Mystery Knock

[Zachary_Huff]

So my S13 recently started making a knocking noise, and I'm unsure if its rod bearing or something else. The original dual cam had 252k miles so I wasn't surprised when I started hearing it, so I bought a S14 KA to swap in. The knocking noise is very faint, probably unnoticeable if I didn't point it out, and it only does it when in gear under load. Starts around 1900 rpm and either goes away or my exhaust drowns it out around 3k rpm. I pulled the engine today and found that one of the inner clutch plate springs was really loose and had broken off and tore up the clutch plate, I thought that might have been the sound all along, so I put a newer exedy clutch on my new s14 engine. Just finished buttoning up the new engine and the sound is still there, anyone ever had a similar issue or have any idea what it might be?

[NukeKS14]

timing chain guide maybe? do you have anything done to the engine? It really could be a number of things. There are a ton of normal 'ticking' noises and some not so normal. Anything from an exhaust leak and aftermarket injectors to timingchain or valvetrain noise from changing motor oil weight can cause a knock or tick noise. A video might help us diagnose it with you. Any other indications? Oil light on?

knocking could be anything from engine knock to a spun bearing. If it were rod knock it would be VERY loud and audible at all RPMs. don't think that's your issue from what you described.

[Zachary_Huff]

It's definitely a knocking sound not a tick, doesn't sound like anything in the valvetrain. It still has the upper timing chain guide and that makes some noise, but this sound Is separate. I'll attempt to post a video today but like I said it's pretty quiet. Oil light isn't on and she's full of fresh 10-30, on the previous engine I switched to 10-40 to see if it made a difference, nothing changed. I'm leaning towards engine knock, I'll check out some other forums and see what could cause that. I got a friend coming to check it out today and he's pretty knowledgable about KA's, hopefully he'll figure it out.

[Zachary_Huff]

https://m.youtube.com/watch?v=BuKTxblvjbg

Here's a link to a video I took of the sound. I think its may be early detonation caused by it running too rich. If I give it too much throttle it bogs out and accelerates slowly. The check engine light is on due to EGR being blocked off. Any ideas?

[Zachary_Huff]

Just read on another forum that deleting the EGR can cause "Part throttle detonation" which sounds like exactly what I'm experiencing. Supposedly the ECU changes fuel and timing when the egr valve is open, so deleting it can throw everything off possibly?

[NukeKS14]

That isn't rod knock. What condition are your motor and tranny mounts in? The engine will deflect under acceleration. It almost sounds like something in your drivetrain. Still on the stock driveshaft? Could be your carrier bearing is worn out. Inspect that.

https://youtu.be/wmtBqNnnvrs

Thats aggressive rod knock. Youll be able to hear it idling or free revving the engine from a standstill.

Follow your exhaust back to near your diff. If your exhaust mounts are loose ive heard of the flange on some exhausts coming into contact with the inner cv joint/output flange on the driver's side axle as well.

Have you put a timing light on it and verified your base ignition timing?

[OnTheChip]

Sounds like a lose pulley.

[Zachary_Huff]

Finally got a chance to jack the car up, carrier bearing is shot

[NukeKS14]

https://www.driveshaftshop.com/import-driveshafts/nissan

I've run those on 2 of my s chassis cars and have one on my camaro as well. Eliminating the tired carrier bearing and taking that extra joint out of the driveline really changes the characteristics of the car. And they use spicer joints. Great quality couldn't recommend them more highly.

[mechanicalmoron]

It's definitely a knocking sound not a tick, doesn't sound like anything in the valvetrain. It still has the upper timing chain guide and that makes some noise, but this sound Is separate. I'll attempt to post a video today but like I said it's pretty quiet. Oil light isn't on and she's full of fresh 10-30, on the previous engine I switched to 10-40 to see if it made a difference, nothing changed. I'm leaning towards engine knock, I'll check out some other forums and see what could cause that. I got a friend coming to check it out today and he's pretty knowledgable about KA's, hopefully he'll figure it out.

For future reference, to diagnose an engine noise without wasting your time, go strait to the heaviest oil you can, it won't hurt a KA. Cheap diesel oil and/or throw a whole bottle of lucas. Glad that's not your problem though.

As to your bogging, it depends what all's been jacked on your car, sounds like plenty, but the EGR actually leans it, because there's less oxygen - being rich prevents pinging.

And detonation is the end of the line, you diagnose it by going back and picking up the parts of the engine in the road. Pinging (though harmful) is not a "knock" sound, at least on any modern engine I've ever met. It's an advanced version of the "wet" sound and feel of heavy engine load, it's a problem with the ratios of timing to fuel to compression to octane, and is basically the engine kicking backwards against itself.

[Zachary_Huff]

One of the first things I did when I heard the knock was change to 10-40, and of course it didnt make a difference. Found out the bogging was caused by my O2 sensor wire being frayed, replacing the connection fixed that. Time to find a one piece driveshaft, thanks for the help guys

[mechanicalmoron]

One of the first things I did when I heard the knock was change to 10-40, and of course it didnt make a difference. Found out the bogging was caused by my O2 sensor wire being frayed, replacing the connection fixed that. Time to find a one piece driveshaft, thanks for the help guys

My point was, that wouldn't have done jack shit to an internal noise. 20w-50 might, especially with some lucas on top.

[Kingtal0n]

two piece will fold in an accident

i am not fond of 1 piece

[jedi03]

get carbon fiber then...will just shatter...jk lol there are several vehicles that still use 1 piece stock...the 2 piece in theory will be safer but i dunno...havent seen crash test results with either...

[mechanicalmoron]

get carbon fiber then...will just shatter...jk lol there are several vehicles that still use 1 piece stock...the 2 piece in theory will be safer but i dunno...havent seen crash test results with either...

Theory? The danger of big solid driveshafts isn't a theory... There's a reason we have carriers like we do.

Also, it takes the very edge off rotational impacts, which is good for everything.

[Zachary_Huff]

So after installing the one piece driveshaft the sounds is still there, along with a much worse noise. It only happens when I'm driving very slow and is worse when backing up. I'm assuming it's the differential considering there was some metal shavings on the drain plug when changing the fluid. There was also metal shavings on the transmission drain plug, and for some reason shifting is worse after changing the fluid. I used Redline 75-90 GL4 in the trans and Valvoline 80-90 GL5 in the diff, the car was level when I changed them. Here's a link to a video of the sound the car is making.

https://youtu.be/5Tf3Ktu5jS0

[jedi03]

how big were the shavings? i would also recommend try some of the favorite fluids across the forum (mine is royal purple 75-90) and see how much changes...if damage was done and the shavings are big then a rebuild is in order...

and yes i say theory as alot of vehicles are 1 piece still...just off the top of my head rx8, avalanche/tahoe/durango...i agree the carrier helps the shock load but doesnt necesarily make it any better...

[mechanicalmoron]

So after installing the one piece driveshaft the sounds is still there, along with a much worse noise. It only happens when I'm driving very slow and is worse when backing up. I'm assuming it's the differential considering there was some metal shavings on the drain plug when changing the fluid. There was also metal shavings on the transmission drain plug, and for some reason shifting is worse after changing the fluid. I used Redline 75-90 GL4 in the trans and Valvoline 80-90 GL5 in the diff, the car was level when I changed them. Here's a link to a video of the sound the car is making.

https://youtu.be/5Tf3Ktu5jS0

Lol no shit.

You have a direct line to the rear, you're hearing differential gear noise. The s13 transmits a lot into the cabin, and more solid aftermarket parts will increase that tendency greatly.

Metal ends up in gear oil. Not like it can leave.

Shifting is harder because you put in something thicker, and maybe better, than what was in there. Maybe stick some friction modifier in there. Your syncros are not grabbing as fast because of the higher viscosity/film strength, so the gear won't engage.

If you want less noise, replace parts with OE rubber, non performance stuff. If you want performance, get used to hearing your car. Old sports cars are loud.

[Kingtal0n]

could be the trans

check trans and engine mounts

almost sounds like a bad pinion angle has chewed something up but thats impossible because you kept the oem shaft until now. unless the mounts are bad.

need pictures of the drain plugs. Some metal shavings is quite normal. It can look like a prickly pear and be 'normal' if the pieces are small slivers and not chunks

Redline Gl-4 is good for the trans. I assume that you are using a stock diff though?

if so, diff is cheap, replace with a 'free' other stock diff (even i have a spare sitting in the back yard) to diagnose that
same with trans, dime a dozen, swap it out. Worst case is the trans you take out is good and now you have a spare.

always keep spare parts for these cars.

other things you can try is, rolling the car in gear vs in neutral, different gears, (reverse vs drive noise). When the carrier is loaded in reverse the whole geartrain has to work 'backwards' as the load is applied to opposite faces... or whatever... so if the noise is strong in reverse or when you engine brake in gear it points to the opposite face of the gears (all of them, trans/diff) which could be the gear itself or the backlash/thrust type of settings

And final word of caution about the single piece driveshaft. If it isn't absolutely perfect it will create all manner of issues. I mean, its balance, phase, length, and the angle, have to be spot on.
Since the car uses an IRS the driveshaft pinion angles need to be equal and opposite. So measure front and back using a $5 harbor freight magnetic angle to be sure.

[Zachary_Huff]

I bought another differential to replace the one I thought was broken, when I went to remove it I saw the 4 nuts that mount the diff cover to the subframe were barely on the threads. Pulled the diff and popped the cover, looked better than the one I bought. Reinstalled it with those 4 nuts torqued down, doesn't make the grinding noise anymore. It still makes the faint knocking noise, I'm guessing it's a bad axle. I know that switching to a one piece driveshaft causes some vibrations/clunking, and I'm fine with that, but the noise that it was making was much worse than that.