Q: Engine over-heating and Radiator then overflows fluid or steam.

asked by on March 28, 2016

We have by-passed the usual route for powering the cooling fan. We are using a switch placed on top of the front fender from the car battery to power the cooling fan "by hand". It seems the engine overheats very quickly, maybe at about 4 miles & definitely by a 10 mile trip on the road, & when it does the radiator starts spilling over with fluid or steaming. You can hear the fluid inside the radiator boiling. We replenish the radiator fluid after one of these leaks & keep driving until it overheats again. I had a simple test done that indicates the head gaskets are still good. The Engine & transmission seem strong, so we don't want to ruin the engine. Someone said he thought there was a leak at the top of the radiator, told me that if we keep over-heating the engine, it will weaken the engine. IS that true? WE need this vehicle for short hauling trips almost every day!. What should we do to fix this that hopefully isn't going to cost more than the van or a newer one?

My car has 182000 miles.
My car has an automatic transmission.

Thermostat Replacement $157.20 - $759.78 Get a Quote
Car is overheating Inspection $94.99 - $114.99 Get a Quote

First of all, overheating the engine will damage it. The list of reasons why is long, but here is a partial list of reasons why overheating the engine will ruin it.

  • The engine oil becomes much thinner at higher temps.
  • The engine oil can bake on to metal parts
  • Engines have very tight spaces for pressurized oil to lubricate the parts. When the engine is too hot, these spaces become smaller, or disappear all together.
  • Gaskets fail easier.
  • Metal parts can become warped.
  • You can overheat the transmission by overheating the engine. First of all they are bolted together and share the heat. Second, the cooler lines from the transmission go to the radiator to be cooled. When the radiator is boiling, this cooks the transmission fluid. Too much heat is the number one problem with transmission failure.

Second, there really isn’t such a thing as weakening it, it’s either runs well, or it doesn’t. Considering that the engine is over heating in such a short time and distance, I would assume that the coolant is not circulating. The first and easiest part to check or replace would be the thermostat (as needed). While the engine is running and full of coolant, feel the upper and lower radiator hoses. If one is hot, and the other is not, the thermostat might be stuck closed.

Finally, I believe, based on my gut feeling, that the the water pump has failed. I have seen the impeller that circulates the coolant come off before. When this happens, the coolant does not circulate. It will heat up quickly when it can not reach the radiator. It will then boil. This does not happen at 212 degrees. A 50/50 mix of coolant and water, under 16 psi of pressure, will boil around 260 degrees. This creates extra pressure in the system. The radiator cap is designed to release any pressure over it’s rating into the coolant reservoir. It will quickly overflow under these circumstances. The cooling fan that you hard wired will not do much of anything because the hot coolant in the engine never gets to the radiator, until its too late and boiling. You can confirm this when the engine is hot, the fan will be blowing cold air.

I would not delay having this repaired. Consider having a certified mechanic, such as one from YourMechanic, come by and address your overheating concerns.

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


Experienced Mechanic?

Earn up to $70/hr

What others are asking

Gas leak by rear tire
Hi. A gas leak is never a good thing and it needs to be repaired right away. If it is leaking near that tire, then the leak is typically in the filler tube. Typically, if it was the tube, then...
Startup issus, error codes
Those codes: P0170 (https://www.yourmechanic.com/article/p0170-obd-ii-trouble-code-fuel-trim-malfunction-bank-1-by-andrew-quinn), P0173 (https://www.yourmechanic.com/article/p0173-obd-ii-trouble-code-fuel-trim-malfunction-bank-2-by-blake-griffin), and P0335 (https://www.yourmechanic.com/article/p0335-obd-ii-trouble-code-crankshaft-position-sensor-a-circuit-malfunction-by-spencer-clayton) are indicating that the airflow coming in that is read by the MAF sensor to set up fuel injection timing does not match what the oxygen sensors are reading based on...
Hesitation, stumbles, and sometimes stalls when accelerating
Hi there, thanks for writing in. It looks as if you've covered almost all of the bases. The only thing that I could think of without being there to complete a diagnostic inspection is that perhaps the idle control valve...
While I'm driving the accelerator disengages and it won't accelerate with the gas pedal pressed all the to the floor.
This loss of accelerator control is a built in safety feature of the vehicle computer and can render the throttle inactive if it sees a problem in a major component or loses communication with the throttle sensor. I have even...
Getting too much gas and it's flooding out through the cylinder
Hi and thanks for contacting YourMechanic. If fuel is coming out of the exhaust pipe, then the fuel is not being burnt. Check the spark plugs and wires to make sure that they are not burned. If the spark plugs...
3100 v6 on 2003 buick century lacks power under acceleration, spits and sputters, hard to get up to speed
If your vehicle is hesitating upon acceleration, it is possible that you have a fuel issue. Some of the potential causes of this issue would include a faulty fuel pump (https://www.yourmechanic.com/services/fuel-pump-replacement), faulty fuel pressure regulator (https://www.yourmechanic.com/services/fuel-pressure-regulator-replacement), or a clogged fuel...
No brake lights 1990 Mercury Grand Marquis
Hi there - check the fuses for the brake lights, the brake light bulbs, and the ground for the brake lights (should be OK since other lights work, but....). If these check out correctly, check for power to the brake...
Is it ok to use green antifreeze in a vehicle that uses orange antifreeze
Hi there: In short; NO - it's not a good idea to mix these two. Most of the antifreeze products on the market currently are ethylene glycol base material with additives to prevent corrosion, lubricate seals and water pumps and...
ESP defective and engine turns off.
Hi there. Trying to diagnose mechanical issues in extreme cold weather you appear to be enduring is nearly impossible without being there to physically check a few common parts. The ESP stability control applies the brakes to the right rear...

Related articles

How to Prevent and Handle an Overheated Engine
An overheated engine can seize the motor completely. Learn how to prevent your engine from getting too hot and causing damage.
Symptoms of a Bad or Failing Coolant Reservoir
Common signs include needing to constantly add coolant, finding coolant leaks, and the engine overheating.
Symptoms of a Bad or Failing Coolant Tube
Common signs include low coolant levels, visible coolant leaks, and engine overheating.