Searched - Wrist Pin Noise?

I have a noise that doesn't fit the normal piston slap, lifter, or knock sounds...it is getting progressively worse. '96 Manual trans., 125k miles. I had the valve cover off a few weeks ago - looks immaculate, i always change the oil.

• Sounds like two spoons clicking together.
• Coming from underneath shifter - definately lower engine sound.
• Audible from outside of the vehicle.
• Was strictly only at idle when cold.
• Now nearly anytime at idle, hot or cold - and getting LOUDER.
• Sound goes away when revved, or at least is deadened/softened.
• Definately softens once engine is at 200 degrees.
• I religiously change oil at 2k miles.
• No loss in power.

Any ideas? A mechanic friend said it sounds like a wrist pin ready to "give out"? Any other possibilities - any cheap fixes??

Intersting, I have the same sort of noise on a brand new engine. Shop suspects wrist pin and is working on it now. Other symtoms I have is very high oil pressure (80 PSI) on new sensor and clean wiring, and a buttt-load of oil in the airbox w/ all new plumbing, etc. I'm talking like 1/2 qt. in 1500 miles (eek!).

If all you have is noise and no other symtoms, I'd be looking at clutch B4 diving into engine.

Glad, or not glad, to hear someone has the same noise. I dont have any blow-by. Oil Pressure normal. Engine runs smooth and quiet other than the clack clack clack.

What involving the clutch could be causing the noise? flywheel?

bacelaw said:

Glad, or not glad, to hear someone has the same noise. I dont have any blow-by. Oil Pressure normal. Engine runs smooth and quiet other than the clack clack clack.

What involving the clutch could be causing the noise? flywheel?

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Shot pressure plate, bad throwout bearing, or worn out clutch disk. When any of these go, they can make noise in time with the engine. Any problems with shifting? Does the noise change when you push in the clutch?

No the noise does not change when i Push in the clutch.
It goes away when the engine is revving, or at least queits down and gets muffled by the engine noise.
No trouble shifting.

Another question - How do i check the flywheel bolts? I don't even know how to access them....any pictures??

bacelaw said:

No the noise does not change when i Push in the clutch.
It goes away when the engine is revving, or at least queits down and gets muffled by the engine noise.
No trouble shifting.

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Hmmmmm... prolly not the clutch then....

it seems to quiet when the transmission is under a load and the clutch is engaged - but that might just be b/c of the revving of the engine.

anyone else have any ideas??

anyone?

This is real hard to explain in text.....but here goes....picture in yor mind the crank, piston and rod....as the engine idles, the piston is going up and down...at the end of each stroke (up or down) the piston has to come to a complete stop before going back the other way....if it's a pin the noise is a double sound that is at twice the rotational speed...sort of like click-click..........click-click....(the described noise isn't exactly accurate)....a broken piston skirt has nearly the same frequency, but a duller sound....you can get a better grip on the matter by observation of the engine runnig...look at the harmonic damper and accessory drives...a timing light MAY aid by giving a visual of the engine frequency IF the ECM does dance the timing around at idle (some do)....

this sound is a constant clack, clack, clack, clack.

when the car is under load, seems to quiet down for the most part.
definately louder when cold
but not it makes the noise even hot at idle, just not as pronounced
It is definately coming from the lower end, but i'm not sure if the lower end of the engine, or closer to the transimission.

It there anything else it could be, or do i just wait and see if she blows in the next few months?

MudDawg said:

This is real hard to explain in text.....but here goes....picture in yor mind the crank, piston and rod....as the engine idles, the piston is going up and down...at the end of each stroke (up or down) the piston has to come to a complete stop before going back the other way....if it's a pin the noise is a double sound that is at twice the rotational speed...sort of like click-click..........click-click....(the described noise isn't exactly accurate)....a broken piston skirt has nearly the same frequency, but a duller sound....you can get a better grip on the matter by observation of the engine runnig...look at the harmonic damper and accessory drives...a timing light MAY aid by giving a visual of the engine frequency IF the ECM does dance the timing around at idle (some do)....

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That's the sound mines making, and given the HUGE amount of oil in the airbox, suspicious that may be it.

If the wrist pin is really shot, you may be able to troubleshoot it some with the engine in one piece. First step is to localize the noise. I use a piece of rigid plastic tubing, often works better than my stethoscope.
In my experience wrist pins and connecting rod bearings, get louder as the RPM goes up, though the other engine noises will mask it some.
Most times the connecting rod bearings go first, then the crank bearings.
If you open the bottom of the engine and use a flashlight. Put the questionable piston halfway up, measure how far you can turn the crank before the piston moves. Compare to a couple of other pistons. I stick something with a point at the piston skirt and cylinder wall as a reference point. The piston movement is sometimes hard to spot, but easier to feel.
Connecting rod bearings and crank bearings are often associated with falling oil pressure.
A lean piston (partially plugged injector) will knock when it fires. Check your plugs for a lean burn condition.
First step is to track down as best as you can exactly where the noise is coming from. Be careful crawling around under the motor with it running. I learned my lesson, watching another guy learn his the hard way, he lost a handful of hair and scalp.

8Mud said:

If the wrist pin is really shot, you may be able to troubleshoot it some with the engine in one piece.

Click to expand...

Thanks for the tips. I'll pass it onto the machine shop where the XJ is. The motor only has 3K miles on a new rebuild, so the machine shop is working on it under warranty.

Sounds like it may be a rod bearing