Since CP4 Replacment, Funny Cooling

[classic72]

Since CP4 Replacement, Funny Cooling

I noticed after I got my truck back that I was very intermittently getting a "check coolant" warning on startup. We are talking only about once a week and I have a lot of starts in my truck so that not often at all.



I checked the fluid both cold and hot and everything was fine and gauge readings were normal. It has been this way for over a month now.



Today I was driving and heard a ding, looked down... overheat warning and something about "idle". Within 3 seconds was into a gas station with motor off. I sat for a few minutes then started and pulled into shade (no overheat warning this time).


I checked under the hood -- coolant again appears to be good on levels. I take the cap off reservoir (no pressure release sound) and can also see fluid in the spout. No boiling, no hissing, nothing from the truck. I checked the upper radiator hose and it's limp and easy to squeeze.


I wait 10 minutes and drive home about 3 miles, no overheat issues, but now the gauge won't leave it's lowest setting of 160.


My guess is thermostats, but I called dealer and he said they removed all coolant and lines when they replaced CP4 and thinks it just needs to be bled -- "Duramax are bad about it".


Just curious your thoughts? I can't get it in to dealer until Tuesday and need my truck for the weekend for trailer use. Where is the bleed valve on the LML... the videos I found are all older DMAX.


Any ideas?

 

[Chevy1925]

Sounds like they either didn’t click the coolant sensor plug all the way in or broke a wire for the sensor

 

[classic72]

Where is it located so I can check? My temp needle is nuts... 160-260 back and forth. Did an infrared thermometer on the part where thermostats are located and am getting 162 degrees after truck has been idling for 20 minutes.

Thanks!!

 

[2004LB7]

Bottom of the reservoir

 

[Cougar281]

Bottom of the resivoir/surge tank is the low coolant sensor. Temp sensor is up near the thermostats.

Sent from my 2PZC5 using Tapatalk

 

[classic72]

Well I thought I found it, unplugged what I thought it was but guess not as gauge still jumps all over. There is a smaller rubber hose on top of motor that transition into aluminum or metal as it goes into block. In the metal part sticking straight up is the sensor I thought?

 

[TheBac]

Look on the bottom side of the overflow (surge) tank. As Cougar said, thats the level sensor.
If your temp sensor was going bad, IMO your truck wouldnt run worth crap. But, if you want to check it anyways, as Cougar said (again), its on the middle top of engine, next to the T-stat housing (follow the upper rad hose to where it enters the engine).

 

[2004LB7]