96' has had a mild engine tick when cold that is not very noticeable once warmed up. Figured it was a little bit of lifter noise and didn't worry about it. Last night when pulling onto the expressway ramp, I head a sound similar to something falling into a moving part then quickly getting knocked out of the way or pulverized. With the radio being loud, I assumed it was one of the dozens of ice buildups that had fallen into one of the wheels as i turned. Maybe like dropping marbles into a blender for less than a second. I am not sure if I had began to accelerate yet or not.

Engine was warm, plenty of oil, and all my gauges stayed normal with no CEL. Once up to speed I listened for any noise and I thought the tick sounded louder than normal. Pulling off the expressway and accelerating, the sound was more of a knock and got louder/more frequent. At idle the engine sounds almost like a diesel tractor at low idle. The noise is worse when throttle is given. Once letting off the throttle it takes a second or two for the knock to quiet, and it almost goes away for a few seconds before building back up again.

I was leaning towards a broken piston skirt due to the knock kind of matched the sound of what I thought was a lifter tick. Also the sound crushing sound i hear could be explained by the broken piece(s) falling into the pan.

Is it possible for a spun bearing to make such a terrible sound when it first lets loose? Oil pressure is still fine and I have no loss in power. No engine misses either.

 

The buzzer in the start is terrible, check your volume!

 

My phones not letting me play the video, could be a number of things. I need to hear it first, I will try when I get home

 

That sounds like more of a valve issue to me.
But the more experienced may have seen/heard/experienced it differently.
I'd yank that valve cover off and see what you have. Put some cardboard around to
control some of the oil splash mess if you need to crank to further narrow down where.
I only have the "normal" slight tick at warm up ( 252+K miles).
Sorry but I would not consider that anywhere near what I have heard.

Good Luck

 

Sounds valve train oriented to me.

 

That sounds normal... Lol I vote valve, or a large crack in manifold

 

Sounds like a valve is making contact with a piston

 

rod

 

my broken piston skirt was a much deeper noise but it did happen suddenly like you noted.

once you look at the valves, the next step is just to pull the oil pan and look for pieces in there

 

noloss in power, i doubt its a valve train issue, oil pressure is fine going off whats in the dash so i would doubt a bearing issue. id pull the valve cover, inspect the valves and valve springs. if all is ok id pull the pan and inspect for broken pistons.

if it was a rod and sounded like that more than likely you would have bulges in the pan or the rod would be hanging out the block.

 

So far it sounds like the top part of the engine. Stuck a hose in the valve cover for a better listen and it did not sound good lol. Buddy of mine thinks the noise is louder by cylinder 2, and I think he was right. Was hard to tell because we were using my high tech old heater hose stethoscope.

Oil pressure is still fine, no smoke or fuel smell. No loss of power either.

The only reason I was still driving this xj was because the motor seemed good. I have been fighting some really bad rust underneath to the point that I was on the edge of parting it out even then. I'm looking for another xj with at least minimal rust and a good engine, then I can use the parts from this one to replace anything else I need to.

 

I think you will find it when you pull the valve cover. What? Idk. Bent push-rod, flat lifter. Sounds like you will find it though!