engine rattle/knock

[itsnever2fast]

i have a rattle/knock under light load/cruise over 2000 rpm. does not do it at idle. it cannot be heard when you let off the gas or at WOT... that may just be because you cant hear it over the motor. any engine experts out there know what it is? i think it may be main bearings... gadamit the motor was rebuilt 15k ago.

[itsnever2fast]

pulled valve cover today... everything looked good... i am not sure if it is the middle of the timing chain or not... i really dont want to pull it all apart and replace it all just to find out it wasn't the chain. ANYONE?

[S13FASTBACKSR]

hmmm well does the chain seem nice and tight? only other thing i can think of is turbo shaft play..check that

[ILikeMy240sx]

it can be the timing chain or it can be a rod knock. I remember when I had my rod knock I swore up and down it was the damn timing chain rattling.

First, you should take out the upper timing chain guide. you dont need it. And see if that gets rid of the noise.

If not, get a mechanic's stethoscope and have someone hold it at the RPM where it starts to rattle and start poking around.

Just keep in mind that EVERY rod knock that I have heard and experienced sounds like the damn noise is coming from the valvetrain. But upon further inspection they were all rod knocks.

You can also unplug the injector one by one and reve it up to see if the noise goes away. For example if you start to hear the rattle around 2000 RPM and unplug #1 injector and reve the engine to 2000 RPM and no longer hear the rod knock then you KNOW that your #1 cylinder is knocking.

Also, one thing to keep in mind is that valvetrain noise is 1/2 times slower than bottome end noise because they spin 1/2 times slower. So if you can fairly count the knocks then its most likely valve train but its very rapid like a bb in a tin can then thats your bottom end.

good luck.

[itsnever2fast]

i changed out the tensioner... no results... i am thinking my chain guides might have broken or something... i have no upper chain gaurd.. that was my first thought.

[ILikeMy240sx]

if its not the timing chain, and the noise is very rapid most likely a rod knock but get a stethscope and make sure.

[itsnever2fast]

disconnected injectors in order... no.2 made it go away. number 2 rod is knocking... anyone want to buy a 240 with an sr swap? LOLanyways... this sucks.

[Blown240sx]

Its not to bad just pull the motor. If you caught it fast enough the Crank should be fixable and bearing are cheap.

[ILikeMy240sx]

disconnected injectors in order... no.2 made it go away. number 2 rod is knocking... anyone want to buy a 240 with an sr swap? LOLanyways... this sucks.

I just saw that you are from Novi. There are lots of people in MI that can help you out including my self. If I had absolutely nothing to do I would come over and help but im extremely busy at the moment. My friend could probably do it if you can tow your car over here somehow. Oh and also let me know if you are serious about selling. I might know few people who might be interested.

[itsnever2fast]

yeah i am serious about selling it. i am leaving for the airforce soon anyways. my friend already offered me 5grand for the car if i fix the rod bearing. idk. i can handle fixing it. its just the time, and the downtime of not having a car. its my daily driver. right now i am running 10w40 oil and keeping it under 2500 rpms to go the 1.4 miles to work.. its 30mph the whole way. someone make an offer. come look at it. I will sell the black car,which has about 7,000 in parts invested, rebuilt motor w/ no.2 rod knock, PFC, front mount turboxs manual boost controller, koyo dual core, my red car 91 hicas auto, very little rust, a spare SR that had a rod knock as well, 2 mint s15 six speeds and about 5 grand worth of race engine internals and parts for 10grand if anyone is interested.

[ILikeMy240sx]

how much are you thinking about selling the car with SR WITH rod knock.

My friend might be interested in buying the car as it is with the rod knock.

[itsnever2fast]

my friend is buying it for 5grand. includes new oil pump and some engine parts. I am helping him R&R the motor before I leave for basics. he is still considering. he likes the price, he just doesn't know were he is goin to keep the car for a few weeks while we are doin motor work.

[kpc_0721]

could be just one of your timing chain guides maybe?

[itsnever2fast]

nah i am decently sure it is the number 2 rod bearing... i already tested it. i am pulling the motor out soon.