Tbi 350


Old 05-23-12, 02:00 PM
Badachevy1990's Avatar
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Join Date: May 2012
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Post Tbi 350

I have a 1990 chevy with a tbi 350 ive had the truck for about six months and its been making a tapping noise in the motor. The truck set for awhile before i got it. I did an oil change and put some stuff from parts store in the gas tank it went away but came back. It doesnt effect the way it runs or drives ive had it in the mud and on the highway it doesnt use or burn any oil. Its always got good oil pressure. Im just wondering what it could be and is it okay too keep driving and how can i fix it. As im looking too sell it.
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Old 05-23-12, 02:08 PM
Gunguy45's Avatar
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A tapping sound to me brings the thought of a stuck lifter. "Knocking" is normally more of an issue.

It could be as simple as using an oil additive that removes varnish or simply removing a valve cover and making a slight adjustment. The adjustment is not normally required after the initial setting on hydraulic lifters. You may have a lifter that has gone bad/collapsed, which would involve removing the intake manifold to replace it.

For about $10 you can buy a mechanics stethoscope to isolate the area of the noise.

At 22 years old....I'd probably try an oil additive/ sludge cleaner and then change to one grade heavier oil (or the type for old engines) to see what happens.

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