Spun Rod bearing: What is it and how can it be prevented?
 

Ive been hearing alot about this one, I think I know what it is but not 100%.

Does it only happen to Y8's? As I hear alot of them go this way.

any input helpful thanks.

i'm curious too... my buddy put a d16y8 from an 1.6el in his 4thgen... the car had no rev limiter and when his friend was driving it over reved and kablamo!!

i think it was the no 3 rod that snapped... is that what this spun bearing what caused this?

spun bearing is when the braring disentigrated and goes in u r oil pan and then your rod starts flapping and usually smapps or causes a knocking in the crank case correct me if im wrong n e one

personally i have no clue... i've heard of spun bushings which also suck...

Where's our Bruno on this one?? :)

basicallyw hat was states before if get's worn out beyond beleif and "spins " in it's "seat" I guess you coudl say...it's from over reving and lack of oil....a knockign rod can be a tell tail sing that yoru bearings are going south

Ok basically here is the theory... the crank rides on a film of oil generally most of the time. There are holes through the crank journal and it supplies oil in there...basically removing the film of oil causes crank to bearing contact, and the bearing is just seated into the block, so it has to give... how badly it gives is up to lady luck...

How to prevent it... I wonder if you can use D16Z6 bearings :confused: Short of new bearings, fresh synthetic oil, quality filters, proper weight oil, no additives (or if your engine is a heap, use Lucas Oil Stabilizer), and being considerate of WHEN you rev the piss out of the engine (ie. at full operating temperature), are all good steps to take. Revving the engine when its not warmed up is stupid... I am in the habit of sitting in the car for 30 seconds before I go anywhere... checking instrumentation, finding a CD or radio station, checking my mirrors, putting my seatbelt on... every once in a while, I'll do a light check and make sure no bulbs are burned out. In this time, oil has been circulated around the engine, and you are ok to drive off slowly. I don't rev past 3000-3200 until I'm certain the engine is warm (ie. the cooling fan has come on).

A worn or spun rod bearing is caused by excessive clearence between the rod and the journal in the crank. When the bearing wears, the clearence increases, when that happens, the area where the oil is pressurized between the two parts, looses that oil pressure, when that happens, steel on alumanum, the alumanum bearing half will get thinner and loop around to the upper or lower side of the rod, thus the "spun bearing". When this happens though, you can either get the cank resized and new bearings installed or replce the crank. The latter of the two is better because if an engine is run with a bad bearing then all the journals that recieve oil after that one will have low or no oil pressure. Change the oil regularly, it wont ever fail. Reving doesnt cause damage like this that will, the more rpm, the more oil pressure. Wear is the only cause.

Revving cold or on dirty oil will...

cold engines dont make the same oil pressure because the oil is thick, reving a cold engine causes accelerated wear on parts lubricated by the wedge effect, dirty oil will also wear the same parts. Excessive wear is what causes loose or spun bearings.