left of straight up 210, always has. Torque says running at 195. That's OK. But if yours normally is straight up and now isn't then yeah you need to change the stat.

Doesn't have to be immediate, but the longer you let it go the longer it may run rich and the greater the chance of clogging up your cat from running rich.

 

[Blckshdw]

the worst thing that can happen is I give up.

This is NOT allowed.

 

[Ghost]

OK eBay is my place to order so. I found a Stant and OEM. Problem is I am seeing several part #s when searching: 2003 trailblazer thermostat

 

[IllogicTC]

One thing to note, removal of the alternator practically (I say practically as there may be workarounds) requires ratcheting wrenches. They're actually found on the cheap, basic Husky ratchet wrench without the flex head won't run you back too far for a set. Metric is the kind you'd need, SAE is just to complete the set if you want to.

 

[KNBlazer]

OK eBay is my place to order so. I found a Stant and OEM. Problem is I am seeing several part #s when searching: 2003 trailblazer thermostat

What I do is go to Rockauto.com and get the Oem part numbers and then search amazon, ebay and such for best prices...

One thing to note, removal of the alternator practically (I say practically as there may be workarounds) requires ratcheting wrenches. They're actually found on the cheap, basic Husky ratchet wrench without the flex head won't run you back too far for a set. Metric is the kind you'd need, SAE is just to complete the set if you want to.

15mm stubby combo wrench is the best invention by far, oh and the internet too

 

[Ghost]

What I do is go to Rockauto.com and get the Oem part numbers and then search amazon, ebay and such for best prices...

15mm stubby combo wrench is the best invention by far, oh and the internet too

I have tools, except specials things like torque wrenches and gear wrenches. Thanks the only part here that makes me nervous is removing the serpintine belt(sp)

 

[Mark20]

To get the engine up to temperature quickly the computer throws in a little extra fuel. If that contiunues with due to a faulty thermostat or temperature sensor that extra fuel will end up in the catalytic and cause problems there. A lot more expensive to replace that.

 

[Ghost]

OK is there anything wrong with stant? Its cheapest of the 3 choices on Rockauto.com
Also do I need the pipe "housing" or can I just replace the thing with the spring (thermostat) ? I will assume its ceased in there so I probably need the whole kit.

 

[KNBlazer]

OK is there anything wrong with stant? Its cheapest of the 3 choices on Rockauto.com
Also do I need the pipe "housing" or can I just replace the thing with the spring (thermostat) ? I will assume its ceased in there so I probably need the whole kit.

unfortunately for us the 4.2 bunch, the entire housing is what is needed... some report lower temps, others report good results with stants.... the majority here, self included if possible buy AC Delco only...

 

[Ghost]

unfortunately for us the 4.2 bunch, the entire housing is what is needed... some report lower temps, others report good results with stants.... the majority here, self included if possible buy AC Delco only...

thanks. AcDelco it is but hopefully can find a proper part # and one that comes with the gaskets

 

[KNBlazer]

thanks. AcDelco it is but hopefully can find a proper part # and one that comes with the gaskets

the AcDelco comes with an O-ring...

 

[dmanns67]

OK is there anything wrong with stant? Its cheapest of the 3 choices on Rockauto.com

I am running Stant t-stat, no issues.

 

[Sparky]

One thing to note, removal of the alternator practically (I say practically as there may be workarounds) requires ratcheting wrenches. They're actually found on the cheap, basic Husky ratchet wrench without the flex head won't run you back too far for a set. Metric is the kind you'd need, SAE is just to complete the set if you want to.

When I replaced my alternator a few years ago due to the bearings going bad I didn't have any ratcheting wrenches, just regular box wrenches and my socket set, and I didn't find it particularly difficult to do. Not super easy, but I've worked on far worse projects than pulling the alternator on my truck.

 

[Ghost]

When I replaced my alternator a few years ago due to the bearings going bad I didn't have any ratcheting wrenches, just regular box wrenches and my socket set, and I didn't find it particularly difficult to do. Not super easy, but I've worked on far worse projects than pulling the alternator on my truck.

I helped my brother dig a big ass hole and pull a semi over the hole and we dropped the tranny from it. So I'm sure this should be a walk in the park

 

[Mounce]

That's impressive I also removed my alternator without the specialty tool(s) it wasn't fun nor quick, but it came out.

 

[Ghost]

Just for some reassurance this is all I need and...what a gallon of green coolant, right ?

http://pages.ebay.com/motors/link/?nav=item.view&id=331080968487&alt=web

 

[Sparky]

Not green, unless you or someone else had done a full drain, flush, and refill. These trucks use the orange Dexcool stock and mixing the two is bad.

 

[Ghost]

Not green, unless you or someone else had done a full drain, flush, and refill. These trucks use the orange Dexcool stock and mixing the two is bad.

I think mine is neon green.
We will find out when the part gets here and I start the project. I'm going to need to drive my truck Monday 5mi and Wednesday 70mi hopefully ill be OK because the part wont be here till next Fri. UPS ground :angry:

 

[Sparky]

That's a short time, doubt it'll cause you any real issues.

 

[Ghost]

The engine light went off yesterday. Hmm I haven't had a chance to read the ecm yet. Part comes in today

 

[Ghost]

Started the project today. Got the belt off so far and this last alt bolt ,bolt #4 is a real pita

 

[Ghost]

Well some thing is fishy here. 5 bolts hold the alt in ?? Or is there more...cause the black bracket on top that hoods the ac hose wont move...:/ nervous.

OK now to find the one below the alt. I see two there...so that's 7 bolts

 

[KNBlazer]

Told Ya it was a PITA :lol:


The bottom bolt, I break it lose with 15mm combo wrench, then with a stubby combo I losen it...

 

[Ghost]

Well got the old one out and it ain't stuck open ???

 

[KNBlazer]

Well got the old one out and it ain't stuck open ???

I think it might open a lot sooner, it loses tension and does not remain closed enough to allow the coolant to stay at optimal operating temps...


Here's a shot of my old thermostat... I was getting P0128, it's closed..

 

[AtlWrk]

Do you see score marks on the outside of the copper cylinder that would indicate it was binding where it slides through the housing?

The fact that your light went off (I think it only takes three successful warm up cycles to shut off the CEL) tells me it was probably just getting stuck but eventually breaking free. Still worth replacing.

 

[KNBlazer]

filled with water, no leaks...

 

[Sparky]

It is probably borderline and opens sooner than it should be. Thermostats don't always fail by sticking.

 

[Ghost]

No clue got new one in. Just got the alt back on, and bracket. Going to remove hose from bottom of alt box and drain the rest out and fill her up with this stuff:
Autozone dex-cool: