Tapping Lifters
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Senior User
Joined: Sep 2004
Posts: 446
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From: Texas
Tapping Lifters
My lifters make a little noise when I first start up. Not bad for the milage, but they aren't quiet either. The problem comes after the engine warms up. I get a loud knocking from the top of the engine. It seems to be every other revolution, so I am almost positive its Not rod knock, but it still has that deep metalic sound of a bad rod. I took the valve covers off and inspected. nothing apears loose or bent. none of the rockers are loose or have any slack, none of the rods apear bent. I can hear the noise more from one side than the other, but it sounds like it's coming from deeper in the engine than the rockers.
My first thought was a collapsed lifter, but shouldn't I have more signs of that? And what could go wrong that would only happen when the truck is warm?
My first thought was a collapsed lifter, but shouldn't I have more signs of that? And what could go wrong that would only happen when the truck is warm?
Post Fiend
Joined: Jan 2003
Posts: 8,600
Likes: 4
From: Iowa
Well what happens, is that the oil is thicker when it's cold. This lets the lifter keep its pressure, and no noise. When the oil warms up, it thins out, and the lifter cant keep hydraulic pressure, thus the noise.
The problems with this are reduced valvetrain life, it's kind of hard on the cam, and you lose performance.
I can think of two solutions:
1. Try a heavier oil. Say if you're using 10w30, switch to 15w40. If that doesn't fix it, proceed to solution #2.
2. Pull the intake and valvetrain, keeping EVERYTHING lined up where it goes, and replace lifters. Do 'em all since you dont get in there too often. Smear some Moly grease on the feet of the new lifters. You'll need new gaskets. Button it all back up, and run the engine at between 1500 and 2500 rpm, slowly varying, for 20 minutes. This is to break in the new lifters to the cam. After that change the oil and you're done.
The problems with this are reduced valvetrain life, it's kind of hard on the cam, and you lose performance.
I can think of two solutions:
1. Try a heavier oil. Say if you're using 10w30, switch to 15w40. If that doesn't fix it, proceed to solution #2.
2. Pull the intake and valvetrain, keeping EVERYTHING lined up where it goes, and replace lifters. Do 'em all since you dont get in there too often. Smear some Moly grease on the feet of the new lifters. You'll need new gaskets. Button it all back up, and run the engine at between 1500 and 2500 rpm, slowly varying, for 20 minutes. This is to break in the new lifters to the cam. After that change the oil and you're done.
