Top end knock
 

I have a knock in the top end. Replaced rocker pivots and bridges. Didn't fix it. thinking it might be pushrods. Any other ideas?

collapsed lifter, or a bent pushrod, or bent valve. most likely a collapsed lifter. did you pull the rods when you replaced the rocker pivots/bridges. also rocker pivots have a short break in time where they will make a slight tick until they seat...

maybe a rist pin noise in the piston pin!??

better hope not...this would mean the wrist pin is failing and your in jeopardy of throwin a rod and/or some serious piston slap :cursing:

its more than a slight tick. its pretty loud. comes and goes sometimes when its cold and sometimes when its hot.

Pull the valve cover and start it, you may spill a little oil but it should become very obvious where the noise is coming from.

rist pin! just drive it it will fine it wont break i have a 4 runner same noise and its been like that for years

x2....pull the rods and lifters and inspect both, that sounds like a collapsed lifter (loud ticking when cold/at idle is because of low oil pressure and ticking while hot is due to low oil viscosity) meaning your not moving enough oil through the lifter.

i've got the same noise and also replaced pivots,bridges,rocker arms and rods. when you guys say 'lifter'....you mean the tappets at the bottom of the pushrod??if so is it possible to replace them without pulling the head??

yep flat tappet cam uses hydraulic lifters.... and get one of the magnets on a stick and use that. get em to start to pull out then give em a quick yank and they will pop right out.

Hope your noise turns out better than mine...

Pull the engine completely apart and dump everything out on the lawn, then put it all back together again. May not fix it, but it will impress the neighbors.

my neighbors just *****ed n moaned about me workin n cussin in the front yard at 2 in the mornin....your neighbors must like you hehe

nope...not on a HO 4.0....Head has to come off.......

ok then so what is it?? the motor is a fuel injected 4.0. its in an 88 xj. My first thoughts say that i cant do it otherwise i would have tried while replacing the rest if the parts. has anyone done this or is it just theory??