99 WJ 4.0L engine noise
Engine ticks or taps deep down definitely not lifters and have had engine out and tore down most of the way had to replace two pistons and put the older 97 zj designed head on due to the known cast cracking issue.
Both pistons were well used and head I cleaned up and lapped valves myself whole deal was a budget fix also any thoughts or known info would be great. Trying to avoid having to pull and tear down again |
Was there a question in that?
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I guess I probably should have been more specific in that there is a question
What is the noise/ticking/tapping deep in the engine not in the valve train ,are there any known issues related to the 4.0 L six cylinder that anyone knows of? |
While you had it apart, did you inspect all the pistons for cracked skirts or ring lands? How about bearing clearances? Did you put the used pistons on your rods or did you install them as a unit from an old engine. There are so many things that may be not right, it astounds me that you're afraid you'll have to pull it again. I've thrown together several "barnyard" engines in my lifetime for dirt-track race cars and sometimes they last, sometimes they don't. If you want an engine to last, everything must be within wear tolerances and the bearings HAVE to be checked for proper clearances. I ran a 4.0 for over 25,000 miles with a cracked piston skirt, but then again I didn't demand too much from it. Diagnosing with a keyboard is tough.
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Ya it was all used and your most likely totally correct on not chking the clearances I'm sure it's probably something in that realm thanks anyhow
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Pull your oil pan off and grap the caps that are holding your Pull arms onto the crank shaft. If your bearings are starting to wear there will be some movement. You will be able to move side to side and back and fourth a little bit. They have a tiny tiny bit of movement from the oil clearances but you will know if one is looser than it should be.
If your bearings wear out any more you may spin one just like what I did a couple of weeks ago. When that happened it trashed my crank shaft and I had to get another. Since I don't have a lift I'm working on moving my trans back so I can drop the crank out. You may need a new timing chain... but as the guys said above it could be anything. For the 20min of work getting the oil pan off you could be saving yourself some serious time by checking out those bearings. The pull arm ones are super easy to change |
I changed my timing chain at 125K miles and it didn't look that bad, not as loose as I had imagined it to be. If all the bearings look okay, you could try using Plastigage to check the actual clearance. It's a strip of round plastic string that you cut a piece off and put it on the bearing, install the cap and torque it down, then take it apart and measure the squashed width against a gauge printed on the package. Pretty cool stuff. Wipe the bearing off but leave the crank oily. That way it sticks to the bearing and not the crank.
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