Updated. You think Mikie's video's bad? Listen to my truck :)

[Gawdzilla.]

The original first post here was a video w/the knocking my motor (SBC 350) made.
In the essence of follow thru since most of these problems are never "closed" here....well, finally got the motor all torn apart. the block is cracked in one of the cylinders. found it when the ridge cutter was going "click... click.....click." what the? Da**it, Bobby...
six o'clock in the morning and the boy still ain't right!
the rod bearings WERE somewhat worn, and the rods are definitely out of round. The main journals are also showing signs of oil starvation. The DSPO bought the wrong oil pan and I wasn't able to see the pickup tube being pushed up out of the bottom of the pan by the baffle when I did the gasket, so never knew it was a problem.

Anyone near me have a good 350 block on hand for me??

[ April 03, 2004, 10:16 PM: Message edited by: Gawdzilla ]

[Stuka]

well, sounds like a rod knock to me, since it gets louder when you get down underneath. and most likely from one of the driver side cylinders. I have heard some colapsed lifters sound like that, but the sound goes away generally after the lifter finally fills up with oil (generally after a few minutes of running and it warms up) I would stick a stethyscope to the block and see if you can track down an exact location. That will tell you if its comming from above or below.

[Gawdzilla.]

thanks Stuka, I guess I'll have to look into that. Love my oil pan....doesn't want to seat flush.
The lifters are new so I doubt it's collapsed already.

[Gawdzilla.]

hey how come you can watch it from the link and I can't??

[Stuka]

did this start right after putting in the lifters? if so, did you prime the lifters correctly?

I had to put the link manually into windows media player.

[Gawdzilla.]

nah, the noise was there before. I think I primed them right...lubed em before putting them, cam break in procedure, etc. (new cam too)
I'm changing the format so anyone else who's interested but not necessarily tech savvy can 'watch' it.

[Merc69]

The souind is like the one I had on PsyOp. It was the result of running way to rich and resulted in washdown on the #8 Cylinder. This caused the piston run very hot and skuff the cylinder wall. Result, remove engine again and rebuild again. Now running great. Get the carb adjusted after the rebuild.

Might not be your problem but worth checking. Hope it works out easier for you.

[Gawdzilla.]

ouch. rebuild is the last thing I wanna do!

[Rogue]

sounds like rod

[fredws]

Yep, sounds like a rod to me as well

[powerhouse]

Sounds Like My Jeep Are you sure you did not sneek over to my house and film My Waggy

[Gawdzilla.]

so if it's rod, would replacing the bearings resolve it or am I just p***ing against the wind?

[Gawdzilla.]

Originally posted by powerhouse:
Sounds Like My Jeep Are you sure you did not sneek over to my house and film My Waggydoes your waggy have a chebby motor? lol

[Rogue]

pi**ing - no crank or rod will wear round - new bearings = band-aid approach and not really fixing root cause of problem - have crank polished or reground and new bearings along with hot tank block than you can sleep at night, and don't go high volume oil pump unless you have a larger than stock oil pan other wise pump will pump it out of pan faster than it can drip back in

[Gawdzilla.]

ok. so is there any way to tell how long I've got before it ribbits (croaks)? I have no idea the actual miles on the motor.

why hot tank the block?

[ January 08, 2004, 01:42 PM: Message edited by: Gawdzilla ]

[Bob Davis '80 Chero]

It's croaked already and doesn't know it. I bet it'll go before you have the money saved to fix it; which would be my luck.

[Gawdzilla.]

Originally posted by Bob Davis '80 Honcho:
It's croaked already and doesn't know it. I bet it'll go before you have the money saved to fix it; which would be my luck.so positive!!! I'm gonna crack it open and look at the rod bearings this weekend I think.
most of the time it only makes short trips anyway.

[Cory]

video is locked for me. However, if it is the rod, fix it soon. I thought I'd have time to fix the rod on my 258, the day I got it from the PO. That day on the way home, blew the rest of the rod through the block.When we pulled the motor, we picked out pieces of the rod about the same size of a broken 8oz. glass, smashed on tile floor.

[Rogue]

its knocking its already out of round - no gauge for how long - kinda like asking how far you can drive on a tire with no tread? the longer you ride it the more it'll cost

[tgreese]

Hi Ed - I listened to your "video" - lol

I counted 88 knocks in 20 sec, or very approximately about 264/min. If your idle speed is about 600, that means the knock is on every other rotation. I could think of three things; rod bearing, piston pin, or piston slap. If it's piston slap, it should be louder when it's cold since the piston expands in the bore when warm. My guess at how to tell the piston pin from a rod bearing is that the rod bearing would affect oil pressure more, and you'd see it at the gauge. There are ways of telling the two apart, and I've read some response about it here, but I can't 'member the specifics. Something to do with the effect of acceleration/deceleration and engine speed on the noise.

The definitive test for the rod bearing would be to pull the pan, inspect the bearings, and Plastigage. You could try switching to 50wt + STP in the meanwhile...

SBC have a cast or steel crank? Could it be something simple like the fuel pump?

[ January 08, 2004, 02:42 PM: Message edited by: tgreese ]

[Gawdzilla.]

Originally posted by RogueStar:
its knocking its already out of round - no gauge for how long - kinda like asking how far you can drive on a tire with no tread? the longer you ride it the more it'll costlol got one of those too!
If I'm going to go thru the trouble of pulling/disassembling to have it hot tanked- isn't that 50% of a rebuild anyway?
What's the best compromise of time and $. I have more time than $... but not a whole lot of either. Drop the crank /machine to(?) and do the bearings?

[tgreese]

BTW nobody's mentioned pulling the plug wires one by one to isolate the noisy cylinder.

[Gawdzilla.]

Originally posted by tgreese:
Hi Ed - I listened to your "video" - lol

I counted 88 knocks in 20 sec, or very approximately about 264/min. If your idle speed is about 600, that means the knock is on every other rotation. I could think of three things; rod bearing, piston pin, or piston slap. If it's piston slap, it should be louder when it's cold since the piston expands in the bore when warm. My guess at how to tell the piston pin from a rod bearing is that the rod bearing would affect oil pressure more, and you'd see it at the gauge. There are ways of telling the two apart, and I've read some response about it here, but I can't 'member the specifics. Something to do with the effect of acceleration/deceleration and engine speed on the noise.

The definitive test for the rod bearing would be to pull the pan, inspect the bearings, and Plastigage. You could try switching to 50wt + STP in the meanwhile...

SBC have a cast or steel crank? Could it be something simple like the fuel pump?LOL gotta love having a physicist's brain lookin at stuff!!! smile.gif

I can pull the pan and inspect the bearings via the shake test...if that passes then what?
Never used a plastigauge so a tutorial would be nice. I don't know if the sbc is cast. what diff does that make?
The sound almost completely diminishes after driving for over 30 mins.

EDIT: believe it or not I did do a search- so I saw that test on other knock posts so I tried it. Couldn't really tell a difference. I can try again tonight I suppose. smile.gif

[ January 08, 2004, 02:49 PM: Message edited by: Gawdzilla ]

[tgreese]

Huh. I'd think a rod knock would get _worse_ as the engine heats up and the oil thins out.

You won't be able to tell anything by shaking the rod end. There's only a noise when the cylinder fires, so it takes a lot of force to squeeze the oil out and make the rod knock, if that's what it is.

You just take the caps off and look at the bearings first. The should be the same color across the face and not obviously hammered by the crank.

Plastigage is a little rod of plastic that you put between the bearing and the journal across the width of the journal. When you torque down the cap, the rod flattens out more or less depending on what the clearance is. You then remove the cap and compare the width of the squashed plastic with the gauge on the package. Should be the same width across the journal, and clearance within spec. You can measure at different points around the journal, and it'll give an indication of roundness too.

Steel cranks are harder (and stronger) than cast iron cranks. I have read of steel cranks spinning rod bearings and then being put back together with some hand polishing and new bearings, and being ok. Controversial topic.

[ January 08, 2004, 03:07 PM: Message edited by: tgreese ]

[Rogue]

yea definetly do the shake test (up/down play not good - also bad rod usually darker in color than rest ) and what Tim said also about the fuel pump it sounds weird but it wouldn't be the first chebby fuel pump that sounded like a rod knock, there are a lot of things you can try and do before yanking this engine - it does "sound" like a rod knock personally what I would do is to get a long piece of hose and use it as a stethoscope and see if you can isolate the noise to an area, pulling plug wire has rarely worked for me and shorting the plug wire out is much better option to avoid coil damage ( only takes one good full field to make a microscopic crack in the case of the coil - then you'll be chasing down a mysterious random misfire - especially fun on an HEI ) a piston pin usually sounds a more "pingy" and last you said it goes away when fully warm? it could very well be piston slap in this case you should be able to put your "stethoscope" on the side of the block to hear it ( note- when doing the stethoscope thing you'll hear the noise everywhere - look for the loudest point )

[Gawdzilla.]

it "seems" to go away when fully warm- at least it's much quieter. I wasn't able to hear it very clearly myself until I recorded it. Too much background noise w/the exhaust and the water pump racket.
Never looked at the fuel pump- I'll try that.
and thanks for the noise note- (and tim thanks for the plastigauge tutorial) I needed that because I DO hear it everywhere w/my steel pipe- it seemed louder/more crisp on the intake mani.

[ January 08, 2004, 03:46 PM: Message edited by: Gawdzilla ]

[GWDriver]

Strange,

Sounds like my GW when it's at idle. I've still got good oil pressure though. Sound comes and goes in intensity. Sometimes it's almost quiet then it gets loud, etc.

[Stuka]

Guy at work had a bad rod in his 350, after fully warmed up the noise went away unless under heavy load. Did it the most at startup. Once going it went away for the most part.

[Gawdzilla.]

update info on first post now.