4.0 Head removal - Jeep Cherokee Forum
Jeep Cherokee Forum

Go Back   Jeep Cherokee Forum > Technical Discussion > OEM Cherokee Tech
Log In 
Search


4.0 Head removal

Reply
 
 
 
 
Thread Tools Search this Thread
Old 02-15-2010, 11:39 PM   #1
Seasoned Member
 
Join Date: Jun 2009
Location: Castle Rock, CO
Posts: 316

View 2.5TURBO's Photo Album My Photos
91 Cherokee
Default 4.0 Head removal

So I 91 XJ that I ran engine cleaner through and caused a bigger problem. So now I have a valve issue (cylinder#2 is non functioning) When I pulled the valve cover and rotated the engine I found one of the valves wasn't operating, I believed it to be the exhaust valve since it was backfiring up the intake manifold.

FIRST
I know the head has to come off on the 4.0 to mess with the lifters. How hard is it to remove the head, is it as straight forward as it looks or am I gonna get a nasty surprise? I've done plenty of headgaskets on chrysler 2.5l 4cylinder turbos and that's a fun little adventure the first couple times.

SECOND
How much damage is being done to the piston rings since it's still compressing but has improper airflow so it makes more drag and no power. I know this because I tested it today w/o a spark plug in the place and it runs likes it's supposed to.

I don't have a whole lot to drop in this repair (about $500) What am I up against?
2.5TURBO is offline   Reply With Quote
Join Cherokee Forum

Join CherokeeForum.com Today - It's Totally Free!

Do you love your Jeep? If so we invite you to join our community and see what it has to offer. Our site is specifically designed for you and it's a great place for Jeep Fans to meet online.
Once you join you'll be able to post messages, upload pictures of your jeep, and have a great time with other Jeep Cherokee fans.. Whether your an old timer or just bought your Jeep you'll find that CherokeeForum.com is a great community to join. Best of all it's totally free!

Join CherokeeForum.com Today! - Click Here JOIN FOR FREE


-->
Old 02-15-2010, 11:47 PM   #2
Seasoned Member
 
djritter1122's Avatar
 
Join Date: Jan 2010
Location: smyrna,de
Posts: 293

View djritter1122's Photo Album My Photos
1997 Cherokee
Default

not to bad to do. i unbolted the intake and left it to the side and then just unbolt and remove.how long has it run with out the exhaust on #2. you may want to remove the lifter and inspect the cam is you can get a gauge on it
djritter1122 is offline   Reply With Quote
Old 02-16-2010, 03:33 AM   #3
CF Veteran
 
5-90's Avatar
 
Join Date: May 2008
Posts: 2,996

View 5-90's Photo Album My Photos
1988 Cherokee
Default

Late-gen MDS setups close the valves on deactivated cylinders to "turn them off", so you probably don't have any ring trouble.

I find it easier to pull the head and manifolds as a piece, but I'm a big guy and have an engine crane handy as well. The manifold gasket, if it needs to be serviced, is done on the bench.

Check the cylinder head screws before you start work - if they're not painted, get some bright colour of paint (I typically use yellow or red.) If they're painted, order a new set. The 242ci head screws (per FSM) may only be fully torqued twice - they're a modification of the old Torque-To-Yield (TTY) head screws used on Diesels. Yes, they can and do fail (rupture) if you try to torque them a third time - I've made a decent amount of money burning them out of blocks sitting in place...

Replace the exhaust & manifold hardware with bronze (best - check marine supply houses) or SAE5 carbon steel. Don't bother with CRES - it's not enough to help - and SAE8 loses strength faster than SAE5 due to heat cycles - it won't be long before the SAE8 is actually weaker than SAE5!

Undercar, like on the clamps and flange hardware, use marine brass. It won't corrode or seize, so it will be easier to remove next time!

Make a "thread chaser" out of a hardware store-bought SAE8 1/2"-13 x 3" screw by cutting two or three longwise flutes down the side. Run it down the hole and back out to clean the crappola out - clean off the screw and repeat through all fourteen holes.

NB: The #11 cylinder head screw hole (driver's side front) extends into the coolant jacket - be sure to coat the threads on this screw with something like LocTite PST, plumber's PTFE pipe dope, or RTV. Treat This Point As Important. (I've used the first two with good results. There's no reason the third shouldn't work - I just haven't used it yet.)

Manifold hardware gets LocTite #272 (or equivalent) or don't bother. It's not tight enough to require never-seez, and other grades of chemical threadlocker will break down due to heat. Replacement studs may be made using 3/8"-16 brass threaded rod (cut to 2-1/4" long,) and replacement screws should be 3/8"-16x1-1/4". Retain the dish-shaped washers and reuse them. If you can't get 1-1/4" long screws, get 1-1/2" long and a bag of flat washers - take up the slack by using flat washers between the screw head and the bowl washer.

Torque specs for just about everything should be on my site in the Tech Archives - taken from FSM. If I don't have your year (yet...) pick a year close to yours.
__________________
Kelley's Works in Progress - www.kelleyswip.com
KWiP Parts Exchange - www.kelleyswip.com/exchange.html

"It's in the shop, being readied for the next failure."
5-90 is offline   Reply With Quote
Old 02-17-2010, 01:43 AM   #4
Seasoned Member
 
Join Date: Jun 2009
Location: Castle Rock, CO
Posts: 316

View 2.5TURBO's Photo Album My Photos
91 Cherokee
Default

Quote:
Originally Posted by djritter1122 View Post
not to bad to do. i unbolted the intake and left it to the side and then just unbolt and remove.how long has it run with out the exhaust on #2. you may want to remove the lifter and inspect the cam is you can get a gauge on it
It's been running this way for about a month and a half.

Excellent info 5-90, I will keep all this in mind when I do it. Hopefully it will hold up until May or June.
2.5TURBO is offline   Reply With Quote
Old 02-17-2010, 06:10 PM   #5
CF Veteran
 
5-90's Avatar
 
Join Date: May 2008
Posts: 2,996

View 5-90's Photo Album My Photos
1988 Cherokee
Default

Quote:
Originally Posted by 2.5TURBO View Post
It's been running this way for about a month and a half.

Excellent info 5-90, I will keep all this in mind when I do it. Hopefully it will hold up until May or June.
I'm not sure I'd put it off that long - maybe a month at the outside. It probably isn't a problem now, but it probably will be a problem later...
__________________
Kelley's Works in Progress - www.kelleyswip.com
KWiP Parts Exchange - www.kelleyswip.com/exchange.html

"It's in the shop, being readied for the next failure."
5-90 is offline   Reply With Quote
Old 02-17-2010, 09:59 PM   #6
CF Veteran
 
fishtaconc's Avatar
 
Join Date: Mar 2009
Location: Watha,NC
Posts: 1,208

View fishtaconc's Photo Album My Photos
Jeepless at the moment
Default

Its been my experince that even with new lifters the cam can still fail, to help slow this down coat the new lifters with ZDDP Paste. Just my .02
fishtaconc is offline   Reply With Quote
 
 
 
Reply

Similar Threads
Thread Thread Starter Forum Replies Last Post
Cylinder #4 dead and findings s10xtremist OEM Cherokee Tech 18 Today 08:43 AM
another 98 cherokee overheating BluJay OEM Cherokee Tech 18 08-12-2015 10:32 PM
NSS removal: what am i doing wrong? VTJeep OEM Cherokee Tech 47 08-05-2015 03:52 PM
Fuel mileage 4.0 dave1123 Grand Cherokee Tech 2 07-29-2015 12:16 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

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 01:55 PM.


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

Emails Backup