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I appreciate the help here, as I still hope there is nothing wrong with the engine and I don't have to tear it apart. But maybe some info has been lost here.
I have driven the car hard for the last two summers (Drag Week included) and never had this noise. I have not touched the cam (still stock). It wasn't making the noise when I took it to the track a couple of weeks ago, then it started after the first full pass I made that day. Now, I start the car up, the noise is there, then it goes away for a bit and comes back as it warms up. I don't have to drive the car at all to hear the noise. Today I started the car in 50 degree weather (noise was there) and let it idle for about 10 minutes to warm it up enough for the noise to come back. No hard driving. The fact that the noise just suddenly started is the only reason I am not ignoring it so far, to be honest.
So if its the same thing as you are suggesting, would it just start doing this one day and not be considered a problem? If so, I'll just look the other way (or whatever the comparable thing would be for listening) as I really don't want to pull the engine this winter. Any suggestions on what makes this noise in your cars? Just a natural seasoning of the block now that boost has been presented for a substantial amount of time?
Though it may sound like it, I am not just looking for someone to agree with me that there is something wrong with my engine. I am just trying to get as good of an understanding as possible with as many ideas as possible. I'm not in any rush to yank the engine at this point, as I have about 5 months before it will be warm outside again (Michigan).
Thanks for the help so far everyone!
OK, so I went back and listened....in complete silence this time. I now hear what it is that has you worried. Sounds like a rod bearing is going away. Take the car out, get up to speed and give it very light throttle....then put a little load on it. If you have a nice rattle at part throttle....I would be inclined to think it's a rod.
OK, so I went back and listened....in complete silence this time. I now hear what it is that has you worried. Sounds like a rod bearing is going away. Take the car out, get up to speed and give it very light throttle....then put a little load on it. If you have a nice rattle at part throttle....I would be inclined to think it's a rod.
Thanks for taking another listen even if its to report back potential bad news. I'll bolt the converter back up and take the car around the block and try your test. I've got a GoPro I can slap on the car to get some more audio too. It won't be until the weekend most likely though, as the work schedule this week is brutal.
Originally Posted by lmt0705
Oil pressure still good? Any Babbitt in the oil filter?
Yea, oil pressure is good, about 35-40 psi at idle warm. The filter element itself looked good, didn't see any metal, but there was a little bit of glimmering in the can of the filter. I should have that pic on the first page of this thread somewhere. The hope is to get the oil analyzed in the next couple of weeks, so this test around the block this weekend will be the last time its driven with this oil.
Its tough to tell from the video but it almost sounds like a bad lifter to me
Lifter is what popped into my mind too. I have a Jeep (known for lifter clatter) and hear that noise every day. As the engine warms, sometimes it goes away, sometimes it doesn't. However, in the case of the Jeep, it does go away with increased RPM.
I know it's also a known issue (noise not performance or reliability) with stock GM truck lifters, however I haven't heard of the LS7 lifters being problematic too.
In my Jeep, every so often I'll run some Sea Foam in the oil and it eventually clears up the clatter and sounds normal for a while. The noise does eventually return. Might be worth a shot to put some in there and put a couple hundred miles on before you change the oil. If it clears up, (my opinion) it's definitely a lifter. Personally, I just live with the clatter. I know it would drive some people nuts though. Everyone that hears it tells me my rod bearings are shot. Oil pressure has been steady and it's been clattering away for more than 100,000 miles since it started occurring.
Anyway, just another possibility. I've heard it said that lifters make a great oil filter... they catch everything. LOL
I had a very similar problem a few months ago, symptoms were exactly the same as yours, and came about after a hard run where I bounced the limiter. Could not find it in any compression or leak down test, could not isolate it with mechanical ears. After a week or so of street driving it wasn't getting any louder, so I assumed it was piston slap or something . After a month or so, it was slightly louder and I had to find it.
In the end I removed the coil, injector, pushrods, and rocker arms one cylinder at a time and started the engine (cold) just long enough to see if the noise was present or not. At #5 it quit, so I checked the push rods, rocker arms, everything looked good. Getting frustrated I pulled the heads and found #5 piston (and a few others) were on the edge of burnt the f*** up. I hope this isn't your problem, but isolating each cylinder is the only way to find it prolly.
Sounds like a bad flex plate to me as well. I just had a very similar issue and I didn't see the crack until I had the flex plate off the motor. Was cracked between the bolt holes holding it to the crank.
I had a very similar problem a few months ago, symptoms were exactly the same as yours, and came about after a hard run where I bounced the limiter. Could not find it in any compression or leak down test, could not isolate it with mechanical ears. After a week or so of street driving it wasn't getting any louder, so I assumed it was piston slap or something . After a month or so, it was slightly louder and I had to find it.
In the end I removed the coil, injector, pushrods, and rocker arms one cylinder at a time and started the engine (cold) just long enough to see if the noise was present or not. At #5 it quit, so I checked the push rods, rocker arms, everything looked good. Getting frustrated I pulled the heads and found #5 piston (and a few others) were on the edge of burnt the f*** up. I hope this isn't your problem, but isolating each cylinder is the only way to find it prolly.
This would be my worst nightmare, and yet it sounds exactly like my situation. I hope to not have to work this weekend, so I'l bolt the converter back on and give this a shot.
So the weather decided to not play nice this weekend and I didn't drive the car. it was 70 and sunny on Friday, but 30 and snowing on Saturday (gotta love Michigan). But I still took a vid of cold start up at 30-40 degrees ambient. I have already began unbolting stuff from the engine and will be pulling it out next weekend. I'm not on Denmah's level of speed with tearing down or building cars
My thoughts are this:
- If its a rod bearing, the K member doesn't have enough clearance to drop the pan, so engine has to come out.
- If its the flexplate, engine or trans has to come out.
- If its a lifter, I feel its just as easy to pull the engine before removing the heads.
I systematically cut a cylinder at a time, and the noise seemed to go away with cylinder 4, but now I actually think I have a bearing and a lifter going out, as there seems to be 2 distinct noises. the noise in the video goes away after a minute or so of warming up, then I start to hear more of a lifter tick type of sound. Like SethU said, lifters can make good oil filters....
I'll let everyone know what I find (if anyone still cares). I am also sending the oil sample out this week, though I doubt they will analyze it before Thanksgiving.
Yea, that motor is definitely hurt. Even if you could get to the bearings while in the car, I wouldn't do that. It's best to just pull it....strip it down to the block, clean everything and start fresh.
Long overdue update here, just in case anyone cares. I pulled the engine, tore it down, and.......found nothing wrong.
I quickly gave up and bought another junk yard 5.3, slapped it in (using the heads/valvetrain from the first engine), fired it up and it is running great.
When I tore the first engine down, I focused on bearings, valvetrain and piston damage, and I didn't see anything out of the ordinary. So recently I was hunting through Denmah's Colorado thread and saw his bent rods, so I decided to check my rods again. Cylinder #4 was a winner.
11-14-2016, 12:07 PM
