2008 F150 loud knocking sound and went away after towing
#16
Join Date: Oct 2015
Location: Somewhere south of Denver
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#17
That's a really great question, Superdave71. I use the recommended 5W-20 Synthetic oil. Like I mentioned, it was strange because both times it did it was when I came to a stopped. What's even more strange is that I have towed the same 25' travel trailer again this past weekend and further this time but did not experience the same issue once. Once in a while when I come to a stop I can kind of hear the same noise, just not as loud but it sounds like its coming from the exhaust manifold. I am really beginning to wonder if even though Ford and my mechanic tell me I don't need to replace that if I really should, I just don't like how it sounds. Other than that, when I get on it and put the pedal to the floor the engine feels and sounds healthy. I am so baffled!
Is the cooling fan electric? If so, with it off, blow some smoke at the exhaust manifold and see if you can identify a leak. They can often be seen that way.
#18
To the OP, if you can get the sound to reoccur, one nice feature of a mechanic's stethoscope is that it muffles the rest of the engine noise and helps you focus your listening on the point that you're touching with the stethoscope. In this way, it's better than using a long screw driver to pinpoint sounds, which does work but will not muffle the surrounding engine noise.
#19
Hi Free Beck, I have a 2007 F-150 and had the same exact problem you have described. It the Manifold! No problem with your motor. I replaced my passenger side for a small crack that sounds like the truck was going to blow up while initially pulling but went away after getting up to speed. I was pulling a 28' Coachman Catalina not a heavy trailer but the engine just doesn't like the constant tourque even though mine has the tow package from the factory. That was a few years ago, this year I had to have the drivers side exhaust manifold bolts replaced the noise started and i knew what the problem was as soon as i heard it. The manifold was good but save yourself the headache replace the passenger and redo the drivers side bolts. Yes its expensive but its fixed and no problems since. Been there, fixed that!! Ive recently upgraded to a 350 because i will continue towing and the 150 is going to my son. Also just a heads up, check your front sway bar link bushings. mine wore out fast with towing. hope this help you out
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