Compression Measurement in the vehicle!!! How
 

Hello Forum,

I was wondering if a compression measurement is possible in the car.

What tool do I have to use?

Do you have any proposal that you can share?

Thank you

BR
Bob

Buy a $20 compression gauge
Remove all spark plugs to minimize engine resistance
Install the gauge into the spark plugs hole one at a time
Remove the fuel pump connections so the car does not start
Floor the gas pedal or somehow open the throttle all the way
Turn the engine with the starter for about 10 revolutions. Make sure battery is fully charged during test.

Read the values on the gauge and interpret.

Are you using a tool with a goose neck?

In the car it is tight.

Yes it is. You need to careful screwing the guage into the spark plug hole. Take your time. You can tell when it feels right, or when it doesn't. Don't force the threading. I use a Snap-On tool that has a nipple that is installed first. Stomski Racing makes a solid piece that will thread into the spark plug hole and end-up close to the outside of the valve cover. You can them thread your compression tool to that.
Here's a link to thhttp://www.stomskiracing.com/products.php?id=23e tool:

Bob,

What Jon said above-- you can make your own although it might just be cheaper to have Stomski send you one in Germany. I have two of these, they are great, just don't lose the o-ring in the engine. They thread in gently into the plug hole and you can do compression, leakdown, whatever.

http://www.stomskiracing.com/images/SR031wht.jpg

Yeah, it's a lot easier to use a two-piece compression tester, primarily to easily attach the tester and w/o messing up the spark plug threads. I have a Penske-Craftsman version with a detachable flex hose (quite generic) - convenient to catch the threads. An O-ring helps seal the test connection without overtightening.

Go to the internet to get an overall idea for the recommended procedure, then review several YouTube videos to demonstrate/confirm the right and wrong way to do it.

BTW, there should be books written on engine rebuilding, watch repair, minor surgery and operating high speed machinery using only one hand (the other is shakily holding a YouTube video camera). :rolleyes:

Sherwood