Coolant in reservoir dropping

[Bushwick]

I check coolant every so often and the level rarely changes. Usually it was dropping slightly (like a 3/4" drop over 4 months) which wasn't concerning. However, during the oil change a few days back, I noticed the overfill was much lower than normal. Usually level was around 2/3's, and now it was around 1/4. So I topped it off back to around the 2/3's mark. About 2 days later, it was around 1/3, which is fairly drastic.

 

 

I'm a little stumped. It's not leaking, it's not burning anything, and oil level is the same. Where is it going all of a sudden? Engine temps are staying at the mid mark. I did notice the old oil was more brown in color and there were bubbles in it as it sat in the drain tub, but I didn't see any actual coolant blobs and it still smelled like oil. The fresh synthetic is still really clear too. 

 

Is this just paranoia? Or could it be evaporating at a rapid rate for some reason?

[lmdew]

It would help to know the year and engine installed.

 

Also check your radiator when it's cold.  Make sure the radiator is full.

 

Coolant loss:

External leak, park one a white sheet or large cardboard piece and look for leaks

Head Gasket Leaks, coolant can go into the combustion area or be pushed out of the overflow bottle by combustion gasses.

Water pump, hoses, water pump, all external leaks

Heater Core leak, inside the car, you'll smell it and the carpet will be wet.

[DaveT]

You can also burn coolant via an intake leak or throttle body leak at a noticeable rate without evidence in the exhaust. I am not sure what engine you have, or the coolant passages in the newer engines. This is based on my experience with ea82 engines. Some leaks can happen iutside, on top of the engine, and evaporate before you can see it or dripping occurs. You have to look while the engine is warming up.

[Bushwick]

Engine and car are in sig. 95' Legacy EJ22. 

 

 

Can't smell any coolant, and my nose is tuned-in to coolant odor. Haven't check under the carpet, but can't smell any inside either, nor are the windows fogging.

 

When doing the knock sensor, there's a hose that appears to be maybe 5/16" that sit right across the area, directly above the knock sensor that feeds to a bottom nipple on the throttle body. It had some coolant exit when the engine was briefly run with it disconnected. Dunno if that's normal with that hose or not? Wasn't a lot of coolant, but enough a tiny puddle around the sensor formed briefly. 

[DaveT]

On EA82s there are a couple of small coolant hoses, and one connects in a similar location. I've seen the hose get a pinhole leak, or coolant seep from the nipple. It will evaporate so it'd tricky to spot.

[johnceggleston]

it is a 20 year old car.

chances are it is a hose leak.

 

did you remove the intake to replace the knock sensor?

how did the coolant puddle / leak?

[Bushwick]

Didn't remove anything to get the knock sensor out. During the 1st install, I pulled the hose that went to the TB just to give a little more hand room. Thinking it was a vacuum line, I restarted the engine after new sensor went in, and I kept smelling coolant (at that point and that point only) during the brief idling then realized it had dripped from that hose. What was odd though was it didn't drip much like you'd expect to see from the water pump. It pooled slightly around the actual knock sensor. About 2 tablespoon's worth. I soaked that up with a rag though.

 

If it's leaking out from a hose (like a pin hole) I'd have to think it'd be giving off a smell. Though a hose with a pin hole facing the ground might actually forgo the engine compartment and spritz on the road as it's moving..... 

 

I'll look closer for a pin hole. When I've had them in the past, I could either smell it or see the steam, so wasn't thinking of that. Will keep eyes peeled!

[nvu]

I've had good luck finding odd hose leaks by pressurizing the coolant system.  Warm up the car, turn off engine, pull out the overflow hose from the tank and put about 10-15psi into it.  Ive found failing hose clamps around the heater hoses and turbo reservoir this way.  Was chasing the problem for months after the engine rebuild.  Car doesn't overheat, no bubbles in system, it just starts losing coolant between fillups.  For my case, coolant would sneak out the heater hose clamps on the firewall.  Which was where I disconnected them when pulling out the engine.

[Bushwick]

I'll take it out later and give it a good run near sundown and pull over and see if any steam is coming up. It's in the 50's right now with no humidity, so it should be apparent if there's steam. Floor is dry, and no odor in cabin, plus no window fogging (all things I seem to remember dealing with when an 84' Rabbit I owned years ago had a heater core issue) so feeling confident this is in the engine compartment or possibly the radiator itself.

 

If that doesn't work, I'll try and attach my 12v tire pump to the overfill hose and put 10 psi in and see if that helps. It pumps so slowly I think it'll be OK to use if psi is 10 or below, although running pressure from the water pump should reveal something as it gets to around that pressure anyways. If there is a pinhole, it has to be fairly small as they are usually easy to find once the engine is at operating temp and the thermostat is open. Around nipples though, that can be a little tougher. Thanks for the advice. 

[idosubaru]

I need to actually keep records like you're doing. My 02 H6 is doing this as well, Iit seems I'm topping the overflow tank off every few months.  No overheating, rad never low in 241,000 miles, so time will tell.

If it's any consolation I think mine has been doing it for a year now and hasn't gotten worse.

 

But coolant doesn't just randomly disappear so I've been wondering where it's going.

 

Pressurizing the overflow tank would push air out from the hose/tank area and lid?  That's where Ej25's like to puke hot air and coolant when they're overheating, LOL.

 

EJ's don't have the shared coolant/intake passages that can leak like EA/ER engines did, so it wouldn't leak internally like that.

[Bushwick]

Not the overfill bottle itself as that's not air-tight on these, but rather the hose feeding it. Pretty sure that's what he meant. I'm guessing reverse pressure with a warmed up engine the valve to the radiator cap should be open, allowing pressurized air to enter.

 

Have to be extremely careful though with not going beyond the working pressure of the system as it can blow out the radiator or anything else not mean to handle it. So shop air would be bad. I know of shops that have ruined radiators thinking they were testing it.

[1 Lucky Texan]

it won't be fun, but comparing the plugs 'might' reveal some difference that would implicate a certain cylinder burning the coolanr.

 

also, Polaris or Blackstone Labs might be able to find, or dismiss the presence of, combustion products in the coolant.

[Bushwick]

If it was burning it, at the rate the bottle is dropping, it'd have visible smoking out the pipe. There was a light amount of cold weather puffing coming out, but it was dispersing within 2' and not lingering.

 

 

I stopped and diligently looked several times for leaks during a 25 mile trip and just could not find any coolant leaks. To make matters worse, it's been raining on/off all day, so oil pan was already wet. 

 

Only place giving a faint coolant odor is back near the firewall, around the same area the knock sensor is. I had a small amount leak out of a throttle body hose I pulled during the knock sensor replacement, so can't tell if it's residual odor or not.

 

Overfill bottle had about a 1/8 left before I started the trip (which I topped off again), which was the lowest I've seen it. It went from a full bottle down to that in roughly six, 5 mile short trips. During the drive tonight, it didn't appear to drop much if any at all, which just makes it even more puzzling. A HG issue would be constant. Oil level is normal, and given the overfill bottle holds at least a qt, it doesn't seem to be in the oil thankfully.

 

Only thing different on tonight's trip vs. the shorter trips was the heater was running the entire trip. But I thought the coolant travels through it regardless if blower is running or not? Heater core hoses leading up the firewall were dry.

 

Only good thing tonight was the expensive Silverstar headlights I run are identical to what I run in my Saab, so that saved almost $30 by being able to swap out

Edited October 4, 2015 by Bushwick

[idosubaru]

i missed that in my first read that it has gotten worse recently...mine is like the overflow tank is lower twice a year or something like that, that's it and we drive that car a good bit - 20,000 miles/year.  i've never had a lot of loss over short miles.

 

not sure if it's already mentioned but some IAC's have a coolant passage through them - does yours?

 

Subaru EJ and EZ headgasket issues aren't always constant, the EJ25D it's actually normal for symptoms to come and go randomly, they can have weeks and months between symptoms.  There's two examples of Subaru headgaskets that can have long stints of time between symptoms.

[Fairtax4me]

Check closely around all the hoses and around the thermostat housing.

It could be a leak that only happens when the system is cool, and it stops when the system gets hot and pressurized.

 

Make sure the radiator is full and has no air in the top. Open the bleeder screw in the top corner to make sure all the air can get out while filing.

Cap it off and fill the reservoir. Then run it to operating temperature and let it cool overnight. Check the coolant level in the morning before starting the engine, and be sure to check the level in both the radiator and the bottle. Top off the radiator if necessary and make a note of the level in the bottle. Drive it for a day or two, then recheck the coolant levels again the next morning before starting.

 

Entirely possible that its a head gasket, and these can burn a fair amount of coolant with no other signs and no smoke or steam from the tail pipe. And they'll pass those fluid hydrocarbon tests that you find at the parts stores.

 

If you have shop air, the best way to check for a bad head gasket is to put each cylinder at TDC and fill it with air up to about 100 psi. Make sure the radiator cap is off before you do it, because any cylinder with a leak will start pushing coolant and bubbles out of the radiator.

[Bushwick]

I don't think this one has a bleeder screw? Can't find anything on radiator. On the upper left (if bending over and looking down from the front of car, it's on the left) front of radiator is a plastic boss that appears like it could have something tapped and put there, is completely smooth with no hole.

 

 

Anyhow, went out and coolant level hadn't dropped. Oil level is still right on the mark too (thankfully). Got to the gas station and checked once more for signs of leakage. It took awhile, but I found some wetness on the actual outer radiator side, directly under the upper hose where it connects. What's odd though is the actual hose is dry as is the mating surface where the hose goes over the plastic, which is why I didn't catch the wetness on the side of the radiator panel as I had just run a finger at the edge of the hose and it was dry before, like it was tonight. Still not convinced this is the leak though, as there was maybe a tablespoon's worth of coolant blotches there and this thing previously dropped at least a qt. Can't find any other wet spots nor is the coolant odor present. Temps are always in the middle, and it's running like it always does.

 

Guess I'll just have to keep checking for signs of it dropping in case it IS a head gasket issue.

 

Could it be possible there was air in the radiator, but not enough to cause overheating, for roughly a year? Like say there was an air pocket and the coolant was high enough to at least keep the engine in-range, but not high enough it was creating a suction to pull coolant from the overfill bottle? Wondering if it's actually just been low and it purged a bubble, allowing it to pull in actual coolant?

[idosubaru]

yes, i've seen subaru's with low coolant levels in the radiator drive just fine. to say it another way, you can remove some coolant from the radiator, have an empty overflow tank, and they can run fine.....to a point obviously and it might depend on the motor.  

 

but wasn't yours dropping multiple times and recently dropped a lot? 

[1 Lucky Texan]

not sure where you are reporting the wetness, but I put small zipties to act as clamps on the little overflow tube at the nipple on the rad neck because I saw coolant under it on one car, and the other one's tube was stiff and didn't feel like it was sealing well. Under normal circumstances, I don't think there should ever be much over atmospheric pressure in that line - but I have seen dripping - and other cars have it clamped.

 

To me, it seems likely air could be pulled in, in place of coolant in the o'flow tank - leading to a low radiator over time and a somewhat normal level in the o'flow.

 

And who knows what happens if you couple the above with an old radiator cap and dirty o'flow tank?

[Bushwick]

The reservoir started dropping. It was topped off, then dropped again. Topped off again and it quit dropping. Before that however, the level in the overfill tank never fluctuated in at least the past year. Wondering if it could have had air trapped near the radiator cap, preventing it from pulling anything in (or hell, maybe the hose had an obstruction?). Or as was pointed out, maybe the cap was sticking and it wasn't passing coolant? 

 

Trying to think of all possibilities before blaming a random HG issue as it's just not leaking anywhere on the exterior to account for the amount that was pulled in.

 

The visible coolant blotches were on the actual radiator plastic end tank the cooling fin rows terminate into. It would seem some coolant made it's way pass the upper radiator hose coupling, though it was completely dry.

[1 Lucky Texan]

plasic tanks can leak where they are clamped to the fins/tubing.('core')

 

maybe a pressure test would find you have a leaky radiator?

Edited October 5, 2015 by 1 Lucky Texan

[DaveT]

Any trapped air will get cycled out in a few drive cycles. If everything is sealed up well. A seep that only happens when hot can be hard to find, since it will evaporate. Air could get in while it's cooling likewise.

[johnceggleston]

see the phillips head plug between 26 and 27 inches?

that is the vent plug.

 

are we dealing with your 99 lego?

you should have one of these.

 

[Fairtax4me]

If there is wetness below the hose the end tank could be cracked along one of the ribs that run around the tank.

[Bushwick]

It's a 95' Legacy. Next time outside I'll double-check if it has something like that. Was visualizing more of a twist valve.

 

I know the inlet piping has an edge broken off as there's no metal sleeving protecting the inner diameter of the radiator inlet on the upper hose, so hose was double-clamped (this was over a year ago) to have more clamping surface area w/o going crazy tight. At some point, the radiator will need replaced regardless, but it was still dry. I tightened a tad anyways.

 

 

Guess it's a waiting game until the level drops (again) assuming it will. Considering it's running what appears to be the original radiator, not exactly in a hurry to pressurize the unit in case it blows something out.

 

What years are a direct fit radiator if I went with used? Do the 2.5L DOHC engines get a larger radiator? Are the bleeder valves only available on particular years/models? Any of the 00's models fit? If going used, the 00's models are fairly common at the pull-a-part with OK mileage. As long as upper/lower hoses line up and are same diameter, only other thing would be the fan shroud and attachment points.

[idosubaru]

00+ has the same basic layout - it uses the same water pump even so that location is identical.  but as you said - fitment, size, and fan attachment will vary.

 

H6 radiators have two top hoses, not just one, and one bottom hose.

 

i'm not sure of all the varieties of radiators in the 90's.