Best of Deals Car Reviews Repair Shops Cars A-Z Radio Show

A Question About Cold Weather and Coolant

So, it was pretty cold in North Dakota this morning by most standards -22 degrees Fahrenheit, almost -40 with windchill. I gave my car ample time to warm up, but when I left the power steering was still pretty stiff and at least part of my brake lines had to be frozen. Pedal to the metal for minimal stopping power. Safe to say my right hand was on the emergency brake for the duration of the trip. But that’s besides the point. After about 7 miles into my commute, I was at a stop light and noticed some steam coming from under the hood and a slight smell of hot antifreeze coming into the cabin.

After I glanced at the temp gauge (inaccurate, I know), it looked normal, but all the same I turned the defroster off in hopes of helping the engine bay retain precious heat. Whether or not that helped, I eased the car all the way to work without overheating/seizing/etc. During lunch, I checked out under the engine bay and there was some left over drips of coolant from the blow over that morning, but nothing major. Same deal when I popped the hood. A little residue here and there but nothing showing visual damage to any components. I decided to carpool home with my fiancee tonight and left it in the parking lot at work to drive it home tomorrow in the 15 degree weather.

My question is if there’s anything I can do aside from checking the coolant reservoir and making sure it’s at the right level before driving it home tomorrow to ensure this doesn’t happen again? While I’m at it, I’d like to keep any potential damage to a minimum. I’m guessing that the car probably hasn’t had its coolant flushed recently if ever. Would a coolant flush and some high quality coolant help prevent this from happening the next time there’s weather this cold? Since the fiancee has the '04 car and I haven’t driven a beater in weather this cold, this is all new territory for me.

You should look for a leak. Check the condition of the hoses, especially near the clamps. Next, check the neck of the radiator. You might not have a good seal with the radiator cap.

I’ll be sure to check the hoses and cap first. If it’s the cap is it possible to buy a replacement cap from most auto supply stores? Also, if it is a leak in the body of the radiator itself, how effective is radiator stop leak in these cases?

Windchill does not apply to your car.  It will only mean it will cool down (to -22 in your case) faster when stopped, but it will not go below that.  

Did you know that if you drove with the wind at the speed of the wind and stuck your head out the window, you would not feel any windchill? ;)

You need someone somewhat mechanically knowledgeable to check the car.

You haven’t told us what you’re driving. It may help.

Engines can overheat regardless of the outside temperature. A stuck thermostat is a possibility, or low coolant level. You need to check the level of coolant in the radiator. Looking at the overflow bottle is not enough.

A coolant flush, a new thermostat and radiator cap are in order.

I’m even more concerned about the brakes. If the pedal goes to the floor, under any circumstances, you should park the car and not drive it. It’s not safe. Brake lines can, and do, freeze.

Get this vehicle to a mechanic and have the cooling system and the brakes checked before you have a serious problem.

Yes, you need to check the level of coolant in the system, but you also need to verify that the concentration of coolant/antifreeze actually protects the engine and cooling system at the very low temperatures that you have been experiencing.

Believe it or not, in addition to a low coolant level producing these symptoms, coolant that is too diluted with water can also produce those symptoms. A “freeze-up” in one part of the cooling system will impede coolant flow and this freeze-up can actually lead to overheating. Yes, I know that this sounds counterintuitive, but it is true.

And, as mcparadise stated, you REALLY need to have the brake hydraulic system checked by a qualified mechanic (NOT a chain operation). My guess is that this car has been so badly maintained that the brake fluid has never been changed, and that accumulated moisture in the brake fluid is freezing. Right now, I would not consider the car to be safe to drive until the brakes have been fixed. And, that would be a great opportunity to have the cooling system checked out also.

Thanks for all the great replies, everyone. Sounds like I have a couple things to take care of. First, I’ll make sure the coolant level is correct, then probably replace the thermostat and radiator cap. Beyond that, I’m going to have the radiator flushed and have some new heavy duty coolant put in. Finally, I’m going to have the brake lines bled and get new fluid put in, since the pads were just replaced. That should take care of most of this.

By the way, this is an '88 Toyota Cressida.

Forget “heavy duty” coolant. YOu just need the proper 50% mix of the stuff that Toy recommends for your vehicle.

Well, the good news is I got it home safely without overheating. Before heading out, with an escort behind me just in case, I added a little coolant to replace the stuff that got spit out the other day. For good measure, I put in a little radiator anti-leak and a new radiator cap to replace the old one. While I was at it, I tested the coolant and it looks pretty crappy. The tester said the coolant is good until about -20 F. Interesting enough, there was some frozen water crystals in the coolant reservoir.

So, I think I’m going to flush the radiator with a mechanically inclined friend (bought a kit for that - we’ll see how good it is). Finally, I think I’m going to replace the thermostat, just in case it’s not functioning well, and that’s besides the fact that for the first several miles on the drive home, the temperature gauge was fluctuating between normal operating temp and cool. The important thing is that she’s back home and I can do some preventative maintenance now that it’s going to be warming up soon. Driving it home probably wasn’t the smartest thing, but I was careful as I could be and it turned out ok. By the way, the brake lines have unfrozen, but I’ll probably bleed and replace the fluid too.

I would not recommend a flush of your cooling system. My experience is that people have more problems after a flush. But you should have the radiator and block drained and then refilled with fresh antifreeze and water. Most people recommend a 50/50 mix but since you live so far north, you would be better off with a mix of 2 parts antifreeze to one part distilled water.

I will strongly recommend that you have the brake system flushed with new brake fluid. As brake fluid ages, it absorbs water and that lowers its freeze point. Flushing brakes is a different process than flushing cooling systems. With brakes, its a method of replacing the brake fluid without introducing any air into the system.

Thanks, for the info, keith. I was going to flush the cooling system, but I can see how it’d cause problems by dislodging all sorts of nasty stuff. Out of curiosity, do you, or anyone else here know what the capacity on a stock radiator in an '88 Toyota Cressida would be? Also, I only know how to drain the fluid from the radiator - would the fluid in the block be come out with the rest of it?

I’ll be sure to consult a mechanically-inclined friend about the brake system.

I would not recommend a flush of your cooling system. My experience is that people have more problems after a flush.

 While I can see how a long neglected radiator could have problems because of a flush, I suspect that most of your experience where someone has problems after a flush is because they only got the flush because they suspected they had a problem to start with and when with a flush and a prayer.  

 For most people who have not waited long past the recommended cooling system maintenance, I would recommend a flush and change.   For those who may find that the flush unearthed a weakness in their cooling system, I would suggest that it only found it a little sooner than it would have been found otherwise. 

 I agree with the brake system, and you are right, the flush and reason for the flush is different.

A properly maintained car with a proper fresh mix of coolant/antifreeze and no defective components (like a bad T-stat or radiator cap) will survive -22F. As already mentioned, “wind chill factor” is only a way of quantifying how quickly the heat will be dissipated and will not cause a body to go below ambient…just get there faster.

I’d recommend that rather than throwing miscellaneous items at the problem you have the cooling system looked at thoroughly. A new T-stat or radiator cap may fix it, especially if conbined with a thorought flush (plain water is what I’d recommend) and refill with fresh coolant, but personally I’d want to know what failed. Something did.

What I’m going to guess from your post is that you may be way overdue for a purging and replacement of the original coolant. How old is the stuff in there?

Do you ever check your coolant level? You may have another problem allowing the coolant to be ingested into the engine, and you want to find out and get that fixed.

I strongly recommend that you do not just top off the coolant. You’re asking for serious damage of you do this.

First, you are assuming that the cooling system has not had regular maintenance in the past. The problem may be due to topping off with water to the point of watering down the antifreeze too much. There may not be a problem with gunk, crud or whatever.

My main problem with flushing a radiator is for most people, that means using a chemical flush. My experience with these is that they damage all the rubber components, even new rubber components. Flushing with a garden hose and not using any “flush” chemicals doesn’t do as much harm but it can leave behind trace minerals that can lead to galvanic or dissimilar metal corrosion. I’d prefer to avoid this as well, that is why I recommend getting a gallon of distilled water.

There is a separate drain for the block, draining the radiator will not drain all of the block, but it will get about half of it in most cases. Most autoparts stores can show you where this drain is and since you have to buy the antifreeze anyway, you might as well go to one of these and get it and the information you need. You probably won’t get this information from WalMart or other discount department store.

If you chose to just drain the radiator, you will need to measure the amount of coolant that you drain out. Then check your owners manual for the system capacity. If you don’t have the owners manual, then the autoparts store folks can tell you this also.

After this, you will need to do a little math. Most antifreeze bottles have a chart on them that will tell you the concentration of antifreeze in the system based on the tested freeze point of your current system. Subtract the amount of drained coolant from the system capacity, then multiply by the concentration of antifreeze to get the amount of remaining antifreeze in the system.

Example: If your system capacity is 6 quarts and you drain 4, then you have 2 quarts left. If -20F corresponds to a concentration of 40%, then multiply 2*0.4 to get 0.8 qts of antifreeze remaining in the system.

Now if you decide to go with my recommended 2:1 ratio (.67 concentration), you would want a total of 4 quarts of antifreeze in the system. Since you have 0.8 already there, you will need to mix 3.2 qts of antifreeze with 0.8 qts of distilled water to refill the system.

Going with this richer concentration will give you a lower freeze point, a little more additional corrosion protection and some buffer for adding makeup water to the system between now and the next coolant drain and refill, which should be in about 3 to 5 years depending on the antifreeze you use and personal preferences.

If you go this way, the remaining 0.8 qts of antifreeze and 1.2 qts of water that did not get changed will not, contrary to popular belief, hurt your system. The new antifreeze will protect your system from any remaining contaminants.

I do want to go on the record that I prefer to drain the block because sometimes I go more than 5 years between coolant changes. So far, since I stopped using flush chemicals, I haven’t had any cooling system problems. I also recommend that you use one of the “Long life” antifreezes, brand does not matter to me as long as its one of the major brands, Prestone, Peak or Zerex. I’m not saying that store brands are not as good, I just don’t know if they are.