false compression readings ? Help

[lone wolf]

Where are you buying a Snap-on or Matco compression testers for $20? Heck two weeks ago my son and I took off to get some tire chains. He had a pair of Snap-On socks sitting on the dash. He said they were a Christmas present from the Snap-on salesman. I bet you if they were selling the socks they would be $30 or more. Show us where you are getting a Snap-on or Matco compression tester for $20.


https://shop.snapon.com/product/Compression-Gauge-Sets/Automotive-Compression-Test-Set/EEPV500

If you take any 1/4 piped air gauge that goes 0-200 lbs you can buy a Snap on Adapter Hose like in my picture the hose is 65.00 .Ask me to look and see what part number or measurements are before you buy there are two sizes one is the standard plug size now a new smaller one too or just buy both hoses. If you look at my pic I made that Compression tester.

 

[lone wolf]

Where are you buying a Snap-on or Matco compression testers for $20? Heck two weeks ago my son and I took off to get some tire chains. He had a pair of Snap-On socks sitting on the dash. He said they were a Christmas present from the Snap-on salesman. I bet you if they were selling the socks they would be $30 or more. Show us where you are getting a Snap-on or Matco compression tester for $20.


https://shop.snapon.com/product/Compression-Gauge-Sets/Automotive-Compression-Test-Set/EEPV500

He is coining an old phrase.

 

[dmb2613]

https://www.ebay.com/itm/3626243876...tkp:Bk9SR6bT2KytYQ&LH_ItemCondition=3000|1000 This is like the one I have had for 40 years works well

 

[Automender]

Closed throttle.
View attachment 1045203

Looks like there isn't that much of a difference if you are troubleshooting for low compression 2 PSI out of 145 psi. Really it seems like to be accurate you would have to take the average of multiple tests.

 

[Old2stroke]

Closed or open throttle shouldn't make any difference, you're just compressing the air above an open exhaust port. As mentioned the schreader valve has to be right at the engine end of the tester, it's the one with the white band and opens at less than 2 psi.

 

[huskihl]

Throttle open or closed makes no difference. If throttle is closed, it will just pull air in from the muffler. As you can see above, 2 psi difference. You could probably test them both again with 2 different readings. And pull until it quits climbing

 

[lone wolf]

Throttle open or closed makes no difference. If throttle is closed, it will just pull air in from the muffler. As you can see above, 2 psi difference. You could probably test them both again with 2 different readings. And pull until it quits climbing

Plus 1!

 

[lone wolf]

Throttle open or closed makes no difference. If throttle is closed, it will just pull air in from the muffler. As you can see above, 2 psi difference. You could probably test them both again with 2 different readings. And pull until it quits climbing

DONT make me do it again!

 

[Okie]

Did not read all of this but compression gauges not reading correctly is why I have at least two, especially when testing small cc engines. (such as chainsaws)
Here is some info and links I've filed away about why for, making your own and some gauges that actually read small ccc engines correctly when purchased.



http://www.arboristsite.com/community/threads/compression-tester-issues.310133/



I got 3 of the Napa 700-9556 compression gauge Schrader valves today after the local NAPA ordered from their warehouse. The come 5 in a box and you can buy them each @ approx. $2.20 each. They worked A-ok. One was defective out of it's sealed package, was not spring loaded on back check due to a broken spring, noticed immediately before attempting install for test..



3 /2018
Napa #700 9556 is obsolete.

Here is a special low pressure schrader valve for compression gauges Milton and Lisle part number's and I seen them on flea bay as still available.

Milton 1251-2 @ about $5 each

Lisle 20100 @ about $7


Update info 12/20

Possible good compression gauge for chainsaws at $40, STANDIX 1023

Mentioned at this link 12/20

https://www.arboristsite.com/commun...mpression-gauge-and-tested-a-few-saws.348043/

https://www.arboristsite.com/community/threads/compression-tester.336165/


A good compression tester for small engines:


Actron CP7828A Professional Compression Tester Kit with 10mm, 12mm, 14mm, 14mm Long Reach, and 18mm Adapters $45 or so







Amazon link for reviewing:



https://www.amazon.com/gp/product/B00020BM28/ref=as_li_ss_tl?ie=UTF8&linkCode=sl1&tag=howtomotorepa-20&linkId=cdbd6f22890e891c57a50a4c630c7756