5.4l triton 3v cam

Asked by Sep 23, 2016 at 09:18 AM about the Ford F-150

Question type: Maintenance & Repair

Hi. Have a question on the cam of a 5.4l triton in a
2007 f150. I am having engine problems so I done
a compression test and was attempting a leak
down test. I got no compression on #8 cylinder. I
took off the valve cover to check everything. I
started to hand crank my engine to get to TDC and
while cranking the cam would jump an 8th of a
turn. The timing chain was fine. It was the cam
phaser turning internally. My question is can I trust
my tests if this is happening and is it normal. I
have got different answers from different
mechanic. One said it was normal because without
the engine running there is no oil pressure to fill
the phaser and therefore letting it move. That
sounds right but doesn't seem right. Any help
would be appreciated.

1 Answer

66,375

Best be would be to get some kind of service manual detailing how to do a leak down on a 5.4 with the cam phasers. If all the rest of the cylinders on that side showed compression I would suspect a burned,bent, stuck or broken valve, broken valve spring or a broken piston. Also check the #8 cam followers before you pull the head. If the #8 intake follower is not opening the intake valve you will have no compression on that cylinder.

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