Knocking??

[scs13]

its a 93 240sx with about 120k miles on the motor. i started the car up one day and started to drive off and when i hit like 2k rpms or so and went to change gears it made this loud knocking sound. it drove fine on the way back home if i kept it under 2k. when it idles you cant really hear it knocking but if you rev it make a loud knocking sound. i will hopefully get some video of it tomorrow if that would help. any idea what it might or could probobly be??

[scs13]

help?

[elwesso]

Does the oil light come on/stay on?

[scs13]

oil light only came on when i started it. i had just changed the oil like a week or so before it happened too.

[scs13]

help?

[Neil]

the rod bearings went bad in my hatch at 170k, they went bad in my coupe at 135k.

something you can do to test is hold the rev or have someone hold it for you where you start to hear the knock. remove a plug boot one at a time... if you hear the knock get cignificantly quieter with one certain boot off, that cylinders rod bearing is toast.

please dont drive your car any more, that would risk damaging the crankshaft which would be more pain. The rod bearings are designed to be the part that goes bad when stuff wears out. to fix my coupe i bought new bearings (40 bux alloemautoparts.com) and put 'em in over a weekend. it sucked... but then it was perfectly happy and took a few drift meet beatings for another like 40k and was still strong the day i pulled it to put in my sr. to fix my hatch, i sold it. hahah

Has your car sounded like its been pinging a lot for a while? if so it wasnt pre-detonation.

[scs13]

pinging? thx for the advice btw. i havent driven it in months. i stopped driving it the day it happened. i only started it up once or twice since then to let people hear it.

[scs13]

if i pull any of the plugs out the knock gets REALLY bad. its hard to hear much of anything when its at idle though.

[Neil]

: \

really sounds like bad rod bearings, but Have you checked under the valve cover to see if the chain guide isnt flopping around in there?

yr gonna have to pull the pan to check out the crank, make sure its not hurt if you want to try replacing the rod bearings. i think you have to lift the motor a little off its mounts by jacking up the transmission to get adequate access... I know i had to do that to get the lower timing cover off to do the chain set while the motor was in the car anyway. wouldnt hurt in any case seeing as how the cross member right there would make it tough to get at the rod cap hardware. Tackling this job will necessitate a hydraulic pump jack, jack stands, nissan brand gasket sealant (to reinstall the oil pan), new bearings, and a torque wrench with (obviously) a compliment of the appropriate metric sockets to reinstall the rod caps.

[scs13]

i took the upper timing chain guide off before the motor was put in. and i took the valve cover off after to check and make sure everything was good under there after it happened. i had some oil two of the spark plug things, but i cleaned that out. i hope its the bearings and its fixable without me putting another engine in it AGAIN. i guess i will have to work on getting at the oil pan again sometime, but one of the nuts is stripped on the sway bar so its gonna be that much more of a pain.

[scs13]

anybody else have a similar problem?

[scs13]

bump