false compression readings ? Help

[michaelounn]

I have a new pittsburgh comp tester from harbor freight. i'm not impressed. everything tests at 40 psi including my good running saws. do i need to return it or am i missing some trick

 

[ballisticdoughnut]

It should have two check valves. One in the hose and one in the gauge. Buddy of mine bought the same tester, ended up having a bad check valve. That would be the first thing I’d check.

 

[Bubster]

Had the same trouble with an Advance Auto tester. You probably already know, but your good saw should read around 150-160 psi. It takes about 5 good cranks to get a good reading, so keep that in mind as well. Sounds like a bad tester.

 

[lone wolf]

Had the same trouble with an Advance Auto tester. You probably already know, but your good saw should read around 150-160 psi. It takes about 5 good cranks to get a good reading, so keep that in mind as well. Sounds like a bad tester.

Dont stop at 5 pull till it stops rising it could take 15 with a long hose.

 

[isawben]

You may have also purchased an automotive compression tester that has the check valve at the gauge, and not at the tester end. Those types will tend to test lower on small engines.

 

[lone wolf]

I have a new pittsburgh comp tester from harbor freight. i'm not impressed. everything tests at 40 psi including my good running saws. do i need to return it or am i missing some trick

China crap! Buy a better one.

 

[isawben]

I’ve had good success with the OTC tester, seems to be good quality.

 

[michaelounn]

i have been reading some other posts here. do you think i need a tester for small engines. i wasn't aware they existed

 

[isawben]

i have been reading some other posts here. do you think i need a tester for small engines. i wasn't aware they existed

There aren’t ones made specially for small engines, but most automotive testers work as long as they have check valves at either end.

 

[lone wolf]

There aren’t ones made specially for small engines, but most automotive testers work as long as they have check valves at either end.

And the adapters on some give false readings.

 

[Captain Bruce]

I have a new pittsburgh comp tester from harbor freight. i'm not impressed. everything tests at 40 psi including my good running saws. do i need to return it or am i missing some trick

Its a gauge with a fitting, not an ACBM. If it isn't working correctly, its the cheap chinesium you hoped would enhance your toolbox. Take it back and buy a Matco, Snap-on, etc. Spend 20 bucks, once.

 

[leeha]

Harbor freight ? Say no more, I agree with @Captain Bruce buy a good compression tester
like he mentioned. i use a Snap on and it has never failed me. Pricey but you will own it for
the rest of your life.

 

[Bill G]

Its a gauge with a fitting, not an ACBM. If it isn't working correctly, its the cheap chinesium you hoped would enhance your toolbox. Take it back and buy a Matco, Snap-on, etc. Spend 20 bucks, once.

I have a Snap On and I will assure it was not $20

 

[buzz sawyer]

Been using my Snap-on comp. tester for 36 years, no problems.

 

[Chevboy0167]

This...

https://www.ebay.com/itm/3932140087...tcHMcHVNY4pwZdW4NjGnWarg==|tkp:Bk9SR5bIwuisYQ
Or this...

https://www.ebay.com/itm/195512705455
No extra connections, no bulls##t.

 

[JoeMay]

I purchased an Echo compression tester and have been very pleased with it. One testing detail that I have wondered about is should the throttle be wide open or at least partially open when cranking to build pressure? Service manuals for older outboard motors specify throttle wide open.

 

[Bforeman]

WTFO

 

[Bill G]

WTFO

EH?

 

[Mr Excitement]

You need the schrader valve as close to the cylinder as possible, but the valve needs to be as weak as piss also. If you can get your hands on the older type of valve with the exposed spring snip off enough coils until the valve only just closes by spring pressure. The ones that SnapOn sell are like this too.
If you use a tyre valve you have to overcome significant pressure just to get to open the valve.
I saw readings go from heartbreaking to 150 psi plus after changing valves.
Any tester designated as being for small engines will have the correct type of valve.

 

[lone wolf]

Its a gauge with a fitting, not an ACBM. If it isn't working correctly, its the cheap chinesium you hoped would enhance your toolbox. Take it back and buy a Matco, Snap-on, etc. Spend 20 bucks, once.

20 bucks? They are more than that.