"chirping" noise coming from engine

[JerryH]

I first posted this under the engine forum, but thought it might get more attention here.

I just finished working on my engine (mostly maintenance), and it is making a chirping sound. It has always made that sound, and it is no worse now, so it is nothing I did. I first thought it might be coming from the fuel injection, but I just can't tell. It seems to come from all over. Most noticeable at idle, as you rev the engine the engine drowns it out. It almost sounds like a compression leak, but compression is good and even all the way around. Has new plugs, properly installed. Old plugs showed signs of a slightly rich mixture, but they all looked the same. Once warmed up for a few minutes, engine runs very smooth. I also thought about the cam drive belt and tensioner, which I have not worked on yet. Anybody else heard a noise similar to this?


This is a very rapid on-off low pitched chirping sound. It's speed changes with engine speed. It is not a bearing or belt, it is a steady noise that stays steady. Moving around the engine, sometimes you can hardly hear it, in other places it is very noticeable. It seems to be coming from the top area of the engine. When the engine is shut off, the last sound it makes is one final "chirp". It is not an exhaust leak, that has a completely different sound. It is either a compression leak, or something in the intake system, that repeats at regular intervals. It could be just one cylinder, or all of them. I will pull the belt covers off and have a look in there, but this seems to be more of a "pulse" type noise, kind of an er-er er-er er-er and sounds like something made of rubber is rubbing on something. I am looking at the fuel injection right now, since it is always under pressure, and this could be a pressure diaphragm or plunger of some kind reversing direction. I have never worked on a fuel injected engine before. It is definitely a "soft" sound, not a hard metallic knock or grinding, so I have ruled out internal engine problems, for now. Jerry.