ticking noise

I have a 1994 F-150 with a 302-V8. It has 135,000 miles on it. The engine is making a ticking, or rattling noise at lower RPM while driving. I assume this is from the valve train. What could it be and what should I do about it?

Gary

Reply to
GARY
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Reply to
jor

The sound is more like a "ping" when the engine is under a bit of a load at lower RPMs. Any ideas?

Gary

Reply to
GARY

At 135,000 miles it may be the plugs. You never know, the previous owner may have never changed them. I sold a 1990 Lincoln Mark once that had 175,000 miles on the original plugs. Had the high performance 302. It was still getting 20 mpg at the time. I would check there before spending money elsewhere.

Reply to
Sam_I_Am

The textbook term for this is "detonation". It occurs when the compressed fuel-air mixture in the cylinder spontaneously explodes without aid from the spark plug. This is capable of burning a hole in the top of the piston. There are a variety of potential causes. If the cylinder is dirty, then the dirt can get hot enough to ignite a spark when the fuel is compressed. IIRC bad spark plugs can also be a factor. Low octane gasoline is another factor -- if the octane rating is too low then the fuel is too volatile and thus susceptible to spontaneous combustion. I would second the recommendation to check the spark plugs first (they're cheap anyways, and checking doesn't require replacment). After that, I'd go back and read my textbook to see what can be done without rebuilding the engine :-). (IOW I don't remember the rest of the details and I'm not at home so I don't have the book handy)

HTH,

-D

Reply to
Derrick 'dman' Hudson

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