I have a situation where I'm getting a tapping after the engine heats up and the oil thins. My gut, and several people on this board, are saying lifter. I would like to confirm this with some understanding. I've seen terms like "pumping up" and "collapsing." The lifters go between the cam lobes and pushrods right?

 

i understand it somewhat myself but i can't really explain. i am not a learner who can teach, more of the student type.

however pumping up is where the oil pressure is still high while the engine is spinning at lower speeds. so when your going down the strip with your m6 and you shift saw 500 rpms past redline the engine is working really hard. (oil pressure is compesating for the lash at all times, but is at its fullest right now) so in return the oil pressure for a fraction of second is still pushing through the valvetrain at its max. the valve then "floats" (suspended so to speak as if say the intake valve was being opened longer then it should be after the lobe has passed the point of the lifter). this would cause the piston to met with the valve since it doesn't seat itself...... causing a bent, broken, etc valve. so pumping up is excess pressure....... please if anyone finds errors in this let him and i know. i am a student at this, but this is my basic understanding. i would love to be corrected and taugh a proper way...or a have it explained in a simpler manner.

as for collasping i am not sure...but i think it would be a lack of oil pressure. if i am right, getting high in the rpms probably wouldn't be likely.

these reasons are why people go with solid rollers to rev higher and avoid these problems, but if valvetrain noise is a problem this wouldn't be your route. not to mention you must set lash roughly every 800-1000 miles, not hard but probably would get to you if you daily drove your car... doing it every week and all.

and yes....the lifter rides on top the lobe and the push rod is on top of the lifter.... hitting the rocker arm pushing the spring down and moving the valve. valve locks, retainers, etc are what holds the spring and valve into place..... maybe missing something.... just felt i could give me 2 cents and mabye we both can get a better understanding.

good luck and i hope someone can better help you.

erik

 

thanks man so then if oil were to leak out of the lifter somehow, I would be getting a lash issue which would tap.

 

yes roughly it would, in theory it would convert to a solid roller. however where the oil is leaking to is an issue i would strongly look into. even if its not even moving anywhere (its going somewhere obviously). maybe its blocked but a broken part. a solid roller has no provisions for oil since it doesn't use it. so right now you have no way to adjust the lash, stay off the gas for awhile to its fixed. not to scare you but pay little now or pay lots later.. just what i would suggest... i'm no mechanic, but like most things in life its better to play it safe then ignore it. ignoring anything small tends to cause big problems in the end...

again this is to the best of my knowledge that i've come to understnad over the years. so its what i can tell you, if someone could put more of an indepth perspective i would love to read up on it.

but yes.... a tap or 'tick' would occur. anyways good luck and get that fixed soon. the more you use it the faster you loose it

erik

 

Lifters can "collapse" meaning they no longer can pump up with oil, and yes you will have a tapping noise when this happens. I know this NOT from my broken POS LT1 car, but from my LAWNMOWER of all things! It has smallblock chevy standard hydraulic lifters. The one bad one I pulled out of it was "collapsed" where the good ones could all be compressed by hand, and have a spring to rebound them. I think the spring broke in this one.

My first post on LS1tech...

 

It's more common for the LSx engines to have bent pushrods than collapsed lifters. It sounds the same as the ticking you are describing and occurs when the engine is mechanically overreved. A GM tech shifted from 3rd to 2nd at WOT and bent three pushrods in my engine on a little "test drive" that he decided to take. I would pull the pushrods first and check them before removing the heads to replace the lifters. Just my $.02

 

I had a bent pushrod before. this only happens once the engine is warmed up. Welcome to LS1tech dieselgeek!!

 

see there you go ken.....it sounds like pushrods, not uncommon ether. pick a book on amazon.com called ls1/ls6 peformance. also cartek publishing makes something similar to this, still need to check it out but ordering soon!

books help, its good that the ls1 is so popular that you can buy books on it!!!

erik

 

bent pushrods tap all of the time. It's got to be a lifter since I've been cruising around for a week and it hasn't got any worse. It actually seems to be happening a little less and it comes and goes on longer trips so I can't think of anything other than a lifter that could be wrong since my car is still running fine.

 

I see that you have a ported oil pump. Did this start after that was installed? If so you may have a cut/damaged o-ring. This can allow air to enter airating your oil and cause your lifters to make that tapping sound.I am chasing the same problem right now.

 

ya I'm going back in to check the o ring when I swap in set of used lifters I bought. I'm just waiting for my parts to get here. I also partially stripped one of bolts that holds the oil pump together. It still had 6 ft/lbs of grab left in it so I just left it. I'm regreting that one. I'll be putting in a helicoil and checking the o ring first, and then if I still get the tappy tap, I'll be going in after the lifters. Fun fun fun!