Coolant not returning to rad from overflow tank

[96tsport]

Just noticed this (or became aware.. of it) last night. Googled it this AM & like alota snags, could be minor but could also be major.

My symptoms are very much like in this thread (but no misfire on start) including:

It's been a couple of days and the problem still persists; the coolant is not returning to the radiator. I did notice something and it finally dawned on me. Everytime I remove the radiator cap to fill it, pressure is being released. It's like opening a soda can. Even when the engine is cold!

Will update..

[Jeffrv]

I would suspect either the hose from the rad to the overflow is cracked or somehow defective, or , more likely, the rad cap is finished..put a new one on.
Jeff

[96tsport]

Yup, gonna go over basics but suspect I have a head gasket scenario & might have even had it the whole time I've had the van.

There was clearly some goop in the coolant from the first day.

Like in the other thread, did a start with the rad cap off & saw

a steady stream of fine bubbles percolating in the coolant

In that thread, a thermostat change seemed to be a fix.. at first.

Dunno how long this has been going on. Flushed the rad with some stuff recently & maybe opened up what the goop that was in there may have been sealing.

Have heat & engine normal otherwise; oil looks normal.

Think i'm gonna at least look into ..engine head gasket/block goop for now..

Might have a miracle like here..

Im a mechanic of many years and have replace many head gaskets. I have also tried a product called block seal sold at many autoparts stores. The car was a 1982 z28 camaro, that had a cracked head or blown headgasket so severe that antifreeze would pour through the engine faster than I could fill it. I drained antifreeze and spent much time flushing the antifreeze from engine and radiator. Poured in the block seal and ran as directions indicated. I drove the car for a year and a half without losing any (literally), never added anymore antifreeze and the problem completely went away. I sold the car and the guy that bought it to my knowledge is till driving the ol girl. Bare in mind most engines blow head gaskets because of over heating, so fix the overheating problem as well.

http://www.allpar.com/fix/cracks.html
http://www.cadillacforums.com/forums...rmagasket.html

[96tsport]

Is "a steady stream of fine bubbles" absolutely a head gasket or other major scenario, or could there be other minor causes?

Doesn't begin until ~ 5 minutes after engine start.

Engine seems normal otherwise.. & driven daily.

Ran across this (Napa Leak Detector Kit/Engine Block -Item#: BK 7001006) combustion leak tester that can confirm combustion gases in coolant.

[96tsport]

Ran across this interesting info. I suppose you can have a minor problem that can last a long time & doesn't get worse.
Or.. van can be fully usable as is. As mentioned, I suspect my issue has been there from the start & continues to run & work normal (~ 55clicks now).

http://answers.yahoo.com/question/in...8010548AAXED1f
[My own credentials... Corporate level engine engineering, field service (worldwide), and training.... retired after 32 years combined with General Motors, Roger Penske, and Daimler-Chrysler...]

3.) Bubbles in the running coolant... usually bad news... compression and combustion pressures are the usual cause... To diagnose, run the engine to full operating temperature... shut down... quickly remove the spark plugs and do a compression test at each cylinder while still hot... If one or more cylinders is low... that indicates a leaking cylinder via a blown head gasket, poorly seated or worn valves, or even possoble a cracked head casting... if the head is removed for low compression, don't just assume a head gasket... Have the head pressure checked and magnafluxed for cracks, and the valves ground at a good rebuild shop... If indeed it is found cylinder pressure is entering the coolant while running, the explanation for the coolant pressure not bleeding off overnight back thru the cylinder leak(s),.. It is not uncommon for the cylinder gas leaks to occur one-way into the coolant at operating temp only... at shutdown the coolant often will NOT leak back in the reverse direction to the cylinder(s) because compression leaks tend to close when cool, and the coolant pressure is lower than the operation cylinder gases...

Dunno what "poorly seated or worn valves" has to do here with bubbles perkin in the coolant?

In the Cady link provided earlier, found out that GM actually sells block seal pellets that were used from the factory (for a time) on their troublesome alum northstar engines.

More comments here from a fella with ~ 6.500 posts.

Due to casting porosity issues in early Northstar engines, GM began to use its Cooling System Sealing Supplement in the Cadillac cars from the factory. As casting integrity became cleaner, they quit using it at the factory, but it's still often used by owners and dealerships alike, and can be bought over any GM dealership service counter. It's the exact same formulation as the Bars Leaks Golden Seal (NOT the Aluma Seal or whatever that is). The Golden Seal and the GM pellets are all natural, and actually include crushed up almonds in there, if you believe it. They help stop small pinhole leaks.

I used the GM pellets twice on non-Cadillac cars. I had an '84 Oldsmobile with the 307 V-8 and had a small front intake manifold seal leak, right at one of the front corners, where the head meets the block. The GM pellets sealed that right up. I also had a '95 Nissan truck with the 4-cylinder and because the truck had so many miles on it (178k when I bought it), I changed the coolant and used a half package of the GM pellets in it. No problems whatsoever. If they don't dissolve right away in the radiator, they get crushed up by the water pump when run. They're a nice addition to any cooling system, because they help to scrub certain parts in the cooling system (like the water pump seal) to prevent debris from lodging, and also add a slight bit of protection against nuisance leaks.