Topic: Is it neccesary to use acetone to test for valve leaks?

[catzor]

I have my new head here and I'm eager to test it. Do I need to use acetone specifically, or is that just what's most preferable? Seems like alcohol, thinner, mek, etc. would work just fine to me, but I must be missing something. 

[paulages]

I use food-dyed isopropyl alcohol, though it is better to vacuum test through the ports. the real test apparatus for this is spendy, but you can make a poor-man's version like this: find a bung or suction cup large enough to fit in the port opening, drill a hole in it for a tube or nipple, and seal it with silicone or whatever. buy a brake bleeder kit if you don't already own one...make sure it has a gauge on the pump to show vacuum pressure. You'll attach the end of your brake bleeder tube to the port bung you've just created so that you can build vacuum in the port and see whether or not it holds. When you pump it up, you'll have to make sure your bung is sealing in the port. It's a bit tricky on some heads. If the valves are sealing, it should hold 20 PSI or so for at least 10 seconds.

[fastbroshi]

  I watched while an old fella rebuilt my head, he was doing something with soapy water, can't remember exactly what.  Maybe that will jog someone's memory and they'll chime in here.

[lrutt]

I always just use either gas or some kind of solvent down the ports and let it set. If there is no hit of leaks after several minutes it's good enough.

[Mark M]

 it should hold 20 PSI or so for at least 10 seconds

So how about just putting a small plunger over the valve - sit the head on edge, and see how long/if the plunger can pull any air
to drop the vacumb and drop off the head, how long do you think? perhaps a weight could be added to show the failing vacumb?

[Shoeboxjoe]

I have my new head here and I'm eager to test it. Do I need to use acetone specifically, or is that just what's most preferable? Seems like alcohol, thinner, mek, etc. would work just fine to me, but I must be missing something. 

I just used brake cleaner and it worked fine.

[MCRider]

I think water is too clingy, surface tension. I use the solvent from my parts cleaner tank, or kerosene, something really runny. Acetone should be fine, but volatile.

[paulages]

it should hold 20 PSI or so for at least 10 seconds

So how about just putting a small plunger over the valve - sit the head on edge, and see how long/if the plunger can pull any air
to drop the vacumb and drop off the head, how long do you think? perhaps a weight could be added to show the failing vacumb?

dunno... could work. I made my rig when my machine shop started charging just to vacuum heads, which they didn't do for years. It cost my about $5, but I already had the brake bleeder.