2008 Trailblazer SS

[wxo]

I installed a new Stant SuperStat that I had bought many months ago (I don't remember why). The SuperStat is different than your normal everyday thermostat. Here's the marketing material:
Unlike conventional thermostats that continually open and close to achieve the proper operating temperature and flood the engine with coolant, the Stant SuperStat® thermostat has a unique v-notch, non-linear design that reduces cycling by precisely metering the amount of coolant needed to maintain proper operating temperature.
The v-notch provides a small initial flow. As the engine heats up, the v-notch gradually opens wider, metering coolant into the system until the desired engine temperature is reached.

After the installation, I went out for a test run and, wouldn't you know it, the temperature was still reading low (104°) and not increasing. When I got to the first stop sign, I turned right and floored it. Suddenly I saw the temperature display jump to 145° !!!?? I guess the thermostat was not the problem. The only other possibility is the engine temperature sensor. I know they rarely go bad, so I focused in on the connector. It looked like a good quality OEM connector but I took a look. The connections were clean and bright, but I decided to spray it with contact cleaner, let it dry, and snapped it back on. Now the test run was totally different. With the new thermostat, the engine temp was right up there where it should be. The thermostat is rated at 187° and the operating temp is around 192°. The other surprise is that the startup anomaly seems to have gone away. It's too early to know for sure, but I'm hopeful. I guess it's possible that an erroneous engine temperature could somehow affect the what the ECM does during startup.

[Basement Paul]

Or your bad connection was sending the wrong temps during startup too and creating that problem also. Have you ever thought about running a cooler thermostat? You live in a warmer climate, and I know those engines like being cooler, so a 170deg stat might get you a few relatively free HP. You would just need to program the fans to come on at 175 or so to take advantage.

-BP

[wxo]

I put a 160° thermostat in there over a year ago until I started seeing the P0128"s. Looking online I saw that some thought that the cause was the low thermostat. Consequently, I put the original thermostat back in. All was OK until now when I began seeing the P0128's again. This brings us up to now. It could be that the problem was the connection to the temperature sensor all along. I'm going to stop making changes to see if I see if any more of these issues show up. I'm not convinced that the low temp thermostat really does what many think it does. I researched this a while back and as I remember it, it is a big controversy with no definitive conclusion.
I've warmed up to the idea of running the engine at the temperature at which is was designed to run. It makes sense to me that the ECM's tables were set up based on this temperature to keep it running efficiently. My current tune was done with the stock thermostat in the truck.

[wxo]

I'm cautiously optimistic that the engine temp sensor connector was the cause of both these recent problems. I've seen no more of the starting anomalies nor the P0128's with the associated cutoff of the AC.

[Basement Paul]

Hard to believe the connector is the issue. But, it is hot down there and the TB is over 10 years old already. Glad to hear the problems are cured without major repairs.

-BP

[wxo]

I'll just let it ride and see what happens.

[wxo]

It's been two weeks since I last saw a P00128 code and related problems. I say it has been fixed by cleaning the engine temperature sensor connector in the block.

Next, I'm working on a very slow AC refrigerant leak. It's been a few months since I topped it off last and I've noticed the outlet temps going up a little. I put the gauges on it and with an ambient temp of 78.8°, the low side read 32psi and the high side read 175psi at idle. After adding one can of R134a the low side now reads 40psi and the high side reads 220psi at idle which is where it should be on the chart I have. Cooling is now back to normal. I bought a dye injector device to add some tracer dye to the system. The dye, itself, is on order and should arrive in a few days.

[wxo]

Last week the TBSS starter began to act wonky. It would engage but then drop out, engage again over and over. Just to make sure it was not a battery problem, I put in a new battery, but the problem remained. Then I swapped out the starter relay and the same symptoms occurred again. Now it was time to consider the daunting task of changing the starter.

I knew it had a lifetime warranty, so the worst part was the labor and time involved in removing and replacing it. After about four hours I had the thing in my hand and took it to Advance Auto where I bought it 6 years ago. They were happy to test it and verified that, indeed, the starter drive was the problem. They pulled out a re-manufactured starter like the old one, but the replacement was about 1/2 inch too long. Then they pulled out a new unit and it, too, was 1/2 inch too long. In my case the working room in the cavity occupied by the starter is very limited, and once up in the cavity, the starter must be turned and rotated to hook up the wiring to it. Due to the difficulty in installing the unit, I didn't want to try to fit something bigger in the limited space. Next the counter guy decided to order an official Delco starter in hopes of getting a replacement for me that was the same size as the old one. A couple of hours later, it arrived and it was even bigger, at one inch longer and slightly larger in diameter. Now I'm at a dead end. It appears that the auto replacement parts industry is culling it's inventory and leaving some of us by the wayside with a useless warranty. After some brainstorming with Maverick, he suggested a local outfit (Johnny's Auto Electric And Marine Electrical services Garner NC) that would rebuild my old starter. After $134 and 5 days it was done. They put in a new solenoid and drive and new brushes. They cleaned it and clear coated it to look like new.

This shows the tight fit and the orientation required to fit the starter into the cavity.

The story ends after another five hours under the truck and a sore neck working that thing up into the small opening and attaching the wires and getting it turned around and bolted up. Now I'm back in business. Nice solid starting.

[Maverick]

Great!!! Don't expect you'll ever have to tackle that job again.

[Basement Paul]

I'm glad you were able to get it back in there, but that's terrible about the warranty. I'm a firm believer in these mini starters. High power, smaller, and lighter which makes all those tight spaces easier to tolerate. I've had a couple so far and wouldn't go back.
I'm surprised this is the 2nd time you've had to replace it. That seems excessive.

-BP

[GMJohnny]

It's bogus when you have to say to yourself "How the heck did they get that in there?" when
working on a project. Then you watch it on YouTube and a guy has your car on a rack with
an engine hoist, trans jack, floor jack, 20' long pry bar and 6 of his buddies there doing the
work. I'm glad it didn't take you a full day to install it!

GM

[wxo]

I'm glad it didn't take you a full day to install it! GM

GM, 5 hours is a full day for me when I spend it under the truck.
Maverick offered to help, but this is a one man job no matter how you look at it.

[wxo]

I'm still experiencing an AC system leak. I've injected dye, but can find no evidence of a leak except for a loss of refrigerant. It's a good thing I have my built-in, low refrigerant indicator noise. When I'm low on R134, I start to hear a whistling noise. After I top it off, the noise goes away. It's possible that the leak is under the dash in the area of the evaporator. I sure hope not. I would expect that the green dye would show up on the carpet on the passenger side if that was the case. I'm going to top off the R134 today and it should hold for a few months. I welcome all thoughts and comments on how to find this leak. One thing that occurred to me recently is maybe, somehow the dye didn't get into the system properly. I think I'll do a quick release of some R134 at the low side and see if some dye comes out.

[Basement Paul]

Unfortunately it's not abnormal to have leaks like that inside the hvac box. That dye is pretty sticky, so you'd probably need a lot of leakage to see it run out of the box IMO. Let's hope that's not it...

-BP

[wxo]

It was over 90° today, so I decided to add some R134a to the TBSS AC system. A few months ago, I had bought an oil/dye injector setup for my AC gauges. I added 1/2 oz of dye and about four cans of R134 before I was able to feel 32° coming from my dash vents. This time I know the dye went into the system. I took a ride to get everything into circulation and then used my ultraviolet light to look for leaks in the engine compartment. Nothing. I guess I will try to get a look into the evaporator enclosure under the dash to look for leaks. Some dye has to come out from somewhere. That's a task for another day. The cool air feels good today.

Fully charged pressures - ambient temp is about 90°

UPDATE:
Filled again on 6/28/2020
Filled again on 7/20/2020