Hello everyone,

I am still new to the C6 and I have an issue with my coolant system. Originally I would regularly see the "Check Coolant Level" warning in the DIC. Chevy then found the fuel pump to be leaking and replaced it. The issue remained. When reviewing the coolant level in the reservoir now, it seems full, more importantly the level remains the same.

the problem progressed into to the "dancing teperature needle", meaning that the temperature of the coolant can jump easily from 100 to 200 in a split second. The erratic jumps are also seen on the temperature display in the DIC.

I again had the car at chevy and they found a few battery wires that supposedly were the issue, after which the issue did not change. If anything it got worse, as the temperature range is bigger now. I have seen everything from 23 to 210. The worsening could also be because now it is generally cooler outside than before. Now the situation is so bad that sometimes the car shifts from extreme cold mode (higher RPM) to overheating mode (full fan, no AC) within a minute or so, which certainly is not good. I also experience hesitant starting, where the engine only starts running if add a little throttle.

Once again I brought it to the service department and now they claim they did a pressure test on the system and found leaks on the coolant hoses. I am not sure whether this is indeed what they did or just, well the next best guess to pinpoint the issue by ruling out possible causes. Anyway, they want to replace a total of 5 hoses for $1300 plus tax (T-HOSE, HEATER HOSES, CROSS OVER PIPE, (UPPER) RADIATOR HOSE, LOWER RADIATOR HOSE). To me that sounds like all the hoses of the coolant system incl heating hose and is IMO a bit vague for pinpointing a problem. They don't want to tackle the temperature sensor, as they believe the leaky hoses are the issue, which they want to rule out first.

I unfortunately don't know the C6 well enough to judge weather there is a good chance that leaking hoses could be the culprit. I still don't see any changes in the coolant reservoir level, nor do I see any drips of coolant on the garage floor or in the engine bay, but apparently, the coolant system can loose pressure through a leaky hose without leaking much liquid. Not entirely bogus sounding, but I am no skeptical.

Long story short, should I go with it or should I just find a different dealer with a more patient technician? Is the price at least near fair or a total rip-off?

Thank you everyone for your advice!

 

Definitely find a different mechanic.
When the temp jumps up from 100 to 200 does it immediately go back down again, meaning does it jump up and down or just up and stay there? If it jumps and and keeps getting hotter I'd say maybe a stuck thermostat.
If it's an erratic up and down I'd say its the temp. sensor.
Hoses? No way!

 

Stay away from that stealership and buy a coolant temp sensor and slap it in you self is in the driver side front of head by #1 cylinder spark plug be sure to use thread sealer do not over tight let us know how it went, merry Christmas.

 

Would take it a step farther, hence pull the sensor, alligator clip to it with a multi meter set to ohms, then drop the sensor in a pot of water to start to bring the water up to boil to make sure that the ohm readings are changing at a constant rate.

Or just change it out since they are only like $15.



If the sensor checks out fine, then the problem is not the sensor, but a wiring problem in the car somewhere that is causing the instant jump back and forth. With the engine normally at 200, and then jumping down to 100, would be a short in the wiring system that is allowing the temp sensor wires to ground out (pray that it not all the way down line in the ECM with a voltage problems instead).



And just a FYI, but there is no coolant level sensor in the car. Hence you get the check fluid level message when the algorithms of the temp changes are way off isntead.

 

Many thanks to everyone!

Great advice and great forum.

I figured, that the coolant level warning could be set off by the temperature jumps, as that would be an important factor in the algorithm. It indeed appears that the sensor generally is able to read the temperature fine but gets an over voltage that brings the value way down. This is kind of confirmed as I now have a check engine light with P0118, which points to the sensor getting a too high voltage, so it is likely the sensor or a wiring issue. In the interest of my warranty, I almost hope for a wiring issue, so I will take it to another dealer. I assume the replacement of the sensor is a mess, if the system is not drained - aka coolant fluid will come out once I unscrew it, which would not be for me, as I promised (to myself) to never do any "wet" jobs myself.

As far as the pressure test of the coolant system goes, I wonder, if that dealer really did it, should it be a concern? Depending where you read, a replacement of the cooling hoses appears to be recommended around 75k miles, which my car has or is it fine as long as it is not dripping? Are there really just five hoses (T-HOSE, HEATER HOSES, CROSS OVER PIPE, (UPPER) RADIATOR HOSE, LOWER RADIATOR HOSE), plus clamps and coolant for the cooling side and the connection to the heater?

Many thanks and happy holidays!

 

Hello everyone,

I never got back with the outcome of my issue. I changed dealerships and the second shop was a lot more competent.

My issue, as it turns out, wasn't even the sensor but the wire harness or plug going to the sensor. According to the service manager, they just fixed the plug and all was good again. Apparently the plug was cracked and so, I assume, a short was created. I am not sure how exactly they fixed it, but they ether replaced the whole wire or reattached a new plug/connector for the sensor.

Secondly, there was a coolant leak, but it was so minor that it did not have anything to do with the other issue. Again, the second shop was a lot more competent about it. Instead of slamming me with the $1k+ bill for all hoses, they figured out that it was the heater hose and replaced just that. Stil $450 for a hose and labor, but I guess that is normal at a dealer shop. On the long run I might switch all (other) coolant hoses, but for now no more leaks.

For everyone in the LA area, my initial experience was with Nissini Brothers Chevrolet in Culver City. Definitely a never again, in my humble opinion. I went to Felix Chevrolet in Downtown next and they dealt with the issue a lot more competent. They addressed the issues I brought up and seemingly did an OK job on those. They do lack a certain amount of protectiveness and of course prices are through the roof.

 

I'm searching for an answer also. Two times the dash said engine hot, no ac. YET..... the temp guage was pegged on dead cold.
I changed the temp sensor for a short term fix.
did the rest on the dash to drop the warning but the coolant fans stayed on, and was too cold to check guage.
Recently changed to 160 thermostat to prevent overheated guides (just returned to service after preventative head repairs -2 exhaust galled/loose)

would be alarmed if engine was hot, it was not. Coolant levels dont change. Pretty sure I have it BLED correctly.

the factory manual states that the ecu reads the coolant temp sensor AND the mass airflow sensor to compare temps. If way off, it will generate a code. PO????

but, THAT DOES NOT EXPLAIN THE ERRANT TEMP INDICATOR.

 

Temp reading if from the temp sensor on the head.

Now actual temp sensor of the motor is easy to check as well.

So would say that you have an electrical problem in the wiring, and although the temp of the motor is not the problem, its the reading of the sensors due to electrical problems the cause of the codes/errors isntead.

So on that note, would check the connectors to the ECM and its ground point, as well as the connectors above behind the battery that leads down line, and wiring from point A to point B as well.

Hence straight shot from the ECM to most of the engine for wiring connectors,


But you have the C186, C180 and C166 (#3 and $4) connectors between the ECM and back of car/to the dash on some models as well.

Bluntly, with you living on the cost with higher salt water humidity in the air, it going to cause connector problems faster, and would dare to guess that the problem is one of corrosion on the connector in the series causing the problems.