The correct kind of compression guage

blsnelling · Mar 19, 2009

This topic comes up every week and often more frequently. You absolutely MUST have a Schrader valve at the tip of your compression guage for use on a small 2-stroke engine. If it does not, you cannot use it, period. A Schrader valve is what's found in the stem of your car rims. The reason it is required is because of the small volume of these engines. It is not enough to pump up the pressure of the hose with every pull and you will end up with a way low reading. I wonder how many engines have been torn down that were perfectly fine? Some guages have a release valve up by the guage. That is not sufficient and does not take the place of the valve at the tip.

This is the valve that you MUST have.

barneyrb · Mar 19, 2009

blsnelling said:
This topic comes up every week and often more frequently. You absolutely MUST have a Schrader valve at the tip of your compression guage for use on a small 2-stroke engine. If it does not, you cannot use it, period. A Schrader valve is what's found in the stem of your car rims. The reason it is required is because of the small volume of these engines. It is not enough to pump up the pressure of the hose with every pull and you will end up with a way low reading. I wonder how many engines have been torn down that were perfectly fine? Some guages have a release valve up by the guage. That is not sufficient and does not take the place of the valve at the tip.

This is the valve that you MUST have.

This needs to be a sticky in BOLD letters

blsnelling · Mar 19, 2009

barneyrb said:
This needs to be a sticky in BOLD letters

That's the whole idea. We've beat this topic into the ground so many times it isn't funny. It's time to put this thing to rest and help out a bunch of good folk while we're at it.

whitedogone · Mar 19, 2009

blsnelling said:
That's the whole idea. We've beat this topic into the ground so many times it isn't funny. It's time to put this thing to rest and help out a bunch of good folk while we're at it.

I'm sure Gary would approve :agree2:

04ultra · Mar 19, 2009

So give us a brand name and part number..

.

blsnelling · Mar 19, 2009

I use a cheapy from AutoZone, forget the brand. It reads more accurately than the Lisle one I have.

04ultra · Mar 19, 2009

blsnelling said:
I use a cheapy from AutoZone, forget the brand. It reads more accurately than the Lisle one I have.

This is not good with out a part number............Find out and get back to us... :cheers:

.

rngrchad · Mar 19, 2009

I use an uber expensive Mac Tools Gauge. I always wonder if it was worth the 157+ dollars off the tool truck...I wanted to buy an el cheapo schrader valve model from Harbor Freight, but my better judgement called up the local MacMan.
Compression Tester "Bling" courtesy MacTools. Brand: MacTools Part # is CT155

blsnelling · Mar 19, 2009

04ultra said:
This is not good with out a part number............Find out and get back to us...

.

There are many guages that will work. It's the valve at the tip that's most important.

WesternSaw · Mar 19, 2009

compression gauge

Hello Brad
I think it is us newbies that are beating this to death.I know myself that before I go and purchase a tool I want to buy the RIGHT ONE.It is hard enough to find dollars sometimes for good tools,but to keep buying the wrong tools is even more expensive!Then there's the never ending,brand debate which for a newbie drives me crazy,you end up second guessing yourself,and don't buy anything.How about if you could post something like this.Taking quality and expense into account,that would end it for me
Thanks Lawrence

GOOD
BETTER
BEST

whitedogone · Mar 19, 2009

Autozone= Actron CP7827

http://www.actron.com/product_detail.php?pid=16171

About $25

lovetheoutdoors · Mar 19, 2009

i thought a compression tester without the valve would give you a high reading...at least thats what i have heard...mine has the schrader valve so i wouldnt know.

rngrchad · Mar 19, 2009

lovetheoutdoors said:
i thought a compression tester without the valve would give you a high reading...at least thats what i have heard...mine has the schrader valve so i wouldnt know.

Mine has all kinds of different connections, valves and other stuff I've never ever used and probably never will. Came in a nice plastic protective case too! I imagine the only tester more accurate than my Mac one might be the Snap-On, that is if they aren't made by the same company!

nmurph · Mar 19, 2009

this is the gauge i bought from Autozone. it is an Actron.

someone (Brad) should also cover the proper way to test compression... i.e. throttle position and why it is important. engine temp, etc....

blsnelling · Mar 19, 2009

whitedogone said:
Autozone= Actron CP7827

http://www.actron.com/product_detail.php?pid=16171

About $25

That's the one I use. I have a more expensive Lisle and it does not work as well. It takes more pulls to pump it up and reads low to boot. Your mileage may vary.

blsnelling · Mar 19, 2009

I usually test my engines cold. It's fine to test hot, but the reading will be 10-15 PSI lower. Yes, lower. Logically I would think it would be higher with thermal expansion, but that's not the case.

It's usually recommended to keep the throttle at WOT for a compression test so that the engine has no trouble drawing fresh air in. However, myself and others have found no difference in the readings. I do put the saw on fast idle when testing.

rngrchad · Mar 19, 2009

blsnelling said:
That's the one I use. I have a more expensive Lisle and it does not work as well. It takes more pulls to pump it up and reads low to boot. Your mileage may vary.

I think I'm gonna buy a bunch of different compression testers and use the one that reads the highest.

blsnelling · Mar 19, 2009

Here's the ones I have. No, the Lisle doesn't read that low, lol. The Homey just has tons of compression.

Stihl MS210

Homelite SXL-925

lovetheoutdoors · Mar 19, 2009

rngrchad said:
I think I'm gonna buy a bunch of different compression testers and use the one that reads the highest.

it will make you feel better anyway wont it...

JJay03 · Mar 19, 2009

I need to pick one of these up also the one I have now isnt too good.

The correct kind of compression guage

Help Support Arborist Forum:

Goosme!

Addicted to ArboristSite

Goosme!

Addicted to ArboristSite

"Out of Control"

Goosme!

"Out of Control"

Addicted to ArboristSite

Goosme!

Addicted to ArboristSite

Addicted to ArboristSite

Addicted to ArboristSite

Addicted to ArboristSite

ArboristSite.com Sponsor

Goosme!

Goosme!

Addicted to ArboristSite

Goosme!

Addicted to ArboristSite

ArboristSite Guru

Similar threads

Join the conversation!

Join today and get all the highlights of this community direct to your inbox. It's FREE!