Calibrate a compression tester

[Iplayfarmer]

This post is somewhat incidental to my "Black Smoke" thread.

How would I calibrate a compression tester? Is it common for shops to test compression testers?

I have a compression tester that I picked up at a yard sale a while back for something like $3. I want to make sure it's giving me good readings before I scrap an engine based on its reading.

[MrJimi]

For $3, I may have doubts also, how about you check it on a good engine that you know has good compression or compare it with a friends tester on the same engine

[kevinj]

This post is somewhat incidental to my "Black Smoke" thread.

How would I calibrate a compression tester? Is it common for shops to test compression testers?

I have a compression tester that I picked up at a yard sale a while back for something like $3. I want to make sure it's giving me good readings before I scrap an engine based on its reading.

Are you sure the tester will read high enough for a diesel?

[slowrev]

Just get a tee to hook it up on the same line as a known good gauge and compare readings.
when pressurizing the line with compressed air. Should be close enough.

[CATMAN]

The couple of diesels that I have used a compression tester on, were in the 410-450 psi range. I would think that some of the older diesels(non-turbocharged) are going to register higher than this. How high does that gauge go? How strong is the hose, tube or adapter that you will be using? Be safe.

[Marlowe]

A compression gauge at best is an indicator,not conclusive evidence. What I mean by that may be best explained by an analogy. Let's say your teenage son drives a pickup. One Saturday morning you walk out to get the morning paper and find an empty beer can in the bed of the truck. That's an indicator that he's been drinking and driving, but it sure isn't conclusive evidence, and neither is the reading on a compression gauge. The best way to read any compression gauge is a comparison between cylinders. They should be fairly close. If not, it's an indication of a problem.

[Iplayfarmer]

The couple of diesels that I have used a compression tester on, were in the 410-450 psi range. I would think that some of the older diesels(non-turbocharged) are going to register higher than this. How high does that gauge go? How strong is the hose, tube or adapter that you will be using? Be safe.

When I posted the question I was at work, and for some reason I thought that this one went higher than it does. Now that I am home I took a closer look at it and it only reads up to 200 psi. That won't do since my engine compression spec is 455 psi.



The question still stands, though, for future use on gas engines. I think the best option is to just test it on a good engine against another known working tester.

Now, I guess the question is what's a good diesel compression tester?

[john_bud]

THe one in the picture is garbage. I hate them. For a couple bucks more get one that screws into the spark plug hole. Press in is junk, garbage and other adjectives and invectives that are best not used on a site like this.

At harbor freight you can get a diesel compression tester for diesels cheap. Yeah, it's a HF unit, but it will tell you something. And for 35 bucks nothing.

Otherwise, you are looking at multi-hundred dollar units. Snap on, Matco etc.

If you get one, get one that can also do leak down. Then you can compress the cylinder and determine how long it takes to leak. That will tell you a lot about rings and valves. Use your ears and you can tell which is leaking.

jb

[DieselPower]

I own a Snap On diesel compression gauge kit. Back when I was wrenching full time I would send it in every 2 or 3 years along with my torque wrench's to get calibrated. Last time around I think they charged me something like $25. But considering it was a $500 plus diesel compression kit I figured it was well worth it.

[Iplayfarmer]

THe one in the picture is garbage. I hate them. For a couple bucks more get one that screws into the spark plug hole. Press in is junk, garbage and other adjectives and invectives that are best not used on a site like this.

At harbor freight you can get a diesel compression tester for diesels cheap. Yeah, it's a HF unit, but it will tell you something. And for 35 bucks nothing.

Otherwise, you are looking at multi-hundred dollar units. Snap on, Matco etc.

If you get one, get one that can also do leak down. Then you can compress the cylinder and determine how long it takes to leak. That will tell you a lot about rings and valves. Use your ears and you can tell which is leaking.

jb

JB, could you be a little more clear about whether or not you like this style or not.

I think I've gotten the $3 out of it that I paid.

I was just looking through another HF ad last night and saw the diesel compression tester. I'm going to be in the vicinity of a store tomorrow night, and I thought I may pick one up.

Has anyone used the cheapo HF diesel tester? I see they have two. Is the cheap one adaptable enough to work with these smaller diesel engines?