Compression Test
Posting Guru
Joined: Oct 2011
Posts: 1,647
Likes: 1
From: Exton, PA
Glenn, i'm sorry for all the trouble you're having as well - I was following your thread in the beginning as I will be doing a compression test soon, but didn't see all the check-valve issues that arose.
if you haven't sorted it out yet, one of these check valves may help and are only a day away by UPS: McMaster-Carr. I just used a 1/4" brass NPT one in adding an extra 35 gallons to my compressed air system so that I can disconnect the compressor and not lose pressure in the extra tank. I was curious how fast the valve would close, but it seems to be instantaneous at 120 psi, so i'd guess it should work well enough in a compression tester at ~300-400 psi.
not free, but it sounds like $10 would be worth it to stop the frustration at this point.
if you haven't sorted it out yet, one of these check valves may help and are only a day away by UPS: McMaster-Carr. I just used a 1/4" brass NPT one in adding an extra 35 gallons to my compressed air system so that I can disconnect the compressor and not lose pressure in the extra tank. I was curious how fast the valve would close, but it seems to be instantaneous at 120 psi, so i'd guess it should work well enough in a compression tester at ~300-400 psi.
not free, but it sounds like $10 would be worth it to stop the frustration at this point.
Logistics Pro
Joined: Oct 2008
Posts: 4,818
Likes: 1
From: Avilla, IN
Guys, IIRC schrader valves are only rated to 250 psi. Maybe they make a high pressure version, idk. You might be stuck using a ball valve to release the pressure.
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Fleet Mechanic
Joined: Oct 2006
Posts: 1,386
Likes: 1
From: Spokane, WA
When i did injectors a few years ago, i had some of the same issues doing the comp test. I just had my son turn it over with the key start position, then I recorded the highest number. If i recall correctly my numbers were not as high as some thought they should be (somewhere around 325 to 375, didn't seem to bad to me most were closer to 375. The test was also done when it had not run or warmed in about 2 weeks.
Thread Starter
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Fleet Owner
Joined: Aug 2004
Posts: 20,418
Likes: 197
From: AZ
When i did injectors a few years ago, i had some of the same issues doing the comp test. I just had my son turn it over with the key start position, then I recorded the highest number. If i recall correctly my numbers were not as high as some thought they should be (somewhere around 325 to 375, didn't seem to bad to me most were closer to 375. The test was also done when it had not run or warmed in about 2 weeks.
I got some fittings today so I now have a check valve. I didn't do the test because of 40 mph winds and I'm working outside. I didn't want dirt in the motor. I hope to do it tomorrow.
Fleet Mechanic
Joined: Oct 2006
Posts: 1,386
Likes: 1
From: Spokane, WA
[QUOTE=oldbird1965;13709153]
If you only judged your results Rich on one compression stroke, then your numbers are low. I think the directions call for four compression strokes.
I don't count the number of times it turns over, I've always just cranked it till the needle doesn't go any higher. I hope I haven't been doing it wrong all these years. I did it the same as with spark plugs (take them all out)
If you only judged your results Rich on one compression stroke, then your numbers are low. I think the directions call for four compression strokes.
I don't count the number of times it turns over, I've always just cranked it till the needle doesn't go any higher. I hope I haven't been doing it wrong all these years. I did it the same as with spark plugs (take them all out)
Thread Starter
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Fleet Owner
Joined: Aug 2004
Posts: 20,418
Likes: 197
From: AZ
[quote=richdawg;13709263]
If you only judged your results Rich on one compression stroke, then your numbers are low. I think the directions call for four compression strokes.
I don't count the number of times it turns over, I've always just cranked it till the needle doesn't go any higher. I hope I haven't been doing it wrong all these years. I did it the same as with spark plugs (take them all out)
I don't count the number of times it turns over, I've always just cranked it till the needle doesn't go any higher. I hope I haven't been doing it wrong all these years. I did it the same as with spark plugs (take them all out)
Fleet Mechanic
Joined: Oct 2006
Posts: 1,386
Likes: 1
From: Spokane, WA
IDK I'm getting to old to remember about the check valve most of the testers I've used in the past have had the check valve, but I am not sure now about the hacked together one i made from the HF kit. anyways It really might not matter if you have a helper crank and you watch the gauge when it stops going up just write that number down and go the the next one. sorry for any confusion i still have that dam CRS and it doesn't seem to be getting any better.