pfarah7

I know this topic has been discussed at nauseum but I'm curious if the engine needs to be cold or at operating temp. Also, does anyone know where the values should be at on an early 944 NA? I appreciate the help.

There's no problems; I'm just curious on determining the engine's condition.

951Tom

Compression test is usually done at operating temp to give more accurate results.

marc abrams

It's recommended that it's done at operating temperature, all spark plugs removed, and the throttle held open. As far compression pressure goes I just look for consistency along the cylinders. I recently did a compression test on my Daytona Turbo Z that has about 25000 miles since I rebuilt the engine and all cylinders were within 2 psi of each other.

Buthter

If it helps, I recently did a compression test on my 85.5. Operating temp, all plugs removed, throttle wide open. My numbers were 170/165/162/164.

pfarah7

Perfect, thanks all!!

Jfrahm

Plug wires removed, I assume.

elanman

DME unplugged. No fuel in cylinders or coming out of spark plug holes also no point in washing bores

neunfünfeins

The catch-22 is, having the engine warm enough for a good test result, but not so hot that when you remove the plugs you end up galling the aluminum threads in the head.

Which leads to... a good argument for using a (small) amount of anti-seize on your spark plug threads as a matter of routine, which will minimize that risk. But not so much that it melts, runs down and fouls your electrodes. There's a "right amount" that takes a little practice to figure out.