Caleb Newcome

iTrader: (1)

Today was finally the day I got my NA6 registered after a couple years sitting. I built the motor with the intent to turbocharge this winter. I did lots of reading and think I did everything the "right way".

On the way back from the VIN Verification place I notice a new noise increasing with engine RPM, initially coming on at about 3200RPM. I figure I've got something loose that is vibrating or some detonation despite my rich tune. The motor has about 40 miles on it at this point, all from driving around the neighborhood with a laptop plugged in to my Megasquirt to get a reasonable tune in it. I've logged most of the run time, constantly monitoring AFR and starting with a pretty rich tune.

I make it home the 6 miles from the VIN Verification, and find that all my valve cover bolts loose as a goose. I torque them all to spec and go out for another drive around the block to see if that did the trick. At first I think that did it, but soon the noise returns and worsens. The noise reduces significantly with the clutch or the car in neutral (this might just be due to my RPMs decreasing). I head straight home. I have a bad feeling that it is rod knock. I park it, pull my plugs (they look fine), borescope all 4 cylinders, and crank the engine over with the plugs out and no fuel or spark. The engine spins normally, and doesn't produce any odd noises. With the plugs back in I idle the motor and pull the plugs one at a time. Pulling number 1 significantly reduces the noise. It is still present, just less frequent.

Does this sound like rod knock (aka how fucked am I)?

I don't have a clip of the noise, but can provide one if you folks would like. I can whip up any or all of my data logs and tune as well.

hks_kansei

How's oil pressure?

Did you check the big end bearing clearances when assembling the engine?

Have you replaced the plugs? (mainly because #1 made a difference you said)

Have you confirmed the injectors are all good? (is #1 stuck and lean enough to detonate)

Have you run the engine in at all? or has all the driving just been cruising around the block.



It's always hard to diagnose a noise over the web.
Impossible without lots of detail or being able to hear it.

Caleb Newcome

iTrader: (1)

I've got a boundary oil pump shimmed to get some extra flow once I add the turbo. Cold oil pressure is quite high (over 60, near the end of the gauge so hard to be sure), but settles down to a hair under 30psi at idle when warm.

I checked some clearances, but definitely didn't do as much in that regard as I should have.

Plugs and wires are all new NGK. I should probably check my spark gap though.

Injectors were swapped over to 460cc RX7 after a few miles on the stock ones. I cleaned them and replaced all the gaskets and filter but did not have them tested before install. Tune was adjusted to suit.

I've started out with the rev limiter down at 5000RPM to start. I've gone to about 75% throttle max, but in general the drives around the block have been "spirited" with good amounts of time from idle all the way up to 5000.

Caleb Newcome

iTrader: (1)

Just ran downstairs in my underpants to take a quick video. Hopefully these links work:

https://photos.app.goo.gl/NqAVECDYZ9wDCVHz8


Here is another of the motor running about 20 miles ago:
https://photos.app.goo.gl/GbmdWGHjRZG5CAkL6

It sounds pretty damn bad to me, so I am mentally preparing myself to pull the motor. I'm mostly hoping at this point that I haven't ruined all the shiny new parts in my built bottom end.

andym

Odd question. But try taking off the alternator belt and try again. I had what I thought was rod knock on my girlfriends miata with a relatively new gates water pump. I even bought a new engine for the car only to find out that the water pump bearings? went bad and were giving me what sounded exactly like rod knock. It's possible you have a bad water pump but it is unlikely.

Caleb Newcome

iTrader: (1)

Thanks. I'll give that a try. Water pump was a new gates unit so I would likewise be surprised if that was the issue.

patsmx5

iTrader: (16)

Sound like rod knock to me. I'd guess there is metal in the oil, you could check. Maybe you put a bearing in wrong on the rod and it's not getting oil flow?

Caleb Newcome

iTrader: (1)

Should I expect to notice metal in the oil by looking at the dip stick alone? I need to grab a clean drip tray before I drain the pan, but that was already on my list.

This is my first ever engine build, so while I tried to be very meticulous and thorough, and read a ton before doing anything and most every step in between, I must admit it is possible that I fucked pretty much any part of it up.

patsmx5

iTrader: (16)

Yeah if you run it recently, and then pull the stick and wipe it down with a clean paper towel. If there's metal you'll see it. You might see a bit just because it's a new motor breaking in. If you see it's full of metal, you know. Could also pull the valve cover and have a look, it will be obvious if there's a glitter bomb worth of metal everywhere in the oil with the cover off. I don't think your motor has shims for the valves but if it did, could look to see if it spit out a shim and a cam lobe is slapping the lifter or something.

Caleb Newcome

iTrader: (1)

Oil looked clean on the dipstick when I parked it right after the sound worsened.

I also did peek under the valve cover before torquing down those bolts and it looked clean. I'll probably still drain the pan a little tomorrow to be sure.

My number two theory is that I've got flywheel bolts loose, despite torquing to spec and applying loctite (I think blue). I might consider that more likely if I don't find any debris in the oil.

Thanks for the support so far guys.

patsmx5

iTrader: (16)

Did you clean the bolts and the hole they thread in with brake parts cleaner or something similar? If those parts are oily, the loc-tite won't work very well. Adhesives don't stick to oil or oily surfaces very well. Hopefully it's something simple!

Caleb Newcome

iTrader: (1)

That was quite a ways back so I'm not too sure, but that sounds possible to me.

oreo

As Pat suggested, I would pop off the valve cover, start it and see if that tells you anything.
With the cover off also check that the cam gear bolts are tight.

sixshooter

iTrader: (12)

What clearances did you measure on the rod and main bearings during assembly?

For clarification, shimming the oil pump does not increase volume. Volume is limited by the size of the gears. Shims only effect the maximum pressure allowed before relieving the excess oil to the tank.

Edit: Pull the dipstick and smell the oil for fuel. Rich is not safe. It can thin the oil and reduce the viscosity significantly.

Caleb Newcome

iTrader: (1)

I think those clearances are just about the only thing during the rebuild that I know I didn't go through thoroughly. I don't think I measured all of them. I'll try to dig back into my notes and find the actual numbers I took. From what I remember they were on the loose end of the spec.

Thanks for the clarification on the shims. That makes more sense and jives with my high cold oil pressure.

By rich tune I mostly mean I've been paying more attention to going lean and adjusting to correct, and less attention to when I it's rich. I have not altered the base AFR targets from the map for the 1.6 I pulled off of diyautotune. I've been using VE analyze live the past 20 miles or so after some initial messing around by hand to get it idling well.

sixshooter

iTrader: (12)

Loose is usually good for a highly stressed engine such as with forced induction.

Check the damper bolts and look for wobble.

I'd spend $10 on a mechanic's stethoscope and listen to it from above and beneath while up on jackstands to narrow down the origin prior to pulling the engine back out.

Did you run a rifle cleaning brush and swab through the crank and block passages after they were hot tanked? Not everyone does and there can be residual solids left behind which can cause trouble. Some shops show more attention to detail than others.

Caleb Newcome

iTrader: (1)

I did not do much cleaning after getting the block back other than wiping off exposed surfaces and hitting it with some compressed air to kick out any dirt and dust that might have collected.

I'll start checking more things out this afternoon after I'm off work, and thanks Six, it's good to have you in here.

tehzack

Make sure your cam caps are tight as well.

Caleb Newcome

iTrader: (1)

Seems like cam caps would pretty well explain my valve cover bolts backing almost all the way off.

I had all the head work done by the machine shop so i didn't pay as much attention to it as I did the bottom end. Perhaps they didn't tighten the caps to spec...

x_25

Put the suspect cylender at TDC and then rotate the crank until it just starts to move down. Push down on the top of the piston with a rod of some sort though the spark plug hole. See if you can feel the clunk. Check all the others for comparison.