Happens every few months. Engine overheats. Does not on highway. Coolant Res empty

[crewxp]

This happens every few months, especially when it gets hot for the first time. My engine overheats when I'm city driving or at lights a lot. When I'm going city to city on the highway, it never overheats. The moment I get off the highway and get stuck at a light, it overheats. My res is empty, but I keep filling it up everytime I see it empty with Prestone Dex 50/50. It keeps overheating for a few weeks then works fine until the res is empty again in a month or two. The only time I check the res is when the car is hot and I have to pull over. Is it normal to be empty when hot?

Any suggestions on what to check? I've brought it to 2 shops and they say everything is fine and just offer to flush the system and put coolant. I want to learn how to diagnose myself.

I just had the coolant flushed 4 months ago. No signs of coolant coloring under the car, could be that it dries too fast. I hear the fan go on once the coolant temp reaches 225.

2010 Camaro. 60K miles.

[Vegas Bound]

I don't know what stock programming is for the fans, but 225 sounds high for stop and go driving in TX. My fans are programmed to come on full speed at 160. I never get above 200 degrees in stop and go traffic.

[Dizzy82]

If the coolant reservoir is bone dry you have a leak somewhere. I had the same issue, every couple of months the overflow tank would be empty. Turns out I had a head gasket leak. I would get your engine pressure tested.

[KenKat]

Agree on the leak comments.

Sometimes you can get a very small or steam leak; it never leaks enough to drip onto the ground but when it gets hot and gets up to pressure, it will leak and quickly vaporize. You can sometimes find it by smell or use a bright, led style flashlight and look for vapor around the radiator, hose joints, etc.

If you can get somebody to help you, look up at them and say “you smell that?” and give a knowing look. (this last part is a joke if it isn’t obvious)

['10CamaroDude]

If your radiator cap is failing, and not keeping pressure, that coolant escapes
into the reservoir, and over-flows. So, when the car cools off and the coolant
is pulled back into the motor, the over-flow is emptied.

I had a bad cap, and that's where all my coolant went, right out the over-flow.

Verify the O-ring is good, and that it's holding pressure. A sign of a bad cap
will also be a collapsing upper radiator hose. That was also a result of a cap
that was not holding any pressure.




UPPER RAD HOSE COLLAPSED:



Check the over-flow for dripping and wet spots.

Check the upper rad hose for firmness when hot, for pressure.

While driving, watch your temp gauge for 220+ degree readings, then a drastic drop.
That is when the thermostat opens with the low coolant.

If you have no visible leaks, then you will need to do a pressure test, for a bad
head gasket.

[Vegas Bound]

Ditto on the rad cap. My upper hose lost pressure after drives. Replaced cap and all was fixed. I decided to change the t-stat and fluid in the rad at the same time. 7 years old, it couldn't hurt.


BTW, get an AC Delco cap. I tried a NAPA cap first and the psi was wrong eventhough the specs said it was the same.

[crewxp]

thanks guys for the replies. I bought a gallon 5050 mixture and filled it up cold. Following the manual's instructions, I seemed to have topped the radiator off.

It took 3/4 of a gallon to fill the block/radiator. If I was missing this much, does anyone know how bad it was? I then used the rest of the bottle to fill the overflow tank.

I'm going to monitor it for now and buy a coolant pressure kit to test in a week or so.

I was also low on oil, dipstick was completely dry except for the very bottom, but I just had the oil changed 2 months ago. No oil warnings on the dash either. Can overheating cause a loss in oil? Heading to the store now to buy 2 quarts or so.

Pics below:

[Vegas Bound]

Replace the cap, the O-ring gasket is shot.

[Dizzy82]

Please, please check your fluids every time you fill up on gas. Doing this will keep you in the loop with potential future issues. My radiator fan usually kicks in around 220, those temps are concerning.

[mikeman]

Who changed the oil? You or someone else?

[FasNuf]

Originally Posted by Dizzy82

Please, please check your fluids every time you fill up on gas. Doing this will keep you in the loop with potential future issues. My radiator fan usually kicks in around 220, those temps are concerning.

Correct here but never open a radiator cap when the engine is hot.
Besides looking for leaks and getting a new cap, check to make sure the fans are even coming on.