broken valve or ???
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FTE Chapter Leader
Joined: Mar 2005
Posts: 23,857
Likes: 9
From: Suppertown, MN
broken valve or ???
I have a '93 f-150 with the 5.0/ auto with 143000 miles on it. I am trying to figure out what is goin on with my number 8 cylinder. I thought I had a bad ring because I had no compression. I squirted some oil in the cylinder and the compression came up from 35 to about 50 psi. So now I am thinkng a valve. But wouldnt I be able to see a broken valve or a broken spring? I am stumped on what to test or look for next. If it is a ring I want to just swap out the motor but if it is a valve I would just fix it. Any thoughts or help would be great. Thanks!!
Post Fiend
Joined: Nov 2001
Posts: 14,947
Likes: 6
From: Topsfield, MA
When the compression increases with oil being put in the cylinder it usually means the rings not the valve.
The #8 is known for prematurely going before the other cylinders on a 5.0 because the PCV is mostly drawn into that cylinder.
You might need a rebuild.
The #8 is known for prematurely going before the other cylinders on a 5.0 because the PCV is mostly drawn into that cylinder.
You might need a rebuild.
Elder User
Joined: Mar 2004
Posts: 660
Likes: 0
Number 8 is the problem cylinder quite ofton. Another theory as to why, has been traced to the number 7 and number 8 ignition wires cross firing. This causes a pre-iginition in number 8. I always make sure the those wires are good and are well seperated.
Too bad, but I also think you will need to rebuild the motor.
Too bad, but I also think you will need to rebuild the motor.
