coolant loss in overflow tank?

[tim land]

info:
vehicle: 2000, acura, integra, gs-r, hatch (3door), 103k original miles
misc info: has overheated once, cause: rad top tank leak at seams.
Hi fam,

So I’ve been chasing this coolant loss on my car for a while now. There is no obvious external leak so I thought it may have been a “blown” head gasket..and many shops assumed that too…however recently i did a leak down test and found i was only losing 5 psi on every cyl. (100psi regulated air, 95-94 psi in cyl). I also did the test where you put your oil on the exhaust manifold to see if it sizzles–doesn’t do that, no white smoke or any smoke for that matter. NOthing indicating a blown head (thank GOD).

You do smell the coolant in the engine bay but cant see any leaks.. someone brought to my attention that maybe it could be evaporating from the overflow reservour, hmm never thought about that. But seems like it actually could be, because the smell is coming from exactly that area near the overflow. But my question is, how does it evaporate from the overflow? BUT interesting point he made. Any suggestions on that? Thank you

Topic

[Stephen Bowen]

How quick is the loss? Are we talking about a massive amount in a day or two? Or very slow and you need to refill it every week or more?

Coolant leaks can be a bear to locate. In general it takes a full check, both visual without pressure, and a pressure tester on the radiator/system to see if you can find any signs of leakage.

Do not discount areas that you ‘think’ are free and clear. I’ve seen water pumps get a very slow leak out of the weep hole and they dribble out under the timing cover (overhead cam engine) One would never even see the leak, because it’s pretty well contained and doesn’t present itself much. Pin holes in radiator or heater hoses. Can hide leaks pretty well, and spray a fine mist that you smell, but can’t really pinpoint or see. (And if it’s spraying on the exhaust? You’ll never really see anything) If you think about it, one should never smell coolant in the engine bay. It’s pretty well a sealed system. I’d see about renting or buying a decent pressure tester and giving it a good look over from top to bottom.

S-

[Andrew]

It still could be a small head gasket leak, or combustion leak into the cooling system – what caused your original rad to fail? Was it just a deterioration of the aluminium/plastic junction, or was the engine pressurising the cooling system? I hope for your sake it was the former. Get your coolant tested for combustion products just in case.

I don’t think that coolant evaporates quickly enough out of the reservoir to cause a noticeable loss. It could be a faulty radiator cap allowing the coolant to overflow too soon, or not allowing it back in – inspect it, and if in doubt replace with Honda OEM.

[tim land]

So the coolant loss is minimal. I would fill it to the full line (engine cold) and so far its been 5months since i topped it to full and now it is just above the min line (engine cold).

I have put a pressure tester on the radiator before, and there was no loss of pressure in 2 hours i left it there. This is with engine not cold though, i should do it after leaving it overnight. I haven’t actually checked the rad cap, which i should. I just didn’t because I replaced it when i replaced the radiator. But I should test it anyways, also I didn’t see a leak and I know that it opens because the overflow tank rises after a highway drive. But i know that doesn’t validate it being good. so i’ll do that.

I didn’t mention, but i did do a block test on it too. WIth the dual chamber block tester. and I need to do it again honestly because I don’t know why, but when i went to check that it would turn yellow by sucking the exhaust gas at the tailpipe, it stayed blue -_- so I don’t know why it did that.

[tim land]

OH, also about the water pump…I actually was leaking at the water pump, because I did check that a year ago and it was leaking at the weep hole. So i replaced that but there is still coolant smell, but now its not the entire engine bay, only near the overflow tank.. THank you for your inputs

[Andrew]

Hmmm, that is a slow loss. With that loss rate and your age of vehicle I wouldn’t worry too much. However, I know it’s annoying when you can’t track these things down but I don’t suspect even a good pressure tester would pick up that kind of leak – it must be a real pinhole.

UV leak dye, drive it for a few weeks then inspect?

As for the lack of colour change, I’ve never tested the exhaust gas directly like that. Could your testing kit be old? Maybe the combustion gases have to be dissolved in the coolant to show up.

[Lorrin Barth]

Going from the full mark to the add mark in the reservoir in 5 months is normal evaporation. I don’t believe you have a leak.

[Ingvar]

No. On sealed well functioning cooling system there is no “normal” evaporation. Proof? They did my Camry water pump 2 years ago. I draw a mark at the coolant in expansion tank level same day job was done. It’s still at the same level.
UV dye is no much $$ to spend and WILL pin point EXTERNAL leaks. Just don’t forget to pressure wash engine best you can to have good results.
There is a chance that when you topped tank on COLD, engine sucked some coolant in during normal operation. Now, if you topped it AGAIN and it starts goiong down – well, Huston we have a problem.

[tim land]

Yeah, I’ve been planning on putting dye into my coolant and seeing if I can either find a external leak or maybe, if it’ll show up in the exhaust pipe if i do have a small head gasket leak. Yeah as for the block tester, I did mess up and didn’t realize that even after taking out the coolant from the filler neck it still rose up so I sucked some coolant into the chamber so that may have caused it, i’ll do it again and see what i get…also its new so couldn’t be that. And I did warm up my car and it was idling at operating temp when doing the test, so combustion gases should have had enough time to seep into the system.

And yeah as for normal coolant loss, I dont know. Because a friend of mine has the exact same car, but with 200,000 miles and he doesn’t loose any coolant. And his engine bay doesn’t smell like coolant, on mine you can smell the coolant after a long drive (thats when its strongest) even with the hood closed.

[Erin]

Let’s be realistic –
It sounds like you are chomping at the bit to find coolant leaks. If top-offs are needed every few months and nothing seems to be acting up, it is probably nothing to worry about.

I don;t think I have owned many cars that didn’t emit a coolant smell now and then but not every car had serious coolant leaks. Coolant heats up, expands, contracts, etc. I find it hard to believe any cooling system is so efficient and tight it would evaporate nothing.

You could tear into a bunch of stuff trying to find it or maybe fix it but that would be a lot of work for something that may not even be serious. Or you could take it to a shop and I promise they will want to do $1,000 or more worth of work.

If you run the dye and still cannot find anything, why worry?

[Michael]

I sometimes smell engine coolant from my engine compartment but on the timing belt side. I had the Timing Belt done at the dealership about 2 years ago. Im thinking it could be the weep holes on the water pump which in the service manual says some leakage from the weep holes is Normal. Or maybe you have a very some leak some where around the radiator.

[James O’Hara]

The find it all trick for coolant leaks. Remove all coolant from the system. Apply shop air at the psi of the system. The psi is written on the cap normally. Spray everything you can get to on the coolant system with soapy water I suggest 60% dawn dish washing soap and 40% water. Hoses, caps, etc. If nothing is seen externally then you must listen for internal leaks. AKA remove the air filter listen that would point to coolant leaking into the combustion chamber. Then remove the oil filter stick and listen for air or bubble sounds. That would indicate oil cooler and/or head gasket. Doing it this way there is almost no way not to find the leak. You are going to want to do it once while the engine is cold, once while warm, and once while hot.

[Author]

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