Pelican Parts
Parts Catalog Accessories Catalog How To Articles Tech Forums
Call Pelican Parts at 888-280-7799
Shopping Cart Cart | Project List | Order Status | Help



Go Back   Pelican Parts Technical BBS > 1- Porsche Technical Forums > 911 Engine Rebuilding Forum

Reply
 
LinkBack Thread Tools Rate Thread
Author
Thread Post New Thread    Reply
Banned
 
Join Date: Mar 2004
Posts: 183
Low Compression causes..

Have a low compression cylinder at #2 on a 2.7L (w/CIS) Apart from a piston ring being chipped or broken which is what I expect - what else might cause this condition? 15K on a rebuild (apparently/supposedly).

Doug C
Old 02-07-2005, 12:04 PM
  Pelican Parts Technical Article Directory    Reply With Quote #1 (permalink)
Still Doin Time
 
asphaltgambler's Avatar
 
Join Date: Nov 2004
Location: Nokesville, Va.
Posts: 5,039
Valve seating issues: Poor valve / seat re-grind or too thin a margin on the valve face, weak spring pressure, chunk of carbon on the valve.

You should do a leak-down test and this will tell you what's happening.
__________________
'07 Jeep SRT-8 - Hauls groceries and Hauls *ss
'85 Guards Red Targa - F@#king Money Pit
'95 Road King w/117ci - No time to ride, see above
'77 Sportster Pro-Street Drag Bike w/93ci - Sold to collector
'72 Yamaha CS5 200 Twin - Sold to fellow Pelicanite
Old 02-07-2005, 02:24 PM
  Pelican Parts Technical Article Directory    Reply With Quote #2 (permalink)
Banned
 
Join Date: Mar 2004
Posts: 183
I feel ignorant asking this but, can a leakdown test be performed while the engine is not installed in the car?

Doug C
Old 02-07-2005, 02:39 PM
  Pelican Parts Technical Article Directory    Reply With Quote #3 (permalink)
Still Doin Time
 
asphaltgambler's Avatar
 
Join Date: Nov 2004
Location: Nokesville, Va.
Posts: 5,039
It should be at operating temp, so yes ideally it should be in the car. Try not to sweat too much here. Just find out what's causing the issue. It may be something simple.
__________________
'07 Jeep SRT-8 - Hauls groceries and Hauls *ss
'85 Guards Red Targa - F@#king Money Pit
'95 Road King w/117ci - No time to ride, see above
'77 Sportster Pro-Street Drag Bike w/93ci - Sold to collector
'72 Yamaha CS5 200 Twin - Sold to fellow Pelicanite
Old 02-07-2005, 02:45 PM
  Pelican Parts Technical Article Directory    Reply With Quote #4 (permalink)
Friend of Warren
 
Join Date: Oct 2000
Location: Jefferson City, MO
Posts: 15,522
Have you checked the valve gap? A valve to tight could also cause low compression.
__________________
Kurt
2003 Boxster S, 1991 BMW 318is
'93 Ducati 900SS, '76 BMW R75/6, '73 350 Honda Scrambler, 2003 SV650 Track bike

Gone, but not forgotten: '86 Carrera, '72 911E, 2001 Boxster
Old 02-08-2005, 06:36 PM
  Pelican Parts Technical Article Directory    Reply With Quote #5 (permalink)
Banned from Pelican
 
snowman's Avatar
 
Join Date: Feb 2003
Location: So California
Posts: 3,787
Do a leakdown or have it done for you. Engine does not have to be in car or be at operating temp. THe leakdown will identify the source of the low compression, ie valves or rings or both. Do the test and go from there.

THe problem you identified is a gross problem, ie low compression. Do not let the relatively small differences between a hot leakdown and a cold one prevent you from doing the test that will still tell you whats wrong with the engine.

Last edited by snowman; 02-09-2005 at 07:34 PM..
Old 02-09-2005, 07:30 PM
  Pelican Parts Technical Article Directory    Reply With Quote #6 (permalink)
 
Now Available for Ordering:   101 Projects For Your BMW 3 Series 1982-2000  [more info]
Reply

Thread Tools
Rate This Thread
Rate This Thread:

 


All times are GMT -8. The time now is 02:19 AM.


 
Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2018, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2017 Pelican Parts LLC - Posts may be archived for display on the Pelican Parts Website -    DMCA Registered Agent Contact Page
 

DTO Garage Plus vBulletin Plugins by Drive Thru Online, Inc.