1999 Ford F-150 Exhaust Rattle and Smoke

FORD F-150
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RACERBOY
  • MEMBER
  • 2 POSTS
:D I have a 1999 ford f150 xlt triton v8, 257,000 miles on it ,never had any problems with it. I am getting a slight noise from underneath kinda like a rattle a mechainic said it was the converter, also getting a very light smoke every now and then from tailpipe, are they connected or should I start thinking about a new truck?
Jul 2, 2006 at 7:48 AM
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TAURUSWHEEL
  • ✓Experienced Mechanic
  • 718 POSTS
check your cat, sometimes the heat shield mounts rust, the shield will rattle,, if that's the case use super-long hose clamps to cinch it tight against the cat. 257k is some serious mileage, I would expect a couple of issues.. light smoke could be anything from worn valve seals or guides to rings.. probably a compression check is the first order of business, see what's going on there,, something you can do, watch how the compression builds up in each successive crank, if cylinders are testing low, wet-test them by squirting a little oil in suspects, see what difference, if any it makes.. your mechanic will know what to do
Jul 2, 2006 at 10:25 AM
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Suggested Repair

Inspect the catalytic converter heat shield; if the mounts are rusted and the shield is rattling, secure it tightly against the converter with extra-long hose clamps. For occasional light tailpipe smoke, start with a compression test, noting how pressure builds on successive cranks, and wet-test any low cylinders with a small amount of oil to help distinguish worn rings from valve seals or guides.

Conversation Summary

The owner of a 1999 Ford F-150 with 257,000 miles reports an underbody rattle that a mechanic attributed to the catalytic converter, plus occasional light tailpipe smoke, and asks whether the issues are related or the truck should be replaced. The expert says a rusted heat shield can rattle and can be clamped tightly to the converter. The smoke may come from worn valve seals, guides, or rings, so a compression test and wet test of low cylinders are recommended first.

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