I have z6 that i bought from a guy. I installed it and everytime im revving a knocking sound coming from the engine. When i open the hood and rev it from the outside, i hear knocking sound. When hood close and i rev it from the inside, i can hear the knockng sound. what you guys think. Please any experience or idea please reply. This will me and others too. Thanks in advance!!!

 

sound like its coming from the bottom end?

 

Knocking = rod bearing
Tapping = Valves

 

im thinking either rods or valves. do you guys know hot fix the rods and valves?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Minglor &raquo;</TD></TR><TR><TD CLASS="quote">Knocking = rod bearing
Tapping = Valves</TD></TR></TABLE>
i agree my dseries had a spun rodbearing drove on it for acouple days ate away the main bearing case and even the crank. totally killed that motor.

 

bye bye motor

 

does the knocking noise only happen when you rev or does it knock when the car is idled? if it knocks at idle your rod bearings are no good. if it knocks when reving your rods or no good, but if it only ticks then your valves most likely need to be adjusted

 

would having the knock affect your compression numbers....i have this same problem....did a valve adjustment and all the valves have clearance except for piston 2 intake valves which dont allow clearance for some reason. seems like the valves are stuck. i did a compression check and it was 210-215 across. anyway to know, draining oil would show if the bearings are wearing away right?

 

the only way to check if the bearings are going bad is if you tear apart your block and remove the bottom part of the rod and check if the bearing spun or not. but if you remove your oil pan and there are shavings at the bottom then most likely a bearing spun and ate away at your crank. really if it is only ticking like "tick tick tick tick tick tick" then it is your valves but if it is knocking like "knock knock knock knock knock knock" it is your block. i hope you figure it out soon and i hope you dont drive your car around because if the problem is not dealt with soon you would ruin your block

 

im thinking either rods or valves. do you guys know hot fix the rods and valves?

 

My buddy had same problem, he drove on it for a while and then crunch. I wouldn't drive on it till you figure out what it is, or you might end up spending more then a crank and a bearing will cost.