I must be a glutton for punishment. 7 months ago I put in a reman longblock which soon after developed a head gasket leak. The company replaced it with another longblock under warranty, which I put in about 6 weeks ago. It's been running fantastic, however about two weeks ago with about 600 miles on the 2nd engine, I noticed a slight knock which has since gotten louder (not real loud, but it's there). It may be a coincidence, but it seemed to develop right after I did my 500-mile break-in oil change. I should also add that it appears to go away once it's warmed up. I have tried to isolated it using a long screwdriver to my ear but really haven't been able to. It does seem to be louder under the oil pan, though. I should add that there is no loss of power (not much left to lose with a 4-cylinder ;-). I also changed all of my sensors during the first longblock swap so I doubt it's the knock sensor. Should I be adjusting my lifters? What do you guys think?
Thanks! Oh ya, forgot to mention, oil pressure is fine at around 55 psi.
Ya, this is killing me. This is the second engine I've put in in the last 6 months. Both installs went flawlessly so I know it's nothing I did. There's only 600 miles on this latest longblock so it's still under warranty. However, the thought of pulling it again....arrgghhh!!!
Hey Que89YJ, I didn't notice that was you. Ya, I had to pull the original longblock as it developed a head gasket leak around a week after I installed it. They sent me another one, and now this one is knocking. This is unbelievable. Like I said, it's not REAL loud and goes away once it's warm, but still... Like you said, it can't be good. I'm just going to run it until it dies, and then bill them for installing yet another engine. I don't know where they're getting them remanned.
Update: I tried changing oil (again) to Mobil 1 with a Fram oil filter, along with oil additive. Still knocking at cold idle. I cut open the filter and checked the old oil and found no sizable pieces of metal. There were some "flecks" in the bottom of the drain tub, but that was it. I'm going to try a Napa filter, because one thing I'm still noticing is that the oil pressure stays high (around 55#) whether it's running at idle or when driving. Before the first oil change, and before the knock, it always dropped down to around 40#when at idle, then would climb to 60# when driving. I know the 2.5 doesn't have an oil bypass and relies on the filter. Could it be that simple. Granted I'm reaching here, but I can't bear the thought of pulling the engine for a THIRD time.
Just for the hell of it, I'm going to try putting the original knock sensor back on to see if it makes a difference, though I doubt it will.
An engine knock- i.e. a bad rod or smeared main bearings or piston 'slap'- is totally unrelated to a "knock sensor." The sensor is designed to detect preignition and preignition is sometimes referred to as spark knock, but if you are replacing engines for spark knock you are barking up the wrong tree.
How many old threads actually convince *you* to read all 36 pages? http://www.jeepforum.com/forum/f12/length-envy-build-thread-629700/
Mine has the tapping sound when cold cranked for about 30 seconds. Mech thanks it is a lifter. After 30 seconds it goes away for the day and does not happen again until cool down, usually overnight. Thought here is: Did your remanufactured engines have new lifters and valve trains put in, or were they transferred over from the old engines? Just curious.
99 % sure it's not lifters. It definitely sounds like piston slap from the #1 cylinder. I had two other licensed mechanics agree. We'll find out this Friday. The replacement longblock arrives tomorrow. This better be the one, since it's the third time I've had to pull this engine. I can do it in my sleep, by now.