Tried out a new compression tester... issues??

[Efisher26]

Tried a husky 36 and poulan 3700, both tested around 120psi. It seems extremely low for how well they both cut. Its a digital meter. Great reveiws on amazon. "Mityvac" brand. Could it need callibration out of the box?

https://www.amazon.com/Mityvac-MV55...000I14M6Y/ref=cm_cr_arp_d_product_top?ie=UTF8


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Just a home owner that likes the older better made machines

Craftsman 3.7 x2
Husqvarna 36

 

[Sepia]

If you have an air compressor, try checking your compression tester gauge vs. the gauge on the air compressor by connecting the compression tester to the air hose on your compressor.

 

[HarleyT]

It is likely correct.....

 

[Efisher26]

Ya I thought about that after I posted, I'll try that tomorrow


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[ANewSawyer]

And post a picture of the set up installed on the saw. Make sure you are using an adaptor that contains a schrader valve.

 

[earlthegoat2]

For best results, clamp the throttle wide open and pull, pull, pull until the needle doesn't rise anymore. At least, give it 6 pulls.

 

[Efisher26]

I switched out the valve to see of that made a difference, nope...


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Just a home owner that likes the older better made machines

Craftsman 3.7 x2
Husqvarna 36

 

[ELECT6845]

For best results, clamp the throttle wide open and pull, pull, pull until the needle doesn't rise anymore. At least, give it 6 pulls.

No need to hold the throttle wide open. You are measuring the static compression and a wide open throttle makes no difference.

 

[Rockjock]

Tried a husky 36 and poulan 3700, both tested around 120psi. It seems extremely low for how well they both cut. Its a digital meter. Great reveiws on amazon. "Mityvac" brand. Could it need callibration out of the box?

https://www.amazon.com/Mityvac-MV55...000I14M6Y/ref=cm_cr_arp_d_product_top?ie=UTF8


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Just a home owner that likes the older better made machines

Craftsman 3.7 x2
Husqvarna 36

It is quite possible that t is indeed out of calibration. What I would do is use a tester that is known to work correctly to check of accuracy.

 

[Little Al]

And post a picture of the set up installed on the saw. Make sure you are using an adaptor that contains a schrader valve.

I would presume that being new the Schrader valve is correct but know that the Snap On/Blue Point tester requires a special valve & the standard car tyre valve insert gives false readings

 

[redunshee]

Tried a husky 36 and poulan 3700, both tested around 120psi. It seems extremely low for how well they both cut. Its a digital meter. Great reveiws on amazon. "Mityvac" brand. Could it need callibration out of the box?

https://www.amazon.com/Mityvac-MV55...000I14M6Y/ref=cm_cr_arp_d_product_top?ie=UTF8


-•------------------------------------------------------------


Just a home owner that likes the older better made machines

Craftsman 3.7 x2
Husqvarna 36

your sig shows two 3700's. what did the other one check out at.? Usually a 3700 should run somewhere between 140and 150.

 

[Efisher26]

I haven't tried my other one yet, but thats what I thought it would be, it cuts too good for 120psi


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[Chris-PA]

Any volume the setup adds between the schrader valve and the saw just adds to the combustion chamber volume. That reduces the compression ratio.

Static/low rpm pressure readings don't mean much beyond a general check of the sealing of the rings.

 

[Karla]

Nice Gauge, Not sure why there are so many different hoses ? Is there a downloadable PDF document ? I would be interrested in more information about the gauge.

Anyhow, I don't have an answer to your question, but my Analog gauge does the same thing. On some engines I get 140 - 150 PSIG readings, and on other engines that I have rebuilt and run great May only have readings of 110 PSIG. I believe one person said it was due to the volume of the different adapters, and I haven't really investigated, so Not really sure why, but I Sort of like "Chris-PA" answer.

 

[Efisher26]

Many engines have deeper spark plug holes( more threads) and different bore size, the kit covers most, theres only 2 in the kit that fit saws, one is too long for mine and would hit the piston, the other is same as plug


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[Karla]

Found the PDF document on the Mighty-Vac site: http://www.mityvac.com/catalog/ede.pdf

Also curious, If anyone has thought about whether fuel/oil can get inside the gauge when testing compressions ? And If you do a compression test on an engine Multiple times will you flood or add fuel to the engines crankcase ? Obviously once your done with the compression check, and run the engine it will burn out the excess fuel from pulling the starter cord multiple times.

 

[Deleted member 135597]

Found the PDF document on the Mighty-Vac site: http://www.mityvac.com/catalog/ede.pdf

Also curious, If anyone has thought about whether fuel/oil can get inside the gauge when testing compressions ? And If you do a compression test on an engine Multiple times will you flood or add fuel to the engines crankcase ? Obviously once your done with the compression check, and run the engine it will burn out the excess fuel from pulling the starter cord multiple times.

I've flooded engines doing a compression test

 

[rocketnorton]

I've flooded engines doing a compression test

wot gets less fuel @ cranking speeds.

 

[Efisher26]

So I connected it to the compressor, its 30psi under the 2 gauges on the compressor. Anyone know how/if can be calibrated?


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[Efisher26]

Never mind they say don't calibrate, just return for new


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