Stupid Question
Thread Starter
Instructor
Joined: Nov 2020
Posts: 130
Likes: 41
From: Central/West, NJ
Stupid Question
I have a "Low Coolant Level" warning light on in my 1990 C4 (L98). I assume that it is a float sticking in sensor, which I believe is in the high coolant tank (upper R/S of firewall). Plan was to drain and remove the tank and then clean it out, hoping to free-up the sticking float. I can't even get the damn cap off the tank. It appears to be a standard 17# radiator cap. The arrow is aligned with the vent tube when closed. I can turn the cap about 30 degrees counter clockwise, to the point that it pops-up, but it won't come free of the neck of the tank. Is there a trick? Is the cap defective? Am I just too weak at my advanced age? This project got halted before it ever got off the ground - HELP?!?
cueguy
cueguy
Thread Starter
Instructor
Joined: Nov 2020
Posts: 130
Likes: 41
From: Central/West, NJ
I thought I had, but apparently not hard enough. Put some weight behind it this time and it came off. Thanks. Tank is drained. Top two vent hoses are off and having a hell of a time getting the two bottom hoses (with spring clamps off). Also can't figure out the release for the electrical connector for the sensor. But we will prevail. Thanks for the helping me past my stupidity.
cueguy
cueguy
Melting Slicks
Joined: Jul 2005
Posts: 2,651
Likes: 864
Removing a hose that's been clamped in place for 30 years is frequently "problematic".
rocco16's suggestion to use a hair dryer is certainly worth a shot. (I assume that you were able to get the spring clamp "off".) Many pros use a pick with a 180 degree bend in it that will get between the hose and the fitting and free it up a little bit at a time (see link below). I've had some luck twisting the hose to break it free - using channelocks - but that can break the hose barb on the tank if the hose is really seized. I'm not sure about the L98 hose routing - but you could also look at disconnecting the other end of the hose...
rocco16's suggestion to use a hair dryer is certainly worth a shot. (I assume that you were able to get the spring clamp "off".) Many pros use a pick with a 180 degree bend in it that will get between the hose and the fitting and free it up a little bit at a time (see link below). I've had some luck twisting the hose to break it free - using channelocks - but that can break the hose barb on the tank if the hose is really seized. I'm not sure about the L98 hose routing - but you could also look at disconnecting the other end of the hose...
Pro
Joined: Mar 2007
Posts: 596
Likes: 355
From: Mt Prospect IL
2025 C4 of the Year Finalist - Unmodified
All good recommendations for removing the hose, I use a cotter key removing tool and slide it between the hose and the barb.
I just looked in Identifix and it says the low coolant sensor is in the radiator tank on the passenger side.
Good luck with the repair 👍
I just looked in Identifix and it says the low coolant sensor is in the radiator tank on the passenger side.
Good luck with the repair 👍
Thread Starter
Instructor
Joined: Nov 2020
Posts: 130
Likes: 41
From: Central/West, NJ
Mission accomplished....almost. I went out and bought a pair of locking spring-clamp pliers. Still not easy, but much better than any of the alternative methods I was trying. Hoses really didn't present a problem and once the tank was free of the hoses, it was easy to see the release for the electrical connector for the sensor.
Shook the tank and there was no rattle at all, so the float was stuck. Used hot water and dish detergent, agitated and drained a number of times. Did get a fair amount of crud out of there and the best part, after the wash/rinse/repeat, was that now I could hear the float rattle when I shook the tank. Paydirt. I let the tank dry overnight and today put everything back together (much easier than coming apart).
With great anticipation, I fired it up. Mmmmm, light is still on. Take it for a drive and let it come up to temperature - still on. Does this need to be reset? Is there a reset procedure? I'm right back to square one.
cueguy
Shook the tank and there was no rattle at all, so the float was stuck. Used hot water and dish detergent, agitated and drained a number of times. Did get a fair amount of crud out of there and the best part, after the wash/rinse/repeat, was that now I could hear the float rattle when I shook the tank. Paydirt. I let the tank dry overnight and today put everything back together (much easier than coming apart).
With great anticipation, I fired it up. Mmmmm, light is still on. Take it for a drive and let it come up to temperature - still on. Does this need to be reset? Is there a reset procedure? I'm right back to square one.
cueguy
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
5 Best & 5 Worst Corvette Daily Drivers
Joe Kucinski
The Headlights of Every Corvette Generation Explained
Joe Kucinski
5 Best & 5 Most Overrated Corvette Track Packages of All Time!
Joe Kucinski
Every 2027 Corvette Engine Explained
Joe Kucinski
Designer Imagines A Corvette That Looks More Like a Corvette Than the Corvette
Verdad Gallardo
10 Ugly Corvettes That We Still Kinda Love
Joe Kucinski
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
Burning Brakes
Joined: Aug 2018
Posts: 891
Likes: 175
From: PA
I bought a pair of Craftsman remote hose clamp pliers. Sometimes you don't have enough room for the pliers and the remote clamp tool works great. It certainly has saved me some grief over the years.
Advanced
Joined: Feb 2017
Posts: 66
Likes: 26
From: New Zealand
Don't know if this is any help, but I had a persistent Low Coolant warning on my '88 following a radiator flush. After 'burping' the coolant system a couple of times all was fixed. It seems that there can be airlocks that cause the problem (in my case).
Intermediate
Joined: Mar 2006
Posts: 33
Likes: 1
I'm having the same problem with low coolant warning coming on after replacing my radiator and heater control valve, it comes on when the thermostat opens at 180~190
I burped it maybe 5-7 times but light comes on right after the thermostat opens. I have new coolant switch sensor I even checked for leaks using radiator pressure tester
still no luck. Also I replaced the radiator cap with 16PSI cap.
I burped it maybe 5-7 times but light comes on right after the thermostat opens. I have new coolant switch sensor I even checked for leaks using radiator pressure tester
still no luck. Also I replaced the radiator cap with 16PSI cap.