Head Gasket leak?

[Drew99GT]

My mom's 2007 Impala had the head gaskets replaced under warranty about 3,000 miles ago. Everything has seemed fine since. I had to top off the coolant just a tiny bit - it was using about 10 ounces of coolant every couple thousand miles before the gaskets were replaced.

Today I decided to drain and fill the radiator and when I ran the engine with the radiator cap off, there were tons of tiny bubbles. I mean it was like sticking a straw in water and blowing as hard as you can kind of bubbling. The level dropped and I kept topping the system off and the bubbling slowed down, so some of it was trapped air, and buy that time it was about to overflow so I stuck the cap on.

There's no other signs of a head gasket leak. No overheating, not steam out the exhaust. I'd think a leak that bad from the combustion into the cooling system would have all the other signs of a bad gasket failure.

What are your guy's thoughts? Anyone had a head gasket leak the made bubbles in the radiator with no other symoptoms? Maybe it was all trapped air.

 

[oggb]

Trapped air would be my guess. Some of the GM engines are a real PITA to get all of the air out of.

 

[Drew99GT]

It didn't even cross my mind that the filler neck is bolted to the water pump housing. I bet the bubbles are from the water pump churning.

 

[cmf]

Sounds like trapped air. A lot of cars upper radiator hose is at a higher elevation than the radiator causing air to get trapped there.

 

[Sayjac]

You may want to read this thread, it may help. I've just finished getting a head gasket installed and I'm going post a follow thread a bit later.

The combustion leak tester was one of the better ideas. I didn't do it, but it seems a reasonable start if you can find one. As questioned in my thread, the bubbles sure seem like a sign of a hg issue. I too had no other signs other than my recovery tank overflowing. But, now I do remember seeing bubbles when I opened the overflow tank when it was first noticed a few months ago.

All that said, mine is a different vehicle and it may not be the hg, could be something lesser as mentioned above.

HTH

 

[229]

After you are sure it is fully burped check it again. If you do not have access to testing equipment then check it again the way you did. This is a sign of gasket failure if it continues. If you have a funnel the size that would seal the filler neck then fill half way up so you don't have to worry about spill and look for bubbles again. You may want to elevate the front end also.

 

[ls1mike]

Trapped air, they are a PITA to get all the air out of. Most of my GM stuff is the same way. I like the cars, I wish they were better at getting air ouf the cooling system.

 

[Drew99GT]

Originally Posted By: cmf
Sounds like trapped air. A lot of cars upper radiator hose is at a higher elevation than the radiator causing air to get trapped there.


On this car, the cap is actually mounted on a filler neck that's bolted to the water pump housing. That makes the cap about 4 inches higher than any other point in the cooling system. I think GM did this to help alleviate some of the Dexcool turning to mud problems from trapped air.

It would be nice if they included an easily accesible bleeder valve...

 

[Drew99GT]

Oops, the filler neck is not bolted to the water pump, so that's not the cause of the bubbles. They're small bubbles - looks like zeltzer water type carbonated bubbles.

 

[scott37300]

Originally Posted By: Drew99GT
Originally Posted By: cmf
Sounds like trapped air. A lot of cars upper radiator hose is at a higher elevation than the radiator causing air to get trapped there.


On this car, the cap is actually mounted on a filler neck that's bolted to the water pump housing. That makes the cap about 4 inches higher than any other point in the cooling system. I think GM did this to help alleviate some of the Dexcool turning to mud problems from trapped air.

It would be nice if they included an easily accesible bleeder valve...


The filler neck is NOT on the water pump. Your not putting coolant into the power steering pump are you?

Most GM cars have a bleeder valve on them that you need to open to get the air out. Did you do this? I've done a 2004 impala 3.8 that has the bleeder valve by the thermostat. It's just a brass screw that is a 6mm or something. You just unscrew it a little and the air will come out. Also you should run your car up to operating temp with the heater on HOT and the fan OFF and then bleed again after the system cools. This gets the air out of the heater core.

If you are 100% positive that ALL the air is out of the system then go buy a combustion leak detector. They are around 40 bucks and will tell you for sure if you have a leak, and it will be cheaper than taking it to a dealer to have them diagnose a head gasket.

Here is a link to one, http://www.tooltopia.com/lisle-75500.aspx

My guess is just air trapped in your system since you never mentioned bleeding it, and I'm pretty sure you should have a bleeder screw somewhere. Usually on the drivers side of the engine somewhere in the cooling system hoses or where they go into the engine.

 

[Drew99GT]

Dude, I'm not putting coolant into the power steering pump. The new Impalas with the 3.5L and 3.9L are 100% different then the older ones with the 3.8, of which I own one. The pressure cap on the new ones is on a long neck that bolts to the top of the engine completely away from the radiator.

There is no bleeder screw on these. From what I researched, the factory service manual indicates a complicated vacuum bleed procedure using a coolant exchange machine.

I'm slowly getting all the air out - it's taking some time.

 

[The_Eric]

Originally Posted By: scott37300
If you are 100% positive that ALL the air is out of the system then go buy a combustion leak detector. They are around 40 bucks and will tell you for sure if you have a leak, and it will be cheaper than taking it to a dealer to have them diagnose a head gasket.



They're not always definitive.

 

[scott37300]

Originally Posted By: Drew99GT
Dude, I'm not putting coolant into the power steering pump. The new Impalas with the 3.5L and 3.9L are 100% different then the older ones with the 3.8, of which I own one. The pressure cap on the new ones is on a long neck that bolts to the top of the engine completely away from the radiator.

There is no bleeder screw on these. From what I researched, the factory service manual indicates a complicated vacuum bleed procedure using a coolant exchange machine.

I'm slowly getting all the air out - it's taking some time.


Dude, OK, maybe a better description next time will help instead of "the filler neck is attached to the water pump". Just wanted to make sure you weren't mixing up the water pump with the power steering pump. You can buy an airlift for 100 bucks if you want to vacuum the system, I have one and they work great. Also a lisle spill free funnel can help to bleed the system.

 

[scott37300]

Originally Posted By: The_Eric
Originally Posted By: scott37300
If you are 100% positive that ALL the air is out of the system then go buy a combustion leak detector. They are around 40 bucks and will tell you for sure if you have a leak, and it will be cheaper than taking it to a dealer to have them diagnose a head gasket.



They're not always definitive.


You're correct, but if he is getting bubbles in the radiator then this tester would turn colors.

 

[morris]

air lock? drill a 1/8 hole in the stat. a recommended thing by Chrysler. have done it lots, no trouble. thats the short story

 

[mechtech2]

Most likely, this is normal.
Air is being churned. It can take a while to get rid of this.
Keep your reservoir 1/2 filled. check it every day for a week.

 

[The_Eric]

Originally Posted By: scott37300
Originally Posted By: The_Eric
Originally Posted By: scott37300
If you are 100% positive that ALL the air is out of the system then go buy a combustion leak detector. They are around 40 bucks and will tell you for sure if you have a leak, and it will be cheaper than taking it to a dealer to have them diagnose a head gasket.



They're not always definitive.


You're correct, but if he is getting bubbles in the radiator then this tester would turn colors.


You know, I'd have thought that too if it weren't for a particularly troublesome 98 Caddy with the Northstar engine. Lots of overheating issues, it would puke coolant out like no tomorrow, but never change the color in the block tester and would pass a pressure test standing on it's proverbial head. Weird....

 

[Drew99GT]

Just an update; the problem does seem to be trapped air. I'm not seeing any bubbles in the filler neck of the cooling system with the engine running. I've been topping it off every day.

I've never seen a cooling system this hard to bleed and I've followed all the tricks - run the engine with the cap off and the heater on, squeezing both radiator hoses etc. The thermostat does also have a bleed valve.

I'm going to buy one of those spill free funnel kits after this episode and be done with it.