Low Compression - Jeep Wrangler Forum
Jeep Wrangler Forum

Go Back   Jeep Wrangler Forum > YJ Jeep Wrangler Forum > YJ Tech Forum

Join Wrangler Forum Today


Reply
 
Thread Tools

Please support our sponsors and let them know you heard about them on WranglerForum.com
Old 11-07-2013, 04:14 PM   #1
Jeeper
 
Join Date: Sep 2012
Posts: 22
Low Compression

So I have low compression in two of my four cylinders, one much worse than the other, and decided to pull the head in hopes of it only being the valves. I have two if not three valves that are obviously in need of repair. Any advice is welcome as I have not done this before but have read a bunch on this forum and watched YouTube videos.
Questions are:
How do I remove the lifters?
What rocker arms to use and where to get them? Assuming they should all have the same shape it looks like two are slightly bent.
What is best to use to clean the carbon off my pistons?
Where can I get good valves or a kit for a good price?
Do I need to check for a cracked block? If yes, what is the best way?

Thanks in advance, I really enjoy how the Jeep community is so willing to help one another.
Attached Thumbnails
Click image for larger version

Name:	IMG_1161.jpg
Views:	34
Size:	202.7 KB
ID:	494034   Click image for larger version

Name:	IMG_1165.jpg
Views:	34
Size:	224.2 KB
ID:	494042  

Click image for larger version

Name:	IMG_1166.jpg
Views:	34
Size:	228.9 KB
ID:	494050   Click image for larger version

Name:	IMG_1167.jpg
Views:	34
Size:	198.9 KB
ID:	494058  

Click image for larger version

Name:	IMG_1168.jpg
Views:	29
Size:	229.6 KB
ID:	494066  

mrem is offline   Quote Quick Reply
Old 11-07-2013, 04:39 PM   #2
Jeeper
 
MTJeepTJ's Avatar
 
Join Date: Jan 2013
Location: Lolo Montana
Posts: 261
Well, I work as a tech in a shop everyday. And there could be a bunch of ways people would tell you to fix your Jeep. Now if this was my 4cyl Jeep and it was possibly just my beater/driver. I wouldnt replace the lifters. I would buy some stock valves for the whole head. I would empty the entire head and clean it. Replace the valve guide seals and lap the new valves to the seat and check the pattern. Then i would install that head and see where i was at. I would spend the least amount of money possible on this project if i were you. I would feel for a bad ridge at the top of each cylinder. If there is a ridge dont expect to have awesome compression. The rest of the engine may not be perfect and that is why i would be on the cheap fixing those burnt valves. Cause the next step would be a full removal and rebuild the entire engine.

__________________
In The Mountains
MTJeepTJ is offline   Quote Quick Reply
Old 11-07-2013, 04:57 PM   #3
Jeeper
 
Join Date: Jan 2010
Location: Las Cruces, NM
Posts: 2,291
Take the head to a decent shop that does that work...have it reworked.
Lifters will come out with a magnet but a special tool is better,
Can get one at harbor freight for a few bucks. If you use the magnet you stand a good chance of the lifter falling off and then some are a bitch to get out. A set of stock lifters, rockers and push rods are not all that $$$ .
__________________
2013 WRANGLER SPORT 2 DR., V-6 ,AUTO,HARD TOP
(Sold)1994 Jeep Wrangler 2.5L, Bestop top
/w steel half door and slider windows
5 speed, 2.5" lift, 31" tires,rack lights
Garyk is offline   Quote Quick Reply
Old 11-07-2013, 09:56 PM   #4
Jeeper
 
Join Date: Sep 2012
Posts: 22
Quote:
Originally Posted by MTJeepTJ View Post
Well, I work as a tech in a shop everyday. And there could be a bunch of ways people would tell you to fix your Jeep. Now if this was my 4cyl Jeep and it was possibly just my beater/driver. I wouldnt replace the lifters. I would buy some stock valves for the whole head. I would empty the entire head and clean it. Replace the valve guide seals and lap the new valves to the seat and check the pattern. Then i would install that head and see where i was at. I would spend the least amount of money possible on this project if i were you. I would feel for a bad ridge at the top of each cylinder. If there is a ridge dont expect to have awesome compression. The rest of the engine may not be perfect and that is why i would be on the cheap fixing those burnt valves. Cause the next step would be a full removal and rebuild the entire engine.
What do you recommend for cleaning the head??
mrem is offline   Quote Quick Reply
Old 11-08-2013, 12:21 AM   #5
Jeeper
 
c5wagner's Avatar
 
Join Date: Apr 2013
Location: Reno, Nevada
Posts: 1,323
Quote:
Originally Posted by mrem View Post
What do you recommend for cleaning the head??
Mopar combustion chamber cleaner is the best anti carbon deposit stuff I've used
__________________
1989 Base YJ, 4.2l, Borla exhaust, offy intake, Motorcraft 2150 carb, CRT HEI ignition, ax15, np231 JB conversions SYE, D30 ARB & Ford 8.8 ARB 4.56, 35x12.5r15 Goodyear MTR's, bds 3.5" springs, 1" body lift, and 1/2" Boom Shackles.
Build Thread: http://www.wranglerforum.com/f330/fi...ld-385106.html
c5wagner is online now   Quote Quick Reply
Old 11-09-2013, 09:31 AM   #6
Jeeper
 
Join Date: Sep 2012
Posts: 22
Ok, got the head all cleaned up and a new exhaust valve installed. My issue is finding head bolts in town so I can wrap this up this weekend, is it possible to use the old bolts or am I wasting my time?? Thanks
mrem is offline   Quote Quick Reply
Old 11-09-2013, 03:25 PM   #7
Jeeper
 
Join Date: Sep 2012
Posts: 22
Got a question about lash adjustment; firing order 1-3-4-2 as best I can find, is it as simple as 1-2-3-4 from front to back?? Thanks again
mrem is offline   Quote Quick Reply
Old 11-10-2013, 10:48 AM   #8
Jeeper
 
Join Date: Sep 2012
Posts: 22
So, got the head back on and am trying to get my rocker arms tightened correctly and I have a few questions about lash adjustment.
Do I need to be careful how much I rotate the cam (?) as I find TDC?
Does the Jeep need to be in neutral or on jack stands to make the adjustment?
Any input on the best way to get everything seated correctly is much appreciated
mrem is offline   Quote Quick Reply
Old 11-10-2013, 11:14 AM   #9
Jeeper
 
0III0forlife's Avatar
 
Join Date: Mar 2012
Location: Ridgway, Pa.
Posts: 3,265
Your firing order is correct and yes #1 cylinder is in the front, 4 in the rear.

There is no "lash" adjustment, cause the motor has hydraulic lifters. You just need to torque the rockers to their proper torque in 5lb increments until you get to the torque number that you need. Don't go over that number.

You need it in neutral, but jack stands aren't necessary.
__________________
'87 YJ, 4.2L built and bored, 8.5" of lift, 8.8 rear, AX15/NP 231, Tom Woods drive shafts, Flat fenders, 12,000LB winch, Custom bumpers, Rattle can paint job. Never completed...
0III0forlife is offline   Quote Quick Reply
Old 11-14-2013, 09:40 AM   #10
Jeeper
 
Join Date: Sep 2012
Posts: 22
Thinking I was wrong in how I described what I am doing; want to find TDC and thought the lash adjustment was terminology. How do I find TDC or do I not need to and just torque them as you described?
mrem is offline   Quote Quick Reply
Old 11-14-2013, 10:17 AM   #11
jokerchief462

WF Supporting Member
 
jokerchief462's Avatar
 
Join Date: Apr 2012
Location: North Las Vegas
Posts: 9,295
The prescribed torque is all that is required. Got to live simplicity.
__________________
89 2.5 TBI, 4" RC lift, 1" Booms, SYE, Adams Driveshafts front and rear, Ford 8.8 with 4:88s, BFG 33X12.50X15, and a ton of other stuff.

AF Jeep Club Tail Number 184
jokerchief462 is offline   Quote Quick Reply
Old 11-14-2013, 11:00 AM   #12
Jeeper
 
Join Date: Sep 2012
Posts: 22
Was hoping it was something I had done, or not done, as I cannot get to restart since pulling head, replacing blown valve and reassembling. Have spark, turns over but just won't catch
mrem is offline   Quote Quick Reply
Old 11-14-2013, 11:27 AM   #13
Jeeper
 
c5wagner's Avatar
 
Join Date: Apr 2013
Location: Reno, Nevada
Posts: 1,323
Quote:
Originally Posted by mrem View Post
Was hoping it was something I had done, or not done, as I cannot get to restart since pulling head, replacing blown valve and reassembling. Have spark, turns over but just won't catch
Try adding a ground from a valve cover bolt to the body
__________________
1989 Base YJ, 4.2l, Borla exhaust, offy intake, Motorcraft 2150 carb, CRT HEI ignition, ax15, np231 JB conversions SYE, D30 ARB & Ford 8.8 ARB 4.56, 35x12.5r15 Goodyear MTR's, bds 3.5" springs, 1" body lift, and 1/2" Boom Shackles.
Build Thread: http://www.wranglerforum.com/f330/fi...ld-385106.html
c5wagner is online now   Quote Quick Reply
Old 11-14-2013, 10:16 PM   #14
Jeeper
 
Join Date: Jul 2012
Posts: 196
Check you basic ignition timing.

Start by putting number 1 cylinder at top dead center on the revolution where both valves are closed.

Confirm that the timing mark is at or near zero.

Crank the engine with a timing light connected to #1 and see where your ignition timing is. I don't see where you listed your model year so ignition system can be different over the years so depending on your system the fix for incorrect timing will vary.
WICruiser is offline   Quote Quick Reply
Old 11-15-2013, 07:34 AM   #15
Jeeper
 
peety's Avatar
 
Join Date: Feb 2013
Location: Almost a PINEY...
Posts: 225
Make sure that the crank sensor is plugged in, also check the Wide Open Throttle switch on the throttle body, they stick closed. I chased that for almost two weeks, just sayin..
__________________
Patience and perseverance have a magical affect before which difficulties disappear and obstacles vanish.

John Quincy Adams
peety is offline   Quote Quick Reply
Old 11-15-2013, 08:39 AM   #16
Jeeper
 
Join Date: Sep 2012
Posts: 22
Model year is a '95 Rio Grande 4-cyl manual

Tried a newer battery and seemed to help but still wouldn't turn over, possibly an alternator??

c5- I put a good ground wire on, thx

Will check timing and wide open throttle today and get back to you all

I am throwing a #33 code as well but havent found a good thread for that
mrem is offline   Quote Quick Reply
Old 11-18-2013, 10:04 PM   #17
Jeeper
 
Join Date: Jul 2012
Posts: 196
Won't turn over is not the same as won't start. If the engine will not rotate with the starter you need confirm that the engine will rotate manually.
WICruiser is offline   Quote Quick Reply
Old 11-21-2013, 01:47 PM   #18
Jeeper
 
peety's Avatar
 
Join Date: Feb 2013
Location: Almost a PINEY...
Posts: 225
Quote:
Originally Posted by mrem View Post
Model year is a '95 Rio Grande 4-cyl manual

Tried a newer battery and seemed to help but still wouldn't turn over, possibly an alternator??

c5- I put a good ground wire on, thx

Will check timing and wide open throttle today and get back to you all

I am throwing a #33 code as well but havent found a good thread for that
What did you find out ??
__________________
Patience and perseverance have a magical affect before which difficulties disappear and obstacles vanish.

John Quincy Adams
peety is offline   Quote Quick Reply
Old 11-21-2013, 02:24 PM   #19
It's a Jeep thing!

WF Supporting Member
 
western196611's Avatar
 
Join Date: Jun 2013
Location: Central Kansas
Posts: 699
Quote:
Originally Posted by peety View Post
What did you find out ??


I'm wondering if the OP lapped in the new valves at least. The way the one in the pic was burnt... should had been reground. may still have a compression problem.
__________________
1995, 4.0, 5 speed YJ, SOA, TC drop, 8.8 swap with 4.10 and LSD, e-grills bumper, 33" BF all terrains on 15" wheels.
western196611 is offline   Quote Quick Reply
Old 11-22-2013, 10:08 AM   #20
Jeeper
 
Join Date: Sep 2012
Posts: 22
Yes I did the lap the valves, put a new exhaust and intake valve in place of one totally blown and one really beat up one. I am diving back into the project this weekend. Have to figure out how to check timing and whether my TDC is correct. Am in a bit over my head at this point so any suggestions, besides take it to a shop, are gratefully received
mrem is offline   Quote Quick Reply
Old 11-22-2013, 10:13 AM   #21
Jeeper
 
Join Date: Sep 2012
Posts: 22
WICruiser- it cranks/turns over but never catches. Not sure if that explains any better, before the project started it would be a PITA to start if it didnt catch first try in the morning. Would have to hold key forward/on and gas on floor for several seconds to get it to fire up.
Have spark, my best guess is timing in relation to TDC is off or valves may need to be redone. THoughts?
mrem is offline   Quote Quick Reply
Old 11-22-2013, 01:37 PM   #22
It's a Jeep thing!

WF Supporting Member
 
western196611's Avatar
 
Join Date: Jun 2013
Location: Central Kansas
Posts: 699
Probably the easiest and cheapest way to check timing is to pull the #1 plug out, roll it to TDC. (can check it with a screw driver laying on top of the piston) Then pull valve cover to make sure both valves are closed, then pull distributor cap to make sure the rotor is pointing to the #1 plug wire.
__________________
1995, 4.0, 5 speed YJ, SOA, TC drop, 8.8 swap with 4.10 and LSD, e-grills bumper, 33" BF all terrains on 15" wheels.
western196611 is offline   Quote Quick Reply
Old 11-22-2013, 05:46 PM   #23
Jeeper
 
Join Date: Sep 2012
Posts: 22
Western- pulled my distributor and rotor is pointing to number four....my question is how do I rotate the rotor to get back to one to one?? Thanks for the help
Attached Thumbnails
Click image for larger version

Name:	IMG_1191.jpg
Views:	15
Size:	226.2 KB
ID:	534850  

mrem is offline   Quote Quick Reply
Reply

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the Jeep Wrangler Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
User Name:
If you do not want to register, fill this field only and the name will be used as user name for your post.
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.



Thread Tools

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 Off
Refbacks are Off




» Network Links
»Jeep Parts
» Featured Product

All times are GMT -5. The time now is 02:24 PM.



Jeep®, Wrangler, Liberty, Wagoneer, Cherokee, and Grand Cherokee are copyrighted and trademarked to Chrysler Motors LLC.
Wranglerforum.com is not in any way associated with the Chrysler Motors LLC