Gumby

Look for expert opnion on sudden engine noise

history, well cared for V8 [carbed], was out driving several nights and all was fine, engine purred like a kitten, drove home parked it.

next day try and go out and its a death rattle on start, not like a simple lifter didn't pump up, like a bunch of them making an awful racket.

one suggestion was the fuel pump, [ busted spring making it slap ] that wasn't it.

removed valve covers and nothing is out of place, start car and even then it all looks normal, push rods all spin, didn't see allot of oil but was just idling.

Put a gauge on it and oil psi shoots right up to 30-40psi

IM just having a hard time wraping my brain around it.

running fine one day, 12-14hrs laters its a racket of noise.

8Mike9

Maybe make a sound clip of it..."death rattle"..."awful racket", isn't much to go by

Also mention the general area the noise(s) come from.

Gumby

I start the car from inside, walk out then open hood

Purring like a kitten, parked, thne this noise on start up...

NY87Iroc

iTrader: (1)

loose rockers? wiped cam out??

8Mike9

It sure does sound like valve train, possible a rocker nut backed off..but sure sounds like more than one, which would be odd.

Do you know how to check valve lash?

I'd check first, before adjusting.

Gumby

Pulled valve covers, all is normal.

almost like oil isn't getting to the valve train, so the lifters can't pump up, yet I have good pressure.

8Mike9

Let's look at it this way, if you can spin all the PR's, then the lifters are too loose, in General, you bring a cyl to TDC (both valves closed) adjust the rocker to "just touch", while spinning it, then 3/4-1 turn more.

So, if you can spin them all, you might be right, as something has plugged an oil passage/etc, and the lifters are not pumping up, IMO, you have nothing to lose by trying to readjust the valves, as if something has plugged up inside/spun/etc, the engine will still have to come out to be checked/fixed.

Gumby

never said I could spin them, I said they spin as normal when the engine is running.

They are not lose. all is tight and as normal.

mmadden55

Check your harmonic balancer.

SouthSide2

Remove belts to eleminate accessories. Cracked piston skirt? I have seen it. Loose converter bolts, unlikely. Timing gear? Maybe. Plastic ones have been known to fall apart and allow the chain to slap the cover.

8Mike9

Never noticed them spinning before, but to be honest, never looked.


Try this...VC off, push down on the rocker while it's idling, see if sound diminishes/lessens...you should be able to get 8 or so lifters at a time.

Gumby

Sorry I forgot not everyone knows my builds beyond my Firebird,

I have shaft mounted rockers, there is no adjustment.

now they can wear out and easily replaced but not all at once while sitting over night.

1-2 making noise sure but everything is noisy.

SouthSide2

I don't know you're build. I assume your sure its valve trian noise. Do you have threaded pipe plugs in all oil passages. If not you may have popped a press in plug loosing oil pressure to your lifters . If you have a high volume pump it may be likely to still have good pressure at the gage's point of reference.

Gumby

Gonna drop the pan at this point and look at the screen.

Drac0nic

Does it sound like it's coming from the back? Could be a cracked flex plate. Check around the bolt holes.

Gumby

Got a local long time several generation local garage guy to come give it a listen, he quickly said one lifter is a bit off and the rest just isn't getting oil. and I do have one lifter that needs a sec to pump up if it has sat for several days but then it will run strong and quiet. [ but how he could tell by ear and go right to it, from a distance ]


First IM thinking, why GOD, everything is new but the body, interior and long block, all rest is new, just put a coat of clear on it, lookin sharp [from 10ft], but maybe thats why, it could be a Big Block Blessing coming.......

But Im hoping the noise goes away as fast as it came, as it was an over night thing. So it wasn't being driven or has moved, just a min or two run. Get oil back up and see how it goes.

Gumby

found hard carbon in oil pick up screen and a big blob of it in pan, right where it would be sucking it up.

so that solves that. [ is the screen suppose to be concave?}


but.... there was also a busted main cap bolt in the pan, the 2nd main cap from front of engine. Only one tiny nick in pan where it dropped, so it wasn't bouncing around in there.

Now this engine runs fine, purred like a kitten before I started this, I romped on it often and no signs of any problems.

Maybe the oil problem was to get me to look in the pan and catch that missing bolt before DOOM happened.

ex-x-fire

Well, what kind of engine are talking about?

Gumby

removed intake, found 2 broken lifters on back 2 cylinders, the cups turned on end.

cam looks great though

intake drivers side, exhaust pass side

86LG4Bird

iTrader: (1)

I hope you're not glossing over this ??
I'd be inspecting that main and any adjacent rod journals before buttoning it back up.

bop11

Did you say you bought a long block for this vehicle? That engine needs lots of work. Was the oil ever changed? With all that buildup I am surprised the rings are any good. I would check concentricity on the crank journals. Probably cheaper to replace the engine. This one needs to be magna-fluxed for cylinder cracks, line bored to true the mains and most internals replaced.

Gumby

All back together and sounds great, just needed a new set of lifters.

But odd how it can run fine one day, then the next on start up 2 lifters top flip over like that. Rest of the lifters felt gummy so I replaced them all, broke them in and all is good.

Bob88GTA

iTrader: (2)

gotta ask....broken bolt and pump screen.......what did you do with them? Just curious. Glad its up and running.

splitty

Some how that crud must of shut off enough oil to not let the lifters to stay pumped up and let them flip over like that. Probably flipped when you shut it off. The broken main bolt would have me nervous. The other bolt on that main cap probably experienced some strain. I would have at least took that cap off and looked at that bearing. And replaced both bolts.

Glad its running alright now.

Gumby

The engine was very clean cept what was in the pan and that was only there cause of how all stock pans are. Its a giant nut welded to the inside of the pan, with 2 tiny holes half way up. Trapping stuff so it can build up instead of flushing out at the oil change. [ the nut should be on the outside. ]

bottom end was fine, bolt had to of been broke for years. replaced bolt and upgraded to a 5/8 pickup.

Lifter break in went fine and its running nice.