Jeep Cherokee Forum

Go Back   Jeep Cherokee Forum > Technical Discussion > OEM Cherokee Tech
Register Forgot Password?
Search


Welcome to Cherokee Forum!
Welcome to Cherokee Forum,

You are currently viewing our forum as a guest, which gives you limited access to view most discussions and access our other features. By joining our community, at no cost, you will have access to post topics, communicate privately with other members (PM), respond to polls, upload content and access many other special features. Registration is free, fast and simple, so please join our community today!


Reply
 
 
 
submit to reddit
 
Thread Tools Search this Thread Display Modes
Old 03-12-2011, 04:13 AM   #1
Newbie
 
Join Date: Feb 2011
Location: Kelso, WA
Posts: 4

View Swampy77's Photo Album My Photos
1989 Cherokee
Default Blow-by with good compression?

`89 Cherokee, 4.0 I6, Just did a compression check. Cylinders were between 138 and 150 psi. Which seems quite good to me! When I pull the PCV valve, or take off the Oil fill cap, I have puffing blow-by! Could this be bad valves? I`m not seeing any water in the oil, and am not losing any coolant. I`m new to these Jeeps, so I have lots to learn. Also, Oil pressure when cold runs around 45 psi, after warm up at an idle it drops to around 15psi. Is this enough oil pressure at an idle? I know it should be around 37psi at 1600 rpm, warm. Any and all help will be appreciated. . Thanks.
Swampy77 is offline   Reply With Quote
Old 03-12-2011, 06:48 AM   #2
CF Veteran
 
Join Date: Nov 2010
Location: In the middle of Minnesota!
Posts: 4,758

View tjwalker's Photo Album My Photos
1999 Cherokee
Default

*Are you actually using oil (IE: having to add?)

*A little puffing with the oil filler cap off is not unusual

*Your compression is good (120-150 with no more than a 30 psi variation between cylinders)

*Oil pressure of 15 psi at HOT idle is fine. The spec is no less than 13 psi at HOT idle.

*Do you have any evidence of oil in the air filter box? That is very common with the 87-90. It can often be managed or eliminated by replacing the grommets and hoses that are installed on the valve cover.

Here is a pretty good thread that explains the CCV (crank case ventilation) system and its weak points. There is no PCV valve on the 4.0 Jeep.

http://www.cherokeetalk.com/forum/f8...d-blowby-5870/
__________________
Without data, all you have is an OPINION!

Past Jeeps: '49 ******, '81 Scrambler, '88 Comanche

Current Jeep: 1999 XJ Sport, bone stock, daily driver.

I work on Jeeps!!
tjwalker is offline   Reply With Quote
Old 03-12-2011, 07:13 PM   #3
Newbie
 
Join Date: Feb 2011
Location: Kelso, WA
Posts: 4

View Swampy77's Photo Album My Photos
1989 Cherokee
Default

Hey TJ, Thanks for the info and the link to the CCV system! I`m headed out to check the smaller line that goes to the intake manifold. Make sure it`s not plugged. The other line that goes to the airbox, does have a pcv valve in it now, and it still will accumulate oil and have a small drip towards the airbox. Should this fitting just be an open 90deg. fitting going to the airbox, so that air can be sucked into the valve cover?
Swampy77 is offline   Reply With Quote
Old 03-12-2011, 07:48 PM   #4
CF Veteran
 
89Laredo's Avatar
 
Join Date: May 2009
Location: Michigan, 48657
Posts: 9,984

View 89Laredo's Photo Album My Photos
1989 Cherokee
Default

hould this fitting just be an open 90deg. fitting going to the airbox, so that air can be sucked into the valve cover?



yes
__________________
I no longer visit here, messages will not be responded to.
Get ahold of me on XJtalk, NAXJA *89Laredo*, Youtube, GL4x4, or My Wordpress Site
89Laredo is offline   Reply With Quote
Old 03-13-2011, 04:19 PM   #5
Newbie
 
Join Date: Feb 2011
Location: Kelso, WA
Posts: 4

View Swampy77's Photo Album My Photos
1989 Cherokee
Default

Cleaned out the small line to the Intake manifold, it was plugged solid! Now I have NO visible blow-by, and also got rid of the PCV valve that someone had installed. Engine seems to be running better, with possibly fewer oil leaks, due to a reduction in inside block pressure. Thanks again for the info TJ ! Still need to change out the Rear Main Seal and pan gasket.
Swampy77 is offline   Reply With Quote
Old 03-13-2011, 06:32 PM   #6
CF Veteran
 
Join Date: Nov 2010
Location: In the middle of Minnesota!
Posts: 4,758

View tjwalker's Photo Album My Photos
1999 Cherokee
Default

Quote:
Originally Posted by Swampy77 View Post
Cleaned out the small line to the Intake manifold, it was plugged solid! Now I have NO visible blow-by, and also got rid of the PCV valve that someone had installed. Engine seems to be running better, with possibly fewer oil leaks, due to a reduction in inside block pressure. Thanks again for the info TJ ! Still need to change out the Rear Main Seal and pan gasket.
Glad I could help. The CCV system is a weak link, especially with the RENIX vintage 4.0

Replacing all of the CCV hardware and a thorough cleaning of the valve cover is always a good idea here. It isn't that expensive ($45 or so for the grommets and hoses) and isn't a tough job to perform.

Now get on that rear main seal and pan gasket!
__________________
Without data, all you have is an OPINION!

Past Jeeps: '49 ******, '81 Scrambler, '88 Comanche

Current Jeep: 1999 XJ Sport, bone stock, daily driver.

I work on Jeeps!!
tjwalker is offline   Reply With Quote
Old 03-13-2011, 06:50 PM   #7
Senior Member
 
Join Date: Jan 2011
Location: N. IL
Posts: 801

View DaddyCat's Photo Album My Photos
2000 Cherokee
Default

Quote:
Originally Posted by Swampy77 View Post
Cleaned out the small line to the Intake manifold, it was plugged solid! Now I have NO visible blow-by, and also got rid of the PCV valve that someone had installed. Engine seems to be running better, with possibly fewer oil leaks, due to a reduction in inside block pressure. Thanks again for the info TJ ! Still need to change out the Rear Main Seal and pan gasket.
Very often the oil filter adaptor O-rings leak and the oil ends up dripping from the bottom of the engine - transmission area leading many people to wrongly assume the rear main seal (and/or pan gasket) is leaking.
Search oil filter adaptor
__________________
Joe
__________________

Thank you men and women of the U.S. military.
http://www.military.com/benefits/res...ort-our-troops
DaddyCat is offline   Reply With Quote
Old 03-14-2011, 02:37 AM   #8
Newbie
 
Join Date: Feb 2011
Location: Kelso, WA
Posts: 4

View Swampy77's Photo Album My Photos
1989 Cherokee
Default

I`ll check the oil filter adapter first. I bought the O ring already when I picked up the Rear Main Seal and Pan gasket. I was thinking that might be contributing to the oil leakage. Thanks for all the help TJ and DaddyCat.
Swampy77 is offline   Reply With Quote
Old 03-14-2011, 08:36 AM   #9
Senior Member
 
Join Date: Jan 2011
Location: N. IL
Posts: 801

View DaddyCat's Photo Album My Photos
2000 Cherokee
Default

Quote:
Originally Posted by Swampy77 View Post
I`ll check the oil filter adapter first. I bought the O ring already when I picked up the Rear Main Seal and Pan gasket. I was thinking that might be contributing to the oil leakage. Thanks for all the help TJ and DaddyCat.
The oil filter adaptor uses 3 o-rings but most of the time it's the one large o-ring that leaks, might be all you need. If the smaller o-rings need to be replace be aware some of the aftermarket kits do not have the correct o-rings. OEM Jeep o-rings or bring your old o-rings to the parts store to confirm sizes.

Good Luck and you're welcome
__________________
Joe
__________________

Thank you men and women of the U.S. military.
http://www.military.com/benefits/res...ort-our-troops
DaddyCat is offline   Reply With Quote
Old 03-14-2011, 08:36 AM
 
 
 
submit to reddit
Reply

Similar Threads
Thread Thread Starter Forum Replies Last Post
oil blow by/leak 87cherokee14 OEM Cherokee Tech 11 07-14-2012 01:24 AM
AC won't blow cold.. TheVision OEM Cherokee Tech 6 03-29-2010 08:19 PM
Blow a U-joint finneys98xj Cherokee Chat 15 01-08-2010 10:38 PM
Had A Blow-Out EvilBlackXJ Off-Topic Discussion 8 06-22-2009 12:07 AM
HELP.....blow by. crashzx6r OEM Cherokee Tech 17 01-26-2009 10:18 PM

Go Back   Jeep Cherokee Forum > Technical Discussion > OEM Cherokee Tech



Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



All times are GMT -5. The time now is 09:14 PM.


This site is in no way affiliated with Jeep or Chrysler.

Emails Backup