88 MJ blowing oil - JeepForum.com
LinkBack Thread Tools
post #1 of 6 Old 04-03-2016, 06:30 PM Thread Starter
Registered User
1988 MJ Comanche 
Join Date: Oct 2015
Location: Roseburg
Posts: 2
88 MJ blowing oil

My 88 4.0l MJ keeps blowing oil through the breather hoses coming out of the valve cover. I've cleaned all of the sludge from under the valve cover. There's no oil being burned and blown through the exhaust so I know the valves and piston rings are good. I just don't understand why it won't stop blowing out through the hoses. Any suggestions?

Nmckinney is offline  
Sponsored Links
post #2 of 6 Old 04-08-2016, 09:55 AM
Registered User
1998 ZJ 
Join Date: Dec 2004
Location: Chagrin Falls
Posts: 591
Try this http://cruiser54.com/?p=131

98 ZJ 5.2, LA n Locked, 242 sye, 35's
87 MJ, 4.0, 8.8, 33's, oba
07 Ram 2500 5.9 ctd
WVZJ is offline  
post #3 of 6 Old 04-24-2016, 07:34 PM
Registered User
1989 MJ Comanche 
Join Date: Jan 2011
Location: Gabriola
Posts: 43
I just had my valve cover off to replace the gasket so I did cut off the fluted tubes as suggested in above posting. The tubes already had a hole drilled in them. I don't have a lot of blow over to the air filter but enough to make it dirty. When I got my Comanche the blow over was terrible. When I removed the valve cover at that time it was full of sludge and was it restricting the flow of oil back down to the crankcase. My main problem is the gasket seem to compress over time and I have to keep tightening the hold down screws.
DonBC is offline  
post #4 of 6 Old 04-25-2016, 04:09 PM
Registered User
Join Date: Sep 2003
Posts: 1,946
Might try a rubberized cork gasket. I also changed to a '95 valve cover. It help a bunch. You would have to cut your CCV tubes. I also did the big CCV tube update. I was sucking a quart a week. Then it was good. I'd start with the valve cover gasket. Any air getting in that way seems to cause the problem.
75SV1 is offline  
post #5 of 6 Old 05-19-2016, 08:00 AM
Web Wheeler
cruiser54's Avatar
1990 MJ Comanche 
Join Date: Oct 2009
Location: Prescott
Posts: 12,285
Use 5 quarts of Rotella T3 and 1 quart of Marvel Mystery Oil with a Wix filter. watch the sludge melt away.

As stated, the CCV tubes need to be in perfect shape, especially the one at the rear of the valve cover.

If you own a Renix Jeep, you must check this out:

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

My Jeep technical photos:

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
cruiser54 is offline  
post #6 of 6 Old 05-26-2016, 08:49 AM
Registered User
Join Date: Sep 2003
Posts: 1,946
On my attemps with this, I found that the valve cover gasket sealing had an affect. Try a FelPro VS50522T. They are about $40. I order one to put on a late '95 valve cover on a '98 XJ. Also, the problem if the oil is going to your air filter, is that there is probably a air leak. The CCV system is not pulling enough air to counter act the suction from the air filter, and the extra air from the leak. So oil goes to the air filter. I did put a '91-95' '90 degree Twist' CCV valve cover on my '88. It helped a lot. I also adapted the big hose CCV hoses from a late model XJ '00-'01.
75SV1 is offline  

Quick Reply

Register Now

In order to be able to post messages on the JeepForum.com forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Please enter a password for your user account. Note that passwords are case-sensitive.


Confirm Password:
Email Address
Please enter a valid e-mail address for yourself.

Email Address:


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page

Posting Rules  
You may post new threads
You may 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 On
Refbacks are On

For the best viewing experience please update your browser to Google Chrome