crazy low compression no's

[gavinlit]

Just got the results sent to me from a ppi & I've got compression results of exactly 90/150 on all cylinders (carrera 3, 1977). I've read all search results on the compression issues & a common consensus seems to be that consistency across cylinders is more important than the reading itself but these are pretty low numbers. Just to further confuse the issue, the ppi says the starter motor is noisy (could this indicate less crank, giving lower numbers). The test was not done at a huge altitude either & it was by a reputable specialist - so I'm assuming they know how to run a decent compression test. I'm confused because the readings are all exactly equal but also super low. Any ideas?

[304065]

Low compression on #6: options

[Grady Clay]

John’s thread covers all the basics. I would get the owner (not you) to put some highway miles on it (200+ KM) and then have it re-checked. This time with an additional cylinder leak test.

What does 90/150 mean? What were the cranking compression numbers and units on the individual cylinders? Discuss with your mechanic how he did the test and what is his interpretation of the numbers.

Best,
Grady

[gavinlit]

Umm - feel a bit embaressed but the compression figure is 150 on all. The reading of 90 was taken as the cylinder compresses or loads up (I guess). Anyway figures are all 6 @150 so all is well