Help me figure out this noise before I go crazy!!

[turbosam6]

Yes, its the infamous tapping noise again! This car is possessed, I need a young priest and an old priest, and some holy water. I drove for awhile tonight, oil press. 18-19 hot idle. Never fluctuates. Jumps up fast when I rev it. But I've got this tapping noise, Seems loudest at 2000-2500 rpm. Sets off the knock guage pretty good. It comes and goes, too. We looked, listened, cut the filter, etc. Can't find nothing. I took it back to the builder, and we beat it silly, no noise. Tried hot AZZ oil temp, no noise. Hot water (210) no noise. I drive for 20-30 minutes, in town or highway, it makes noise. Now we can't pinpoint it. It used to seem to come from the valve cover on the driver side. Still there, but also now seems to come from everywhere. I'm at a loss. Maybe cam sensor? It doesn't seem loud when I put the screwdriver on it, like a stethascope. I would say rockers, but Its so intermittent. What should I do? HELP! BTW, crank endplay was good when I checked it 7-8 thousanths. Could a really loud injector do this? Exhaust leak? I got insurance, and a stick of dynamite for this b!tch if all else fails!

 

[Richard Inglett]

Might be a characteristic of the cam.

My valvetrain is louder than the typical flat tappet setup but not by much. I have a PTE 210/210 billet roller cam and on occasion, old knock sensor beeps way too much in the 2000 to 2300 rpm range. Was quite concerned at first but after checking most everything, don't really worry about it anymore. With zero degrees of knock retard on the Scanmaster, whatever is causing the beep has to be minor. In my case case, increasing the rpm eliminates the beep so it is not a rod. And, I also have excellent oil pressure so the mains OK. For whatever reason, 85 degrees seem to be the trigger for the beeps. Otherwise, extremely hard to recreate.

I'm guessing that the roller cam might be the source because of old stories that I heard about solid roller lifters and their incombatability with knock sensors. Might be that hydraulic roller lifters all but eliminates this scenario.

Hope someone knows.

 

[turbosam6]

Thanks Richard, I've wondered that, too. It seems to me like if it was the cam, it would do it more often. Idrove this thing at operating temp for a long time, it was fine until right before I got home. You can be cruising at 40-45 for 5-10 minutes, all is well, then all of a sudden, tap tap tap... then you can rev it and it will do it again, then maybe stop for awhile. Its not consant. Holding it at a constant rpm, like when on the highway, definitly makes it act up sooner. Like I said, oil pressure is good, and doesn't change when this happens. It could even be an accessory on the front of the motor, but what? This sucks, cuz it runs good aside from this, and its causing me to not drive the car as often. Any suggestions are appreciated, Thanks!

 

[Cakes]

I have a VERY simimlar noise coming from my car around 1800-2300 rpm. Its been doing it for a while now (4 weeks or so) so if it were a rod I think/know I would have blown it up by now. Using a stethascope(sp?) all over the front of the engine where the sound is coming from I hear the same sound while revving coming from the timing cover. I have also just recently read that double roller timing chains stretch tremendously over short periods of time and also when you use them you are not supposed to use the tensioner. I think this is my problem and I am going to look further into this when I get the time. If you can get a stethascope try probing everywhere you can to duplicate the noise. Thanks and keep me updated!