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Mustang Nut
Joined: Sun Oct 22nd, 2017
Location: Horsepasture, USA
Posts: 1692
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I determined by logic my 00 with the 4.0 ohv has indeed developed either a head gasket leak or a lobe on the cam is wearing down, possibly both.
Any way it goes it has to come apart so I'm considering all the options. I'm guessing it is at the 220+ mile marker and it has not been easy miles evidently.
Jim, also another thing to consider is cracked cylinder heads with the 4.0. When I purchased my Ranger back in 10/2013 soon after I purchased it the engine developed a miss under load. I pulled all the plugs & replaced them, #-4 cyl plug was fouled. After about 1 month it developed a miss again under load, #- 4 cyl plug was fouled again. This went on for about 6 months, when it developed the miss I would just replace the plug & drive it until the miss came back, then I would replace the plug again. I finally pulled the heads off & found a crack in the heads between the valves in # - 4 cyl (drivers side front) & # - 3 cyl (passengers side rear). I purchased new updated castings cylinder heads & have not had a problem since. If you look very closely in the attached pic between the valves that were removed you can see a crack in the head. The new heads have thicker metal there & are not supposed to crack. While I had the heads off I also replaced all the lifters & rebuilt the rocker arm shaft assemblies.
Old head.
New heads
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21 Bronco Sport Big Bend (Wife's DD)
05 F150 XLT Reg Cab, 2WD, 5.4L, Auto (My DD)
69 Mustang Coupe 5.0, 5 spd 9" rear(Project)
14 Kawasaki Vulcan (Wife's Toy)