thoughts on replacing the low coolant sensor?

"Mike" wrote

It's not real difficult. You simply need to unhook the wire clip that holds it in place, and pull it out of the rad. On those vehicles, the hardest part is getting other things out of the way, so that you can reach the sensor.

Ian

Am I going to get a Dexcool mess while doing this? It looks like my big hands will have some problem, but with this engine the low coolant level sensor is a must have! Thanks Ian, I knew I could count on you.

"Mike" wrote

You might lose a bit of coolant, you can open the rad drain c*ck if you want. I just put a pan under the sensor side of the rad and catch what little drains out.

Ian

Ian, Having never seen one of these, I'm curious.... How is it that it sits inside the radiator, and is connected to wires outside the radiator, and is still simple to remove with only a small mess and no convoluted gasket problems and doesn't leak? NPT threads?? GW

shiden_kai wrote:

You might lose a bit of coolant, you can open the rad drain c*ck if you want. I just put a pan under the sensor side of the rad and catch what little drains out.

Ian

If you are loosing antifreeze you better have the lower intake manifold gasket checked. Next stop is busted cam and corroded engine. This is a major problem on the GM 3400 engine. Do a google search on GM3400 and read the horror stories on this engine. I did the research after the dealer wanted to change the gasket for $800 and wouldn't explain why. I now check my level daily and watch for oil changes and crud on the oil fill cap and dipstick....

I am painfully well aware of the 3400 problems. My levels are fine and the low coolant level light is on, so I need a new sensor. End of story. I am thankful that you are spreading the word on these POS engines. I have alienated many people in my "bull headed" pursuit of "Goodwill" from GM. I figure for every person I help catch this problem during the warranty period, I win. The way I figure, $326.50 of goodwill would have eliminated thousands of dollars of warranty work I have helped owners recover.

The only reason I am holding this 3400 is in hopes of GM making me whole with a recall. It will be gone however by winter.

GeeDubya, it probably looks like an engine temp sensor. They usually have pipe threads. Unscrew the old sensor, quickly screw in the new sensor and hardly any coolant should get out.

"Geoff Welsh" wrote

The radiator has a small round hole. The sensor has a small tube with two o-ring seals. It just slides into the hole and is retained by a clip that is on the sensor and engages a section of the radiator. The sensor tube is hollow and allows coolant into the sensor section where it senses that there is or isn't coolant at that level.

Ian

-- GW - Conservational Ergonomist - note incorrect email address "It's good to yell at people and tell them you're from Tennessee. That way you'll be safe." - Gary Busey

"Geoff Welsh" wrote

Yes, the sensor sits on the outside of the passenger side radiator tank.

Ian

Service Manual instructions

1. Drain antifreeze to below sensor.
2. Remove sensor electrical plug.
3. Lift one leg of the retainer and pull outward with a twisting motion.
4. ensure that the coolant level module seal is not damaged.
5. Lubricate new module seal with coolant
6. Ensure retainer is installed correctly and install module.

Replaced the "module" today to the tune of $41US. I am pretty sure the clip is on right. I had to move both ends of the spring clip up above the slots they fit in and once I thought the sensor was as far in as it was going to get, I snapped the top clip down into place and that clipped the bottom one too. No leaks yet and low coolant level light stays off now. The old sensor looked like it had an oily crud all over it. I cleaned it all up with simple green and it looks just like new. Do you think it will work again Ian? Thanks for the info too!