Can I drive home if I put more coolant in?

October 19, 2019 12:21 PM

I have a 2000 Camry in generally good shape. While I was driving just now the check engine light came on. When I pulled over, I popped the hood & saw there was no coolant in the coolant reservoir & the radiator looks crusty on top. I live about 4 miles away; is it ok to drive home on surface streets if I let the car cool down & add more coolant? How long should I let it cool, if so?
posted by needs more cowbell to Grab Bag (18 answers total)

We don't know where the coolant went or why. We could guess, but we couldn't say for sure whether this would work, and you'd be risking major engine damage.
posted by jon1270 at 12:29 PM on October 19, 2019

Also relevant: did the temperature gauge indicate overheating, or was it just the Check Engine light? Was it flashing or solid?
posted by jon1270 at 12:30 PM on October 19, 2019 [2 favorites]

Was it just the yellow check engine light? Not a red light?

Then you are probably okay. The yellow check engine means just that - check at your convenience. I does not mean imminent catastrophic failure.

It is very likely that the check engine light has nothing to do with your radiator. Do you have a temperature gauge on your dash. Does it show normal? And no red temperature light is on? You could just drive it home and worry about the radiator later.

The empty reservoir may mean that you have a slow leak in a hose or the water pump, but this probably isn't the cause of the check engine light. Let the engine cool until the radiator cap is cool to the touch. Remove it and see if you can see coolant covering the radiator fins. If so, just replace the cap and drive home. If low, I would just pour some water directly into the radiator up to the top. It doesn't need to be coolant because if you have a leak, you are probably going to have to replace the coolant anyway when you have the leak repaired.
posted by JackFlash at 12:34 PM on October 19, 2019 [1 favorite]

Response by poster: I can’t see fluid covering the fins when I unscrew the cap on top and peer down.
It was definitely the yellow check engine light, not flashing but solid. Unfortunately I didn’t notice the temperature gauge while the engine was on or immediately after (it’s been a bit over an hour now.)
posted by needs more cowbell at 1:03 PM on October 19, 2019

Response by poster: If I pour water in is there anything I should watch for or so right after, before or during my drive home?
posted by needs more cowbell at 1:05 PM on October 19, 2019

If you pour water and it was excessively overheated and still too hot, you can in principle do more damage. But you probably would have noticed that the engine was super hot when you opened the hood.

How much time do you have? If you don’t mind extra time spent, you could start it and idle it for a minute to see if the temp is gonna spike. If it does, you’re back to square one and you lost your hour’s cooling. If it doesn’t, then you have valuable info that you can probably limp it home slowly while watching the temperature, and pulling over and waiting and then adding water if it does get into the red.
posted by SaltySalticid at 1:08 PM on October 19, 2019 [1 favorite]

Just make sure you get the radiator cap on tightly. Keep an eye on the temperature gauge. Try to keep track of how much water you have to pour in to bring the coolant level back up. One quart? Many quarts? That could provide important information for future repairs.
posted by JackFlash at 1:10 PM on October 19, 2019 [1 favorite]

If your temp light wasn’t on then I would say you’re fine and that the empty reservoir is something that can wait long enough for you to drive it home and then to the shop to get the radiator fixed.

The yellow check engine light is likely unrelated but something else you should have the shop look at.
posted by Tell Me No Lies at 1:26 PM on October 19, 2019

If there is no water, there is no water to activate the temperature light. See answers here: https://ask.metafilter.com/335592/Its-been-one-week-without-a-radiator-cap
posted by GeeEmm at 1:35 PM on October 19, 2019 [3 favorites]

Just on general principles, take a look at your oil level too; oil cools your engine as well as preventing heat from being generated in the first place
posted by jamjam at 2:28 PM on October 19, 2019

I wrecked an engine in aToyota by adding water when it was still too hot; don't be like me. Drove a different car home with a bad radiator by blasting the heat and driving very slowly, eagle eye on the temp gauge.
posted by theora55 at 2:43 PM on October 19, 2019

Response by poster: Once we added coolant and turned the engine on it became clear there’s a substantial leak. Parked on a side street and headed home in an Uber. I’ll get it towed Monday.

Thanks everyone!
posted by needs more cowbell at 2:46 PM on October 19, 2019 [7 favorites]

The coolant doesnt stay in the reservoir. It flows through the coolant system and goes into the reservoir after the cycle ends. The coolant may have not been the problem. If you didnt get an overheating indicator you may just want to take it to your nearest parts store for a free code reading
posted by The_imp_inimpossible at 3:18 PM on October 19, 2019

A couple of miles? I'd buy a few gallons of distilled water, fill the radiator, and drive to the repair shop, unless it involved driving in standstill traffic or a highway or something. On a reasonably cool day, from ambient temperature, none of the cars I own would have even begun to circulate coolant before that drive was over and done with.

Newer cars, especially of the turbocharged variety, are a completely different animal, but the small 4 cylinder naturally aspirated engines of that era still used simple analog thermostatic valves to regulate coolant flow and took a long time to get hot if you weren't beating on them.

I might hesitate if it was literally leaking coolant as quickly as it could be added and would thus be running completely dry, but with a relatively slow stream from a split hose, it's totally possible to drive a car a few miles without overheating it so much as to damage the engine.
posted by wierdo at 8:48 PM on October 19, 2019

If you're going to drive a car that potentially going to overheat one thing you can do is roll the windows down and turn on the heater. It might buy you an extra minute or two.
posted by rdr at 5:32 PM on October 20, 2019

As The_imp_inimpossible said, you can't always see coolant in the reservoir. I learned this lesson two years ago when my radiator cracked. The check engine light came on with an audible beeping, then the engine shut itself off. And it was snowing outside!

I learned to add more coolant while the engine is running so that it will get sucked into the system instead of just sitting in the reservoir.
posted by tacodave at 4:51 PM on October 21, 2019

Response by poster: There was definitely not enough coolant (if any) in the radiator itself, and as I said, once there was coolant in the radiator and the engine was running, there was a pretty visible leak (I'm not sure where, but not just from the reservoir, unfortunately). The temp gauge got at least midway up even in the parking lot with the heat on, so towing seems like the best bet going forward.

I have towing coverage, but I don't need my car for daily use so I'm punting so I can read a little and maybe call around to get price estimates for having the radiator replaced - it sounds likely to be needed. I want to keep this car, and while I don't have a lot of money, because I can easily go without a car for awhile, doing some very temporary cheap fix doesn't make sense. (I wanted to just drive it home on Saturday if possible because I was with someone I'm dating, we both just wanted to go home, and we were across the city from my house in a location bad for public transit and it's not like I could get easily it towed to my mechanic at 4pm on a Saturday anyway.)
posted by needs more cowbell at 6:01 AM on October 22, 2019

From your description, it might be a blown radiator hose. If the radiator is original and has plastic tanks (which deteriorate with age, and can result in catastrophic failure), as a matter of course I would replace it anyway (otherwise take the advice of the mechanic), and replace both top and bottom hoses. The top is most likely to fail (it gets the hottest), but the bottom is hardest to get to usually so when the radiator is out it is easier to replace both.
posted by GeeEmm at 1:45 PM on October 22, 2019