Texas 4x4 Forum banner

1 - 17 of 17 Posts

·
Super Moderator
Joined
·
6,117 Posts
Discussion Starter #1
A few weeks ago my 454 started knocking after me and cody did some wheeling. It doesnt do it when it's cold, but gets louder when it warms up. It gets pretty quiet when under load, but is very noticeable when coasting. It still runs ok, just knocks.

I pulled the valve covers and everything looks good there. I also tried adjusting the valves, but it didnt help anything.

I havent done a compression check yet, my tester is back home. Do stuck rings typically show up on a comp. test?

My only other guess would be a loose rod bearing.

Anyone have any other ideas? I wish I could just completely rebuild it, butI need to get this thing up and running again so I'll have something to tow my junk with in a couple months. Unless someone has about 3 grand they want to part with. 1funny1
 

·
Mas Tequila
Joined
·
18,256 Posts
#4 Main bearing,
 

·
Super Moderator
Joined
·
6,117 Posts
Discussion Starter #3
Is that a common problem?
 

·
Mas Tequila
Joined
·
18,256 Posts
no... but it sounds very familiar to what I had once in my old dually

and a main will knock when the motor goes back to idle, what kinda oil pressure do you have at idle?
 

·
Registered
Joined
·
469 Posts
Change the oil and look for metal, might have knocked the skirt off a piston? Also might check to see that the harmonic ballancer hasent come apart?

Catfish 8)
 

·
Premium Member
Joined
·
13,159 Posts
4x4Freak said:
Is that a common problem?
might be mine started is doing the same thing, i did do a comp test they were all low 120 ??? sounds like a rattle ?
 

·
Mas Tequila
Joined
·
18,256 Posts
low compression won't make it knock...

Wrist pin will knock - Pull off a plug wire and the wrist pin knock will go away

Main knock.. low oil pressure will make a loose main knock

Rod knock.. will do it all the tme

Cracked flywheel ... will sound like a rod knocking

plus what Catfish said above
 

·
Super Moderator
Joined
·
6,117 Posts
Discussion Starter #8
Yes, like a rattle. I did change the oil, didnt notice anything. Oil pressure is good. Balancer also looks good.

I'm gonna pull the oil pan off next. I was just wanting to see if anyone knew of any similar or "common problems" with the BBCs.
 

·
Registered
Joined
·
3 Posts
my sb 350 doing same thing

my chevy 350 is doing the same thing yours is when i first start it it sounds fine after it warms up 5 mins or so it starts knocking down by oil pan.runs ok no oil pressure loss or power loss just starts knockin when cominig to red lights or at idle and fades away as im driving.havent as of yet to figure out problem pullin oil pan of today to inspect it any suggestions would be helpful
 

·
Registered
Joined
·
3,059 Posts
hmm

Are the lifters maybe not holding up after it warms up? Maybe some trash or gunk got into one or more of them.
 

·
Undele' vato
Joined
·
4,970 Posts
sdutch69 said:
when i first start it it sounds fine after it warms up 5 mins or so it starts knocking down by oil pan.runs ok no oil pressure loss or power loss just starts knockin when cominig to red lights or at idle and fades away as im driving.
When you come to a red light or idle situation the oil pressure drops because RPM is low. When the engine warms up the oil is thinner, but the engine isn't warmed up after only 5 mins. Does it knock under a load?

sdutch69 said:
pullin oil pan of today to inspect it any suggestions would be helpful
I would plastigage all the journals on the bottom end to check clearances. How old is the engine?
 

·
Registered
Joined
·
1,199 Posts
Pull the pan and check the bearings. Then you can eliminate alot of variables. Worked on a Vette one time that had a knock. Pulled the pan. Found a nut loose on a rod cap. It probably won't be that simple. But it will be a good place to start. You may be able to do a quick fix. Maybe just change one bearing until you can do a complete tear-down.
Good luck.
 
S

·
Guest
Joined
·
0 Posts
I had a jeep that did that. It was a combo of bad gas and a faulty spark plug on the no. 6 cylinder.
 

·
Registered
Joined
·
3 Posts
Well Pulled All the bearings and replaced them few of them were pretty scored mainly the front two. knocks gone now but kinda wondering what made them get that bad in the first place, kinda thinkin theres a more serious problem that made them go like that.
 
1 - 17 of 17 Posts
Top