Tick goes away after i rev

[mr frog]

i got this loud ticking sound coming from the bottom end that seems to go away if i rev it up past 3k. it eventually comes back, but after a while of sitting idle. oil pressure seems to be ok. tick doesn't go away when plugs are pulled. tick seems to be twice the speed of timing. any idea of what it would be and why it goes away when revved like that?

[bigjim350]

I would say its either gonna be the lifters leaking down, or more likely loose bolts on the flywheel (common problem) However loose bolts on the flywheel usually sounds like a knock rather than a tick

[mr frog]

i'm hoping it is the flywheel or flexplate. would that be normal for the sound to go away like that after revving it? the sound seems kinda low to be lifters. and don't lifter sounds normally get better after the engine is warm?

[bigjim350]

Well loose or a cracked flexplate would sound like its from somewhere low. And yes most of the times a lifter noise goes away after its warmed up. Although if its a bad lifter the noise from it never goes away until replaced

[mr frog]

i'm pretty positive my flexplate may be cracked, actually... but i just want to know what phenominon makes the noise go away just because i've revved the engine. has the plate warmed up enough to warp to make the tick then somehow straightens itself when i turn it faster?
even the stethescope seems to point to the flexplate... but why why why does it stop when i rev?

[bigjim350]

its all about centrifugal (spelling ?) force. When its spinning at low rpms there is enough gap for it to flex and knock. When it revs the gaps close.

[Joliet Johnny]

So the bolts come loose on one thats never been apart too? This may explain what I had classified as typical XJ noises.

[bigjim350]

Yep loose flex plate bolts are a very common problem on xj's that have never been apart. In fact thats what helped me buy mine real cheap.

[mr frog]

it may have been apart at one point in it's life. i got this jeep for 600 bux... it's been worked on obviously. new gasket on the head, manifold bolts loose, oil residue round the pan. one of the flexplate bolts was pretty loose. i think there is a crack in the center of the wheel. just about everything under the hood is new (radiator, every pump, ignition system) so if it craps out on me i can prolly get more than i paid in scrap.
centrifical force sounds good to me until i get around to unbolting that plate. would i be ok running it for a while with those bolts out and the plate pushed back? it only makes the noise after it gets good and warm

[jeepkid03]

So the bolts come loose on one thats never been apart too? This may explain what I had classified as typical XJ noises.

Yup. I've seen the bolts only be finger tight on XJs that have never been apart.

[LizardRunner]

Factory built may or may not mean proper locktite was used at tightenup time. I always use locktite red on bolts that aren't going to be coming out on a regular basis and blue on the ones that will or might. Proper torque loads stretch the fastener and it's been my experience that car factories usually think that is enough to keep fasteners from working loose, which is not my experience.

[amunoz]

i am having the same problem but the ticking is always there, well, only when I am driving not when its just parked/neutral. and the faster I go the faster the thinking noise

[bigjim350]

Does it sound like it could be an exhaust leak "tick"