Engine Chatter

[BeermasterJon]

I have a 1967 Plymouth Belvedere II with a rebuilt 318 in it. (engine was rebuilt about a year ago) And ever since I rebuilt the engine I've been getting a chattering noise. It only seems to happen around 65 or so mph. If I slow down or speed up the noise will disappear. Oil level is good and oil pressure is about 20 psi @ 500 rpm and about 45 psi @ 1000 rpm. Now, when I rebuilt the engine I replaced the camshaft, the lifters (hydraulic), the springs and the shafts the rocker arms ride on. And reused the pushrods and the rocker arms. (now Im thinking I should of just replaced them too) But the other day I ran the engine with the valve covers off and did not see or hear anything unusual. The only thing I did notice is that the rocker arms do have some play in them when then cylinder is on compression stroke (or whenever the lifter is on the heel of the lobe). And by "play" I mean some forward and aft slide of the rocker arm on the rocker shaft. Should it have "play" in it like that? Could it be the rocker arms are knocking into one another? And with hydraulic lifters, can there be any play in the pushrods? Now Im not talking about a lot of play, but is there a minimum clearance? (Im also not sure if the pushrods got put back in the same cylinders they came out of. Not sure if it matters with hyd. lifters either.) And also, is there a minimum clearance between the hole in the rocker arm and the shafts they're mounted on? meaning, should they be able to wobble on the shaft? Once again, Im not talking about a lot of wobble, but ever so slightly. Im thinking of just replacing the pushrods and the rocker arms with OEM parts, if found too far out of clearance. Im not looking to upgrade or anything, just want the cheapest fix. So if any one has any ideas or can point me in the right direction that would be great. Thanks for your time. ~Jon

[warlockpowerwagon]

I hate to say this but I have heard rod bearings clatter at speed when they are loose. Step on the gas and the clatter disappears, decelerate and the clatter disappears, cruise at steady 50-60 mph and distinct clatter.

[cuda66273]

Things that clatter in the dark....

Wrist pins
Bearings
Piston slap
Lifter colapse
Wrong preload on lifters
Shafts installed backwards and not getting oil to rocker arms
Timing chain whacking the cover
Oil slinger not installed right
Fan hitting shroud
Water pump bearing
Alternator bearings
Flex plate loose
Wrong bolt size in convertor
Exhaust rattle

I'm not real impressed with your oil pressure on this new motor....20 pounds?

It sounds like you may have some sort of harmonic vibration, was this motor balanced? Have you checked your harmonic balancer to see if it's slipped on the rubber sleeve?

Why don't you pull the oil filter and cut it open and check for metal....just to be sure.

Just for grins, check the end play on the thrust bearing, I believe it should be .005 to .008

Did they resurface the heads? and how much did they cut?

Can you make it rattle by just bringing the RPM up in the driveway? Does it sound like crank speed or cam speed? Will it rattle at the same RPM in 2nd. gear? 1st gear?

Have you checked your u-joints?

There goes your weekend....LOL

[BeermasterJon]

Thanks for the list of Things That Clatter in the Dark CUDA. Well, I took the car out today to see exactly when all the noise happens and to check some other things. (I rarely drive this car so some of the info I posted earlier was a little off) Oil pressure is higher at idle. 30 psi @ 800 rpm, 35 psi @ 1000 rpm and 65 psi @ 2500 rpm. (but the earlier 20 psi @ 500 rpm does fall into the minimum range detailed in the service manual) The engine noise will not duplicate in the driveway. I ran the engine from idle to 3000 rpm. Accelerating slowly and accelerating fast, nothing. Then I took it out on the highway. If I start from a stand still and ever so slightly accelerate up to 2900 rpm (70 mph) no unusual noises will be heard. But if Im cruising around and I try and accelerate a little faster (which is how I usually drive due to my heavy foot) I will get a chatter between the rpms of 1800 and 2900 (45 to 70 mph). The chatter noise will disappear once the engine stabilizes to the new position of the accelerator pedal. Now this engine chatter is not a ticking noise, so it is not a "timed" tick to crankshaft or camshaft speed. To me it seems like its more of a vibration noise. And its definitely coming from inside the engine. (Im thinking top or front of engine) Maybe something is reaching its natural frequency? And if its something vibrating, could it be the little play in the rocker arms I spoke of in my earlier post? The only other thing I was concerned about in your list was the timing chain whacking the cover. (I only wish it was as easy as the fan hitting the shroud. If only I had a shroud for it to hit. LOL) But could a timing chain get that out of whack to the point that it hits the cover? And if it was out of whack wouldn't it duplicate at speeds with no load on the engine? And to answer two of your other questions, yes the engine was balanced and Im not too sure if they resurfaced the heads. Maybe thicker head gaskets were used causing me to have that slight play in the pushrods? What do you think? And about the ripping the oil filter apart, Im changing the oil this weekend so Ill check that out. (My weekends not ruined yet. LOL) ~Jon

[jkailholz@aol.com]

Have you thought about your rockers hitting the underside of the valvecover. Look for marks underneath on the oil baffles. I've seen some rockers scrape the underside with larger than stock lift and duration. Just a suggestion.

[Glen440]

Could it be pinging? Sounds like it only happens under load.
Bearings will chatter at certain rpm and will do it in neutral. Wrist pin seizing will make a hell of a knocking sound, wristpin coming loose will jingle. I've had the missfortune to have had both wrist pin types fail and heard some bad bearings.
If it is timing try to retard it a bit.