imported_janz3n

my engine has been knocking for a few months now. i read that if you pull one plug wire at a time and the knocking stops its a spun bearing. the knocking only happens at cold start ups and goes away when its warmed up. iv also read it can be piston slap but im starting to think it isnt that. iv never noticed metal shavings in my oil but iv never really looked for it either. can anyone confirm if the plug wire method for checking for a spun bearing is true or not?

zeeman

iTrader: (1)

well....the spun bearing will still make noise if that cylinder is getting spark or not, so i don't see that as a real good way of checking for a spun bearing.....drop you're oil pan and check for metal shavings.
From my experiences with spun bearings, they usually don't make any real noise until you start revving it up...but i've only seen a few in my days.

LEITNER

sure its not the valve lash? i have heard some noisy top ends that sounded like a bearing but it was the lash...no joke.

VTEC_Thunder

Usually a spun bearing will make noise whether the engine is cold or warm....from what I've heard anyways....

Sounds like piston slap to me.

I can see how pulling a plug wire will stop the knocking on a spun bearing...suddenly there is no violent explosion pounding the rod onto the crank journal thus, no more knock.

Not sure if that is 100% true though...

imported_janz3n

i dont have the place to drop my oil pan. can i just have piston slap on one piston? is piston slap bad?

zeeman

iTrader: (1)

You don't think that the fact that the crank/rods are spinning on a misaligned (spun) bearing would cause a knocking noise? The crank/rods are spinning regardless if there is spark (in one specific cylinder) or not.

iwanna93sihatch

Hahah well generally its not a good thing or sound, i say time for a heart transplant fawker

BOND007

When I spun the bearing on my car anything over 3000rpm and it knocked and banged like a banshee

imported_janz3n

i wasnt planning on swapping till im done school in the spring because i dont have the time place or money at the moment. would pulling the plug wire stop the piston slap? its only one cylinder making the noise i think its #3. second from the distributor.

zeeman

iTrader: (1)

This is what happened everytime i've seen a spun bearing.

Janz3n:

Try pulling the spark plug wire off and find out.

imported_janz3n

sorry , iv already pulled the wires to check if the sound stops.. and it does on one cylinder. which i think is #3. it knocks at idle or any rpm only when its cold..once it warms up the sound is gone completly

Oldspower

yup.. its a piece of ****

imported_janz3n

kinda like your cutlass?

imported_mikepasini

when i had a spun bearing, like bond and zeeman said, it only made noise above 3000 rpm... it made a little close to it, but once you hit it or went above it sounded like... your engine was going to explode or something.


maybe that spark plug wire thing works just to tell you what cylinder its on... and it probably stops making noise because when you remove the spark you wont get combustion thus no real pressure being built up inside the cylinder? and maybe the noise only works when there is that much pressure??

just a though, i might be wrong...



BWAhahahahahahahahahaha

VTEC_Thunder

^^ Thats what I was trying to say.

when you take away that huge load of combustion....it's just enough to quiet it down.


If you have ever owned a GM product...you'd know what piston slap is....LOL.. ...brand new engines from the factory----SLAPSLAPSLAPCLACKCLACKSLAPCLACK....even when warmed up...mostly in the 3100 and 3400 V6's.

chris_si98

his cutlass is better than your piece of **** old *** honda.

have fun replacing bearings, hope your journals aren't scored

imported_janz3n

betsy84 is my friend.. i was joking around. youv never seen my **** old *** honda before so please dont comment. thanks for the help though.. your always a helpful guy.

and i wouldnt reaplace the bearings because i read that the crank would be too messed up if it wsa a spun bearing. and it wouldnt be worth it anyways since id rather put in a better engine.

imported_dr.drew1987

lets settle this on the track boys

imported_janz3n

lol.. im sure my honda is slower so theres no point.

Oldspower

lol, ok to be fair, I'll run the Cutlass in reverse.