When good KA's Go bad.....!!!!!

[Thee 240sx Owner]

So yesterday i'm leaving for work at about 5:45am.... about to head out on 17-92 and bam my car just shuts off... tried to start it again and i could hear the starter turning but no stress on it... So i push the car back home (2blocks) Pop off the valve cover because my thought was that the timing chain snapped or came off becuase i had a rattle along with my spun bearing. so after i got the valve cover off... looked at the timing chain and it was all there.. went to go check it to see if it jumped off the teeth and my whole cam gear sprocket along with the chain came right off the camshaft. I thought i may have just broken the cam gear but i snapped it off along with a part of the camshaft... So since i had a spun bearing i know what happened.. The bearing siezed up, locked the motor up... stress the chain and snapped the gear off....... so i'm laying down another KA to rest (yes this is my second motor already)... bought another one.. yes for some reason i'm partial to the KA..... but who cares.. you people doing your SR swaps are selling these ka for like 100 bucks.. keep em coming

[MikeMurphy]

thats crazy. what are the symptoms or a spun bearing? could you explain the concept to me a bit.

[Touchdown038]

Spun bearing is where lack of oil inside the bearing causes friction to rise, up until the point where the bearing and the crank journal melt together.

Apparently not too common on the KAs, but it does happen occasionally.

[MikeMurphy]

cool. Were talkin the rod-crank bearing right? Or am I wrong?

[GA240]

Did it make noise before it seized up and broke? If so what kind of noise? Ive got a "noise" in my de. Im hoping its the guide or timing chain, but I dunno.

Hes talking about the cam bearing. See the valvetrain? Cam gear?

[deviousKA]

damn, never seen that happen before, must have locked up really quick. Does the cam still spin in the head with the rocker assembly removed? Needless to say you have plenty of reason to dump that engine.

spinning bearings on the ka, when it does happen, is usually due to a shredded timing guide. As far as i have seen anyway. Plastic particles is the cancer of ka. Filling the crankshaft passages etc, and causing obvious damage. Check/replace timing chain guides, a must-do for everyone.

[p00t]

i also must throw in the question of how old is your oil... its like sludge black

[Drift Machine]

The guy who owned my 240 before me, had the same thing happen.

[Thee 240sx Owner]

Well the symptoms of a spun bearing is you start to hear a slit low rattle that sounds like its in the head and it normallys starts around 3k rpm and eventually gets lower on the rpms as it becomes worse.. i knew about it for about 2months but its too much to replace a set of bearins and its my only car.. My oil was 2 months old... changed every 3k like it should be with 20w50 valvoline.... The same day that happened i bought another KA for 80 bucks so i got that motor in the following week. I even noticed that the came gear cracked half way through as well. damn torquey KA's... And yes we are talking about the connecting rod to the crack shaft bearing. (rod bearing) and also... its not just shredded up guides that cause spun bearins.. its excessive revving above 5k that cause it as well.... Ka bearings are made to well design wise.... I'm gonna turbo this KA that i have in right now so hopefully that'll work out well....