This is very interesting, and enlightening. The water pump would be a logical place, if it weren't completely blocked by the oil tank. Not being a mechanic, I can't help but wonder why it couldn't be placed near the radiator, since all the coolant passes through there, or in one of the lines leading to or from there. Sometimes it seems like things are placed in a position without much thought given to future maintenance.

 

SBC [350 etc ] had the unit in the left side head too but all in all wrenching for 55 years on many things the sending units were not that common on any car going bad . .....bottom line is lets make a sacrifice to the fire gods gm isn't sitting on a batch of these lil time bombs .....like their 60's motor mounts . Hey andy is the belt correct on your 283 pulley ,photo shows it deep in the groove

 

I dunno. I probably thought it was correct when I replaced it. But is been a good while since I did that.

If your'e looking that close, you probably also noticed it does not have a fan clutch. I have an original, rebuilt, correct clutch, in cabinet somewhere.

 

I can only speculate about that. But, little or no coolant flows through the radiator until the thermostat opens. I think they want to measure temperature in or near the block. I do not understand the coolant flow paths in this beast. They are complex with multiple lines and and thermostats. And blow up of the water pump manifold also looks like that may be internally complex. I think (this is the speculation part) that there might be some coolant flow in the area where the sensor is located before the thermostat(s) open. That does not mean it couldn't have been put in a more accessible location.

 

Complex is an understatement :-) All I can say for sure is that this faulty sensor has caused my brand new car to be in the shop for 2 weeks, (if it's ready when promised) and I'd really like to drive it someday. So far I've only driven it from the dealership home, and from home to the dealership.

 

i have a 62 ? chrome corvette valve cover right above me on the wall here .....with the intake manifold cut outs and the top closer bolt holes , yes i remember the Philips screws and trying to find a dropped washer and making sure of the ground strap , road draft tubes , cork gaskets , wiped 283 cams etc

 

I picked it up yesterday. The problem was indeed the engine coolant temperature sensor. They had to do a partial drop on the engine and had my brand new C8 for 2 weeks. i took it out for a spin today, 60 miles, no problems. Fingers crossed that it stays that way.

 

Were you able to see what the cost of this repair was?

 

No, it just said "Warranty", but the list of things they had to remove is long, and included things like evacuating the A/C system and recharging it. If anyone is interested, I could post the complete description. I'm sure the labor cost would have been in the thousands.

 

Please send your list of parts required to fix this issue

 

You might be able to see the cost in your chevy account. On mine I can see the list of services reported by the dealer. One of them goes all the way back to when I had the "free" service performed. That service is billed back to GM as a warranty procedure. But it shows up in account and in that instance it does in fact show the amount - I assume it was the amount billed to GM.

The list would be interesting. Does it list the labor hours?

 

It does not show labor hours, nor the cost, I might be able to see it in my Chevy account, but haven't checked.
Here is the description of work performed.
Confirmed check engine light, scanned for codes and found P0116.
Checked for power and ground and verified power.
Determined Coolant temp sensor internal failure
Disconnected negative battery cable
Relieved fuel system pressure
Recovered refrigerant
Drained engine coolant
Removed air cleaner assembly, radiator hoses, underbody rear air deflector, rear bumper, wheelhouse liners, rear suspension components including adjust links, stabilizer links, lower control arms, wheel drive shafts and shields, exhaust front insulators, muffler hanger brackets, fuel hoses, brake hoses and pipes, engine wiring harness retainers, and connectors as required.
Removed rear suspension cradle to allow engine lowering using hoist and propulsion system lift table.
Dropped complete engine assembly in order to access ECT sensor.
Disconnected electrical connection, removed failed sensor and installed new sensor per procedure.
Reinstalled engine, rear cradle and all previously removed components in reverse order of removal.
Refilled and bleeded coolant, bleed brakes, recharged A/C.
Performed crank shaft position learn and throttle body idle air flow reset, cleared DCT's verified proper sensor and fan operation.

Here is a list of parts required.
ECT Sensor - 25186240
Coolant - 123462390
Seal - 13418808
Seal - 13418809
Bolt - 11546938
Retainer - 11546938
washer - 11611965
seal - 12672699
seal - 12671472

Total Invoice $0.00

I looked for service records, and found this:

• Your service may have been performed within the past two weeks. Records are not available until after this time.

 

Wheel alignment should have been done as well due to rear control arm removal.

 

I think that if that was listed in GM's procedures, it would have been done. At least that's what I'd like to think.

 

It is a complex path but the procedures call procedures. The sensor replacement procedure lists the preliminary procedure as Oil Tank Replacement. The OIl Tank Replacement procedure calls the Engine Replacement Procedure. The engine replacement calls out suspension removal and replacement procedures. The suspension removal and replacement procedures all alignment procedures. So, if they followed all that, it was done. I did not make this up. I traced the steps.

Here are two of the steps in the engine replacement procedure:
58. Rear Suspension Adjust Link Outer End @ Rear Suspension Knuckle >> Install - Rear Suspension Adjust Link Outer End Replacement
59. Rear Suspension Lower Control Arm @ Rear Suspension Knuckle >> Install - Rear Suspension Lower Control Arm Replacement


And here is step in the Rear Suspension Lower Control Arm Replacement:
18. Measure and adjust the wheel alignment. Wheel Alignment Measurement

So I'm thinking you are good.

 

Wonder how the car would handle if the rear alignment was off if not performed following the procedure. I'd definitely notice if the front wasn't aligned due to steering feedback.
I'd request a readout of the alignment as well.

 

Got the bad news yesterday. The dealership will have to drop the engine, remove oil tank, remove suspension, remove rear bumper, remove air box, remove exhaust, and drive shafts, drain coolant, discharge AC, and replace temperature sensor, bleed breaks, recharge ac, refill coolant, perform wheel alignment, etc. etc... Only 65 total miles on new 2026 and my advisor indicated this is the 1st occurrence he knows of this happening at this location. It's documented to be a 15-hour procedure.

 

The invoice finally showed up on my account. The total cost to replace a defective engine coolant temperature sensor, which is a $25 part was $5,311.19

 

Thanks! A perfect example of why one would purchase a protection plan. The likelihood of this and similar failures might be low, making the average cost of repairs across all cars low (lower than the cost of the plan), but when a failure happens the cost will be pretty high. The mid-engine configuration of this car, and the overall compact nature of components will in general make repairs labor intensive and thus costly. I noticed too that the cost GM was billed for the DCT filter change and engine oil change was considerably lower than what forum member report when they must pay for the same services themselves. The point being that if you had to cover this out of pocket, the cost would likely have been even higher.

 

Wow. I'd be really upset if this sensor failed after the warranty expired and have to fork out over 5K. Surprised it's not a more common issue as I've seen little to no other occurrences of this sensor failing on the C8.