Is This Cheap Walmart Compression Gauge Good Enough?

[Frank_Hassa]

https://www.walmart.com/ip/Equus-3612-Innova-Compression-Tester/14644667

I have two 1997 Seadoos I'm bringing back into service. I need to check the compression on both machines. I've never needed a compression gauge before and I'll probably never need one again. I might check the compression on my 1991 Miata, just out of curiousity, but that's it.

Is this good enough?

 

[Coastiejoe]

Most cheap gauges tend to read low. But it would still give you useful information.

 

[benjilafouine]

I bought a cheap 40$ one last month and it was 10% off scale (it was telling me I had 135 instead of 149). It took a 400$ gauge to really know what was going on.

Benji.

 

[mikidymac]

I have one of the actron gauges from Autozone. I think it was about $30 and has always been accurate.

 

[tobytd]

auto parts houses 'rents' tools Rent 2or3 and average them should be pretty accurate

 

[Lake Sailor]

Frank_Hassa, no, a cheap Wal-mart one is not good enough, you need what I've got, a cheap Harbor Freight one

 

[jcleary93]

I got mine at Sears for about $35 and it's been accurate

 

[benjilafouine]

I bought a "Lisle 20250 Compression Tester" and it was horrible. At 135, I was almost ready to cry after replacing my engine last year. But it was actually at 149 with a professional tester.

Benji.

 

[Ruff Cut]

How can you test your tester for accuracy?

 

[ORION '95 Speedster]

The most important information that a cheap compression tester will give you is this: Cylinder compression consistency.

 

[Frank_Hassa]

The most important information that a cheap compression tester will give you is this: Cylinder compression consistency.

I get the concept but do not know why it's important nor a method for testing. Are you comparing cold cylinders to hot? From one stroke to the next? From one day to the next? Etc... I don't see how a cylinder can be "inconsistent" in the 1st place. The pieces and parts are all the same from one stroke to the next, so what changes?

And if a cylinder's compression is inconsistent, what problem would cause it? Say you had an inconsistent reading. What would be the problem, and what would be the solution?

 

[RodInEscondido]

By consistency here we are speaking of between cylinders, not between tests of the same cylinder. I believe the number from the experts here is to have the cylinders read within 10% of each other.

We generally test with cold engine, throttle wide open.

As stated above, recommend testing with 2 different testers, especially before doing something major based on compression; I have 3.

Hope this helps a little.

 

[ORION '95 Speedster]

Yep, what Rod said. Compression examples on one engine:

Good:

Cylinder 1: 150
Cylinder 2: 148


VS


Bad:

Cylinder 1: 150
Cylinder 2: 112