had my truck out today for a 150 mile trip and all was ok, but later on this evening i fired the truck up and noticed that the low coolant lamp was on. i checked the coolant in the surge tank and it was at the full cold level . there were no signs of coolant on the engine or on the ground. the sensor on the surge tank is connected.. is there any other low level sensors i should be looking for?? i recently changed out the thermostat and changed the dex-cool and filled the surge tank to the full level and i can't figure out why the lamp came on.:mad:

Thanks in advance for the replies
Kevin

2002 GMC 2500 C/C SLT Bone Stock Except for Edge/attitude

I'd just open the radiator cap when the engine is cold and top it off. Just make sure you haven't put too much in the surge tank to have some room when the engine warms up. If you don't have room you'll be spilling dex-cool on the ground. Not a big deal just makes a mess.

from what i can tell there is no rad cap... only cap is the one on the surge tank and the when the engine is off and cool the surge tank is full to the full cold line

ok so this morning i went out to the truck.. checked the surge tank and the level is still up to the full cold mark.. fired up the truck and within 5 minutes, the low coolant lamp came on, so i unhooked the connector and took a piece of mechanics wire and jumper the terminals on the plug and the light went out.. so that should tell me that the sensor is screwed correct?? called the local stealer and they told be that it is an non-serviceable part . i would have to replace the surge tank itself for the low low price of 75.00 (CDN) and change.. will look for a used one from one of the local wreckers i think.

Kevin

If you have a decent level in the surge tank it likely is the sensor. I would want to find the radiator cap and have a look just too be sure. though. $75.00 for a plastic surge tank and a sensor is ridiculous. I'd be doing the same thing and looking for one at the wrecker first.

rock shoes,

The Duramax has no "Radiator Cap" per se. The only cap/access to the cooling system is through the cap on the surge tank. It a screw on cap that is pressure rated to 15 psi IIRC. It also acts as a vacuum break to allow air back into the cooling system as it cools after the engine is shut down.






Gary

Makes a whole lot more sense as to why flipper75 couldn't find a rad cap.:rolleyes: Never done any work on a D-max so that's good to know. How do you fill the radiator when you change the coolant? Do you just dump it in the surge tank and wait for it to bubble down? Maybe fill it most of the way from the upper rad hose?

you fill the rad through the surge tank .. you loosen the front bolt on top of the thermostat housing until you get a steady stream flowing out the hole then put the bolt back in and fill the surge tank the rest of the way to the full cold line. this afternoon before i went to town i plugged the sensor back in and the low coolant light hasn't come on since... got me confused... anyways no light is a good light...lol

Merry Christmas to all!!

Kevin

Maybe just a good ol' self fix, we like those kinds in the aircraft industry, Could not duplicate, and no more discrepency, ie.. reset system operational check good, kinda like disconnecting the battery cable for 10 minutes...........

Mine went goofy today also. Drove to work ~22 miles and all is fine. Left for lunch and while sitting at a stop light low coolant lamp came on. Surge tank had plenty of coolant and no evidence of leaks anywhere. When I left to come home everything was fine again.:think:

How do you fill the radiator when you change the coolant? Do you just dump it in the surge tank and wait for it to bubble down? Maybe fill it most of the way from the upper rad hose?

you fill the rad through the surge tank .. you loosen the front bolt on top of the thermostat housing until you get a steady stream flowing out the hole then put the bolt back in and fill the surge tank the rest of the way to the full cold line. Kevin

Here's the filling procedure from 2002 Helms:

-Fill system throught expansion tank, with premixed 50 to 60% solution, to a level slightly above tank split line.
-Start engine.
-Idle engine 1 minute.
-Loosen tank cap. Do not allow the system pressure from building.
-Vary engine idle in 30 second intervals, until coolant temp reaches operating temp and the thermostat opens.
-Stop engine.
-CAREFULLY and SLOWLY remove tank cap. Avoid the hot coolant.
-Start engine.
-Idle for 1 minute, then fill tank level to 1/2 inch above cold full mark.
-Install tank cap, and cycle idle until at coolant operating temp.
-Monitor tank level over the next several cool-downs, and fill tank as necessary.

Any gas in system is supposed to be exchanged with coolant, as the coolant contracts while cooling down. Watch your expansion tank level for the next week or so, and add new coolant as necessary.
When your system is gas free, your expansion tank level will rise when heating to operating temp, and your upper rad hose will be hard, with system pressure near 15 PSI.

Thanks for the info modified. It's all good to know as my next truck will either be a Duramax or a Cummins.

Sometimes the sensor can get stuck on. This sounds harsh but pounding on the resevor tank should put the light out. Not sure why it would come on but if that is part of the problem it is a fix. Working at a Jiffy Lube and doing Radiator services we have ran across that fix and has worked most of the time. There are some stubbern ones out there that wont allow it to work on.