SR20DET, what did I blow?

[Nikzilla]

So I was doing a pull in 3rd gear, 6800 rpm, shifted to 2nd instead of 4th.

The RPM's shot up and the tires just chirped before I re-clutched.

The car sounds fine at idle and low rpm, but when you take it to about 3000 rpm you can hear a rattling, as if something metal is bouncing inside the block.

I doubt it's a spun bearing, because it would be RPM dependent, but the frequency doesn't noticeably change with RPM, just the loudness.

I was sure I just chipped a rocker or something.

I babied the car home, let it cool off and pulled the valve cover off. There is no visible damage to the rockers, and no noticeable shards in the head.


I'm thinking of installing curcuit sports RAS, closing her up and re-oiling so I can start her and isolate the sound.

Do you guys have any ideas to what I might have destroyed, or anything I should check before I close her up?

Thanks.

[97nismo]

maybe a ring chip? or part of the clutch was destroyed sr20s are pretty stout

[Nikzilla]

I was thinking about the clutch too, especially consideting mine is pretty dead already, but wouldn't I have noticed a difference in the feel?

[Nikzilla]

Should I just disassemble the head and check the clearances?

Also, could it just be air in the hydraulic lifters?

[oni jake]

Should I just disassemble the head and check the clearances?

Also, could it just be air in the hydraulic lifters?


Holy shit no. Please do not go straight into the block to solve this problem. If your car is running fine but making noise at a specific RPM, it is a harmonic issue. Locate the source of the rattle first. Use long screw drivers as stethescopes if you feel the noise is inside the block. It would probably be best to do a simple compression test.

What type of exhaust do you have?

[Nikzilla]

Holy shit no. Please do not go straight into the block to solve this problem. If your car is running fine but making noise at a specific RPM, it is a harmonic issue. Locate the source of the rattle first. Use long screw drivers as stethescopes if you feel the noise is inside the block. It would probably be best to do a simple compression test.

What type of exhaust do you have?

No, not take out the head. Just pull out the cams and check rockers, lifters and springs individually.

I've got 3inch w/ test pipe going out of a T28 blacktop.

[fliprayzin240sx]

Do a compression check, I bet you one of the cylinder is dead from a bent or broken valve.

[Nikzilla]

Ok so it seems I was right. I pulled the cams out, rockers seemed fine. However, the bank 1 intake lifter had air in it.

FSM says that if you can push the lifter plunger with your finger more than 1mm, it will cause a noise and requires bleeding. Mine went down like 5mm.

Pulled it out and bled it, now it holds up fine to the finger test.

85% sure that this was the problem.

However, I made the mistake of cheapening out on a new torque wrench so I sorta snapped a couple of cam retainer bolts. Not to worry, I will drill them out tomm (gotta be extra careful though), but does anyone know where I can find a new set?

Also installed RAS :)

[Mikester]

^^You realize that although RAS are effective in combating rocker float, they also can cause a rocker to 'hang up'... meaning that instead of bouncing around freely in the event it lets go, it can hang up in the valvetrain bnecause it's jammed down by the RAS- causing extensive damage...

I ran RAS for quite some time with no issues whatsoever... Just not sure if you were aware that could happen.

[Nikzilla]

^^You realize that although RAS are effective in combating rocker float, they also can cause a rocker to 'hang up'... meaning that instead of bouncing around freely in the event it lets go, it can hang up in the valvetrain bnecause it's jammed down by the RAS- causing extensive damage...

I ran RAS for quite some time with no issues whatsoever... Just not sure if you were aware that could happen.

Good to know! Thanks!