blown head gasket?

Question

How can you test for a blown head gasket? motor is a '73 small block 350,, has goop in the radiator but it may be stop leak,, oil is indeterminate and the car deosn't overheat, no steam out of tail pipe.

Answer 1

There are several ways to check for a blown head gasket. Start the engine cold with the pressure cap off. Watch the coolant in the for signs of bubbling or "false boilling". If so then it may be a sign that combustion pressure is entering the system through a failed head gasket.

Pump up the cooling sytem pressure with a cooling system pressure tester pump. Hold it at 15psi for several hours. Keep pumping it up if the pressure drops. Pull the plugs in the mean time. After several hours holding pressure rotate the engine with the starter with the plugs out. Watch for coolant spewing out the spark plug ports as a sign of a leaking head gasket.

With the cooling system full, apply 120psi shop air to each of the combustion chambers, one at a time, thru the spark plug port. Make an adapter out of an old spark plug shell and run shop air to the port. Rotate the engine so that the valves for that cylinder are closed. Watch the coolant in the surge tank for bubbling. If the chamber holds the 120psi with no bubbling then chances are the head gasket is fine.

Good luck!

Answer 2

There are several ways to check for a head gasket. Start the engine cold with the pressure cap off the pressurized surge tank. Watch the coolant in the surge tank for signs of bubbling or "false boilling". If so then it may be a sign that combustion pressure is entering the system through a failed head gasket.

Pump up the cooling sytem pressure with a cooling system pressure tester pump. Hold it at 15psi for several hours. Keep pumping it up if the pressure drops. Pull the plugs in the mean time. After several hours holding pressure rotate the engine with the starter with the plugs out. Watch for coolant spewing out the spark plug ports as a sign of a leaking head gasket.

With the cooling system full, apply 120psi shop air to each of the combustion chambers, one at a time, thru the spark plug port. Make an adapter out of an old spark plug shell and run shop air to the port. Rotate the engine so that the valves for that cylinder are closed. Watch the coolant in the surge tank for bubbling. If the chamber holds the 120psi with no bubbling then chances are the head gasket is fine..

Blown Head Gasket Symptoms
The coolant must be going somewhere, maybe out the exhaust. There are several ways to identify a blown head gasket between the cylinder and the cooling system. The condition of the spark plug you described does indicate a blown head gasket. But, if the engine is overheating, and suffering detonation, the white deposits on the spark plug may be aluminum particles from the poston crown. Look carefully. Excessive steam from the exhaust, especially on a hot re-start after parking for only a short while, is also a strong indicator of a blown head gasket. On small block Chevy engines (and most other engines, for that matter), a blown head gasket will not usually allow coolant into the crankcase, so you won't see water in the oil. More often, the result will be combustion gases leaking into the cooling passages.
(checking the obvious)
Remove the spark plugs and crank the engine over (if you strongly suspect a blown head gasket, you should do this before starting the engine anyway, to avoid "hydro-locking" a cylinder and causing more serious engine damage). If any water sprays from any spark plug hole, you got a bad head gasket.
(checking the less obvious)
With the engine cold, relieve any pressure in the cooling system by removing the radiator cap, re-install the cap tight and pinch the upper radiator hose tight with your fingers. Block the drive wheels, set the parking brake firmly, start the engine and put a load on it (do this with someone you trust will NOT run you over) by putting the trans in drive and raise the engine speed slightly with a foot FIRMLY on the brake. If the head gasket is blown more than just a "little", you will feel the radiator hose inflate as soon as the engine is loaded (cylinder pressure leaking into the cooling passages). If the gasket is leaking a lot, you may feel the hose begin to inflate as soon as the engine starts, or even while cranking.
(checking the even less obvious)
Take the car to a shop that has a block-tester (most radiator shops will have this). The block tester is a small squeeze ball air pump on a clear plastic cylinder, with a reed valve and filter inside. The cylinder is filled with a blue liquid that turns yellow when hydrocarbons are disolved in it. Using the squeeze ball, gases from inside the radiator are drawn through the inidicator liquid. If there is even a small cylinder leak into a cooling passage, the liquid will change color, indicating the presence of combustion gases in the cooling system.
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When checking for a blown head gasket, one of the most common tell-tale signs is a milky-gray ring around your oil cap. When coolant enters the engine oil through a crack in the head or through a blown gasket, it evaportats and leaves a milky ring around the oil cap. Another easy way to tell is to check your oil dipstick. Change your oil and pull out the dipstick. Make sure that you take note of how far up the dipstick the oil is. Top off your cooling system and fill your cooling resevoir to the top. Screw radiator cap back on and start engine. Run engine for about 20-30 mins. or until it reaches normal operating temperature. Allow engine to cool (engine must cool completely to get accurate oil reading!!). Check oil dipstick again. If the oil has a watery appearence and has risen noticibly up the dipstick, the you probably have a blown head gasket or a warped head. Also look for a dripping, sweet-smelling liquid coming out of your tailpipe. Any of the above symptoms could be the result of a blown head gasket. The easiest way to tell is with a compression meter. This replaces the spark plug and lets you know what compression each cylander is running at. If your compression is abnormally low, then you have a blown head gasket or a warped head. (note: consult repair manual for appropriate compression of each



I've had this happen to me and these links I posted pretty much tell all the horrible details.. I hope this helps a bit.

Answer 3

Check for blown head gasket.
1) With the engine cool, fill the radiator, and overflow tank.
2) Start the engine, remove the radiator cap, and place your hand over the filler neck. Now, watch the over flow tank for bubbles.
3) Have a buddy hold the brake pedal, and rev up the engine.
If there are bubbles coming up out of the small hose between the radiator and into the overflow tank, you have a leaking head gasket.

Stuck thermostat.
With the engine cool, look into the radiator to see if coolant is running thru the cooling fins. If it is while the engine is cool, you have a bad thermostat

Answer 4

definately blown if nothing is coming out of tail pipe, that means its coming out of someplace else exe. the gasket leak