P0128 code for a LS nonbeliever ('15 5.3 Silverado)

[pagrunt]

Well between trying to sleep, searching parts & getting Jr. off to school I saw the over flow tank is still low at what I'll say half. It was at the same spot when I parked it. Now I jave to wait for the wife to get home so I can at the least top it off. With this world of special coolant for everything I need to get some orange stuff as I only have green for the Monte Carlos & the blend for her Hyundai. Need to stock up on some universal for a back up. Still will cover "worst case" with it going to a dealer. This way I'll get an AC Delco thermostat.

 

[Streetbu]

 

[pagrunt]

I've had two P0128 thermostat repairs on two different FIAT/MOPAR in the last year. One I did myself, the other I let the shop do because was tucked out of the way.

I don't know if older designs from like Gen1 SBC era used to fail closed, leading to overheating, but the modern thermostats seem to fail open, safely keeping the engine colder and the ECU in open loop.

They mostly failed close with no fail safe but they could still fail stuck open.

 

[pagrunt]

View attachment 253003

I saw this last night but don't have the wait time as this is a gotta ASAP.

 

[Streetbu]

Im sure there is a local AC Delco distributor near you

 

[pagrunt]

For a local around me it'll be a dealer & a road trip. Past few years it seems like the few locals went with cheaper on hand inventory. The local I went to for coolant years ago had AC Delco but the new supplier don't carry it for quick delivery.

Topped off, ran for about 15 minutes, fans started screaming on start, temp gauge never moved. The upper rad hose never went ove 95 when I hit with the temp gun., over flow never dropped from the full cold. Random spots I hit on the engine never really got hot with the rear most spot I hit was about 220, still blew 74 at the dash with the heater set at 74. Fans never quit screaming until the end of the key off cold down cycle. I did get an appointment for tomorrow at a smaller dealership for tomorrow as a back up plan if I don't get it done myself today.

 

[doood]

They mostly failed close with no fail safe but they could still fail stuck open.

Understood. I've been lucky to have two fail open on my vehicles this year.

 

[Ernest]

I concur with everyone else... its the thermostat.

The place i work at has a 2009 chevrolet 1500 single cab long bed work truck running with the 4.3L / 4L60E combo with just over 400k miles. One day, the dual electric fans went full bore, temp gage never moved from the cold side and the A/C function was disabled by the ECM, the truck still ran fine, but very annoying to say the least. Changed out the thermostat, and whalla, temp guage worked like normal again, the A/C was functional again and the dual fans stayed off till needed.

 

[pagrunt]

Thanks for all the input on this. I didn't do it myself today so tomorrow off to the dealer. Did stop in at the O'Reilly & looked at the full cost with one of the few counter guys left from when it was a local independent chain. He even said it's an easy fix but compairing the cost of DIY & the deductible why not just have it done & the dealer & get better parts installed (the recommended & prefferred AC Delco stuff.) Even if there's a slight chance the temp sender is bad I'll still pay the hondo & won't need to run back out for additional stuff. Since this is one of the older smaller dealers maybe during the wait I might find some of the older wire terminals I'm looking in their dusty stash.

 

[pagrunt]

Good & bad for today. Good was it was just the themostat, was a super quick fix & the service department boss was able to get the Ally to eat the deductible. Bad was trying to get AAA to tow it in. They keep on wanting to send a tow company that's closer to joesregalproject than to me which they tried to do last year for the wife's car. Then when I finally get them to send a local they never did show up until I got back to the house after gettting it done. It was scheduled with them but AAA kept bumping me out for other tows & never sent me any updates or notificaions. That company's operator apologized for the AAA screw up. So I did drive the truck up dispite not wanting to make the fans scream & really oly wanted to run it as needed. Monday I'll fight with them about sending someone 1.5 to 2 hours away or even from the Pa/Oh boarder, why there is "never" a local that's about 20-30 minutes away (atleast 6 of them) that they can send, how they think I'm located somewhere in Pa than where I really am. I did try to talk to someone today just to hang up on her after she got defensive said their service is just for emergencies only & not for a tow for repairs.