So, my 94 XJ has a tick which I can't figure out where it's coming from.

It's very similar to BurninBridges's in his first post here:
https://www.cherokeeforum.com/f2/how...ocking-125547/

But I've checked my flex plate bolts and they are all nice and snug.
I also tightened the donut bolts at the header/downpipe and the bolts for the header.

The tick comes after about a minute and is about half the speed of the RPMs, give or take. If I shut the engine off the tick is gone at the next startup. It also all of a sudden goes away when idling/driving, but then slowly comes back (low tick, higher tick, very loud tick, sudden silence, low tick, higher tick...)

It has had it for as long as I've owned it, about 8 months.

I went underneath and checked with a hose and I can hear the ticking/knocking rythm from the oil pan. Checking from top I only hear the lifters and their noise is faster than the tick.

Of course I didn't bring the camera, but the sound is very similar (if not identical) to BurningBridges's.

What could be the cause and what would be the next step?
Flexplate cracked but not visible thru inspection plate?
Rod knock and something about to give?
Lifter completely stuck?
Bearings?

Any help on this is much appreciated, I'm learning as I go along.

edit. Forgot to add, the tick/knock follows the rpm (at half speed) but rarely/never follows over 2000 RPM.
Also, (maybe completely random) it seems to sometimes stop when the electric fan comes on, but not always.

 

Came to think about something, how does a harmonic balancer gone bad sound compared to the prev. vid.?

And to test it, do I just take the belt off to exclude accessories knocking/tapping/ticking and then try and wiggle it?

 

I was about to say. I'd start by removing the belt to eliminate accessories. I can't watch your video at work and I can't quite picture what you're explaining. Maybe when I see the video I can help more.

Pull the oil pan and have a look around.

 

You can usually see the balancer hitting the timing cover.
Sounds like you've got a sticky lifter.

 

I'll start with the accessories and maybe over the weekend I'll have some time to drop the oil pan and check it out – really hoping for some nice clean oil, .

How long can I let it run without the accessories and should it be done when hot or cold?

Ok, I'll check and see if it's hitting.
If anything, I'm hoping for a sticky lifter instead of something deep down.
When checking if lifters do I just take off the cover, disconnect coil and crank it? If sticking the rockers won't move all the way up/down?

Also, when checking for an issue down in the bottom end – would a compression test help? Or do I do the spark plug removal on 1,2...6 and listen for a change in sound?

I'll post a vid tomorrow with the sound.

 

bingo

 

If it comes and goes, it's pretty much gotta be a lifter. The fact you say it's half the engine speed says lifter. Not something you need to be pulling the pan for.

Drain out a quart of oil and replace it with a quart of Marvel Mystery Oil and see what happens to your tick.

 

Rod, bearing and wristpin noises aren't exactly what I'd classify as a "tick". More like a thud or thump...it's a deeper noise than lifters. They don't normally come and go either.

Does sound like you have a lifter that's not staying pumped up. Might be clogged, MMO will help...or might be worn and need to be replaced.
Won't hurt to take the belt off and run it for a half- minute or so just to rule things out. Not much longer than that...no water pump and your temp gauge won't warn you with no water flow.

 

Thanks all for helping out, I haven't been able to go to the garage today (still at work) but hopefully I'll have some time tomorrow.

Btw, I've tried to find MMO over here but can't seem to find a shop that carries it, does anyone know of a EU-webshop that has it?

 

See if you can find this:


http://www.restoreusa.com/Engine_Restorer.html

 

That was alot easier to find, is it about the same as MMO?
Did find a store in the UK that has MMO, about 70USD for a gallon.

Easiest stuff to find here is Wynn or Omega 909, but if I'll pour any additive into the oil I rather it be the MMO or eq.

 

Restore got rid of a lifter tick for me that MMO failed to work on.

 

Kind of an update,

I ran a can of Engine Restore in the engine earlier over the summer with no real change in ticking.
However; before last oil change (1000 miles back), I ran a can of Omega Engine Flush and changed oil. Ticking gone, until now – it's slowly coming back.

Could this be due to oil losing it's viscosity (running dino Wolf's Head 10W30) or what else?

 

I'm a bit weary of that engine restorer, I put a can of that in my engine and my oil pressure dropped to 0psi at hot idle a few weeks after. Replaced the engine and just got around to tearing my old one apart. I'll post some pics up of what that engine restorer actually does. It's not pretty.

 

I don't think it did much to my engine, no new knocks or ticks – just the same ol' annoying one.
Would be interesting to see what it did to the guts of yours tho.

edit.
Forgot to add; my oil pressure is still fine.