logically tracking down a valve train noise



logically tracking down a valve train noise

Postby grumpyvette » January 19th, 2012, 10:33 am

Jack brought his friend over yesterday to have me look at his newly acquired pride and joy, a 1970 Pontiac that some previous owner had installed a 396 BBC engine and TH400 transmission into, now the car runs reasonably well but it sounds like its got a valve train problem, because while its got that sewing machine like rhythmic clicking, at idle, that USUALLY more than likely indicates a solid lifter cam, its not uniform, and adjusting, what would usually be the OBVIOUSLY hydraulic valve train doesn,t make the valve train run quietly.
so the first step I suggested was looking at the rockers ,and after pulling the valve covers too inspect those, we found , he had comps roller tip, stamped rockers on the car. when he purchased the car.so after the valve covers were removed and a quick visual inspection for obviously busted push rods and valve springs etc. was completed,we started looking closely and listening to each rocker individually,, and placing a hand palm down on each rocker as the car idled to see if that pressure changed the sound which might help locate and isolate the source, if one rocker seem looser that might indicate a cam lobe wear issue.
you always need to verify the true problem before looking for solutions,logically you would start with a visual inspection to verify the ignition firing order, ignition timing are good , and doing a compression test on all the cylinders, a careful inspection of the valve train, and re-adjusting the rockers.
logically if you adjusted the valves that were previously too tight, and the compression increased it was the result of a more effective seal as the piston moved up working against sealed valves.
BTW its very common for the stroker crank, counter weights or connecting rods in a 383-400 SBC too touch a stock UN-modified 350 oil pan, and make a ticking or knocking sound, if you don,t clearance it correctly a bit more, with the necessary grinding on the block or a bit of oil pan dimple work with a ball peen hammer on the oil pan rail area, Id also check the dip stick as some touch the rotating assembly,id also suggest inspecting the rockers carefully , a burnt trunnion bearing or rocker ball can sound like a bad rod bearing , a cracked flex plate or exhaust leak can also make a similar noise
and if you have similar issues with an engine, if post CLEAR detailed color pictures of all the spark plugs labeled as to the cylinder they came from it would help diagnose the problem.
If theres some chance you previously over tightened a rocker and caused either valve train or cam lobe damage as a result, locating that damage and correcting it will obviously be required.
ok, step by step, first the plug pictures, then we will get into isolating the cause,if you need to pull and inspect a cylinder head, look for detonation damage, or track down a valve train , fuel distribution or ignition issue.
its just a mater of logically breaking down the problem to each potential source and testing to verify if thats the cause. Assuming youve located the lifter tick to a single cylinder location, do this quick test, look carefully for an exhaust gasket leak, if you don,t find one .swap a couple rocker arms that are NOT near each other and see if the problem stays with the lifter or rocker arm location
a good many lifter ticks are rocker related

do yourself a favor and swap the rocker and push rod thats clicking with one at a different location on the other cylinder head, and see if the clicking moves with the rocker and push rod or remains at the original location, and check the valve spring and rocker stud during the swap process as a first test.you might also very carefully inspect the push rod slot to push rod side clearance , AS I have seen cases where it rubbed and would not allow the push rod to seat centered in the lifter seat during the full cycle thru the rocker arc.
because once we had the valve covers off you could place your fingers on the rockers at idle and feel the roughness there was obviously a mechanical problem ,in many cases a close visual inspection or simply placing your hand on each rocker for a few seconds as it cycles thru its 720 degree repetitive cycle, will allow you to feel and roughness or binding or clearance issues enough to warrant further inspection when you feel the rockers not moving silky smooth, and they won,t move effortlessly if the rocker balls burnt from previously being starved for oil, or the rocker slots binding on the rocker stud.
as with most problems its best to start with the basics and do some testing, its very common to find valve train clearance issues, well before you start any engine, issues like
getting close to spring bind, piston to valve clearance, failing to degree in the cam.
Or having retainer to valve seal clearance issues
or rocker stud to rocker slot binding.
or rocker body to rocker adjustment nut clearance issues,
or rocker body to retainer issues, incorrect rocker geometry from the wrong spring install height or push rod length,that can cause valve keepers to rapidly wear. anyone of which can easily result in a valve train failing or cause it to self destruct.


[b][color=#00BF00] as always its isolate and carefully test,don,t assume you know whats causing the noise, or problem like most guys do, and try to prove it, look at the facts!as you find them,and let them lead you to the cause, don,t ever assume a new part can,t be defective or that you could not have installed it incorrectly, WE ALL SCREW UP OCCASIONALLY!. THINK THINGS THRU,BE OBSERVANT! Id suggest you pull the valve covers, and carefully inspecting the rockers and valve train components for indications of excessive wear,and look at the valve springs and check for coil bind , and rocker to rocker stud clearance,and rocker to jam nut clearance, rocker to retainer clearance,especially if the cam you installed has over .480 lift and your still using the stock valve springs,and then place your hand on each rocker as the engine idles and listen for changes in the sound and feel the rocker movement, a defective or improperly installed rocker arm,or one binding on the jam nut can and will make that sound and exhaust rockers are more prone to fail, if you adjusted the rockers without having the engine idle try it the old way at idle ,yeah, I know,what you heard, try it any way.
you might also find that pulling one spark plug wire off the distributor cap at a time and replacing it then moving to the next and removing that one, etc. etc. will help you locate the cylinder causing the ticking sound, by the change in sound when that cylinder does not fire.
you might also do a compression test and check your ignition timing curve, look for vacuum leaks and post clear detailed pictures of each spark plug labeled as to the cylinder as its condition can tell you a great deal about the combustion in that cylinder

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BE aware you need to verify rocker adjustment lock nut to rocker slot clearance and yes it varies even with the same manufacturers different rocker designs
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at times lash caps or longer push rods will be needed to change the valve train geometry to gain rocker clearance or get the proper geometry
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AND YES CAM LOBES AND LIFTERS FAIL..even ROLLER LIFTERS
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related info
viewtopic.php?f=52&t=181&p=215&hilit=broken+rocker+stud#p215

viewtopic.php?f=52&t=6237&p=19552&hilit=broken+rocker+stud#p19552

http://www.hotrod.com/how-to/engine/ctr ... ubricants/

viewtopic.php?f=44&t=4949&p=13698&hilit=broken+rocker+stud#p13698

[/b][/color]
LIKE THESE which had worn to the point of being junk due to low oil flow rates
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these four pictures below are off the internet but notice the heat discoloration on the rockers, and Ive seen more than a few roller tip stamped rockers fail over the years
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looking closely I found several with loose roller tips that looked about ready to self destruct and two had obviously heat scars and rough rocker pivot balls that at some point had been run with limited oil flow to cool them, looking further it seemed rather obvious from the layer of internal sludge that previous maintenance and oil changes were less that frequently done, I suggested after pointing out the impending valve train failure that he replace the rockers,and do a oil and filter change and an engine flush, as the current parts were a disaster waiting to occur.
now let me be clear here I,M NOT suggesting a commercial solvent engine flush that breaks loose sludge as that frequently causes problems I,M suggesting he drain the oil, replace the oil filter and fill the car with 4 quarts of 10w30 oil and 2 quarts of MARVEL MYSTERY OILand let it idle with that mix in the engine for about 30 minutes than take a short 30 minute drive , and drain the oil and replace the filter again with 4 quarts of 10w30 oil and 2 quarts of MARVEL MYSTERY OIL as its sure to remove a good percentage of the sludge without doing much if any engine bearing damage, then to run the car for the next 2500 miles and change the oil and filter, to remove the remaining sludge. I also removed the push rods one at a time and used carburetor cleaner solvent and high pressure air to clean sludge out of the interior passages
I had him purchase new roller rockers pbm805-16 from erson and in the mean time gave him a set of used factory stamped rocker arms to get the car running, Id also suggest you closely inspect rockers for wear and rocker stud to rocker slot wear or contact markings
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read these threads also
viewtopic.php?f=52&t=7716&p=29797&hilit=broken+valve+springs#p29797

viewtopic.php?f=52&t=126&p=35548&hilit=longer+slot#p35548

viewtopic.php?f=52&t=181&p=19781&hilit=long+slot+rocker#p19781

viewtopic.php?f=52&t=5931&p=18267&hilit=long+slot+rocker#p18267



http://www.pbmperformance.com/store.php?catId=24

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the difference in engine sound even with the stock rockers, I provided after the engine flush and fresh oil was amazingly smoother and softer, very noticeably better
IF YOU CAN,T SMOKE THE TIRES AT WILL,FROM A 60 MPH ROLLING START YOUR ENGINE NEEDS MORE WORK!!"!
IF YOU CAN , YOU NEED BETTER TIRES AND YOUR SUSPENSION NEEDS MORE WORK!!
grumpyvette

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Re: logically tracking down a valve train noise

Postby grumpyvette » March 26th, 2013, 10:00 am

IF your not getting oil flow at the rockers, do a few basic tests, don,t assume anything!
If you start getting a noise you don,t recognize from any engine, shut it down instantly and determined the source of the problem, clacking or tapping , especially on a new engine, it means something some wheres not correctly clearanced or adjusted.
ARE you 100% sure the push rod feed holes line up with the oil feed holes in the rockers at some point in the engines rotation, can you stick a small paper clip wire thru the oil feed hole in the rocker tip so it goes into the tip of the push rod, and have you used solvent and air pressure to flush out the interior of the push rods to verify oil can travel up thru them?
try to isolate the location, is it a loose fly wheel, loose rocker? is it a belt driven accessory coming loose?
simply removing the valve covers and placing your palm firmly on each rocker while the engine idles will quickly let you locate a loose rocker, by feel or change in the sound.
try backing off on the adjustment nut as the engine idles to the point the rocker clicks noticeably then slowly tighten just to the point the noise stops , then add only a 1/4 turn, and see if that doesn,t cure the oil feed issue
There is an oiling hole in the tip of the rocker that feeds from the lifter to the rocker, as the lifter rides up the cam lobe the spring compressed the oil trapped in the lifter, forcing it up the push rod, that oil in the push rod has to, at some point, line up with the hole in the push rod to rocker oil feed hole. Maybe its not lining up and thats why theres no oil coming out, it can,t, if the holes don,t line up at some point in the rotation.
look for exhaust gasket leaks, and keep in mind it may be an indication of something really bad like a bearing failing , or a busted valve spring or busted rocker or piston to valve contact, or something minor like a loose flex plate bolt, but in every case YOU NEED TO LOCATE THE PROBLEM!
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flat tappet lifters are designed to spin as they pass over the rotating cam lobe to reduce friction, they are not centered over a slightly beveled cam lobe center line
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read some related links

viewtopic.php?f=52&t=7716&p=29813&hilit=busted+spring#p29813

viewtopic.php?f=50&t=609&p=26934&hilit=reluctance#p26934

viewtopic.php?f=50&t=5893&p=18037&hilit=reluctance#p18037

viewtopic.php?f=87&t=4687&p=15289&hilit=reluctance#p15289

viewtopic.php?f=52&t=181

viewtopic.php?f=71&t=447

viewtopic.php?f=44&t=799&p=1161&hilit=erson+break+in#p1161

viewtopic.php?f=71&t=2400
IF YOU CAN,T SMOKE THE TIRES AT WILL,FROM A 60 MPH ROLLING START YOUR ENGINE NEEDS MORE WORK!!"!
IF YOU CAN , YOU NEED BETTER TIRES AND YOUR SUSPENSION NEEDS MORE WORK!!
grumpyvette

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Re: logically tracking down a valve train noise

Postby grumpyvette » April 30th, 2013, 1:15 pm

navygunner08 wrote:Hello,

A couple weeks ago I posted about some rocker arm issues. Grumpy suggested I bore out the pushrod hole with the louis tool. I did that and it helped tremendously. For some reason though my rocker arms will not stay adjusted. They will be fine for about 100 miles and then I will have to re-adjust them. Im thinking the nuts and locking key are backing off. Does anyone have any suggestions for correcting this? Should I just adjust them and put lock-tite on the stud?


the symptom could indicate the rocker adjustment nuts getting loose but it could also be the result of lifter and cam lobe wear issues that are causing the slack in the valve train.
the first step in diagnosing the problem is a quick visual inspection of the rockers and valve springs , put a strait edge like a yard stick across all the rocker studs to verify they are all at a similar height,Use a pointed punch and put a mark on each nut at 12 o'clock, on the rocker nuts if you suspect they are slowly backing off, causing the slack in the valve train,Drive it for a while then check to see if the punch marks are still at 12 o'clock.
I find so many guys ignore the obvious here and assume its the rocker nuts backing off when it can be and frequently is related to cam lobe or lifter wear or rocker studs pulling out, which gets ignored until its extremely obvious, wear or parts failure.
place a metal strait edge like a carpenters square on all the tips of the rocker studs, they should be very similar in height if you find ones significantly taller that may indicate a loose rocker stud.
if you look closely at the number of threads on the rocker studs sticking out above the rocker nut they should be very similar between the separate individual cylinders,on all the intakes and all the exhaust rockers, if you find one or more adjusted significantly lower yet the tips are the same height its frequently a good indication of cam/lifter lobe wear.
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If you suspect the rocker adjustment nuts are slowly getting loose, after you get them correctly adjusted mark them all on the same location, with a nail punch so you can easily see if they have moved, like with the tiny blue dots I placed on the rocker nuts in this picture I posted ABOVE


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flat tappet lifters are designed to spin as they pass over the rotating cam lobe to reduce friction, they are not centered over a slightly beveled cam lobe center line
notice when the rockers are adjusted all the rocker adjustment nuts sit at approximately the same height on the properly installed rocker studs,regardless of rockers style used, if thats not the case a rocker stud may be pulling out or bents or a rocker or valve mis adjusted or a spring or retainer might be loose
ndv wrote:Thanks GV!

With this information and the research I did online. I adjusted the pushrods to zero lash with 1/2 turn preload.

A short run with the valve covers off, clips on, it kind of sounds like a quiet typewriter (for those of us old enough to remember those :P ). But you have to get your ear down close to hear it.

With the covers on you can't hear the valves much.

If a valve is in the open position I cannot spin the pushrod.
If the valve is close I can spin them but there is no lash (no up or down movement).

Starts right up and runs smoothish. Smoothest since I've owned it, doesn't gallop or buck as much as before.


I really appreciate the tech data GV.

I'm almost there. But I have this "ticking thump" in the driver's side valve train. If you get close you can hear and you can feel it in the valve cover. Only issue is it only happens when the cover is on.

I'm going to recheck the lash on the driver's side to see if something is amiss.



if it "only happens when the valve covers on"
Id strongly suspect a valve train clearance issue relating to a rocker contacting the inner surface of the valve cover, now theres a huge selection of valve cover designs and some have noticeably more internal room than others, id expect a close detailed inspection would show indications of a contact or clearance issue. it might be something cured easily with a thicker valve cover gasket or a bit of belt sander time on the offending rocker in the appropriate area to gain a couple thousands extra required clearance or you might need a different valve cover design, or a change to different rockers or your rockers and push rod guide plates might be mis-alighned, some rockers have oil separators or breather extensions that extend down between the rockers that can cause rocker clearance issues, big block rocker covers also have drip tabs that interfere with rocker movement

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http://www.hotrod.com/how-to/engine/ctr ... ubricants/

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IF YOU CAN,T SMOKE THE TIRES AT WILL,FROM A 60 MPH ROLLING START YOUR ENGINE NEEDS MORE WORK!!"!
IF YOU CAN , YOU NEED BETTER TIRES AND YOUR SUSPENSION NEEDS MORE WORK!!
grumpyvette

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Site Admin
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Posts: 14105
Joined: September 14th, 2008, 1:40 pm
Location: florida


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