Double Knock on Decell Only

[mtocrs1]

I now have a double knock on engine decelleration only. It is a tinny type of sound. Does not sound like a rod knock to me. My guess is a wrist pin. I am looking for some advice from the experts before I start tearing stuff apart.
I have alreasy checked all the usual stuff.

 

[mtocrs1]

Maybe Ill try this a different way. :biggrin:
So what are the normal symptoms of wrist pin knock?

 

[TurboBob]

I think there is not a lot of response because rod bearings and wrist pins are not common failures in these cars.

However I did have another car (V8 powered) that hurt a rod bearing that had a slight double-knock sound once warmed up. The sound was only audible under very light coasting conditions, just as you back out of the throttle.

Bob

 

[TurboBuRick]

Possible stretched timing chain slapping the case?

 

[mtocrs1]

Possible stretched timing chain slapping the case?

I guess anything is possible however the sound can be clearly heard from underneath the car and in the passenger side wheel well. The timing chain is a double roller and it still has the tensioner

I think there is not a lot of response because rod bearings and wrist pins are not common failures in these cars.

However I did have another car (V8 powered) that hurt a rod bearing that had a slight double-knock sound once warmed up. The sound was only audible under very light coasting conditions, just as you back out of the throttle.

Bob

Yes, my knock is audible from the time you let off the throttle until the engine reaches idle. Oil pressure is good. 20psi hot. The noise just does not sound like a rod. It has a clack sound to it. Also only happens when engine is warm.
Thanks for the replies.

 

[kidglok]

you have comp lifters?

 

[mtocrs1]

you have comp lifters?

No, they are GM. However I know one is bleeding down. I just dont think lifters would cause a doble knock. Especially just on decel?

 

[TurboBob]

Time to dig:

remove the oil filter and cut it open. look for 'badness'

remove the oil pan and look around, wiggle rods, look for 'badness'

remove front cover, inspect chain and hardware, look for 'badness'

If you have a double roller chain with the stock "tensioner"/damper, it may have disintegrated and be part of the noise, so you will need to do this part anyway.

Bob