Really strange knocking!!

[bdmcewen]

Ok so i have an abnormal knock coming from my motor. It sounds somewhere in the middle of a lifter and a rod but only knocks just before it shifts, when i very first start it for a few seconds , or sometimes not at all. Any ideas what may cause this?

 

[bradshawtech]

Ok, I'll bite on this one.

Details please on what vehicle, engine, transmission, mileage, what weight oil are you running, recent work done to it......
It could be any number of things. Ignition timing too far advanced, piston slap, rod or main bearing damage.
What part of Colorado are you in?

 

[Chevy305]

I have the SM465 and it will do that if the input bearing is bad, check out this youtube video of it:

[youtube]c-CnMW8BLGY[/youtube]

 

[kennyw]

I'd vote flexplate is cracked if you have an automatic. But this type of things is hard to diagnose over the internet.

 

[blaznjon]

if its a old motor with high miles check the thrust bearing on the crank.grab the dampner by hand and see if it moves back and forth alot.

I had a buddy with a real high miles motor if you started it with the front end down hill it would knock on start up.pointed up hill no knock.it knocked right before it shifted all the time.he had good oil presure too.

we went to pull the pan and i was draggin myself under the truck grabbed the dampner and it moved big time.