Ruh roh!

[KATwo40]

I'm pretty sure I've developed a little bit of a rod knock, but I'm not entirely sure. It may just be some nasty chain slap (but I seriously doubt it...very solid sounding clack) or a worsening of the piston slap.

I get it around 2500-3000rpm only at cruise throttle. With any load above cruising, the sound is gone completely. Any rpm above or below this range and the sound is non-existant, regardless of load.

Any suggestions? Remember, it's a brand new engine, but that doesn't mean the builder didn't fudge it up.

[NateDogg]

Could it be an exhaust leak?

[nissanfanatic]

I've had many cases of rod knock on my engine. Most of them turned out to be something loose or rattling.. **** I have one now..

What I did to verify it wasn't is press the throttle with my hand and put my head under the car as close to the engine as possible... Rev the engine and listen. You should be able to hear it loud and clear from that location..

[wild_maxx]

another way to listen for the rod knock is using a long screw driver. Run the engine around 3k rpms with the screw driver up to your ear.. put the other end on each cylinder and see which rod is the loudest.

[KATwo40]

Yep, it's a knock. I can hold it at 3k rpm steady, then feather the throttle slightly closed and get the knock to occur.

SWEET! I love spending $2500 on a new motor just so I can put only 2000 miles on it.

[WDRacing]

Sounds exactly like how my neighbors started John. I went through the motor, pulled the top chain guard etc. Things continued to get worse and he finaly tossed a rod...the #3 of course.

If its rod knock, stop now and you can probably swap out the bearings and retorque the everything. Just make sure things aren't scored.

Or, rip the KA completely out and do one of those swaps we've been discussing.

WD

[red boy]

I had rod nock 4 a year, before something finally came loose in my engine. The chattering came in between 2500-3000rpm, right before the auto transmission shift gear, then it was gone. It got louder about the last 3 months. In case you didn't Know. On some ka engines there is a clearence problem with the CLEVITE main thrust bearing. HRT won't even use them, TOP HAT said they wet sand it. I Don't know what AMS do to them but they still use them.

[KATwo40]

I had rod nock 4 a year, before something finally came loose in my engine. The chattering came in between 2500-3000rpm, right before the auto transmission shift gear, then it was gone. It got louder about the last 3 months. In case you didn't Know. On some ka engines there is a clearence problem with the CLEVITE main thrust bearing. HRT won't even use them, TOP HAT said they wet sand it. I Don't know what AMS do to them but they still use them.

What is the issue there? Does it allow the crank to shift just enough to throw the rod alignment out of whack?

I'm gonna park the car now, yank the motor, find a donor block and start over, before the rods and pistons get damaged. I don't trust this block anymore and high mileage running KA's are cheap.

However, this time around I think I'll use OEM Nissan bearings.

[eazye2000]

ZOMGWTFMANDONTSAYTHISCRAPNOW?!?!?!

I literally JUST put my motor together today with Clevite 77's from AMS...

I guess we'll find out soon enough..

[TheOne]

i know that feeling, my current engine has rod knoc kand i haven't even boosted it yet.

its bad rod knock but still drives fine, am hoping i can get away with changing the bearings but seriously doubt it.(been driving it with rod knock for the past couple of months, don't have another car, but am gonna rebuild engine in the next couple of weeks)

[WDRacing]

When the knock sound starts to mix with a screaching noise at all, park it. The rod is about to exit the block.

[KATwo40]

Changing bearings won't cut it. There's something out of alignment. If you just change the bearings, it'll wear them out in a few hundred miles.

[DammitBobby]

Hey KATwo40,How did you rebuild this motor? I have rebuilt mine using AMS basic with ARP hardware and clevite bearings. I had everything balanced including pressure plate and flywheel, which was way off balanced. I would find it hard to believe the the clevite bearsing are to blame for the rod knock. So far I have around 1k miles on mine with no engine issues. When you tear it down take some pics.

Very sorry that you are having problems with your engine I feel for you. 1st motor rod knock wiped bearing and 2nd engine broken ring lands:( The only thing I can say about my mishaps is that it has been a learning experience.

[red boy]

I talked to the guyz at TOP HAT, HRT,and AMS. TOP HAT says its some ka engines not all of them. Its not the rod bearing its a main thrust bearing that can cause engine failer. HRT will use CLEVITE rod bearings but won't use the mainbearings at all.

TOP HAT,and the guyz from HRT have talk to Ivan at AMS and both disagree with Ivan on this issue. But Top HAT told me it can be fixed by wet sanding it. A bunch of trial and era they said. NOTE: NOT ALL KA ENGINES HAVE THIS PROBLEM

[KATwo40]

After further diagnosis, and finding that the noise does not occur under ANY load situation, we've determined it's wrist pin noise.

Now, why it's rattling is beyond me, but it's pretty certain that the noise is very high in the engine, very fast repetition and too light to be rod knock.

As it stands, I'm running it for now.

[klattr1]

Take a video or get an audio sample of it...If the sound completely disappears at lower or higher RPMs, then I doubt its rod knock. You would be surprised how many sounds can be mistaken for it...Stupid, simple things like a heatshield rattling at a certain resonant frequency, etc. Do you have your timing chain guides all removed? Have you narrowed it down what area of the engine its coming from (block, head, towards end of crank near clutch/flywheel, etc)?

[KATwo40]

All upper chain guides are removed, the lower guide is still intact.

The sound definitely is from the upper end of the engine, toward the front.

I'm certain it's not a rod. Either some really nasty piston slap or a wristpin.

I've had a chain issue once before and it sounded nothing like this noise. This is a dead knocking, but not deep and slow like a rod. It's a faster rhythm.

Maybe on the Saturday track vid you can hear it. I'll post it up Sunday.

[eazye2000]

Hmmmmmm... After this new info, I'm thinking something in the timing tract?

Maybe something in the head? Valve guides worn?

I suppose we can speculate all we want. But if it sounds 'light' enough to keep driving, keep on truckin'... <--funny it came out like that since it's been dubbed a 'truck' motor... funny to me only? I guess so.. hah

Just don't Deep-6 anything to make it not usable again!!

[KATwo40]

I could always do what the Mustang guys do when the engine's limpin'....

SEMD THEM bishez THROUGH THE HOOD!!1!!!1111!!!!

J/K. I think it'll be fine.

[Logan76]

hey man, when you motor starts running crappy or making a noise, just push the throttle to wide open.

[WDRacing]

I did, then you have to find a whole block...

I hate hearing these things about the KA...makes it hard for me to be in love with it. Seem to be alot of factory defects. Some like Cory's bullet proof block seem to take all kinds of abuse, others see a little boost and just crap themselves.

Oh well...

Odd you never hear of the SOHC motor have these issues...

[KATwo40]

Now that I've pretty much determined it's a piston slap, I see no issue with the block/crank, aside from weighing as much as an LS1. LOL

[wild_maxx]

Odd you never hear of the SOHC motor have these issues...

Thats why I am still rockin the SOHC motor!

I am using clevite 77's main's and rod bearing with around 1k miles on them with no issues... the hydro lifters tick like a mofo though.