SuperWade2 Posted November 4, 2009 Share Posted November 4, 2009 The guys that have been around CC.Com a while have heard me constantly piss and moan about my engine knock and how I need to swap engines, etc. Since all but a couple of you guys aren't close enough to come help me wrench on the truck, I thought I would record the knock and get the collective opinion of the ComancheClub brethren as to how much I really should worry about this. The Video isn't important...listen to the audio... http://www.leishman.net/videos/knock.mp4 Thoughts? Link to comment Share on other sites More sharing options...
Oizarod115 Posted November 4, 2009 Share Posted November 4, 2009 sounds like a 4.0L... if it ain't knockin it ain't running. seriously though, the machine shop our shop uses' owner has a 4.0 cherokee said it's knocked since brand new, and it now has 200,000 on the clock. some of them do, some of them don't... i wouldn't worry about it TO much, and know that the potential of a replacement junkyard motor is VERY likely to do the same. Link to comment Share on other sites More sharing options...
Oizarod115 Posted November 4, 2009 Share Posted November 4, 2009 also if the engine was cold in the video some of that could be attributed to cold slap of the piston. Link to comment Share on other sites More sharing options...
SuperWade2 Posted November 4, 2009 Author Share Posted November 4, 2009 also if the engine was cold in the video some of that could be attributed to cold slap of the piston. It was cool'ish, but it pretty much sounds like that all of time, hot/cold or otherwise! Link to comment Share on other sites More sharing options...
Geonovast Posted November 4, 2009 Share Posted November 4, 2009 It's just one piston. You've got 5 more. Have you had the pan off at all? If you yank the pan you should at least be able to figure out if it's a bad rod/wrist pin/whatever else. Link to comment Share on other sites More sharing options...
Oizarod115 Posted November 4, 2009 Share Posted November 4, 2009 also if the engine was cold in the video some of that could be attributed to cold slap of the piston. It was cool'ish, but it pretty much sounds like that all of time, hot/cold or otherwise! if you have the money/time for an overhaul and don't mind spending it, i see no reason not to. Even without the noise you're hearing, the motor is 20 years old and i'm sure could use going through. if you're not in the position to overhaul it, or don't want to; i don't see that it's to much to worry about. at this point you could check oil pressure and possibly do a pump, rod bearings and a rear main just dropping the pan which would cover your bottom end and should be easy-ish. third option would be let it eat til it quits. chances are its been doing it for years and will continue on for years before it goes kaput. Link to comment Share on other sites More sharing options...
SuperWade2 Posted November 4, 2009 Author Share Posted November 4, 2009 also if the engine was cold in the video some of that could be attributed to cold slap of the piston. It was cool'ish, but it pretty much sounds like that all of time, hot/cold or otherwise! if you have the money/time for an overhaul and don't mind spending it, i see no reason not to. Even without the noise you're hearing, the motor is 20 years old and i'm sure could use going through. if you're not in the position to overhaul it, or don't want to; i don't see that it's to much to worry about. at this point you could check oil pressure and possibly do a pump, rod bearings and a rear main just dropping the pan which would cover your bottom end and should be easy-ish. third option would be let it eat til it quits. chances are its been doing it for years and will continue on for years before it goes kaput. Option 3 is the most realistic in my current position right now... Link to comment Share on other sites More sharing options...
Oizarod115 Posted November 4, 2009 Share Posted November 4, 2009 third option would be let it eat til it quits. chances are its been doing it for years and will continue on for years before it goes kaput. Option 3 is the most realistic in my current position right now... Link to comment Share on other sites More sharing options...
Dave Stark Posted November 4, 2009 Share Posted November 4, 2009 Do the 4.0's have hydraulic lifter tappets? If so, that's what it sounds like to me, since the sound goes away when the engine is revved (O/P goes up). :hmm: Link to comment Share on other sites More sharing options...
Geonovast Posted November 4, 2009 Share Posted November 4, 2009 I think that's just exhaust noise. Does the sound seem to match up with the rockers moving, or twice as fast? Link to comment Share on other sites More sharing options...
mfpdm Posted November 4, 2009 Share Posted November 4, 2009 Sounds like a lifter tapping to me. Is it louder from above the engine or below? I've been told that if it's louder from the top, it's a lifter, and if louder from underneath, it's a rod bearing. I'm not saying that is 100% but makes good sense I guess. :cheers: Link to comment Share on other sites More sharing options...
dakal Posted November 4, 2009 Share Posted November 4, 2009 sounds like one noisy lifter to me. let it run. Link to comment Share on other sites More sharing options...
64 Cheyenne Posted November 5, 2009 Share Posted November 5, 2009 :agree: Link to comment Share on other sites More sharing options...
shelbyluvv Posted November 5, 2009 Share Posted November 5, 2009 Lifter. They are a PIA to change too. Leave it be until it blows. A lot of times you can run a little diesel fuel in the oil and it will clear the blockage in the lifters. Once in awhile it will kill the rest. It is a crap shoot. Link to comment Share on other sites More sharing options...
ejndssn Posted November 5, 2009 Share Posted November 5, 2009 :agree: xmany with the rest of the team here lifter my question is :hmm: would the marvel mystery oil clear that blockage up just an :idea: Link to comment Share on other sites More sharing options...
dunl Posted November 6, 2009 Share Posted November 6, 2009 Could try some 2cycle too.... Link to comment Share on other sites More sharing options...
veritas4156 Posted November 6, 2009 Share Posted November 6, 2009 Seafoam quieted mine down for about a week. After that it came back. Lucas seems to work the best. Another problem I've found with 4.0L motors is the rocker arms tend to bend. I've pulled apart the heads on 3 or 4 of these motors(not all driven by me) and two of the four had bent rocker arms that were causing the noise. Easiest way to find out exactly where the noise is coming from is to take a length of hose and use it as a stethoscope kinda device. One end next to your ear, point the other end at stuff to find noises. Link to comment Share on other sites More sharing options...
dakal Posted November 6, 2009 Share Posted November 6, 2009 yes to that and marvel mystery oil Link to comment Share on other sites More sharing options...
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