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Losing Coolant...why??

dyeager535

dyeager535

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This is going to end up long I suspect. :)

As short as possible. Getting coolant overflow from the expansion tank. Problem is, tank never goes past half full. Pull over and look, and sure enough, there is a droplet on the expansion overflow "vent" and some on the metal below it.

Never seems to be enough to drip.

No bubbles in coolant, no "smoky" exhaust, etc.

I replaced the radiator cap, but no difference. I swore that had to be it, if I'm losing coolant, and apparently know its coming from the overflow, I'm not sure what else it could be.

It does seem odd that for some reason, even though the expansion tank is only half full, it is spitting fluid. It would seem to me that if it is half full, it would take a massive surge of pressure to blow it out of the "vent" in the expansion tank.

I haven't checked since I put 84 miles on it until today, and the coolant was so low I couldn't see any in the radiator. Didn't overheat, but also didn't pick any up from the overflow tank.

I'll have to double check that the overflow hose isn't somehow plugged up, but I just don't get where this coolant is going.

Like I said, the thing doesn't leak coolant anywhere I've seen except the expansion tank, and that never seems to go over half full, so I'm at a loss as to where it's going. It runs smooth as ever, so bad head gasket(s) seem out of the question.

Anyone got any ideas or similar experiences? Really seems to be just an odd problem.
 
pressure test it or tae it somewere to get it pressure tested. are there puddles under the vehicle? take a flash light and check out the intake, t-stat housing, water pump, freeze plugs, hose clamps, heater hoses if you have them. are you smelling coolant? some times if its a very small leak coming from the intake, wp, t-stat housing, freezeplugs the heat from the motor will burn it off before it reaches the ground. check for stains around said objects. not sure why it would only leak around the overflow(thats what i call it not sure if that the technical name) unless theres a small hole or crack in it.
 
Doesn't leave puddles, just enough that you can see it on the inner fender/core support below where the overflow vents. (mines mounted near the battery tray)

No coolant smell, nothing on the windshield like a bad core when I turn the heat on, no leaks anywhere I've been able to see.

Not that this means anything really, but the radiator hoses, water pump, radiator, t-stat, and radiator cap were all either replaced when I put the engine in a few months back, or new in the last few weeks.

Never overheats, temperature doesn't "spike" or anything like that, just acts normal.

It's not leaking AROUND the overflow, it's coming out like it should, IF the overflow was actually full, which its not.

Yesterday drove it around until it heated up to operating temp, then parked it, overflow was at the same level as when the engine was cold. Shouldn't have been, the radiator was at most half full and should have pulled it in from the expansion tank. Just went out and popped the cap on the cold radiator (since yesterday) still evidence of pressure in the system, and the radiator is a bit more full.

Maybe some more driving, and if the overflow goes dry and radiator level continues to drop, then I know the problem still exists.
 
if you cant figure it out id stop at a local repair shop and see what they think. or see if they can point you in a better direction.
 
I agree I'd think you'd see smoke if that much coolant is being burned due to a cracked head or head gasket,I've seen heads with slight cracks use a quart or two in a week or so of daily use with no smoke visible at the tailpipe,that were stopped by using stop leak like Aluma-seal...it must be a steady pinhole leak spraying on a hot surface and evaporating fast enough not to show as a leak--but you should be able to smell it--another thought is maybe the water pump is leakig at the "weep hole" only while its running and letting it escape--this will cause air and foaming in the coolant sometimes also--that might be causing the cap to release and it leaks out the overflow--if all else fails,you could use the blacklight dye stuff in the coolant and use the black light to pinpoint any leaks.....
 
Wow, that is an interesting one.

If I understand you correctly the level in the radiator drops but it never pulls from the overflow tank. There are a few reasons that will happen:
The overflow is too low (distance top to bottom) to pull from,
The hose is too long,
The hose is obtructed,
The radiator cap is malfunctioning,
There is a leak in the system allowing pressure/vacuum to bleed (path of least resistance) and the system cannot pull the fluid from the overflow back into the system,
or a combination thereof.

Since you state that you are losing fluid I would say your "overflow system" is probably working OK, but due to vaccum bleed it cannot function properly.

You say you are definitely losing fluid, so I would start there and fix that. Once you figure that out, then you can work on the overflow issue.
As suggested, I would do a pressure test and see what happens. I have seen head gaskets leak and lose quite a bit of fluid without causing driveability issues or excess smoke. I just replaced the head gasket in my 91 Cavalier (2.2L) which is known for head gaskets. It had leaked externally for years (slowly) enough to notice a constant green on the block, and it started coming out the tailpipe for a couple of months. I decided to replace it when I was going through a gallon of coolant during a 47 mile round trip to work each day. I would have gone a little longer without replacing it as I was just using de-ionized water from work (from the dialysis machines) to keep mineral deposits to a minimum (and it was free), but now that the weather drops below freezing I needed to start mixing with antifreeze and it was getting expensive. The funny part was I did not notice ANY difference in driveability before, during, or after the headgasket replacement. I have also seen other vehicles that would go through far less coolant than I did and have driveability issues (so who knows).

If it's not the head gasket, I would look at the thermostat housing, along the intake manifold where it meets the head, radiator hoses, and heater hoses. A pinhole leak will only show up when the system is pressurized and it may be enough to spray fluid in a misquiding direction. It would also allow air to enter the system instead of pulling from the overflow and not drip while sitting in the driveway.

I lost a motor (actually a head and then I decided to junk the motor) to that on a trip down to N.C. when I was younger. I replaced all the hoses (except one as the store was out) before my trip. During the ride down I never noticed any smell or steam, until I hit West Virginia and the idiot light came on (but it was too late). Once it cooled I fired it up and it ran, I started to add some H20 and it sputtered like crazy (water seeping in through the cracked head). After a tow and some diagnosing and seeing the hood "underlayment felt" covered with antifreeze, the local mechanic said I probably had a pinhole leak in one of the hoses. He pressurized the system and even with the crack in the head, we saw water come out the upper radiator hose (the one I did not replace). The funny part was is as soon as the pressure bled off, you could not see the hole in the hose....

Well, this reply was longer than I wanted it to be, but hopefully some of what I went through will help...

Let us know what you find.
 
Do you have Vortec heads? Look for cracks. Maby bad head gasket.
You said you checked for bubbles. Did you pull the thermostat housing off and start it up? that is the only real way to look for bubbles form a crack/bad head gasket
You didnt say if you checked the spark plugs
Do a plug reading. Take it out run it hard for a while then check the plugs. They should also tell the tail.
 
No, haven't pulled the plugs yet. I HAD, but that was before I had to pull the heads back off. Yes Vortecs, but if they are cracked, it's got to be leaking into the cylinders or intake runners, because there are no external leaks. I didn't notice the coolant issue before pulling the heads, so can't say whether there was a problem or not there already. The heads looked fine when I pulled them, but if it was a hairline crack, I wouldn't have noticed. I had the stock rocker arm studs pulled and put in ARP studs, but I used the thread sealant recommended with them, and the oil isn't coming up contaminated, so I don't think that is an issue either.

I could be wrong assuming this, but the fact remains that even at a half full overflow tank, fluid is still being expelled for some reason, when that theoretically shouldn't be possible, as it's nowhere near the level that should let it spew coolant.

What kind of color would I be looking for on the plugs for coolant problems? I'm sure if 7 look one way, and one looks different, it's a problem, but it oculd be multiple cylinders too I guess.

The overflow is the stock one, but I know there were two styles, one up on the fender and one down low, mines the one that is down low. I'm going to check the line running to it, and the tank to make sure it doesn't have crud in it, but I know I did that before starting the new engine.

I replaced the T-stat with a 16PSI one from the 13PSI one I had laying around that I had been using, but the problem didn't change. I've been watching the thermostat housing, as there was a bit of green sitting on the intake, but that could have been from when I was swapping everything around. I double checked tightness and dried the intake though, so with some more driving, if that is a/the problem, I should notice pretty easily.

All my hoses are routed cleanly, so I can easily see their entire run, and there is no leakage going on there.

Appreciate all the replies, I'm keeping an open mind on this, I really just need to drive the thing more often and maybe I'll notice something I haven't yet.
 
Going from recent memory (two weeks ago) when I pulled the head of the 2.2, it was obvious which cylinder had issues. The porcelain on the spark plug was darker (not in a carbon fouled way), actually it just looked like a deeper tint than the others. Also the top of the piston was actually lighter in color than the others (less carbon). Granted mine had a longer run time with the bad gasket and went through a lot more fluid, so mine was a lot more noticable than most.

My buddy said if the head has a large enough crack or the seal on the head gasket is bad enough, you can find out by disconnecting the ignition and turning the motor over with the starter. Remove the plugs as soon as possible and you should notice moisture on the plugs in the "bad" cylinders (again this is assuming head or head gasket issues).

Pulling the plugs probably isn't a bad idea anyways as it might give a quick indicator of any problems.

Also you said you recently removed the heads. Did you re-use the head gaskets????? I know you probably didn't, but just checking.
 
I have seen some overflow bottles themselves develop leaks (hairline cracks). I would definatly look there if your pressure test passes.
 
Emmettology 101 said:
Maybe there is an air pocket in the system somewhere?
Click to expand...

I guess that is a possibility. Luckily my intake has a purge fitting on the back, so I can pretty easily check that out.
 
When your truck is warmed up and running are the coolant lines hard? I almost bought a truck with a blown head gasket (wasnt running before we got there), there was white smoke pouring out the exhaust and the coolant line was hard as a rock. Just something you can check.


Later
 
Nope, haven't had a chance to play with it. Probably this weekend. Of course, rain all over everything doesn't make it easy to see coolant leaks. :(
 
Most of the motors I've pulled the heads off of that had leaking head gaskets you could tell right away which cylinder was guilty--it will be washed clean of any carbon,same with the spark plug--even if only a small amount of coolant is leaking into the cylinder,that cylinder will be much cleaner looking than the others..a head gasket can leak compression into the water jacket and raise the pressure enough to make the cap release coolant into the overflow,without leaking any coolant into the cylinder also,I've seen that many times too---.

A guy I know has been using the block sealer made by Moroso to seal cracked heads and head gaskets that have a slight external leak on the outside of the block(common on chrysler K cars) with very satisfactory results--its called Moroso ceramic engine block sealer--they have 2 versions of it--one for use with anti-freeze,and one without for racing--he uses the street version used with anti-freeze--he's saved hid daughters mercedes that was smoking out the tailpipe so bad you couldnt drive it--its been 2 years so far,so good--no smoke,no coolant loss.You have to drain the system,put in the sealer with water only,run it the required amount of time,drain it and let it sit 24 hrs,then re-fill with anti-freeze and water--its worked for several of hi customers with "winter beaters" and plow trucks that didnt want to spend any more cash on their vehicles....:)
 
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