| Bad Valve Lifter? [message #211276] |
Sun, 16 June 2013 14:12  |
Darryl
Messages: 144
Registered: December 2011
Location: Northern California
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Senior Member |
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78 403 with 61,000 miles.
I've had an engine noise developing over the last 1,000 - 1,500 miles that I think I have finally determined to be a bad valve lifter. The noise is somewhat intermittent at idle although it's most of the time now. It usually diminishes or disappears as the engine speed increases although with the engine cover off I can now here it up to 1500 rpm or so. It's more of a tap than a knock although it's become a pretty substantial "tap".
I put a timing light on it and it appears the tap sounds every time the light flashes which indicates a valve-related problem (1/2 engine speed), right? It sounds too "sharp" to me to be an exhaust leak (I have headers) and I don't hear anything through a hose near the gasket and don't feel anything.
I put a HF stethoscope on it and I hear it most in the drivers side head although I can't pin it down to a cylinder. I haven't pulled the valve cover yet or started pulling spark plug wires.
Questions:
- Is there anything else I should do to firm up my diagnosis before I dig into the engine?
- How urgent is it to fix this? Can I drive it a few hundred miles without much risk of creating a much bigger problem?
- Is this something I can do myself? I actually did this once, over 40 years ago on a 1968 El Camino 307. As I recall the results were less than stellar, as in I couldn't get the engine to start once I got it back together. In retrospect, I think I probably put the distributor back in wrong but I'm not sure I figured that out at the time.
- If I do it myself what kinds of problems am I like to encounter? It doesn't look like the distributor has to come out although I think I would probably pay more attention to how it came out this time and probably get it back right. Breaking bolts I can probably deal with. Getting the intake manifold properly seated and sealed seems less critical with the OEM manifold than with the aluminum upgrade. I would probably use Jim K's "block-off plate with gasket" to block off the cross-over while I've got it apart.
Darryl Meyers
1978 Eleganza II
El Dorado Hills, CA
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