Where is the coolant drain pipe in a Toyota & is rust-colored coolant a bad thing?

June 14, 2009 1:49 PM

Where can I find the coolant drain in a Toyota Avalon 1995?

We just got a car, a used Toyota Avalon '95. It's previous owner didn't really take car of it at all, so now I am going through it and replaced the fluids, replaced the wipers, etc. I also refilled the coolant last week, but when I checked today the reservoir was empty again and the little that is left is rust-colored (coolant was bright yellow), but, as far as I can tell, not oily. I refilled it again and wait and see what happens. There are no puddles under the car.

However, I was also thinking about flushing the coolant system just to clean it out (I'm pretty sure that this hasn't happened in the last 10 years) - but I can't find the drain for it. Could it be under the car? A car repair book that I have explains the process in a way that makes it seem like you can't miss the drain, but I am lost.

So my questions are:

rust-colored coolant and disappearing coolant = bad?
and
Where is the coolant drain located?

Thanks!
~d

posted by Bearded Dave to travel & transportation (9 comments total)

Usually, it's a small valve, called a petcock, located on the bottom of the radiator. Look for something that sorta resembles a wingnut.

Also, disappearing coolant is bad, yes, and so is rusty coolant. That you're not seeing puddles means that it's not likely to be a radiator leak. Start by checking the easy and obvious stuff - look for bulges in the upper and lower radiator hoses, the weep holes in the water pump, stuff like that.

Beyond that, I would start checking cylinder compression, which would test for a cracked engine block, cracked cylinder head, leaky head gasket. Specifically, you would be looking for one cylinder with substantially lower compression than the others.

I've also seen a mechanic fill a (COLD) radiator directly all the way to the top with water, then crank the engine. Apparently, if it spouts like a geyser when cranking, that's an indication of a head or block problem.
posted by deadmessenger at 2:04 PM on June 14

Not sure about the rust color, but disappearing coolant definitely bad. Any chance it's going out the tailpipe? (head gasket).
posted by jon1270 at 2:04 PM on June 14

It is most likely to be at the lowest point, so almost guaranteed to be under the car. However, this should be obvious to anyone familiar with working on cars, so maybe invest in a Haynes manual or similar as you can screw things up poking around without good information.

rust-colored coolant and disappearing coolant = bad?

Hmmm. How much disappeared, and in what sort of mileage period? The rusty water is not a major issue, as it probably means that it hasn't had the amount of coolant (ie the non-water bit that is also a corrosion inhibitor) so as long as you maintain the correct proportions when you refill it, you should be ok. Most of your engine is aluminium, so it is unlikely to indicate major internal issues.

It is possible that there was an airlock, so you need to look for a consistent loss of water. Track it over a few days and check everywhere for leaks dilligently. A loss of small amounts of water over a period (like if it only leaks when hot and/or being driven) may not show drips under the car and still be harmless. There's no need to panic without more information, but it could be a sign of an issue, I'm afraid. However, there is not enough information to even guess at the severity of the issue (it could be a loose clamp or something stupid like that).
posted by Brockles at 2:05 PM on June 14

For some odd reason I seem to think my 1996 Camry didnt actually have a drain -- and I had to pull the coolant hose off to drain it.

That being said -- I might be totally wrong.
posted by SirStan at 2:39 PM on June 14

Thinking a little more about it, SirStan is right in that not every car has a radiator drain - on a lot of cars you have to pull the lower radiator hose to drain the radiator. I did a little poking around, though, and found this: a site selling a replacement for the Avalon's petcock, with a helpful picture to show you exactly what you're looking for when you're under the car.
posted by deadmessenger at 2:49 PM on June 14

Open the radiator cap and pull the lower hose off. Those petcock drains take FOREVER. Just get out of the way before you yank that hose. It'll be messy.
Those petcocks are typically plastic and, on an older unmaintained vehicle, they're usually stuck and very easy to break.

That lower hose will almost certainly be stuck on like a sumumabitch. Once you get the clamp off, put a screwdriver between the hose and the radiator and spray a silicone spray in there. Then slide the screwdriver around the circumference of the hose to break it free from the radiator. Twist the hose as you pull it off.

You can also rent a cooling system pressure tester from Autozone, I think. After you've filled and bled the cooling system hook up your pressure tester (car off) pump it up to about 20psi and see if anything is leaking.

Good luck!
posted by Jon-o at 5:43 PM on June 14

Better yet:

Pressure test the car BEFORE you do the fluid flush. That way, if you need to open the system to make a repair, you won't be draining out good, new coolant.
posted by Jon-o at 6:20 PM on June 14

Oh! I just remembered, too.
The coolant reservoir on your Avalon isn't a sealed thing that will have a consistant coolant level. If I remember correctly, you've got a radiator cap with a little overflow pipe coming out. When the pressure/heat in the cooling system reaches a certain level, some coolant can bypass the radiator cap into that reservoir.
Likewise, when the system cools down and the pressure drops, it will draw coolant back into radiator from that reservoir.
So, that's just an expansion tank. Its level is not indicative of actual coolant level.

The BEST way to ascertain the coolant level in your Avalon is, when the car is cold, open the radiator cap. The coolant should be full up to the top.
posted by Jon-o at 6:27 PM on June 14

Thanks for all the great info! I will go and get that Haynes Manual that Brockles suggested. Thanks for posting the link.

Jon-o, yes, there is a coolant reservoir on the left side - i forgot to mention that. Sorry, you can tell that I have never owned a car before in my life. So the reservoir is what is getting empty, which makes sense if the motor is cold, right? I will check the radiator itself and see what's going on in there. I looked around under the radiator and it seems that, like the Camry, it might just have a hose that you have to pull out in order to drain and not a petcock. I will wait until I get some more technical documentation and keep an eye on the temperature until then, I think.

Again, thanks for the help, I know that this is a definite newbie question.
posted by Bearded Dave at 5:46 AM on June 16