Car overheating until I add coolant

Hi guys.

Having an intermittent problem on my 2002 Chrysler Sebring LX (about 132,000 miles). Often I can drive around and everything is okay. However, it seems like every 11 days or so, the temperature gauge starts to climb above the halfway mark and toward the danger zone. Only once has it gotten all the way up to the red danger zone and illuminated the warning light, and that was the very first time. It was fortunate that this happened the exact moment I reached home and parked in my driveway.

When the temperature gauge starts to climb above the halfway mark, I’ve tried to turn on the heater to cool it down, but this doesn’t work. The heater just blows cold air. So far I have been taking the following steps:

  1. Stop driving and park the car for 10 minutes or more.
  2. Fill the coolant tank under the hood with coolant. I’m putting in about half a gallon each time.
  3. Continue driving.

After this process, the heater is again blowing warm air and the temperature gauge is staying at a safe level. It seems to persist for about 11 - 14 days then the cycle starts all over.

It happened last night following a drive of about 5 miles home from the gym. Since I had no more driving to do that day, I just parked it overnight to see if this was a fluke and if it would be necessary to add more coolant.

This morning I drove the same 5 miles. Temperature gauge stayed pretty low for about half the trip, but then rapidly shot up. I got to the gym before it reached the danger zone (it was probably about 3/4 of the way up). I parked for a little over an hour while I went inside to exercise. Then I again added half a gallon of coolant and drove home without problems.

Any thoughts? The last time I had overheating issues, the coolant rapidly spilled out of the bottom and the overheating was not preventable. I got the radiator replaced. This was in October 2013. I’ve also tried some of that stop leak fluid. It didn’t help, but I’m not so sure I used it correctly. I didn’t flush the tank and I think I might have poured it in on a normal driving day (coolant pretty full).

You are losing coolant. The fix for this problem is to find out why the coolant is disappearing. It can be something as simple as a bad radiator cap or something far more sinister like a blown head gasket. You need to find a good independent mechanic to get the problem corrected before you crack a cylinder head or engine block. You have been lucky so far but your luck will run out eventually and you will be facing larger repair bills.

Classic blown head gasket symptoms.

+1 to the preceding comments.

Step #1 is to add coolant to the radiator, rather than the overflow tank, when the radiator is totally cooled down.

If coolant has to be added again w/in a few days or weeks, then–yes–there is a leak, either from the radiator or the hoses, or in the worst case scenario the engine is “burning” coolant that leaks into the cylinders via a breached head gasket.

Isn’t a cracked head gasket already pretty expensive?

Also don’t you usually see white smoke coming out of the tailpipe when this happens?

I know a good mechanic, honest and competent guy who I trust. I’m hearing that blown head gaskets are pricey but there may be some hope and I can just pour bottle of $40 Blue Devil Head Gasket sealant if this is the problem. Anyone have experience with that?

Check your oil. If it looks creamy/white then you definitely have coolant going places it shouldn’t be going aka blown head gasket. Those “head gasket repairs in a bottle” are just bandaids that don’t always work. They are not a replacement for fixing a mechanical problem. If this is a vehicle that is in otherwise stellar shape, I would consider getting a quote on an actual head gasket change. They might also have to send the head out to be machined in the event it was warped due to excessive temperature, but that’s on a case by case basis.

Isn’t a cracked head gasket already pretty expensive?

Not compared to a whole new engine. That could be the path you’re on if you continue to ignore the problem. Nobody can know from a distance why you’re losing coolant. There are a number of possible causes ranging from inexpensive on up. One thing is for certain, these things never get better with time and use…

Well I just dropped it off at the mechanic.

To address everyone, but Billfrank85’s response in particular: I said to take a look and give me an estimate, but if it is a head gasket problem I might not go through with the repair and try the Blue Devil stuff. This car is old, has been giving me a lot of trouble the past few years, and every repair must be weighed against the possibility of another costly repair soon. It’s like an elderly parent who you tell the doctors “see what you can do, but no extraordinary measures”.

Mechanic isn’t really sure what’s wrong. He said he ran a pressure test doesn’t see any apparent leaks. Said it might be the water pump but no confidence in that.

Gonna try Blue Devil and keep an eye on it. Might just get a new car.

Doesn’t a bad head gasket usually have other symptoms? Like white smoke from the tail pipe and milky white color in the oil? I haven’t seen any smoke coming out of the tailpipe and the oil on the dipstick looks like the brownish-black I’m used to.

Do you think it could be the thermostat?

Doesn’t a bad head gasket usually have other symptoms?

Yes, but they can be masked.

For example, the gasket can fail in a way where the coolant is slowly consumed by the engine’s combustion process. No smoke out the tailpipe doesn’t mean moderate amounts are not being burned. The cat converter can mask some of it as well. The true indicator of long term exposure is to pull the spark plugs. Any with bright white ceramic insulators are usually definitive evidence of coolant consumption.

It may not even be a head gasket leak. It could be dripping on the ground or vaporizing on a hot manifold. A half gallon every two weeks is a moderate consumption rate that may not present obvious external clues to the casual observer.

It’s probably safe to say, if that amount was going into the oil, that would be obvious by the condition of the oil so it’s not likely going there.

Any mechanic suspecting a head gasket breach should run a sniff test at the radiator cap, not just a pressure test. A sniff test uses equipment that can detect the presence of combustion gases in the coolant jacket.

A stuck thermostat could cause a boil-over, but that would be obvious.

Try this:
Begin with the engine stone cold.
Remove the radiator cap and fill the radiator. Replace the cap.
Feel the top hose. Note how soft it feels.
Start the engine and as it warms up look carefully around the radiator and water pump for drips or squirts.
I’ve seen water pumps dribble a bit then stop as they heat up.
The hose should get firm before it gets hot. If it doesn’t get firm the system is not building pressure.
A bad radiator cap can keep the system from pressurizing.
Without pressure it’s possible for the engine to boil over after you’ve shut it off and walked away, due to hot spots.
Take a whiff of the exhaust. Does it smell sweet?

I never had white smoke with my head gaskets. Just overheating and cold air out the vents. I nursed it home 30 miles once with the radiator cap off. I was never satisfied with the long term fix of replacing the gaskets and everything else that went with it like machining the head, checking for cracks, doing the valves etc. I think maybe its time to put this one to sleep since you said its old anyway.

Mechanic said he was doing some sort of test to check for a head gasket, and it passed. But he didn’t seem particularly confident that the test was conclusive. Maybe I need a second opinion.

Now I really wish I hadn’t gotten those 2 new tires last week… How transferrable are wheels?

First thing you need to do is check the coolant level every morning and add coolant as needed. If you continue to drive it and wait for the temperature gauge to rise before checking it, you will blow a head gasket if you haven’t already.

You are losing coolant so the problem is not a thermostat. You need to find the leak. It could be anywhere. Your mechanic could add a dye to the coolant that will show up under a UV light. Even if the coolant has dried, the trail will still show.

I would look at the heater hoses, sometimes those are over looked. You could also just have a cracked overflow reservoir or a leaking water pump. Check the little hose between the radiator and the overflow reservoir as well. It could be something cheap, or very expensive.


So the mechanic did a block test, and the test fluid did not turn yellow

Well, he’s right in that those tests are not always 100% conclusive

Still sounds like a possible breached head gasket

here’s an idea . . .

Get the engine up to operating temperature and drain the oil into a tub

if there’s water and/or coolant in there, you will know

I’ve worked on some vehicles where coolant was getting into the crankcase, yet the oil on the dipstick looked just fine. But when the oil was drained into a tub, it clearly was contaminated with coolant

Brownish black oil!!!

When was the last oil change on this thing …miles not decade!!!

I have no faith in the miracle in a bottle either. It may fail at a less fortunate time and place.
I’d get it fixed right. Have the mechanic retest it. I’ve had a few that the pressure loss is not negligible untill it’s been on the gauges for a few hours.


If you can drive it for several days after filling up the system and it does not overheat, then I think the head gasket is probably good and you just have a leak. But you need to find that leak and stop waiting until the gauge rises before checking the coolant level or you will need a head gasket.

Checking the cooling system to see if it holds pressure was a good idea. Sounds like it does. The head gasket does a lot of stuff, keeps the combustion gasses inside the cylinder until they get vented by the exhaust valve, keeps the oil from getting into the coolant, and keeps the coolant from getting into the oil. So there’s a couple of other things – besides looking for white smoke out the exhaust – you can do if a head gasket breach is suspected.

  • Remove the radiator cap and see if there are any signs of oil or viscous gunk on the inside surface.

  • Remove the oil filler cap and see if there is a milky looking gunk on it.

  • Peer into the radiator (wear protective glasses, even better a full face shield) when the engine is idling and see if there are any air bubbles (actually they’d be exhaust gas bubbles) coming up to the surface from below. Bump the rpm a little, see any now?

  • Try a chemical test kit for exhaust gasses in the coolant.

You may or may not have a head gasket problem, but until you discover the source of the loss of coolant it’s going to be difficult to diagnose the problem. The no-heat from the heater symptom is usually caused by either a low coolant level or air in the cooling system. Both can cause overheating too. Do you see any coolant leaking onto the ground?

Edit: FYI, In a situation like this, when checking the fill-level of the cooling system, that should be done at the radiator, by removing the cap, not at the plastic overflow bottle. On a properly filled cooling system the coolant level will be right at the top. Don’t remove the radiator cap until the engine has cooled off of course.