Valvetrain noise causing false knock?

[87ttypeV8]

alright well i had this same problem before my timing chain broke...

the car will sound fine at an idle... but if you rev it up you can hear some noise in the valve train... it had a cam in it before... lunati 200-200 but that wiped a lobe

i replaced the TC with a rollmaster double roller... no tensioner..
i put in the comp cams 206-206 cam
some new lifters... cant remember which brand off the top of my head but aggressive performance said they always use them...
stock pushrods... stock rockers... ported heads/intake
this noise appears around 2500 rpms if just cruising around under no boost... if i get under boost... noise goes away?
very odd the worst part of it is that this LOUD noise will set off the knock sensor and it will make its way all the way up to the red... WORST light

if i let off and step on the gas again... no problem... so i am wondering if it is a push rod problem that could cause this or what? this problem didnt occur until i got my car back from the shop after putting in used stock injectors... it was quiet until i got on the gas and then the problem slowly arouse and countinued to get bad...

could the injectors make this big of a problem?
do the lifters need to break in?
push rod problem?
what about an engine mount? not likely
maybe a torque converter problem like a loose bolt but this problem is mainly RPM specific and sounds like it comes from the top area of the engine

i have been chasing this down forever and just need some help

thank you in advance

 

[bigdaddy3312]

ley me know what you find out.... i have just done lifters and valve train(push rods and rockers)and mine has that same style of noise,but i think its my timing chain,it turns into a chatter with mine.....with accel,and gets quiet with out load decel.... but i would love to listen to what it is.....from the top front of the engine.....

 

[gofstbuick]

How did the cam bearings look? I had valvetrain noise, that would create some KR at light boost. When I pulled my timing chain, it was loose, and I noticed a piece of aluminum in the oil pan. The cam bearings started to push out of the juornal. During teardown, I had to pry the cam out of the block. The cam and journals (block and cam) were fine, just all the cam bearings were trashed. I have my short block assembled (heads are not installed), and I noticed the timing chain in now very tight. Even with the bad cam bearings, the cam spun very smoothly. I suspect the valves were not opening enough (with all the play in the cam journals) and causing it to lean out (thus KR) or the valve train noise was setting my knock sensor off.

 

[87ttypeV8]

hmm bearings looked alright... the motor was in the car still and i gave them a quick check and looked fine... no gouges or anything...
the cam came out with ease and was no unnecessary pulling on it except it was a little tight at the very last one... front of the engine bearing...

hmm would injectors cause this?

 

[gofstbuick]

It has 009s, but I had other issues that contributed to the engine failure. The machinist hung the odd rods wrong. I'm in the middle of assembly now, just waiting for parts. I doubt if injectors would cause your issues unless it leaned out. Also, hav you checked lifter pre-load?

 

[87ttypeV8]

no i didnt check preload as i was told not to by a few local sources... IE.. my neighbor

arg

well is there any way at all to check it without pulling the intake off?

is there any way to shim maybe the rocker arm shaft to see if the pushrods are too long?

that would make sense to me but just wondering how i could check w/o pulling the intake?

and does improper preload really make alot of noise... enough to set off the knock sensor?

 

[gofstbuick]

I would think you could check lifter preload with just the valve cover removed, and checking clearances between the rocker arm and valve tip. You would be able to grasp the push rod and spin it to simulate a consistent drag.

 

[87ttypeV8]

whoa whoa whoa...
i like the idea on how you are saying to check it from just the valve cover but not really understandin ya... if you wouldnt mind maybe elaborating more with a step by step kinda thing... this preload thing i dont understand for some reason... i am pretty smart just this whole concept is right over my head... just need it explained pretty good as i am in the dark with what it is and how to check it and what not

thank you for the replys!

 

[gofstbuick]

Rotate balancer to line up with TDC. You should be able to grasp a hold of the push rod and rotate it. There should be a slight drag as you rotate the pushrod. If you're concerned that the lash is not near zero or spec, then loosen the rocker shaft bolts until you can play between the rocker arm and pushrod. Then as you tighten the shft bolts back down, you should feel pushrod close up against the lifter and the gap between the pushrod and rocker arm close to zero or near zero. Then rotate the pushrod and it should have a slight drag on it. Now rotate the balancer to the next cylinder and rotate the pushrods, each should have the same or approximately the same drag as the #1 cylinder set. Kind of primative, but should work in your case, as you're just looking for an excessive gap (as this may cause valvetrain noise) between the rocker arms and pushrod.

 

[87ttypeV8]

alright, well i have sorta done this before.. had the valve cover off and i cant turn any push rods.. they are all very tight...


so i am thinkgin my pushrods are too long and i need to find the correct length... so i was thinking of trying to find some shims for the rocker shafts and then find out what works... then have new pushrods cut and remove the shims or just leave the shims in place?

 

[gofstbuick]

Probably a better idea to use an adjustable pushrod to simulate the the length you need and then build a custom length set of pushrods. Are you sure you're on TDC #1?

 

[87ttypeV8]

no i wasnt on TDC... unless some magical way it was actually lined up that way but i didnt do it on purpose...

the DS is a pain to get off... isnt there any easy way on the passengers... well i will try to DS in a few minutes... adj. pushrod would be easy to tell? i would imagine that i would need 12 of them to make sure eh?

 

[gofstbuick]

Since you're only checking one cylinder at a time, you'll only really need two. Also, before you check the preload of any cylinder, you must be at TDC for that particular cylinder. Of course it will be tight if you're not at TDC for that particular cylinder, the cam lobe may be in a position to begin opening or closing a valve.

 

[87ttypeV8]

alright thanks for the input... i will have to give it a whirl shortly! too much work for me kills the motivation though

i really appreciate ya replying to my posts./.. you are my savior

 

[87ttypeV8]

alright well i got some rocker shaft shims and shimmed the rockers .010 first
no help, so i shimmed them again to .020 again nothing at all... feels like i lost spool up quite a bit... probably because .020 lift has been taken away?
well anyways i then am thinking maybe torque converter bolts and nothing there... all tight as heck
but when i am down there i have someone start the car and rev it a little and it really sounds more like the noise is at the bottom of the motor now... which i dont like

it isnt a ticking but is a clattering.. i dont know how to explain it really but it is noisey, sets off the knock gauge, is RPM and load specific... meaning it comes on around 2200 rpms under normal driving conditions... if i boost it, noise is gone... also noise appears when driving under slight boost, 4 psi, and then i left off i can hearr noise fluttering./...

please help just wondering if a spun bearing does this or a loose piston pin or what... i am stumped and have no money to get it looked at

 

[gofstbuick]

If it is that loud, then buy a pan gasket, pull the pan off and check the rods. When I spun a rod bearing, all I had to do was push on the rod and it moved an obscene amount. Then if it is not rods, use a flashlight to look at the cam bearings. You shouldn't see any bearing s hanging out. Do a visual of the thrust and if you have a dial indiator (with a magnetic stand), check the crankshaft end play. If all is well, put it back together and put new oil and filter into the engine and remove the serpintine belt. Start car up and see if noise disappears. If so, then your belt tensioner may be bad. Then remove the trans shield and check the torque converter bolts. That should complete your check.

 

[MSDGN]

You're asking for trouble by shimming the rocker shafts when you don't know the current lifter preload...if preload was very little or none you've just made the problem worse...before you do any damage get a pushrod checker from Comp Cams or other cam company...you put each piston at TDC of the compression stroke so both valves are closed...use the pushrod checker to obtain zero lash...determine the length using the increments on the checker then add .035 for the preload...order custom pushrods of that length...I have a CC 206/206 and I ended up using adj pushrods because I would have had to order 4 different sizes of pushrods to get the correct preload...you could also use the following since you have shims:

http://www.gnttype.org/techarea/engine/pushrod.html

...either way you are most likely going to have to get adj pushrods or custom length ones...the stock ones aren't the right size...at least in my case they weren't...

 

[87ttypeV8]

ok thanks for the replies.. the torque converter bolts are all tight... i will try to pulley first but i really doubt it since the noise sounds really loud in the back area of the engine only...
arg i hate doing oil pan gasket and this would make it the 4th time ive done it... geez .. but if a bearing was gone down low it would be real easy to tell? the connecting rod would move alot or should i pull the main caps to tell?

as for the pushrods... i will remove the shims... hmm and after i get 2 adj. pushrods... how do i know when they are the correct length... when you cant spin them when the cylinder is at TDC? i am really clue less in this area of the car just because i have never worked on it before... so any help is greatly appreciated



thanks again for help diagnosing the car

 

[gofstbuick]

If the rod bearings are bad (or spun), you'll know it once you push on the rod. You may have to pull each main cap to look at the mains. It would seem like a pain to do it on your back. Especially re-torqueing the main cap. Also, you'll be able to see if there are problems with the cam bearings (best to use a flashlight). If there are major issues with the cam bearings, it will be noticibly visible.
Regarding the pushrods, remove all the spark plugs. Put you finger against the spark plug hole of the cylinder you want at TDC. Have a buddy crank the engine until it blows you finger away from the spark plug hole (or use a remote starter attachment). That is TDC for that particular cylinder. Now check the lifter preload. I suspect the lifter preload is okay. Hydraulic lifters are very forgiving (if you've ever set preload on a SBC with the engine running, you'll know what I'm talking about, and since Buick rockers are mounted on a shaft, there problably needs to be a lot of clearance before it starts rattling).

 

[MSDGN]

To check current preload leave everything as is...with valve covers off get a piston at TDC...make sure it's on the compression stroke...put a straight edge along the top part of the head and butt it up against the pushrod...mark the pushrod...then loosen the rocker arm bolts so there is no pressure on the pushrod and use the straight edge to mark the pushrod again...measure distance between the 2 marks...that will be your preload...you are basically just using the straight edge as a reference point on the pushrod in relation to the head...do this for all pistons...to accurately set the preload you should use a pushrod checker and all I know is when I put in the 206 cam the stock pushrods were not even close to being the correct length...can't remember if they were too short or too long...this was on stock untouched heads...