I bought a Durango with a 4.7 V8 engine, with 322,000 miles. It had a very light tap-tap-tap noise when I bought it, thought it to be a lifter as they're notorious for failing in these engines. A few weeks ago I pulled the valve covers and replaced ALL of the lifters with Melling brand ones. I soaked them in clean oil for 48 hours before installing them. While doing lifters, I noticed a timing chain guide was broken so I also replaced all of the timing set with a new Cloyes chain, tensioners, and guides.
The lifters I removed were very worn. I could squeeze them with literally zero effort. They weren't stiff like the new ones were.
I also replaced the exhaust manifold gaskets a few months ago, which eliminated many of my exhaust noise anomalies. I'm wondering if I could still have a little exhaust leak somewhere there though.
Everything went back together great, everything torques to spec. Engine started right up, and runs well. However now, I'm getting an even louder tap-tap-tap at idle. It's basically the same tapping I heard before, but louder now. It seems to disappear once I rev the engine just a little bit. Even a couple hundred RPM seems to either mask or eliminate the noise. It's completely gone at cruise speed or even at any RPM above idle.
Mechanical gauge oil PSI is a solid 70 PSI at cold start/idle. Above 50 PSI at hot cruise, 1500 RPM. If it kicks out of O/D, at 2000 RPM I see about 60 PSI. At hot idle, I'm seeing dead on 20 PSI. The gauge immediately responds to RPM change.
I know all of the lifters are good. I know the timing set is good. I know that all of the rocker arms are back in place correctly as I installed them personally. Where could the noise be coming from?
I really don't think it's a rod knock based on other videos I've watched. Rod knock sounds "deeper" and mine doesn't seem to sound this way. It's more of a higher pitched "tap" instead of a more solid "knock".
The lifters I removed were very worn. I could squeeze them with literally zero effort. They weren't stiff like the new ones were.
I also replaced the exhaust manifold gaskets a few months ago, which eliminated many of my exhaust noise anomalies. I'm wondering if I could still have a little exhaust leak somewhere there though.
Everything went back together great, everything torques to spec. Engine started right up, and runs well. However now, I'm getting an even louder tap-tap-tap at idle. It's basically the same tapping I heard before, but louder now. It seems to disappear once I rev the engine just a little bit. Even a couple hundred RPM seems to either mask or eliminate the noise. It's completely gone at cruise speed or even at any RPM above idle.
Mechanical gauge oil PSI is a solid 70 PSI at cold start/idle. Above 50 PSI at hot cruise, 1500 RPM. If it kicks out of O/D, at 2000 RPM I see about 60 PSI. At hot idle, I'm seeing dead on 20 PSI. The gauge immediately responds to RPM change.
I know all of the lifters are good. I know the timing set is good. I know that all of the rocker arms are back in place correctly as I installed them personally. Where could the noise be coming from?
I really don't think it's a rod knock based on other videos I've watched. Rod knock sounds "deeper" and mine doesn't seem to sound this way. It's more of a higher pitched "tap" instead of a more solid "knock".
