Damn it !!! Disappearing Coolant !!!

[Mellemel]

I'm still having coolant loss issues here ! Can anyone say where it's going ? There's a new radiator, a new radiator cap, a new T-stat, new hoses and clips, no visible drips anywhere now from any hoses ! I filled the overflow tank to the Full mark yesterday and topped off the radiator Today, after driving less than 100km's the coolant in the radiator needed filling back to the top with approx a pint, the overflow tank level never moved ! It did not get pulled back into the radiator. I have no oil in the coolant and I have no coolant in the oil. Yesterday I had a clean tailpipe, meaning no steam after warming up. Today I did have a little amount of steam even after an hour of driving, the weather was the same both days, +10c ish.

When I switch off the engine I can hear an air bubble escaping into the overflow tank once every 3 seconds only and not for very long. I don't think that's normal ! Is this a sure sign of a bad HG ?

Now if there is a high-pressure leak happening would it lose up to half a pint to a pint of coolant in under 100km's of driving?

Is it possible I have a crack in the Head allowing the coolant to evaporate off or burn off in the engine which is giving me the steam in the exhaust even after an hour driving ?
No, I have not done a cooling system leak test yet, I might have to.

I have some block sealer which will be a last resort.

 

[StreetCreeper]

I'm still having coolant loss issues here ! Can anyone say where it's going ? There's a new radiator, a new radiator cap, a new T-stat, new hoses and clips, no visible drips anywhere now from any hoses ! I filled the overflow tank to the Full mark yesterday and topped off the radiator Today, after driving less than 100km's the coolant in the radiator needed filling back to the top with approx a pint, the overflow tank level never moved ! It did not get pulled back into the radiator. I have no oil in the coolant and I have no coolant in the oil. Yesterday I had a clean tailpipe, meaning no steam after warming up. Today I did have a little amount of steam even after an hour of driving, the weather was the same both days, +10c ish.

When I switch off the engine I can hear an air bubble escaping into the overflow tank once every 3 seconds only and not for very long. I don't think that's normal ! Is this a sure sign of a bad HG ?

Now if there is a high-pressure leak happening would it lose up to half a pint to a pint of coolant in under 100km's of driving?

Is it possible I have a crack in the Head allowing the coolant to evaporate off or burn off in the engine which is giving me the steam in the exhaust even after an hour driving ?
No, I have not done a cooling system leak test yet, I might have to.

I have some block sealer which will be a last resort.

I would start with the simple things like your coolant overflow hose that connects to the underside of the coolant overflow bottle cap. Perhaps it has simply fallen off and is not allowing for the radiator to suck the coolant back into the radiator when the coolant cools down.

Should look like this. If yours doesn't, it is probably sitting at the bottle of the overflow tank.

​

 

[Mellemel]

Checked that weeks ago. Took the overflow tank out and cleaned it out along with the pipes too.

 

[traffic61]

I had a very sneaky little leak in my heater control valve that vexed me for a bit. Just a thought.

 

[Mellemel]

How much were you losing? and how often did you have to top up ?

 

[Yoder68]

Napa sells a kit for checking for the presence of combustion gases in your coolant. My old 22re had symptoms like you describe. The test kit revealed combustion gas in the coolant.

I pulled the head, and it was pretty obvious where it had started leaking!

I was worred about the bubbling into the coolant reservoir after shutting off the engine... apparently for good reason!

Hopefully yours is something simpler!

 

[daniresch]

I'm sorry to say, but from everything you have described sounds like a leaking head-gasket and your coolant is coming out the tail pipe. When the motor is cold it will not leak, however, as the car warms up it will start to leak coolant into the cylinders. Over time the leak will get worse and worse and the bubbles you hear when you turn the motor off will become greater and more persistent.

 

[reelamin]

I have a 02 Suburban...with 290K. It has burned coolant for years. I put all new lifters in it at 250K, and my mechanic said I had a leaking head gasket. Put it all back together...she still burns coolant....and there is not one tell tale sign "normal"...not one. But...if I let the dust build up it actually has a orange tint near the exhaust outlet...hmmmm the DexCool is orange. Most would call that a clue. I just dumped in another half gallon, and a quart of oil...again not one bit of visual evidence. What am I going to do to fix it? Not a GD thing...I'm driving the ***** until she quits!!!

Buy you a beer if it's not a leaking head gasket.

 

[Mellemel]

I think I'm gonna hafta do the same Reelamin ! I get too concerned about my motors not running right. It's really only my work car, I shouldn't worry about it like I do. F*** it.

Daniresch, also dude I fear you are correct.

Thanks guys.

 

[mtbtim]

Hey Mel, if you want to delve deeper into investigating this problem, you could buy a compression tester and test all your cylinders. Whichever cylinder(s) are low, you can then do a leak down test on them. When you test the bad cylinder(s), a positive test for a bad head gasket is you'll see bubbles in your radiator because the air pressure is making it's way out past the head gasket and into the coolant channels. Another positive test for a bad head gasket is you have two cylinders next to each other that are low because the head gasket between the two have failed letting the pressure leak from one to the other.

Low cylinder pressure could also be caused by worn out piston rings, or bad/out of adjustment intake or exhaust valves. If you take off the oil fill cap and you hear air escaping, it's bad piston rings. If you hear air escaping out of the throttle body, it's an intake valve problem. If you hear air escaping out of the exhaust tail pipe, it's an exhaust valve problem.

If you don't want to buy a compression and leak down tester (you'll also have to own an air compressor to do the leak down test), you could just have a local shop you trust do this for you so at least you know without a doubt what the problem is. But, from what you've described, it sounds like a bad head gasket.

 

[JayRolla]

I would do a simple pressure test of the coolant system before compression and leak down tests.

 

[thegipper]

I would do a simple pressure test of the coolant system before compression and leak down tests.

^Do this first.

The next steps would be to pull the plugs and see if any are wet. If they are, then you'll need to do a leak down test. If any of the plugs are wet, it's pretty safe to assume you have a head gasket leak and that cylinder will fail the leak down test.

I'm hoping you just have a leak somewhere in your cooling system but by the sounds of it, you may be in a bit of trouble.

Good luck

 

[blaze17]

Check that heater control valve if you haven't yet. Behind engine, top center firewall. The drivers side hose fitting breaks down and develops cracks.

 

[Mellemel]

New heater control valve last summer ! It's not leaking. The old one was, but not anymore.

 

[muellernautique]

Did you ever find out the source of your leak problem? If so, what was it and how did you fix it? Sort of battling the same issue right now.

 

[marshmarsh]

Did you ever find out the source of your leak problem? If so, what was it and how did you fix it? Sort of battling the same issue right now.

I too am having the same issue but this thread cut out. Any developments? anyone?

 

[TX3G4R]

I too am having the same issue but this thread cut out. Any developments? anyone?

Mine had a very slow leak where the IAC valve connects to the throttle body, I'm assuming the IAC gasket had failed. It was dripping coolant onto the transmission and other places.

 

[Staticrider]

The first thing I use is UV coolant leak detector from NAPA and a IR flashlight in a dark shop.

 

[marshmarsh]

Mine had a very slow leak where the IAC valve connects to the throttle body, I'm assuming the IAC gasket had failed. It was dripping coolant onto the transmission and other places.

Thanks, that's what I was hoping for. So I just removed throttle body and IAC, cleaned them well and replaced both gaskets and am about to start driving her again to see if there is still a leak. I just had it at the garage and they performed a compression test and said everything was fine there.

 

[wangissimo]

Would love to hear from [MENTION=100539]Mellemel[/MENTION] about what the problem & solution was. I'm apparently having the same symptoms as well. All of a sudden, my coolant levels were abysmally low - I'd had to put probably 3/4 to 1/2 gallon to refill the radiator and the reservoir. Then I'd drive, keeping my eyes on the OBD readings for coolant temp, where it would stay constant at about 190F for 100mi (climbing up to Lake Tahoe, about 7000ft elevation gain (if that makes a diff). After stopping, I'd open up the hood to check on the reservoir - looked the same as before. No weird exhaust, no leaks onto the ground. Then overnight, I'll check the engine bay again in the morning, then lo and behold, the reservoir level went from right between the high and low marks, to the lowest end of the low mark -losing probably around 250ml, or half a pint. I'd check the ground again to find no leaks.

Furthermore, in my case:
2000 4runner 6cyl
no white exhaust
dipstick & oil cap looks not milky
nothing dripping onto the ground
radiator cap looks good

any pointers would be greatly appreciated