Low coolant help
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1st Gear
Joined: Feb 2024
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Low coolant help
I’m just wondering if anyone had to replace their thermostat, or has had the same issue as i do. My temps were usually right at the 220 mark until one day it went up to about 240. I checked my coolant reservoir and it was almost empty. So i topped it off with coolant again, but after a week it was low again. The cars temp is now in the 150 to 200 range. I’m assuming the thermostat stayed in the stuck open position, that’s why it’s over cooling my car. It has been running fine and there no leaks. Just wonder if it could be something else. Thanks in advance
Melting Slicks
Joined: Sep 2021
Posts: 2,555
Likes: 1,213
A bad thermostat alone will not cause coolant loss.
It's leaking somewhere, you need to figure out where. Compression check might give you a clue if it's a bad head gasket you'll probably have lower compression in two adjacent cylinders.
Are you seeing any steam/white smoke coming out the tailpipe? Odds are the cats are catching any small leaks so you won't see anything amiss.
Pull the coolant reservoir cap when cold and start the car. Watch in the reservoir with a flashlight. Do you see any bubbles? Let the car run until the thermostat opens and keep watching. If you see a steady stream of bubbles it's from a cylinder pushing air into the cooling system.
It's leaking somewhere, you need to figure out where. Compression check might give you a clue if it's a bad head gasket you'll probably have lower compression in two adjacent cylinders.
Are you seeing any steam/white smoke coming out the tailpipe? Odds are the cats are catching any small leaks so you won't see anything amiss.
Pull the coolant reservoir cap when cold and start the car. Watch in the reservoir with a flashlight. Do you see any bubbles? Let the car run until the thermostat opens and keep watching. If you see a steady stream of bubbles it's from a cylinder pushing air into the cooling system.
Last edited by Dads2kconvertible; Feb 5, 2024 at 02:00 PM.
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Good luck finding the source of the coolant loss - hope it turns out to be an easy fix.
Melting Slicks
Joined: Oct 2004
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From: Sunnyvale CA
I had something similar a couple months ago. My car overheated and I discovered the overflow tank was almost empty. I filled it and when I checked it later it was almost empty again. I filled a second time and it has not leaked since. Don't know why it lost fluid but I hadn't been checking it regularly (and just did with no problems) so it could have happened over a long period of time.
A couple weeks later my water temp started periodically reading zero, Rev. Matching stopped and fans ran on high when turning off the engine - classic signs of an open thermostat (thanks CF for that knowledge). I had the thermostat replaced and have not had any problems since.
A couple weeks later my water temp started periodically reading zero, Rev. Matching stopped and fans ran on high when turning off the engine - classic signs of an open thermostat (thanks CF for that knowledge). I had the thermostat replaced and have not had any problems since.
