compression question - JeepForum.com
Search  
Sign Up   Today's Posts
User: Pass: Remember?
Advertise Here
Jeep Home Jeep Forum Jeep Classifieds Jeep Registry JeepSpace Jeep Reviews Jeep Gallery Jeep Clubs Jeep Groups Jeep Videos Jeep Events Jeep Articles
Go Back JeepForum.com > Models > Jeep Wrangler Forums > YJ Wrangler Technical Forum > compression question

FS: 2007-2013 Jeep Wrangler "HALO" Angel Eye KitTHE NEW! VANCO DUAL MODE 15/16″ Big Brake Kit w/BlaFS: Wranger BRIGHT License Plate LED! Just $3! Great value

Reply
Unread 10-08-2002, 03:30 PM   #1
DanyJeep
Registered User
 
Join Date: Jul 2002
Location: Montreal, Canada
Posts: 52
compression question

hi,

I'd like to know what the compression should be at on a 94 yj 4cylinder mpfi
to my knowledge the compression ratio is 9.2 to 1
and i did a compression test and i got
130, 130, 135, 145,
is this a good compression?

thanx dany

DanyJeep is offline   Reply With Quote
Unread 10-08-2002, 03:57 PM   #2
NaeKid
JF Administrator, eh?
 
NaeKid's Avatar
1988 YJ Wrangler 
 
Join Date: Nov 2000
Location: Calgary, AB
Posts: 6,879
Some of those numbers are a little low .. they should all be around the 145 to 155 mark (if I remember the numbers correctly). If you have a Haynes manual handy, the compression numbers should be listed in the 4-Cyl statistics page.

I am at work, so I can only go by what I think I remember reading while I was in the ThroneRoom
__________________
Hello, my name is Vance and I am a Jeepaholic.
Its better to be naked with your friends, than to be clothed with your enemies
  • From street to trail, '88 YJ on 38" tires does it all well
  • Silver 2006 TJ Unlimited, zombie ready as the daily-driver
  • a Kawasaki KLR650 DualSport bike

- - - - - - -TEOTWAWKI- - - - - - -


NaeKid is offline   Reply With Quote
Unread 10-10-2002, 11:47 AM   #3
DanyJeep
Registered User
 
Join Date: Jul 2002
Location: Montreal, Canada
Posts: 52
nae kid.....

would you be able to confirm those numbers?
please. i'll tell you why later
DanyJeep is offline   Reply With Quote
Unread 10-10-2002, 12:03 PM   #4
RCHavok797
Registered User
2005 LJ Wrangler 
 
Join Date: Jan 2002
Location: Oxford, CT
Posts: 2,434
From the Haynes manual: Cylinder compression pressure should be between 155 to 185 psi.
__________________
2005 LJ Impact Orange 4.0L Automatic (Tigger) - new ride
1991 YJ Sahara 4.0L Automatic
1978 Dodge Lil Red Express - work in progress
RCHavok797 is offline   Reply With Quote
Unread 10-10-2002, 12:57 PM   #5
Newfie
Registered User
 
Join Date: Apr 2001
Location: Republic of Newfoundland
Posts: 123
As long as all the cylinders are resonably close, you shouldn't have any issues. An older motor will not have anywhere near the compression that it came from the factory with. It's when you get 1 or two cylinders that are way out from the others that you need to worry. Your's are not completely unreasonable, but my guess is that it's almost time for new rings.
__________________
No officer, that wasn't an accident. I did that on purpose...
Newfie is offline   Reply With Quote
Reply
Thread Tools


Suggested Threads





Jeep, Wrangler, Cherokee, Grand Cherokee, and other models are copyrighted and trademarked to Jeep/Chrysler Corporation. JeepForum.com is not in any way associated with Jeep or the Chrysler Corp.