"stryped" wrote in message
...
On Apr 22, 8:52 pm, "Don Young" wrote:
"stryped" wrote in message

...I
got to thinking, I know this is a "red neck" way of doing this but
if a person wanted to see if a crack in a head (like my old heads) was
a "functional" leak, would it be possible to somehow plug the coolant
ports in the head with some material like stuffing parts of a rag or
something in there, filling the head partially with water, paint
thiner, etc, and introducing compressed air into a port to see if a
crack between the valves leaked? I just got to thinking about that
last night. I am not going to re use these heads but wondered if it
would work?

The surface tension of water makes it less likely to leak through a small
crack. Kerosene will often do better or a little soap in the water might
work.

I have taped up the ports and pressurized with the outlet of a vacuum
cleaner or an air blow gun to find some leaks. Just a little air pressure
and some kid's bubble solution seems to work pretty good for me sometimes.

It is very controversial but Bars Leaks or other sealers sometime work
well.

Don Young

Would it be better to plug the ports, pressurize with air compresser,
then dip in a tank of water and watch for bubbles? Or To plug the
ports, pressurize and spray saop and water on the head?

When you talked about using a bubble solution I was not sure if you
meant inside of the head or on the head.
To me, the easiest way is to turn the head upside down so that the bubble
solution will pool around the suspected crack area in the combustion
chamber. You only need a thin layer. Then stick the vacuum hose or blowgun
into a coolant port and blow as much pressure into it as you can reasonably
manage, just holding the hose with a rag around it or something similar. It
doesn't take much pressure to make bubbles.

This is not a 100% sure method because there are cracks that leak only under
high pressure or temperature but I have found it to be very useful and it's
cheap enough.

Don Young