Rod Knock or noisy topend?

[TheRBguy]

So i have been reading a bunch of threads on here about rod knock and noisy top ends in an Rb25, but none of them really seemed to be doing the same thing mine is, it only does it at idle when it is cold it goes away as soon as its warm, it is not really that loud but just a steady tick, it is not my exhaust manifold because i just fixed that, all i want to know is should i worry about this? and is this the start of rod knock or just a noisy top end? Or if there is already an existing thread about this could you please point me in the right direction thanks.

[putang29]

I had a similar problem with my Z before and a very common cause of this is usually a sticky lifter, something that is annoying, but not hazardous to the motor. A good trick for this is to get a 3-6inch piece of 2x4 and hold it over each cylinder with the motor running and put your ear up to the other side of the wood block. It works kind of like a stethoscope and lets you hone in on what cylinder the noise is comming from. If its a small very discrete ticking sound, more than likely its one of your valve lifters not getting the oil it needs on the top end. This is more noticeable when the engine is cold because the oil has not reached its full density and ran thru the lifters to fully lubricate it. If its a deeper, more pronounced knock however, youve got yourself a rod issue. Thats all I got for ya, good luck.

[TheRBguy]

The reason i belive its not a rod bearing is because it only does it when its cold and completly quits when its warm and runs smooth and quite, you would think if it was a rod knocking it would not quit, thanks for the info i will try that board trick.

[putang29]

yea dude its a lifter tick then. The exact same thing happened in my Z. Its not a problem tho. Some guys in the Z community recommended I run a heavier weight oil to help with it. Some said seafoam too tho. Both couldn't hurt to do, as long as the oil weight isn't extreme, maybe 10w30 or something instead of the 5w30 to help when its cold.

[ItzGenX]

Most likely it is a sticky lifter. Cold oil takes a while to really flow into small holes, esp to pump the lifters up. Cold oil also holds larger bubbles, so air gets caught til the oil thins out to untrap the air. One thing you can do about it is do an oil flush to knock all sludge loose.

[TheRBguy]

Ok thanks guys that is a load off my shoulders, i also live in PA so it has been really cold here so my oil is definately really thick when i start it.

[l0nestar]

My 25 does the same thing until the oil has been warmed up for a while. Sometimes I even still hear a slight tick. nothing to be worried about.

[Carl H]

def a lifter issue...i know i have a few sticky lifters that drain off after being run...hot start its like a windup clock under the hood for about 5 min!

[TheRBguy]

Yeah mine only does it when it is cold as soon as it is warm my engine makes no noise what so ever now that i got my leaking exhaust manifold fixed.