1. #1
    TennesseeCJ's Avatar
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    258 vacuum hose question

    I'm a proud new owner of a 1985 CJ7. Mechanically, it's in really good shape...it just has some rust in the typical places that need attention however, the frame seems to be in great condition. It had an oil leak around the valve cover so I decided to attempt to fix it. Well, my first attempt failed since it seemed to leak more oil afterward. So, I decided to try it again. This time I made 100% sure that the surfaces were extremely clean, trashed the cork gasket and used "The Right Stuff" from Permatex. After all of this, I still have the oil leak from the valve cover so I'm just going to assume I have to live with it.

    The real reason for this post is the configuration of the vacuum hoses. In the process of taking the valve cover off, I don't think I've got them all reconnected correctly. Before, the engine idled and ran very smoothly...now, it has a rough idle. Does anyone have a photo of the connections? I've looked at the diagram and cannot follow it either.

    I think I'll send some pictures tomorrow so you guys can assess all that I need to do first...oh yeah, if anyone happens to know of a good CJ mechanic in the Nashville area, please let me know.

    Thanks.

  2. #2
    wm69's Avatar
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    Re: 258 vacuum hose question

    First off, go on ebay and buy an aluminum valve cover. The factory cover is plastic, warps from heat, and then won't ever seal right.

    As for vacuum hoses, and idling, the only things that should be on the valve cover are a hose going from back port (on valve cover) to air cleaner, and front port to somewhere lower down on the carb (manifold vacuum).

    Plan on ditching the carb if it's factory and swap on either a Weber or a MC2100 (Motorcraft/ Ford 2 barrel).

    Google the carb swaps and you'll get tons of info. The factory carb is finicky at best.
    85 CJ7 258, borla header,jacobs, weber, T5, B&M shifter,1pieceaxles,warn hubs/ XD8000i

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    TennesseeCJ's Avatar
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    Re: 258 vacuum hose question

    Thanks for the reply...already has an aluminum valve cover and a 2 barrel Weber carb. I have the two hoses you speak of. The front one has a PCV valve coming from the valve cover. Other than these two, there are smaller hoses running all over the place....not really sure if they all have the correct home. Would these affect the idling?

  4. #4
    wm69's Avatar
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    Re: 258 vacuum hose question

    Yes, if you have a vacuum line off it will likely not idle right. It depends on what you have left from the OEM setup. I tore out everything except the PCV line, vent line, vacuum advance line, and bowl vent line (IIRC) Everything else I did away with, but I don't have emissions testing in Arkansas either, so that didn't cause any issues for me.
    I've got two aluminum valve covers (one Clifford, one "4.2" logo), both with cork gaskets, and neither leaks. You do have all the bolts in and tightened down (don't overtighten or you'll crack the aluminum cover) to spec right?
    Do the TFI mod listed on this site in the how to section and you'll see a big improvement in ignition (should help your idle) but if it's been running fine and this is a sudden development it sounds like you pulled something loose.
    My weber equipped Jeep is at the parents (where I hunt) and I put the Weber on there in 1998, so don't remember exactly how I set it up. Redline should have some vacuum diagrams on their website for the weber carb though. Might give that a try.
    85 CJ7 258, borla header,jacobs, weber, T5, B&M shifter,1pieceaxles,warn hubs/ XD8000i

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    TennesseeCJ's Avatar
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    Re: 258 vacuum hose question

    Well, I found the problem. If you look at the photo, in the upper left part of the picture there is a hose that was connected to the port coming out of the firewall. I have drawn a white line to where it was connected. As soon as I disconnected this hose, the engine immediately smoothed out. Now the question is...where does this hose go?

    Any suggestions?
    Attached Thumbnails Attached Thumbnails 258 vacuum hose question-2.jpg  


  6. #6
    wm69's Avatar
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    Re: 258 vacuum hose question

    My motto with all the vacuum lines has always been, if you can cap it/ get rid of it and the thing still runs ok, get rid of as much as possible.
    I've gotten rid of all that stuff on my two CJ7's. Dad has a Scrambler that is still stock (actually stock with about 3600 miles on it). If you don't have it figured out in a couple of weeks I'll look under his hood next time I'm down there.
    85 CJ7 258, borla header,jacobs, weber, T5, B&M shifter,1pieceaxles,warn hubs/ XD8000i

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    Re: 258 vacuum hose question

    Yeah...my only issue is emissions testing here in Tennessee. I'll have to figure out what I can get rid of.

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    Re: 258 vacuum hose question

    Would this help?
    Attached Thumbnails Attached Thumbnails 258 vacuum hose question-vaclin-1.bmp  

    258 vacuum hose question-jeep-258-vacuum-hose-diagram.jpg  

    Last edited by TerryMason; 06-09-2009 at 09:21 AM.

  9. #9
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    Re: 258 vacuum hose question

    Now this makes sense to me! Thanks for sending this...you guys are awesome.

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    Re: 258 vacuum hose question

    Quote Originally Posted by TennesseeCJ View Post
    Now this makes sense to me! Thanks for sending this...you guys are awesome.

    Were you able to pass emissions? I'm sorting through vacuum woes now after failing emissions on an '81 CJ5 258 I've been restoring. Runs great, but failed emissions in Nashville. Have any tips?

    *New cat conerter, DUI distributer & wires, egr& MC2150 carb

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