What are normal compression test values? |
|
Porsche, and the Porsche crest are registered trademarks of Dr. Ing. h.c. F. Porsche AG.
This site is not affiliated with Porsche in any way. Its only purpose is to provide an online forum for car enthusiasts. All other trademarks are property of their respective owners. |
|
What are normal compression test values? |
Barry Brisco |
Sep 26 2010, 02:29 PM
Post
#1
|
Newbie Group: Members Posts: 17 Joined: 8-October 09 From: California Member No.: 10,905 Region Association: None |
I've run a search for posts talking about "compression test values" but can't find an answer to my question, and my Owner's Manual and Haynes repair manual don't seem to tell me either: what are normal compression test values in a 914?
These numbers are for a 1.7 engine with an unknown number of miles, it's in a 914 that is for sale: #1 130 #2 150 #3 140 #4 150 I am concerned about the #1 cylinder. That is a 13% drop from the highest cylinders. Here are some online references about how much of a difference is acceptable between cylinders, and what indicates a potential problem: http://www.automedia.com/Engine_Compressio...ccr20050801cc/2 QUOTE If all the cylinders check out within 10 or so PSI of each other, and those numbers sync up with the factory specifications, then you're good to go. If one or more of the cylinders show a difference of 15 or more PSI, then there are problems inside http://www.freeengineinfo.com/compression-test.htm QUOTE The cylinders should all read within 5-10 psi of each other. http://www.aa1car.com/library/compression.htm QUOTE As a rule, most engines should have 140 to 160 lbs. of cranking compression with no more than 10% difference between any of the cylinders. So, at this point I'm thinking that this 1.7 engine is a bit tired and in the near future it will likely need some major attention: maybe a bad exhaust valve, maybe worse. And yes, a leakdown test would be helpful. Comments? Thanks, Barry |
Lo-Fi Version | Time is now: 3rd June 2024 - 05:23 AM |
All rights reserved 914World.com © since 2002 |
914World.com is the fastest growing online 914 community! We have it all, classifieds, events, forums, vendors, parts, autocross, racing, technical articles, events calendar, newsletter, restoration, gallery, archives, history and more for your Porsche 914 ... |