glove test video; questions.

[alwaysFlOoReD]

I'm posting a link to a vid posted on another forum I frequent.
Its a Subaru Brat. A boxer engine I think.
In the vid the glove pulses quite slowly, not what I'd expect from a bad head gasket or crack in the head. Then it shows a moment of complete vacuum... I'm baffled...
Anyone?

@RonD

 

[Uncle Gump]

I would say the pulsing was the equivalent of the coolant raising and falling slightly in the radiator just prior to the thermostat opening. The suction on the system is when the thermostat actually opened.

 

[RonD]

Yes +1 ^^^^

Not a blown head gasket or cracked head

Glove test should be done on cranking engine not running engine
You can see a well defined pulse, and you can then remove 1 spark plug at a time, repeat the test, and can then find out which cylinder, or cylinders are leaking

If you want to test running engine just fill rad to top, leave cap off, and start cold engine, if water/coolant keeps overflowing the rad then there is a blown head gasket or cracked head
No glove needed

The pulse in the video is the water pump, and then the suction was most likely air that was purged because of a small coolant leak