How Much Compression

1. l33-lsh Newbie Joined: Jun 2007 Posts: 13

   #1 2nd June 2011, 13:12

   Hi all, looking at the head gasket.
   
   The garage done a sniffer test and came up posititive.
   
   I done a compression test and its 248psi accross the board.
   
   Whats expected, seems very high for a motor with 110k on the clock.
   
   Done Cambelt yesterday and piston tops are Very Very clean! I expected some coke on the top on the pistons.
   
   I brought the car at 80k on the clock about 4 years ago and no engine work.
   
   With expected head gasket failure i was thinking atleast 1 would be low?
   
   So is 248 High?
   
   Many Thanks Lee
2. Stevo123 Established Member Joined: Apr 2009 Redcar Posts: 1971 2000 Posi Blue vtr

   #2 2nd June 2011, 14:32

   I woul dbe happy with 180+ to be honest. Equaly important is how long it takes to build that figure. 1-2 seconds should see the highest pressure (give or take a few psi of course).
   Your figure does seem high, I wonder if your head has seen a good skim in the past that you don't know of?
   As long as it runs okay I would not worry about it to much mate. happy days!
3. l33-lsh Newbie Joined: Jun 2007 Posts: 13

   #3 2nd June 2011, 14:37

   yer couple seconds it reaches prob about 220-230. it runs fine. but i ran on untill it stopped going up. which was 1 more second. if its been skimmed so much could prob do with vernier timing kit then if i end up doing head gasket.
4. carlsmith715 Established Member Joined: Nov 2010 manchester Posts: 2099 2000 1.6 furio

   #4 2nd June 2011, 14:38

   is a higher compression good or bad or does it not matter?
5. Stevo123 Established Member Joined: Apr 2009 Redcar Posts: 1971 2000 Posi Blue vtr

   #5 2nd June 2011, 14:43

   Higher is better than lower to a point.
6. l33-lsh Newbie Joined: Jun 2007 Posts: 13

   #6 2nd June 2011, 15:10

   so with such good compression you really think head gasket has gone?
   
   i was getting abit of white smoke and sniffer test came up positive.
7. tarzan Frequent Poster Joined: Apr 2010 Lurgan Posts: 767 2001 black saxo furio 2001 black saxo vts

   #7 2nd June 2011, 18:06

   compression in the 1.4s and vts' are all in their 1:10's where as the rest exept for diesel is 1:9's.
   
   head gasket failure means that compression is leaking so the total number would be lower.
   
   
   getting the head skimmed means taking less that 1mm but with less area in the cylinder when TDC the compression would be higher.