I have one of the Actron Compresison testers. I bought it new a couple of years back and it has worked fine, but I haven't used it in probably a year. I can't get it to read any compression. I took the hose off and tried to blow through it, and no air would pass in either direction. It has the valve inserted and I would expect this to stop air from going in and out. Question is, what pushes the valve in to let the air into the guage from the cylinder? The guage has the button release to let it out. I think I'm missing a piece, but can't find anything else. Anyone have one of these - I think it model CP7828.

If I remove the valve, I can get a quick compression reading, but without the valve, it just leaks back out before pressure can build. Maybe the valve should let air in and not out? I have an extra one that came with it and that one did the same thing? I checked Actron's web site.

Thanks,
Dan

 

The valve in the end of the hose is basically the same as a valve stem on a tire- one way in, no way out (except the release valve on the gague). However, the valve differs in on important way- it takes very little pressure to open the valve. If you try to install the valve from a tire stem it will physically install BUT your compression readings will be about 40 PSI lower. Trust me, I tried it.

Either steal the hose off another gague from the store or chuck it and buy new. I've tried repairing them but never been successful. I can't find replacements for the special low pressure valve they use in these gagues. For $12 it's worth the peace of mind to buy a new gague.

What kills them: schmutz getting in the valve (and they turning into glue since the last time you used it) and either preventing it from opening or preventing it from closing again and holding pressure.

New gague time.