Slow Coolant Leak

[CDsDontBurn]

The last time I did work to my was back when I replaced the spark plugs a few months back. After changing the plugs I checked all the fluids and noticed that the coolant was low in the radiator and was empty in the overflow tank. I filled them up and called my work complete. Fast forward to yesterday, and I go check my fluids again and noticed the same thing - low coolant level in the radiator and empty overflow tank.

My question here is, where can a slow leak like this be coming from?

I don't see any drips of coolant on the floor where I park at work and at home. I don't smell any coolant. The oil doesn't look like a chocolate milk shake. So, where can the coolant be going?

 

[RedRyder]

If you’re not blowing white smoke and your oil looks good, it has to be leaking somewhere. If you don’t smell it, it may be leaking somewhere where it isn’t dripping on a part that gets hot. Or you don’t smell it or see it because the leak is just super slow. I’d grab a small mirror and flashlight, and painstakingly examine all hoses, radiator, reservoir, lines, etc etc. Maybe it’s a slow drip on the bottom of the radiator onto the aero panels under the car or something weird.

I don’t know if the UV trick is okay to do with coolant, but if so that may help.

 

[CDsDontBurn]

I can check with my UV light. Hopefully I can find it.

 

[agginline86]

I'd refill it and place a piece of cardboard under your car
let it sit overnight, wherever the cardboard has water stains or is wet, start looking there
slow leaks suck

 

[CDsDontBurn]

I'm thinking that one way of finding the source of the leak would be with a pressure test. If it's an external leak from a hose or something, that would be able to bring it up real quick.

I just need to be able to find a shop that will do this for me for cheap, or find a way to do it myself.

 

[Chris Vu]

Now, you probably aren't overheating yet, but check your radiator cap to make sure it's not damaged or broken. If it is, the coolant will boil over at lower temps and cause it to steam out of the reservoir. However, it wont steam enough for you to notice when sitting in your car. I was outside of my car when I noticed it because I was having the exact same problem as you. I let it warm up and sat there for a while watching the bay and under my car just to notice a boiling noise and steam coming out of the reservoir tank.

 

[CDsDontBurn]

The temp needle has only shot up once and that was a couple years ago when the rad cap was indeed broken. I made sure to check that when it was removed and it looked fine. So unless the spring is no longer "springy" it should be fine. I guess I can go to autozone or something to have them check if the cap is working as it should though.

 

[xci.ed6]

I'd borrow a pressure tester from a parts store.

Let the car sit overnight, so it is completely cool. Then pump it up to the pressure on the cap or a little more and wait an hour or so. If the pressure hasn't dropped, there's no leak. If it has dropped, you'll be sure to find it.

 

[001Stunna]

Assuming the car is cold...first top up the radiator once again, and top up the reservoir to the max line once again(some may jump in here saying that topping to the max may be wrong as it should be at max when hot, but personally ive always done max when cold). After doing so start the car and let it run until the rad fans come on. If you see any bubbles on the radiator neck which cause the level to go down just add fluid accordingly to bring it back up to full. Ideally what you're doing here is bleeding the system of air...just in case. Once the rad fans come on once and there hasnt been any large bubbles put the radiator cap back on with the car running. *careful* coolant will be around 95oC* so wear gloves or handle the cap with a cloth as you spin it on.

Clean any overspill caused by keeping the car running or when putting the cap on with adequate amount of water, as coolant can be harmful to pets/animals.

Check all the coolant hoses (small and big) and looks for any white marks on them, sort of like white crust. If it's leaking from a hose you'll see such marks on it as the coolant dries on the hose.

Get underneath and take a peak for any traces of coolant dripping and drying before it hits the ground.

As already mentioned check that your rad-cap is ok (no missing parts in it).

Lastly, you can buy some UV dye from most parts stores. Make sure its acceptable to be used in coolant before buying and throw it in. Let it run for about 3-4 days and then throw on your yellow stained glasses and a black light and go hunting.


If none of the above helps, then you can move to more costly things such as having a pressure test done or checking for exhaust gasses in coolant.

 

[RichBinAZ]

I have a 2000 V6 also and the radiator is leaking around the top manifold seal and the expansion tank is empty. The wife drove it home and it smelled very strongly of anti-freeze, so she popped the hood and there was some white blow back onto the engine and the green trace all around the crimped area at the top of the radiator - still there today. Perhaps the OP's bottom seal has gone - that would be hard to see.

That doesn't look fixable so off to autozone tonight for a new radiator. $90 + the governors cut. I already have new coolant and I think I have tranny fluid too - better check that.

It's a Denso made in Michigan part. After some bother recently with an Avalon starter relay, I'm beginning to think that Denso is the new Lucas of auto parts.