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'77 CJ-5, 258 issues.......

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luvintrucks View Drop Down
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    Posted: 09 September 2008 at 6:42am

I'm at my wits end with our CJ-5 258.  In short, after replacing:

- entire wiring harness with a painless kit

- fuel pump

- coil

- distributor

- plugs

- wires

- cam / crank sprockets

- timing chain

- ignition module (2 of them; one was defective)

- vacuum hose

- rebuilt carb 3 times

- fuel filter
 
the 258 is still not running right.  Seems I've been chasing my tail for months now as one "issue" leads to another.  We bought the Jeep in June of 2007 and didn't get it on the road until Feb of this year (after replacing the wiring harness).  After starting to drive it, the 258 would never get above 51 MPH as it lost power and started backfiring.  Additionally, on some days (not all) it would lose power and backfire coming out of 1st and going into 2nd (about 34 MPH).  On other days, it would only act up at 51 MPH.  All of this took us down the timing path.......  I then noticed that I couldn't get it timed to the spec 3 degrees BTDC--the 258 wouldn't start after setting it.....  We then replaced the ignition module and distributor (after several weeks of troubleshooting)--still no appreciable change.  A friend came over and figured out that the vacuum advance was hooked to the wrong carburetor port---yea, some progress, we can now time it to 3 degrees BTDC and it starts without needing to advance the timing.  Oh by the way, the compression is good and all carburetor ports are confirmed clear and the float is properly adjusted......

After all of the above (and then some), I'm now at the point where it idles really nice however, when you increase the RPM's (sorry--don't have a tach so don't know to what level) it backfires (aspirates back through the carburetor).  The Jeep is not drivable and I don't know what else to do; family is getting pretty frustrated as well...........

Does anyone know of a reputable (and reasonable) service shop that could analyze the situation and tell me what's wrong?  I'd still like to perform the fix (if it's not to involved) however............
 
Thanks for any help you might be able to pass on.
 
Jeep owner frustrated in Madison..........
 
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NOT4HWY View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote NOT4HWY Quote  Post ReplyReply Direct Link To This Post Posted: 09 September 2008 at 7:03am
Timing chain indexed correctly?  Steve                                                                                                                                                                                    Danny @ Rocket City Offroad 883-1131 can probably give you a few pointers.

Edited by NOT4HWY - 09 September 2008 at 9:32am
Club member since 1992, Club President 1995-1999 Trail rig:S-Blazer,Rockwells,507 Caddy,T-400,203/205, Tow-rig: '23 F350 4x4
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Post Options Post Options   Thanks (0) Thanks(0)   Quote scoutman Quote  Post ReplyReply Direct Link To This Post Posted: 09 September 2008 at 7:57am
Well my first guess was the vac advance but you've already touched on that.  Which carb does it have?  Does the accel pump on the carb have interchangeable cams on it?  Still sounds like a carb and or timing issue to me. 
76 Scout II in pieces
96 Jeep XJ 33's
99 Jeep XJ Limited
06 Dodge 3500
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Post Options Post Options   Thanks (0) Thanks(0)   Quote luvintrucks Quote  Post ReplyReply Direct Link To This Post Posted: 09 September 2008 at 8:03am
Hello Danny,
 
I indexed it per our Chilton manual (15 pins / 7.5 links). 
 
I'm heading off to an appointment otherwise I'd give you a call.  How long are you going to be available at the number you provided?
 
Thanks so much for the reply---look forward to meeting you at one of our next meetings.
 
Scott
 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote luvintrucks Quote  Post ReplyReply Direct Link To This Post Posted: 09 September 2008 at 8:06am
It's got the 1 BL Carter.  I don't know about the interchangeable cams--will have to research that. 
 
I failed to mention that I pulled a vac test on it and that passed as well............18.5 to 19.
 
Thanks for the post,
 
Scott
 
 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote scoutman Quote  Post ReplyReply Direct Link To This Post Posted: 09 September 2008 at 8:57am
Danny hasn't posted yet.  You'll probably have to call him to get his opinion as he doesn't post here much. 
76 Scout II in pieces
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06 Dodge 3500
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Post Options Post Options   Thanks (0) Thanks(0)   Quote NOT4HWY Quote  Post ReplyReply Direct Link To This Post Posted: 09 September 2008 at 9:31am
Sorry-corrected wording in my earlier post.   Steve
Club member since 1992, Club President 1995-1999 Trail rig:S-Blazer,Rockwells,507 Caddy,T-400,203/205, Tow-rig: '23 F350 4x4
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Post Options Post Options   Thanks (0) Thanks(0)   Quote cj8lvr Quote  Post ReplyReply Direct Link To This Post Posted: 09 September 2008 at 9:47am
The backfiring is telling me that you've got a timing issue or a bad valve perhaps.  For it to backfire, you'd have to have either  an intake or exhaust valve open depending on which way it's backfiring (through the carb or the exhaust).  Is it an honest to goodness scare the pants off you backfire or just a bad sputter / hesitation?
___/| [_\__\],
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Post Options Post Options   Thanks (0) Thanks(0)   Quote luvintrucks Quote  Post ReplyReply Direct Link To This Post Posted: 09 September 2008 at 11:48am

Hello Steve----sorry about thinking you were Danny..........  I should have figured it out from the picture of your awesome truck!

I did talk with Danny and he said that he thought it was a timing issue--suggested I redo the compression check and ensure that I'm not a tooth off on the distributor.
 
Thanks again,
 
Scott
 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote luvintrucks Quote  Post ReplyReply Direct Link To This Post Posted: 09 September 2008 at 11:51am

Great question!  It's a bad sputter, hesitation......

Thanks to Steve's suggestion, I called Danny and briefly talked to him.  He as well said it's got to be a timing issue.  He suggested I redo the compression check and double check the distributor to be sure I'm not a tooth off........
 
As Danny said, the engine is so simple I've got to go back to the basics--gas, air and spark. 
 
 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Guests Quote  Post ReplyReply Direct Link To This Post Posted: 10 September 2008 at 1:32am
Just throwing an idea here but after everything you have done it wouldnt be really difficult to check your rocker arms;to tight or loose,pushrods:one may be bent, and valve springs:weak spring. Also how is your oil pressure? Oil not pushing to the top of the engine will cause camshaft failure over time. These are probably long shots but I am just considering other crazy reasons why your engine is popping.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote luvintrucks Quote  Post ReplyReply Direct Link To This Post Posted: 10 September 2008 at 3:42am

I pulled the valve cover this weekend to "see what I could see."  In general (to a novice), everything looked ok--nothing really obvious.  All springs, rocker arms, push rods looked good---all generally well coated with oil.  The only one that I was concerned about was the number 6 cylinder--the exhaust rocker arm did not have much oil sitting on top.  I then pulled both arms and rods out to inspect.  The rods are straight but, the #6 exhaust push rod was plugged with a hard coal like substance (the rocker arm also had similar deposits on it as well).  When I installed the push rod, it didn't make metal-to-metal contact on the tappet--felt like there was more of the heavy residue on top of the valve tappet.  After pushing the rod down on to the tappet and then pulling it out, the rod was again plugged with the hard, coal like residue.  I did this a few more times until the rod came out "clean."

With no other ideas, I then drained a quart of oil and added a quart of Marvel's mystery oil to see if I could get the residue cleaned.  That was Sunday afternoon.  I've since started it twice, ensured it was good and warm and then let it sit.  Engine is still exhibiting the same symptoms.........  Per your suggestion, I definitely need to pull the valve cover again and see how the #6 is doing.
 
Thanks for the post!
 
Thank you all for your wisdom and advice.....  This is all new to me so, I'm learning every step of the way!
 
 
 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote NOT4HWY Quote  Post ReplyReply Direct Link To This Post Posted: 10 September 2008 at 4:58am
If it's undriveable- one of us could help you tow it to Danny's shop. I think at this point you have done all you can-sometimes you just need help. Steve
Club member since 1992, Club President 1995-1999 Trail rig:S-Blazer,Rockwells,507 Caddy,T-400,203/205, Tow-rig: '23 F350 4x4
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