Q: Overheating and hissing

asked by on June 14, 2016

Today I was driving and my engine temp seemed to skyrocket. Today is a pretty hot day which I could see it being warmer than usual, but it climbed hard and fast out of nowhere. The coolant was about halfway but it has been lower and held lower temps. It should not have climbed like it did for no reason.

My car has 154000 miles.
My car has an automatic transmission.

Car is overheating Inspection $79.99 - $89.99 Get a Quote

You stated your coolant was about halfway. It’s an important detail to know where you are checking your coolant level. Are you checking in the coolant overflow jug, or in the radiator after you remove the radiator cap. Also, you should be checking it while it’s cold or at least cool. Checking it hot is dangerous and not very accurate.

If the coolant level in your overflow jug isn’t necessarily an accurate indication of the rest of your cooling system. If the coolant level in the radiator is half full, then you have a coolant leak and have been lucky you haven’t experienced overheating until now. Either way, your vehicle is overheating and will need to be repaired.

If the cooling system is low, then you will need to locate the leak and fix it. I would also recommend replacing the thermostat as well. Thermostats are usually damaged when a car overheats. So replacing it maybe necessary. It’s at least a good idea.

If the cooling system is full and the car is overheating, you will likely need a thermostat or possibly the water pump impeller has failed. Either way, I would begin by making sure the cooling system is full when cold and checking to make sure the thermostat is opening as it should. This can be done by running the motor from cold, touching the radiator hose that the thermostat feeds, and wait for the hose to become hot. When it becomes hot, the thermostat has opened. The most accurate way to monitor this is with an infrared thermometer. This way you can monitor the actual engine temperature while the car is warming up. If it reaches more than about 220 degrees Fahrenheit, and the stat hasn’t opened, (the radiator hose hasn’t become hot), then you likely have a thermostat problem.

If your water pump impeller has problems, this is usually a result of a rusty cooling system. But water pump impellers have been known to fail in other ways. Either way, you need to test for coolant flow. This is done by removing the water pump bypass hose, coolant bleeder hose or a heater hose and starting the car. Be careful if you are doing this hot. You should see coolant come out of the removed hose. Of course, be prepared for a mess and some way to catch the coolant or clean it up after. Don’t expect the kind of pressure you get out of a water hose from your house, unless you rev the motor. If there is little to no flow, I would suspect the water pump. But keep in mind, choosing the correct hose to test for flow takes and understanding of the dynamics of a cooling system. They are different for every vehicle.

There is also the possibility of failed head gasket. But these motors are not known for that, so I wouldn’t expect it, unless you have driven it to far with a low coolant level. If you have, every vehicle is prone to such a failure.

I’d recommend having your car looked at by a certified technician, they will be able to diagnose your overheating symptoms firsthand and make the necessary fixes to get your car running normally again.

Good luck. I hope I have helped you.

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

What others are asking

Car stalled in high water

Hopefully, its just the starter that is faulty. If the engine did suck in water it may be hydro-locked. You may remove the spark plugs and turn the engine over by hand to remove the water. Worst case scenario is...

Lose rpm and hard to start. I have a code p0336 that is read on a scanner.

Hi there. The code for P0336 is referring to the crankshaft position sensor loosing a signal to the computer. I recommend replacing the crankshaft position sensor and it should fix all of your problems. If you need further assistance with...

Transmission

An appropriate diagnostic to resolve your issue is a failure to shift inspection. Of course, first check your transmission's fluid level and condition. A really low fluid level can cause shift difficulties. Typically, if a transmission fails to automatically shift...

ABS light on and pic of a car swerving light on

Your car is definitely worth fixing as this is somewhat common and something that any qualified mechanic should be able to correct. The grinding sound you hear is likely worn brake pads and rotors. When the brake pads reach a...

Engine light lids

The knock sensor is located on top of the engine beneath the intake manifold which must be removed to gain access. With regard to diagnostic trouble code P0325 that code does not mean the knock sensor has failed. All that...

I'm thinking of buying a 2007 lexus GS450H, its a hybrid with 101829 miles on it, do i have to worry about the batteries? and if s

Hello. First off, your vehicle is equipped with a timing belt. This should be changed soon if it has not already. As for the battery, I typically see these last until about 120,000-150,000 miles. If you need quotes for these,...

No heat after adding coolant and thermostat almost to H

Hello. If the coolant was that low then that will cause the heater to not work. The most important thing at this time would be to determine where the coolant went. For it to be this low that means it...

Car overheats when only in idle

Overheating at idle could be due to non functioning electric cooling fans. Other causes of overheating include trapped air in the cooling passageways, a faulty thermostat, a plugged radiator, collapsed hoses, and a faulty water pump or drive belt. Certain...

Hi I have a 07 impala 5.3 and I've been having an issue when I try to accelerate if I give it to much gas it starts to buck and he

Hi there. It sounds like you may have a low fuel pressure concern. A car can idle with low pressure, however when demand is placed on the system it will fail as in your case. The engine is possibly starving...

Related articles

How to Buy a Classic Pontiac
Whether you want to buy a classic Pontiac for yourself or as a gift, here are some tips on buying one for a great value.
Pontiac Certified Pre-Owned (CPO) Car Program
If If you’re in the market for a used Pontiac vehicle, you may want to check out cars under their certified pre-owned program. Many manufacturers have a certified pre-owned (CPO) program, and each one is set up differently. Read on...
The Best Used Cars to Buy for Occasional Drivers
Not Not everyone relies on their car on a daily basis. Maybe you aren’t the type that deals with a daily commute, and running from here to there constantly. If that’s the case, you may be looking for a car...