I did a fairly stupid thing and drove my car with half of the coolant removed from it.

I finished changing the timing belt on my 1998 Toyota Corolla (1.3 4E-FE engine), and I started it a month ago and completed it the other day. The reason being I hurt my knee so couldn't physically get under the car. I did intend to replace the water pump before I hurt my knee, and I drained the coolant from the radiator in preparation for it. I didn't turn the car on or flush the system in order to drain it completely, so I know some coolant was still in the engine and reserve tank. A month later, I finished the job. I was preoccupied with a squeal from the engine, so once I diagnosed that issue I decided to take it for a spin around the block.

The drive consisted of a 30mph stretch of road, followed by a 50mph stretch, and then 30mph. I traveled for no more than 5 or 10 minutes. The moment I saw the needle hit H on the dashboard I turned on the heater and threw it to maximum so it blew hot air in to the cabin away from the engine until I got home. I did notice that the air wasn't exactly hot.

I parked up and turned the engine off. With the engine off I could hear bubbling, like a kettle was boiling. I lifted the bonnet up and left it for a few hours after it. I didn't open the radiator in fear of whatever liquid was there would scald me.

Yesterday I filled the radiator with 50/50 mix of red coolant (which is what should work on my car). Once the radiator was full I turned the engine on, let it get to temperature and the liquid went down and I topped it up until it wouldn't take any more liquid. The coolant I had came in a 5L bottle, and about half of it went in to the car.

Without driving the car which I can't do at the moment until I get it booked in for an MOT as it expired the day before Yesterday, with what I've described, what sort of damage could I have done to my engine, and what can I do as a pre-emptive measure to fix any damage before it damages anything else?

EDIT: Thought it would be worth updating this question after driving the car for some time after this issue.

Since I drove it without coolant, there has been no noticeable problems with the engine. There is no water in the oil and no mayonaise gunk under the oil cap. I have dodged a bullet, and the car is going from strength to strength!

2 Answers 2


It's hard to say what kind of damage has been done at this point. Any time a vehicle is allowed to overheat, it places wear on the engine components that wouldn't normally be experienced at the designed operating temperature. Having driven only 5 to 10 minutes you probably didn't destroy the engine. How long was the needle on hot?

At this point there's not much to be done in ways of preemptive measures. The damage that was done is done. Overheating engines can warp heads and ruin head gaskets allowing coolant into places in the engine that you really don't want it to be.

I'd say start the car up, allow it to reach operating temperature, and then heavily monitor the temperature and coolant levels from there. If the car starts overheating again then instantly shut it off. If coolant seems like it's being used rapidly by the engine or it continues to overheat then you've probably damaged the engine. If you wanted to get even more in-depth, you could pressure test your cooling system. There are plenty of resources online to guide you through the steps.

On the other end, if the engine seems to operate fine and doesn't overheat at all then you can count yourself lucky and continue on your way. Good luck!

  • The needle was on hot for at least 30 seconds to a minute, but that's only when I noticed it as I was paying attention to the engine squeal I was trying to get rid of. Yesterday when I filled it with coolant I did let it run and the needle stayed at 90C (in the middle), no noticable leaks but that was standing still on my drive way. I will have a look at the pressure test to see if that points to any issues. Commented Aug 24, 2016 at 13:11
  • You're probably fine. It sounds like it was overheating for only a minute or so. Just keep an eye on your fluids (coolant and oil) for the next week or so.
    – Spivonious
    Commented Aug 14, 2017 at 20:03

As opposed to running an engine that potentially already has an issue up to operating temperature, I'd suggest a compression test or leak down test to establish the health of the engine and integrity of the gaskets. Only if this highlights no issues would I be happy to attempt to run the car up to temperature.

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