Knock? Rod knock? Help :(

[ST240]

So after putting my rb30 back together (entire engine was apart, replaced rod bearings), ive driven it around 200 km or so on a rough tune.

Recently ive noticed a knocking sound. It only occurs around mid to high load, and only at above 3k rpm. If i bring the RPM up very slowly i can get to 6k+ RPM, i cant hear it. It also doesnt occur revving the crap out of it it neutral. When I hear the sound, boost is just building up to 0 and thats it.

Does that seem like rod knock? or spark knock due to a bad tune? Or what the heck... It didnt seem so apparent when i first started driving it around. How much timing would i have to kill to get rid of the sound if it was knock? I richened the hell out of it in that region like 10.5:1 .

Im thinking lifters maybe?

Im so confused....

[Carl H]

rod knock is typically very consistent with a noticable noise at idle which increases with revs.
what kind of ecu are you using to tune and what kind of maps are you working with?

[ST240]

rb20 ecu stock rb20 map. resized and tuned the k for 740s and z32 maf. idles and runs like a champ.

The weird thing is it wasnt doing that for the first 150 km or so... so ive kinda ruled out the tune.

I'm thinking its coming from the valve train because its so consistent everytime when it happens. Lifters? s*** man this is frustrating. Yeah i dont think its rod knock really...

[Carl H]

might be flat lifters...did you clean and rebuild the lifters before you put the engine back together?
when i was troubleshooting my setup i had my cams out and found 2 dead lifters, replaced them with ones i had cleaned and rebuilt and it works flawlessly now.
Also stock map isnt the best for power or even daily driving...i was seeing high egts with the rb20 base map and NOOOOO power.

[ST240]

No i didnt even look at them... What does cleaning and rebuilding involve? I think i could pillage some from my rb20 head. What does a dead/flat lifter look like? FML if i have to take apart the head with that engine still in there. Talk about zero room.

Edit: Do they just randomly die like that? Like i said, it seemed to run ok for the first 150 km. Could it be possible that theres air in them? I'm just trying to figure out what the hell is going on before i tackel the b**** of a task that is taking the cams off with the engine still in there...

And yeah, i know the stock map is junk. I was gonna get to tuning but had some other issues to sort out and i thought that was spark knock. But evidently not.

[Cjmartz2k]

Post up a vid of the noise.

[SullivanRacing06]

Post up a vid of the noise.

+1

[ST240]

Ask and you shall receive .

http://www.youtube.com/watch?v=L0aDi_KCDQo

It should be pretty obvious, but you can hear it best at 0:09-0:11 and again at 0:38.

Edit:

The sound in this one is even better:

http://www.youtube.com/watch?v=jOvG7s8CZJ0

[Cjmartz2k]

I could only *briefly* hear something, and it wasn't enough to tell. Take the vid with the car parked, the hood open, and gently increasing the rpms with the throttle. Rod/main bearing knock has nothing to do with how hard you press the gas, it's all rpm related. Usually a nice knock around 3-4k rpm that goes away with changes in rpm, but usually comes right back at the same rpm.

[ST240]

Really? I thought it was pretty obvious... It's that rapping sound just as the turbo starts to spool kinda. The sound doesn't happen when revving the engine with the car parked.

[Darius]

You don't notice the knocking at idle at all? Lifters that haven't pumped up with oil will often times make it sound like a diesel engine.

Check this link out for how to clean them:

http://twinturbo.net/net/viewmsg.aspx?f ... dtSearch=3

I honestly don't think you'd need to replace a lifter unless either the ball check valve within them stops sealing or the spring breaks in there. Both would be fairly difficult to do.

What does your oil pressure look like? Do you have oil restrictors in the block?

[Carl H]

restricting the head is very important on an rb30 block...the stock restrictors are HUGE compred to the normal dohc gear.
I installed two tomei oil restrictors and all seems to be well thus far.
the sound does sound a bit like detonation, have you verified base timing on the engine with a light and not via consult?
how much boost are you pushing into the engine at the moment?

[Darius]

CarlH, that's what I was leaning towards too. It doesn't sound like a lifter issue because it would be loud at idle when oil pressure is lower and you wouldn't hear it as much at higher rpms (free-revving). This is the exact opposite of what ST240 is describing, so that's why I am thinking you might want to back off some timing as it builds boost to see if that helps.

[ST240]

CarlH: I left the restrictors standard which may have been dumb, but id heard reports of guys having noisy lifters on heads with hyrdraulic lifters with non standard orifices. Further to that, I'd imagine I would be able to reproduce the sound free revving it if that was the case.

Yes base timing is set to 15* BTDC which also matches consult when warm.

If you watch the first vid, you can see that I'm just barely spooling up to atmospheric ala 0 psi! Is it even possible to knock at those levels? In the second vid at the end i built up to 3-4 psi tops.

I've tried killing timing and richening it up to the point of zero power, but i still get the sound... I suppose it wouldnt hurt to try again just to be sure.

[ST240]

Darius, oil pressure is great, and no i didnt install orifices like i said...

[R32ONP]

for it to only do it on load it sounds like detonation not rod knock...ie its only knocking wen under load

[ST240]

Gonna double check timing/afrs when i get home again tonight cuz for it to only happen under load is the real odd thing... Is what im concluding from this discussion. Keep the comments coming the mean time.

[ST240]

Ok this is really starting to piss me off... Its spark knock, no its rod knock, no its the lifters, no its spark knock. No.

It definately isnt spark knock. Just logged a run, AFRs in the low 10s, timing was 10* (!) map was anywhere from vac to 4 psi. And it still makes the sound as loud and as consistent as ever. Please tell me that isnt spark knock, although i wish it was.

Edit: Heres a vid of me free revving it.

http://www.youtube.com/watch?v=5OGooy9Hubw

You can hear a whine which i think is the timing belt, or tensioner. Or not?

Edit again:

http://www.toyotanation.com/forum/showt ... p?t=313967

Uh oh... Exact same symptoms.

[Cjmartz2k]

Are you running a base map? Like was said above, if it's not knocking in neutral, it's not rod knock. Many other things can cause knock knock besides a/f ratio and base timing like hot spots, improper quench height, super high compression, bad tune, etc.

[ST240]

I ran the rb20 base maps when i first got it running and took it for similar pulls (all the while monitoring knock) and i didnt hear anything like that at all...Thats also what im running in those vids. It just gradually started making this noise.

[ItzGenX]

My old 500whp SR developed a rod knock that wasn't present at idle or low loads. I disabled the injector for that rod's cylinder on my haltech while loading the engine, and it would stop. When I disabled any of the other 3 injectors, the knock would stay present under medium and higher loads over 4k rpm. I didn't believe it was a rod knock either, and the knock slowly got louder over time and later became present even at idle (pulling it's coil would stop the knock). 500 miles later upon pulling the motor, yep, bearing #1 was scored along with the crank. Total miles on bearings, 4000. For me it was probably my rod bolts stretched past their limit. I did replace the rod bolts and new rod bearings with a new crank, and the motor still kicks after 20k miles to this day. Moral of the story, rod knock isn't only at idle. It has freak cases where it doesn't show itself at idle/low load until it is too late. I should have pulled my oil filter and chopped it open when I first heard it at high load, and it possibly would have saved me from a new crankshaft. The filter was full of the metalic flakes from the culprit rod bearing.

[ST240]

Did it sound like what you're hearing in my vids? Thanks man I'm gonna go home and drop the oil and cut the filter to see what i can see... How can i distinguish bearing flakes from regular engine gunk?

[gawdzilla]

bearing flakes are like very fine, shiny dust that you can rub between your fingertips. imo it's hard to cut open a filter without introducing your own crud in the cutting process, but worth a shot.

my vote is also for the very beginning stages of rod knock. what did you do when you replaced the rod bearings? did you re-mic everything? re-used fasteners? did the motor have a spun bearing originally and maybe you did not do a good job cleaning it fully? (oil cooler, pump, etc.) did you polish the crank again? if you do find out it's rod knock there is a chance something was done wrong in the rebuild process and you def don't want it to happen again.

not saying you don't know what you are doing or anything, but sometimes being overly cautious helps. as you know, changing bearings isn't really like doing a brake pad swap

[ST240]

I had arp rod bolts fitted and the tunnels resized. I mic'd it all with a good set of mics and i used a snap gauge to check the bore. Everything was within spec. I didnt check for out of round. I polished the journals with oil and 1500 crocus cloth. It was a pretty ramshackle affair though; i did it in my garage which is a less than clean environment...

And yeah... no offense taken. This is the first engine I've taken apart and rebuilt in my entire life and look what happened .

[ItzGenX]

My past issue with rod knock sounded more like a hammer being banged on the block lightly and eventually grew and started sounding like a big a** hammer hitting the block per combustion stroke. I can barely hear in your videos. Rod knock changes frequency with rpm, so it should knock faster and faster as the rpm goes up. I remember my old Blitz Dual SBC ID boost controller would make rattling noises that I can hear from the inside of the cabin after a set amount of pressure regardless of rpm. It turned out to be the solenoid clicking open and closed at high frequency before reaching preset boost levels. Try unplugging the boost solenoid if you have one and see if it's the culprit for being a scary loud solenoid. Just watch out and don't overboost while testing.

[ST240]

Well there was shiny particulates in the oil/filter. Quite a bit and smaller than grains of salt. The oil also had a silvery swirl to it. For comparisons sake i changed the oil in my dd 240sx beater with at least 2k+ km since last change and there wasnt nearly as much. Under half the amount. So for the RB to have double the f*** particulates on 200 km doesnt look good at all.

Is there any point in pursuing further? Are particles typical on a rebuild? I was going to try driving it while disconnecting one injector/coilpack at a time to see if i could isolate it. But i definately do not want to wreck the crank. FML. Serious.

Edit: pretty sure the silvery swirl is from the arp fastener lube...

[USMCgetsome]

ncvs? i had that same knocking on the intake cam at a certain rpm. Hmmm.

[ST240]

ncvs? i had that same knocking on the intake cam at a certain rpm. Hmmm.

If only. Its a rb25de head = no nvcs.

[Cjmartz2k]

?? RB25de's had VCT also. You mean this is an early RB25de head out of an R32? I know those didn't. The ports on the head were smaller too on those.

[Carl H]

how many times have you changed the oil since the rebuild...i had changed my oil 3 times before i had hit 500 mi on my engine...even now i still have a minute amount of crap coming out of the engine but its no where near as much as what it was on the first and second oil change.