Top End Knock

[93rev2sev]

Any word Viper?

 

[ViPER1313]

UPDATE: Its the timing belt (at least 99% sure) - I took the top cover off and can see the belt slapping around when the car is running. It doesn't appear tight - I don't know if the tensioner is bad or if I can just tighten it up (I will try the latter later tonight as a temporary fix.) I will also get a video of the belt with the top cover off just so you guys can see it. Thanks again for all your help - I guess if I did a 60k every 60k miles (65k since last) I wouldn't have had this problem

 

[ViPER1313]

http://www.youtube.com/watch?v=duitTd0z72I

Sorry, no sound - it wasn't knocking while it was doing it anyways (little slapping noise from the belt though) - the video doesn't really give an appreciation for how much the thing moves up and down.

 

[ViPER1313]

UPDATE 2: OK, now I'm doubting the timing belt. It doesn't seem to have any more slack or skip a tooth when it starts to knock, and the noise is not coming from the belt itself. I'm at the end with this car. Noise really sounds like it is inside the motor.

 

[JustinSane]

noises can be hard to pin point as you are finding out the hard way they travel threw objects very well, the report you posted above listed they found readings in the used oil indicating a possible knock, this hint alone tells you those metals wouldnt be from a loose belt. you stated that under load the noise goes away and the fact these motors are known to wear out rod bearings makes me think you have a bearing going south. and lastly this type of knock would be temperature related as the oil "thins" out when hot. A old car lot trick was to put the thickest oil they could or even a additive to hide these noises untill well after the car was sold.

 

[ViPER1313]

There was more iron but not an unreasonable amount. IDK, I'm going to take a stethoscope to it and then open up the pan when I get a chance - really doubting anything except engine internals at this point.

 

[ViPER1313]

OK guys, everybody ready for this?? I have had this intermittent issue for over a year now - it pretty much went away after I changed the spark plugs out in the motor, only to return immediately when I put colder 3923 plugs in for nitrous.

The cause of the knock was:

THE COILPACK

After I changed it out, there is no faint knock on startup, no loud intermittant knocks when warm and the car feels like it is running better than it has in the past 30k miles.

All I can figure was that it was causing incredibly bad spark-knock at times.

Just figured I would share this.