Rod knock, sound goes away when....

[VQ35HR]

Help please, i couldnt find specifics... so here the deal, a 95 gst with big 16g, 89-90 CAS. problem is when my motor is idling, the engine runs smooth, only when i rev it up to 2k+ i get this loud tapping noise in cyl/valves #1. then at idle is like stock nice n quiet. i checked the lifters/lashers, it is good, also rockers dont move. when i remove the spark plug, or the injector, the noise stops almost completely, hard to tell with the engine missing+ loud exhaust. so cant be valves right?? must be rod knock?? also it doesnt throw engine light!!! anyone got an idea? im gonna rip the oil pan first, before the rip the head off. side note i put ina brand new gasket awhile 8 months back!
Mahalos for your help and time!!

 

[Rajin]

Usually with rod knock the symptoms are well, the opposite of what you said. Rod knock is usually present at idle (most commonly) and can fade when oil pressure builds. (in extreme cases the knock continues thru idle, this usually leads to catastrophic failure though)

Also, the tapping noise can be something like lifters being stuck and so on (which is possible, they make noise when they don't work too their full capacity)

I would honestly check lifters, then pull the pan. It could be a spun bearing but the symptoms lead me to think otherwise first off.

 

[VQ35HR]

i took out the lifters, cleaned, bled them, oiled, n bled again. re installed them in diffrent positions twice. and always same thing from Cyl 1!? i know it can be the valves or the lifters. cause the sound goes away when i pull the spark wire, or the injector harness. lifter noise would be constant right. ill try post a vid! thanks for ## help!

 

[92AWDHX40]

How do you tune your car?

 

[JusMX141]

Early stages of rod knock will be loudest only in the 2-3k RPM range when the crank can reach an "unloaded" stage.

At idle the crank is normally always loaded by the pistons / rods, but at 2-3k the RPMs can "float" meaning there is a second of decel in there when the crank actually loads the pistons / rods instead. That's when you get your noise.

If it progresses to the point where you hear it at idle, you're in need of a lot more than just rod bearings.

http://www.youtube.com/watch?v=lpzff1Rm-Gg

 

[Sam@RRE]

Sounds like rod knock to me. The part y ou say about remove the plug/injector causing it to stop is kinda tell tale. Best thing is to drop the pan and confirm it.

BTW, I was just out in Hawaii last month. Loved it and will definitly be back next year.

 

[DOHCTA]

Spun bearing?

 

[pos4g63]

Cant the balance shafts also cause a knocking sound if bearings are worn?

 

[crash89]

Best way to really be sure would be to drop your downpipe and oil pan and visually check. If all checks good you know you have a different problem somewheres.

 

[re-rx7]

Sounds like rod knock to me. The part y ou say about remove the plug/injector causing it to stop is kinda tell tale. Best thing is to drop the pan and confirm it.

BTW, I was just out in Hawaii last month. Loved it and will definitly be back next year.

+1 There is a test on here if you search. Pull each plug wire off one at a time then replace and go on to the next one. If you pull a plug wire and the knocking or tapping stops on that plug then you have your answer. Rod kock, bearing ect...

 

[ahaley1]

i had the same problem it was a rod

 

[VQ35HR]

i have a iphone vid just dontt know how to upload it...
Sam@ree if u ever in hawaii hiy me up.. show u the spots!!

 

[evileagleawd]

drain the oil if you see a bunch of metal its a rap tear the motor out get started on your rebuild!

 

[VQ35HR]

haha.. fawk me.. sittin longer then i drove it.... fawk me..... i miss my nissans.... Lol

 

[Funfettie]

Rod knock. Its happened to me many times. All cases i have seen is it knocks when under load, not at idle. In second gear, get the car rolling at idle. Then punch it. Is you hear knock all the way up, its the rod bearings.

 

[VQ35HR]

its confirmed.. spin bearing..... rod bearing.. fawk..