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General Forums => The Mess Hall => Topic started by: shovelhead on May 26, 2012, 10:25:58 PM
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My 1997 Jeep TJ, automatic makes a terrible rattle when it's cold. Many times after sitting for an extended period of time the engine is initially quiet, then after about 20 seconds it starts to make this rattling noise. The noise is almost completely gone once the engine warms up. Oil pressure when cold is about 50 lbs, hot about 25 lbs at idle. I've tried using a mechanics stethoscope to isolate the source of the rattle to no avail. I removed the dust cover off the transmission and checked the bolts to the torque converter, and they are tight. I removed the belt, and ran the engine beltless, and the noise is the same. I unplugged the spark plug wires, one at a time, with no change in noise. All the spark plugs are perfectly light golden brown in color. I suspect that I have a cracked flex plate in the center where I can't see it. I posed a video on YouTube here. Opinions?
http://youtu.be/DO0aXJh46_w
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imo piston skirt or connecting rod bearing in that order. Hard to make out from the sound in the video though, could also be a stuck lifter
it's fairly loud to be honest and it doesn't sound like a lifter but it could be the way the camera captures the sound.
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Would a piston skirt or connecting rod bearing get quieter, almost gone, when the engine is warmed up? And would the sound change if the related spark plug wire was pulled?
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I think I'll pull the valve cover and see if there's anything obvious there. I have a reputable transmission shop who said they can tell me by the sound whether it's a flex plate or not, I just have to get it down there. I did find another video on YouTube of a Cherokee with a cracked flex plate that sounds very similar.
http://youtu.be/Ros1znVrcgs
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Would a piston skirt or connecting rod bearing get quieter, almost gone, when the engine is warmed up? And would the sound change if the related spark plug wire was pulled?
Piston slap would quiet down some when warmed up, sound should change when you pull a spark plug wire. Flexplate generally the sound would change some when you put it in gear, does it?
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It does get a little louder when in gear, and under load.
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It does get a little louder when in gear, and under load.
My 2000 GMC Sierra 1500 Has that very same noise. When Cold it is loud, drop it in gear and its really loud. Been going one for about 4 years. When warm it is so quite I have almost tried to restart it a couple of times. The way I drive if it was going to come apart it would have a while ago.
But its piston slap, that year truck is known for that, the skirt is too short. So to me if it was that there would be others with this noise or your engine has been rebuilt at some time.
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Have one other after looking at the TSB's. Are all your exhaust bolts there. Seems the outer ones are breaking off.
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just from your video it sounds louder under hood than under the Jeep, not sure if that means anything for the flex plate or not, if it wasn't going away i would have also thought of a stuck valve maybe, but since it quiets down when warm that doesn't seem to be it. Lifter or piston slap is still my best guess. For the flex plate, common sense tells me it shouldn't go away with engine temp, but who knows. Looking forward to hear what's the culprit once you have it figured out.
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I recently replaced the exhaust manifold, it had three major cracks, and all the bolts were OK. When I started it this morning, it was perfectly quiet for about 20 seconds, then the rattling noise gradually started. After a few minutes of driving, it quiets down again significantly.
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I would check for exhaust leaks.
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Here is something to try.
NOTE: Cold engine piston slap that ceases after a few minutes operating time is normal on 1980-81 Jeep 4 cylinder engines.
(1) If noise is not sensitive to engine load, clean engine piston tops and combustion chambers with AMC combustion chamber cleaner or equivalent.
(2) If noise ceases after using combustion chamber cleaner, return automobile to owner.
(3) If noise does not cease, check piston-to-cylinder wall clearance. if clearance is excessive, pistons may be knurled to provide desired clearance. However, if knurling service is not readily available, 0.005 oversize piston and ring sets may be installed to obtain desired clearance.
NOTE: Piston-to-wall clearance should be 0.0027 - 0.0033 (0.0635 - 0.0838mm). Measure piston diameter at the pin centerline 1-3/16 below the piston pin (on the piston skirt). Measure the cylinder bore at a point 2-1/4 below the top of the bore. Cylinder taper should be no more than 0.001 (0.0508mm).
But has the noise been there before you changed the Exh Manifold gasket. Mine also had a noise and it was a broken bolt/Stud.
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that's a totally different motor, not normal for the 2.5L or 4.0L TJ (same pistons).
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that's a totally different motor, not normal for the 2.5L or 4.0L TJ (same pistons).
Actually the piston Slap was listed for a tj when I did find it.. I was just showing the above as a way to check for piston slap.
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For some reason, I started it up today, and something strange happened. It started, then coughed and died just after starting. I restarted it, and now the rattling noise is almost completely gone. It runs and idles fine, and there's just a faint tick, like a lifter.
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Actually the piston Slap was listed for a tj when I did find it.. I was just showing the above as a way to check for piston slap.
for the 2.5L 91 and up they had some issues with the tolerances in the block, the fix was to install slightly oversized pistons (at the stealership under warranty) based on the bore, the pistons on these can't be knurled, the alloy they are made of is harder. There were also some engines that came out of the factory with o/s pistons and also o/s main and rod bearings (issues with the crank machining). I read it somewhere in the FSM, but that's when they're almost new, when there's lots of miles on them the issue is probably different and not factory machining errors.
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I had a weak fuel pump for about a year, ever since I bought the Jeep. I posted about it in another thread. Who knows how long it was weak before I got it. I wonder if there is a carbon build up issue, due to the prolonged period of a weak fuel pump. Perhaps the fact that the Jeep was unable to be run hard enough to clear out some of the carbon once in a while led to that rattle. Friday afternoon I was able to really step on it, driving on the freeway, up a steep incline. I'm hoping that it doesn't come back, and was just a carbon buildup issue.
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The rattle noise is back. It seems like there's two distinctive sounds being generated. I think that I might have two separate issues. One sounds like its in the top end, perhaps a rocker or lifer issue. The other is more pronounced when it's cold. I took the belt off this afternoon and briefly ran the engine and used a hard wood stick, and held it to different parts of the engine. One of the loudest areas was on the timing chain cover. I could actually feel the knock there in time with the sound. I pulled off the dizzy cap, and used a wrench on the harmonic balancer to see how much play there was in the chain. There's a bit of play between turning the balancer and when the rotor on the dizzy turns. Perhaps I have some timing chain noise along with lifter noise? I made two more videos as well.
http://youtu.be/kVC4SWDOVqY
and
http://youtu.be/6ukm_Bi3zJE
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Broken piston skirt, cylinder #3.
http://assets6.pinimg.com/upload/137641332332254126_J7h51Z6A.jpg
http://media-cache-ec0.pinterest.com/upload/137641332332254125_0bW3MH7N.jpg
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Does anyone know of a reputable and reasonable automotive machine shop in southern California?
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Dang dude. That sucks. Might be easier to just get a fresher engine and drop that in. I don't know about in CA but a decent used 4cyl is only bringing around $3-500. Unfortunately that is the best idea I have.
Mine also makes a similar noise, but not as bad. It lasts about 30 sec after startup and only does it occasionally. Did you notice the engine ran rougher or had more vibration when it ran?
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HAve not used this place in years But Smokies Cervice Center on Hill Street in OceanSide Calif. Searching they still seem to be open.
And just have to say would not Piston Slap cause that. :slapfight:
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I've had that rattle issue for close to a year. It just started getting much worse in the last few days. It might have been piston slap before, which progressed into piston failure. I didn't notice any loss in power, but I did have quite a bit of blowby coming out of the valve cover. There might have been more vibrations, it's difficult know know, because I recently replaced the motor mounts with Brown Dog polyurethane mounts, and you feel everything with those.
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What is the likelihood that I could get away with putting four new pistons and piston rings in? Would this require a rebuild?
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If the cylinder walls look good then it wouldn't be a problem.
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Rather than do the piston and ring job, I decided to go for a rebuild. I used a local shop in Anaheim, CA. They picked up my engine from my house, and dropped it off when they were done. It took about a day to get the engine installed. Started her up, ran through the initial break in, and she purrs like a kitten now.
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That's cool, a door-to-door service.
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Your sound was a lot like mine in my 97. My son fixed it in July by throwing the #3 rod out the side of the block. Mine would get quieter when warm. I also got rid of some of the noise by going to a High Mileage semi synthetic oil. Good luck with it. Post it when you find the issue.
AWK
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Your sound was a lot like mine in my 97. My son fixed it in July by throwing the #3 rod out the side of the block. Mine would get quieter when warm. I also got rid of some of the noise by going to a High Mileage semi synthetic oil. Good luck with it. Post it when you find the issue.
AWK
he found the issue, broken piston skirt and he replaced the motor (you missed the last couple of posts)