My C4 overheating problem w/solution
Thread Starter
Burning Brakes
Joined: Dec 2017
Posts: 1,043
Likes: 414
2023 C3 of the Year Finalist - Modified
My C4 overheating problem w/solution
Just figured I’d share in case someone else encounters the same problem.
ive had my c4(1994) for about 6 months now, and have put 2k miles on it.
it was holding temp just fine since I’ve owned it, but last time I drove it, it got up to 243 digital and analog was past 260. boiling coolant was entering the overflow tank and steaming off.
Got it home and started exploring when it cooled down.
I noticed the pressure tank had some evidence of leakage from the cap. The overflow tank had some liquid, but it was very low. Upon inspection the rubber gasket around the cap was in poor condition.
I ended up adding 1.75 gallons of coolant to it, and I replaced the cap. Problem solved, holds temp great again.
what I speculate has happened is that the cap was leaking some, allowing coolant to leave as steam. Small enough of a leak that it wasn’t noticeable driving/idling. Over time it lowered coolant levels until the point that it’s started heavy boiling and then a lot of coolant was lost.
it’s the only thing I can figure since it doesn’t leak coolant, the oil is just oil, and it’s not burning it(no smoke of any color from the exhaust)
If you’re having overheating problems, check the cap!
ive had my c4(1994) for about 6 months now, and have put 2k miles on it.
it was holding temp just fine since I’ve owned it, but last time I drove it, it got up to 243 digital and analog was past 260. boiling coolant was entering the overflow tank and steaming off.
Got it home and started exploring when it cooled down.
I noticed the pressure tank had some evidence of leakage from the cap. The overflow tank had some liquid, but it was very low. Upon inspection the rubber gasket around the cap was in poor condition.
I ended up adding 1.75 gallons of coolant to it, and I replaced the cap. Problem solved, holds temp great again.
what I speculate has happened is that the cap was leaking some, allowing coolant to leave as steam. Small enough of a leak that it wasn’t noticeable driving/idling. Over time it lowered coolant levels until the point that it’s started heavy boiling and then a lot of coolant was lost.
it’s the only thing I can figure since it doesn’t leak coolant, the oil is just oil, and it’s not burning it(no smoke of any color from the exhaust)
If you’re having overheating problems, check the cap!
Melting Slicks
Joined: May 2014
Posts: 2,891
Likes: 591
From: New Port Richey FL
It's good to check whole system integrity, but you're though of it creeped down to a failure has merit but your Low Coolant light would have screamed at you before you had a melt down.
But now you have the system full and sealed and hopefully circulating, you may want to check the front radiator under the bumper and the space between the AC and Radiator it is very common for road debris to build up and block the air flow
But now you have the system full and sealed and hopefully circulating, you may want to check the front radiator under the bumper and the space between the AC and Radiator it is very common for road debris to build up and block the air flow
Drifting
Joined: Nov 2021
Posts: 1,732
Likes: 385
From: People's Republic of Nueva York
Keep in mind that the pressure in the system raises the boiling point of the coolant. I've gotten away with compromised systems before, but on vehicles that operated at 180-195°. These things normally operates over 200° which becomes pretty marginal for coolant by itself. So, as the previous post stated, make sure the system isn't losing pressure or coolant, or you will have a repeat performance.
Thread Starter
Burning Brakes
Joined: Dec 2017
Posts: 1,043
Likes: 414
2023 C3 of the Year Finalist - Modified
It's good to check whole system integrity, but you're though of it creeped down to a failure has merit but your Low Coolant light would have screamed at you before you had a melt down.
But now you have the system full and sealed and hopefully circulating, you may want to check the front radiator under the bumper and the space between the AC and Radiator it is very common for road debris to build up and block the air flow
But now you have the system full and sealed and hopefully circulating, you may want to check the front radiator under the bumper and the space between the AC and Radiator it is very common for road debris to build up and block the air flow
