How do tell if your head gasket is blown

[jm29henry]

How do I tell if my head gasket is blown.? There is no smell or sign of anti freeze on the spark plugs ,no bubbles in the radaitor.?

[Special Coupe Frank]

What makes you suspect a blown head-gasket ?

What symptoms does the car exhibit ?

[SeaSlugs]

Well start off answering these questions:

What were you doing to suspect this? Give the entire scenario so we know if you were tinkering or hopping in to drive off as normal.

What was the last thing you replaced on the car?

Was the engine hot or cold?

Dos any color smoke/steam come out of the tailpipe?

Are you loosing coolant?

If you are is it steaming out of the radiator or forced out of the overflow or does it just seem to disappear?

Does the engine stumble or have no power or refuse to start when hot?

Does the inside of the radiator smell like exhaust fumes?

Does the car seem to have alot less power?

[tbirdtbird]

let us know how you make out

[Tom Wesenberg]

Years ago I used an old spark plug to make an adaptor to inject compressed air into the cylinder with the piston exactly on TDC compression. Then I can look for bubbles in the coolant or mist spraying from the cylinder when the starter spins it over.

I just made a set of blank off plates to cover the water inlet, water outlet, and water pump holes. I threaded the two inlet and outlet plates with my 1/8" pipe tap so I can install a pressure gauge and adaptor for compressed air. This way I can test it dry before I install the engine in the car.

[Special Coupe Frank]

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I'd vote for a compression test.

[Mitch//pa]

I vote for a cylinder leak down test. A compression test is sketchy for checking a head gasket and still won't tell you where the problem lies..
You can also use the combustion gas tester, then do the leak down

[George Miller]

Leak down test and you can also look for bubbles in the radiator when you gun the engine.

[Special Coupe Frank]

So, again:

Originally Posted by Special Coupe Frank

What makes you suspect a blown head-gasket ?

What symptoms does the car exhibit ?

[Special Coupe Frank]

Originally Posted by George Miller

Leak down test and you can also look for bubbles in the radiator when you gun the engine.

Remove fan-belt first.

[jm29henry]

Thanks for the help she is running rough on idlle.tried replacing carb off of my good running a. Swap out distributor with a rebuilt one and new cap rotor,rechecked Timming ,check for vacuum leak with propain tank no change .she does run better if I turn the GAV to the left counter clockwise. She start right up cold and run ok cold it's start running rough when it's warm up.cleaned plugs no change the car still has good power .no over heating no signs or smell of anti freeze. Oil is clean engine was totally rebuilt less than 2500 miles engine is quite she was running perfect on my last outing she sat for about 6 weeks when she started everything appeared normal I only noticed rough idle when pulling into garage that about all I no for now

[tbirdtbird]

you are shotgunning by changing out parts without doing diagnostics.
this could go on for a long time

[steve s]

I don't think head gasket is your problem, but the way to check is to go to local NAPA store and buy the block tester kit. If you're car is a '28 or '29, you will also need the adapter for large filler neck opening, usually sold for trucks.

I agree with others encouraging a systematic analysis. Two things happen during warm up: (1) thermal expansion of nearly everything, which can create temporary leaks and disconnect marginal electrical connections, and (2) the fuel becomes more volatile.

The nastiest thermal expansion story I've read is the one about the bolts holding the repro junction box to the firewall short out to the firewall when it gets hot enough for expansion to cause electrical contact.

While you're grasping at straws, did you try retorquing the head bolts?

[Mitch//pa]

Since it running rough at idle try and short out each cylinder / plug , see if you get a rpm drop when doing each one..

[jm29henry]

Thank learning as I go willing to do what ever it takes

[jm29henry]

Up date she purring like a kitten . It was something in the distributor I swapped it out for a rebuilt one by a car club member it has not run this perfect since the engine was rebuilt.thank you all so so much for the great advice

[Special Coupe Frank]

Glad to hear it was something simple, jm29henry.

[Bob Bidonde]

Compression test!