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For years, the trusty 22R-E has made an odd chatter, almost knock-like sound, but only when:
- first run of the day, and within first few minutes, and
- between 2 and 3,000 RPM with light throttle pressure. Like cruising at 30-35MPH in 3rd gear (MT) on a flat road.
It doesn't make the sound when unloaded, when accelerating (or at least much quieter), or when decelerating. It's loudest with that light throttle pressure (load) and in that RPM range. Been doing this for thousands of miles (years). No noise when starting, and no noise after it's warmed up for three minutes or so. Definitely an engine sound. I don't hear the metallic rattle that is common in the videos I've reviewed which are cam chain tensioner failures.
I'll try to capture an audio recording, but before then....anyone heard this before?
Mine has similar mileage to yours, makes a similar noise, especially noticeable when the temp has dropped overnight to about the 40’s.
If you can make it do it, pull each spark plug wire and see if you can isolate it to a certain cylinder(noise will stop when pulled).
in my case, i believe it is caused by piston slap or loose clearance on the wrist pin. I won’t know for sure until I take the engine apart.
I had a Corolla that had about 275k miles on it that made the same noise for years(maybe 50k miles). Never got to the bottom of it...
Last edited by Melrose 4r; 01-24-2021 at 07:30 PM.
The description "The best way to listen for piston slap is when you rev it to any rpm and then quickly let off, right at the instant that the load is inbetween "power" and "coast" the internals are in a free-play and that's when you notice the piston slap." seems to match what happens while driving when it's just a light load.
Right now, I just avoid operating in that range where it makes the noise.
Attached is a sound recording taken this morning under the hood from a recorder on top of the valve cover. Ignore the "blow-y" sound -- it's the diesel-like sound that begins at around 15s that is of interest when cruising at about 30MPH.
Test setup in photograph: Note sound recorder on valve cover
The fact that it only does it when cold and only when its a slight load tells me it is piston slap. If it were a rod bearing or wrist pin, it would continue to knock when warm (and would be louder when warm). You can drive an engine with some piston slap if you don't do the slight load thing too much. But I recommend saving for a rebuild or a new engine as it will damage the pistons and the cylinder walls.
01-24-2021, 05:03 PM
