• The Ford 5.0 in my CJ has been running rough and down on power. I pulled the plugs and here's what No. 7 looks like:



    That shiny black stuff is oil. I changed the rings a couple of years ago when I did the rod bearings, so I'm thinking valve seals. I've been getting a valve tap lately too. Ideas?

  • Mine looked like that until I had Aldermans do the heads. My valve seals were old and toasted. Pretty much once the heads are off it would be crazy not to do the valves and seals.
    Or just change the plugs and "let it eat!"

  • any chance u can run a compression test?

    I don't have a compression tester, but I ordered one of these:
    You attach it to the spark plug hole and use air pressure to hold the valves in place, so you don't have to pull the heads to change the valve seals. Will I be able to hear it if the head gasket is leaking?

  • I think it depends on where the leak is. If it's leaking near the outer edge of the block you will hear it and possibly see smoke. If it is between cylinders it will run poorly because two of the cylinders are leaking compression into each other (that will show up in a compression check). Are you seeing anything odd in your oil (gas or antifreeze)?

    Member since 2000

    Jeeps Owned'79 CJ5:

    Specs-

    - 258 I6

    - '93 Cherokee fuel injection and HO head,

    - bored 30 over

    - with 4x4 cam

    T18 tranny with granny low / Dana 18 t-case

    Dana 44 front and back from late '70s Wagoneer, both locked and loaded with 4.88 gears

    SOA on modified YJ springs with shackle reversa

    Fiberglass tub with 6 point cage mounted to the frame


    2015 Grand Cherokee Limited
    Spec-

    Quadratec Floor mats

  • No oil in the coolant and no coolant in the oil. It could be leaking between 7 and 8 (power is down), but it would also have to be leaking oil--but there's no smoke from the exhaust. I got a compression tester but the plugs are recessed in the heads so I had to order another adapter.

  • What do the rest of the plugs look like? I think you are getting ahead of yourself. Before you rip the motor apart check other things. Maybe you just have a bad wire on that cylinder or a burnt cap and rotor. If there is no coolant in the oil no white smoke etc...it likely isn’t a head gasket. If the cap rotor and wires pan out and that’s your only oil fouled plug then A compression check is a good Thing to try. The gauge can be bought for cheap at HF.


    Best option would be to get rid of that boat anchor Ford engine and put in a chebby.

    2000 Sahara, All custom...
    2000 Cherokee Police package, Beater....


    I may be slowest and the stupidest

  • Thanks, Ed. No. 8 plug looks a little oily, but not as much as No. 7. They don't smell of fuel. The other six are normal. The cap and rotor were pretty burnt. I replaced them and it still ran rough. I've got a new set of plug wires. I'll try those next.


    I ran a compression test. Nos. 1 and 5 (the front two) are at 110. The rest are all at 125+.

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