sr light rod knock?

[sil14zenki]

turned on my car this morning and this is what i hear
http://youtu.be/n-c0tRY8Mos
sounds to me like a very low rod knock.
car ran fine last night and oil pressure was normal and still is normal
i will be doing compression test later. any other ideas what else can make
or duplicate this noise?

gt2871r,dw810 inj.tomei poncams, bc valve springs+retainers,cosworth hg,arp head studs.

any input would be greatly appreciated.

[GroundPerformance]

It does sound like Rod knock to me. Is this freshly built?

[sil14zenki]

stock rods and pistons
oem rings,acl bearings
arp rod and main studs.
engine balanced. main bearing bore alignment and rod reconditioning
broke in for 1k miles without passing 3k rpms
waiting for friend to get home so i can do compression test.

[GroundPerformance]

stock rods and pistons
oem rings,acl bearings
arp rod and main studs.
engine balanced. main bearing bore alignment and rod reconditioning
broke in for 1k miles without passing 3k rpms
waiting for friend to get home so i can do compression test.


I take it that the crank is stock or maybe polished.. I've seen few failed builds just because they use aftermarket standard size bearings like yours ACL. Dont get me wrong I like those bearing but I would usually have the crank cut and go oversize on the bearings. As for compression check it has nothing to do with the noise. I would plan on re doing the rebuild soon before it cause further damage. This time have the main and rod journals cut and go oversize. GL!

[AsleepAltima]

im not convinced that that is rod knock. it almost sounds like a broken piston skirt. let it run at an idle and remove power to each coil, one by one. if the knock goes away, a lot of times its a piston skirt.

[fliprayzin240sx]

Sounds like rod knock to me but it might not be. Usually, rod knock is at a higher sweet spot/rpm...around 3000-3500. Not when you just popped the throttle. That almost sounds like something to do with the load on the engine. Compression/leak down like said before, then I'd drop the oil pan and see if you have any piece of the bearings. Also, pop the valve cover, might be something in the head too.

[s13drob]

It could be knock. Do you have the timing chain top guide on? My audio sucks right now but maybe timing chain rattle?

[sil14zenki]

I take it that the crank is stock or maybe polished.. I've seen few failed builds just because they use aftermarket standard size bearings like yours ACL. Dont get me wrong I like those bearing but I would usually have the crank cut and go oversize on the bearings. As for compression check it has nothing to do with the noise. I would plan on re doing the rebuild soon before it cause further damage. This time have the main and rod journals cut and go oversize. GL!
it was polished yes. thanks for the advise.
im not convinced that that is rod knock. it almost sounds like a broken piston skirt. let it run at an idle and remove power to each coil, one by one. if the knock goes away, a lot of times its a piston skirt.
i did this and the noise persisted.
It could be knock. Do you have the timing chain top guide on? My audio sucks right now but maybe timing chain rattle?
no top timing chain guide.


compression test results
#1-152
#2-152
#3-149
#4-149
i did have the block and head decked and i'm using
a 1.5 cosworth hg

i also popped off valve cover and everything looks fine.

i will try and pick up a leakdown tester and remove oil pan tonight.

[sil14zenki]

whats the difference in going oversized?

[GroundPerformance]

whats the difference in going oversized?
Very Simple.. Factory cranks are not cut equally that why Nissan sells OEM Main/Rod bearings in different grades. Going oversize ensure that all the journals are now cut equally with same tolerances to work with aftermarket bearings that has all the same grades. GL!

[sil14zenki]

makes perfect sense. well i do have a spare block and crank. so i might just start building that one. thanks for all the input.

[sdrmiami]

Im pretty sure you have a rod knock. i wouldnt drive it till you find the problem out so you dont ruin it. im doing a motor right now that has the same knock and it was a rod. hit me up if you have any other questions im located in miami

gl..