• The site migration is complete! Hopefully everything transferred properly from the multiple decades old software we were using before. If you notice any issues please let me know, thanks! Also, I'm still working on things like chatbox, etc so hopefully those will be working in the next week or two.

Low coolant light off and on

Brammer

Brammer

New member
My 2002 GTP has been having the low coolant light come on and turn back off multiple times while driving, in addition the temperature will range from normal to 3/4 of the way up the gauge after it's warmed up. 2 years ago I did the LIM job with aluminum elbows and all has been well since then, this is a new development. I've added coolant to the reservoir as well as topped of the rad when the car was cool. Any other ideas?
 


The coolant light is going off and on while driving. After I let the car cool down the other day I added some coolant into the reservoir and uncorked the radiator and added maybe 8oz of coolant directly to the radiator. Didn't make any difference, driving right after, I was still getting the coolant light coming on and going off with temperatures fluctuating as well.
 
take it out and clean it or replace it, level sensor in the rad. take the pass side head light out and you can see it in the side of the rad tank.

or just unplug it and never see the light again.
 
Scottydoggs said:
take it out and clean it or replace it, level sensor in the rad. take the pass side head light out and you can see it in the side of the rad tank.

or just unplug it and never see the light again.
Click to expand...

Do I not need to be concerned about the uptick in temperatures and how much they are fluctuating?
 


that was the part of is it low every time you check it?

if you sit and idle temps go up, drive they drop. if its hot driving on the hwy or goes up and down driving you might have trapped air.
 
Sorry Brammer, I didn't see the part about your temperatures. Scotty is right. Usually this is caused by trapped air. I chased this for months and used the correct bleed procedures and everything from the factory service manual with no avail! Finally had a tech do one of those fancy "negative pressure" fills and haven't had issues since. (although I should say this is a bit different because this is after rebuilding my engine from scratch and it was dryer than a bone when I started, so might not apply here).

P.S. ONLY use the bleed screw with the engine OFF!

If it still has issues, and it's not leaking at all after being bled properly, I'd suspect water pump failure or a clog somewhere.
 
wstefan20 said:
Sorry Brammer, I didn't see the part about your temperatures. Scotty is right. Usually this is caused by trapped air. I chased this for months and used the correct bleed procedures and everything from the factory service manual with no avail! Finally had a tech do one of those fancy "negative pressure" fills and haven't had issues since. (although I should say this is a bit different because this is after rebuilding my engine from scratch and it was dryer than a bone when I started, so might not apply here).

P.S. ONLY use the bleed screw with the engine OFF!

If it still has issues, and it's not leaking at all after being bled properly, I'd suspect water pump failure or a clog somewhere.
Click to expand...

You may have been chasing your tail with the trapped air due to your own advice...engine should be running when using the bleed screw on the t stat housing!
 
231FUN said:
You may have been chasing your tail with the trapped air due to your own advice...engine should be running when using the bleed screw on the t stat housing!
Click to expand...

Not according to the GM dealer tech that I talked to, or the factory service manual I have right in front of me...

Makes sense why not with the engine running. The bubbles are going to be pumped straight past the orifice and back into the system
 


wstefan20 said:
Not according to the GM dealer tech that I talked to, or the factory service manual I have right in front of me...

Makes sense why not with the engine running. The bubbles are going to be pumped straight past the orifice and back into the system
Click to expand...
Regardless of what the tech or the GM manual says W body/3800 folks have been doing it this way for years...it's what works! Bubbles are going to travel to the highest point which is straight out the bleeder on the t stat housing when the t stat is OPEN with engine RUNNING at temp...that's what makes sense
 
Ehh.... Engine hot so T-Stat is open.

Engine off.

The water pump will foam the air into the coolant, and it *air* won't come out of the bleeder, just a little foam....

1) But Yeah: First is it actually low on Coolant?

Listen for the waterfall sound under the dash when starting cold. Trapped air in the heater core being displaced means Low Coolant.
A radiator that takes more than a quart of coolant, means Low Coolant.
Coolant disappearing from a refilled overflow tank means it <the cooling system> is leaking, or not yet full, which means, Low coolant :)

2) If it's not low, or consistently taking more coolant, is there air trapped in the system? Bleed it. Engine warm, engine off.

I open the bleeder, and squeeze and hold the rad hose to force air out. Then tighten the bleeder with one hand then release the hose. Milks coolant into the system. Restart the engine for a few secs, Engine off. Let in sit for a minute, then repeat, open bleeder, squeeze hose....do that 3 times or until you squeeze the hose and clean coolant squirts out. That's usually enough to get the major air pockets out.

3) So it's not low on coolant, and you think most of the air is gone...but the engine is hot, the gauge still says it's too hot.. but cold radiator, and/or cold hoses?.... means *No Flow* Bad water pump, stuck t-stat or a blocked radiator.

That's what I would check first. If it's not Dexcool gunked or the blades aren't corroded off the water pump... oil in coolant, or the oil looks like a milkshake... Then I would start worrying.
 
Last edited:
You must log in or register to reply here.
Back
Top