genEus Posted August 1, 2008 Report Share Posted August 1, 2008 One fun night after another, it just doesn't end! So I put in new LIM gaskets and when I started putting stuff back together I broke a rocker arm bolt when I accidentally overtightened it. (http://www.w-body.com/forum/index.php?topic=70015.0) Long story short, I managed to wiggle out the broken bolt from the head and replaced the rocker arm with a brand new one I got from the dealer. Well, I finally put everything together and the car started up instantly. But now there's a knocking sound from the engine!! So I have no problem tearing everything apart but how do I know what is knocking? I am blaming a loose rocker arm - or a misaligned pushrod, I mean, what else can it be? But, how do I find out exactly? Can I remove the valve covers and run the engine to see what is happening in there? Do you think the replaced rocker arm could be the culprit? Thanks!! PS. Oh yeah and I got the Check Engine light on too... Quote Link to comment Share on other sites More sharing options...
rockfangd Posted August 1, 2008 Report Share Posted August 1, 2008 ouch. that is not fun at all. does the noise sound more like upper or lower. I would have to say maybe the roller rockers are adjusted a little too tight Quote Link to comment Share on other sites More sharing options...
AL Posted August 1, 2008 Report Share Posted August 1, 2008 i say find out what code its throwing Quote Link to comment Share on other sites More sharing options...
spiderw31 Posted August 1, 2008 Report Share Posted August 1, 2008 Get a long screwdriver, and place the tip of it on various locations around the engine. Hold your ear to the end of the handle while doing this, and you should be able to hear where the noise is the loudest. Go looking for troubles in that area. Good luck! Quote Link to comment Share on other sites More sharing options...
genEus Posted August 1, 2008 Author Report Share Posted August 1, 2008 Well, the knock is very clean sounding, rhythmic and not random, and it speeds up and slows down with revving the engine up/down. The only thing I can place the blame on is the rocker arm that I broke and replaced. I just wonder what could have gone wrong there? Is there any chance that it was not identically matched? I mean, it looked identical to the stock ones and it was a GM part. I dipped it in oil before I installed it and I torqued it to whatever I was supposed to (this time around) - 168 in-lb. It had no problem going in and staying in, so it didn't seem like I stripped the inside thread. And, besides, when I removed the broken stud it just unscrewed easily and it wouldn't have had the thread been broken. So, again, in order to see the valves, can I open just the valve cover and watch the rockers in operation or no? Or do I need to tear everything apart again? Thanks!! Quote Link to comment Share on other sites More sharing options...
spiderw31 Posted August 1, 2008 Report Share Posted August 1, 2008 I think you can remove the rocker covers on the 3.1 and still have everything assembled enough to to run, but I'm not sure. What I do know is that if you try to run the engine with the covers off, you will send oil flying EVERYWHERE! I know that you used to be able to get little guide plates that would keep the oil in when you had the covers off and the engine was running, but that was back when you had to properly adjust valve lash. I don't know if you can get any that are suitable for the 3.1. My guess though is that if your knocking is very audible (and possibly caused a code to be set), you will be able to see it plainly when you pull the covers. Quote Link to comment Share on other sites More sharing options...
BXX Posted August 1, 2008 Report Share Posted August 1, 2008 You changed the LIM gaskets... Was the oil all milkshakey??? You may have a bottem end giving up the ghost from washed bearings. Quote Link to comment Share on other sites More sharing options...
genEus Posted August 1, 2008 Author Report Share Posted August 1, 2008 You changed the LIM gaskets... Was the oil all milkshakey??? You may have a bottem end giving up the ghost from washed bearings. No, actually the oil was clean because none of the coolant got into the oil. I noticed green puddles on the driveway and I was losing about a quart of coolant a week, so I got scared and decided to change the gaskets but no coolant got inside. However, I guess I wasn't careful enough when I took the manifold off and some coolant did actually spill inside since when I did the oil change after I put everything together about half a glass of coolant ran out before the oil... Quote Link to comment Share on other sites More sharing options...
Brian P Posted August 1, 2008 Report Share Posted August 1, 2008 Pushrods are all installed correctly? Quote Link to comment Share on other sites More sharing options...
genEus Posted August 1, 2008 Author Report Share Posted August 1, 2008 Pushrods are all installed correctly? Will find out tomorrow I guess. (Friday night somehow my girlfriend takes precedence ) For now I'm just hoping I don't have to tear it all apart again. It was my first time doing it and it took me about 6 hours to go one way and about 6 to go back up, not counting the time to get the broken bolt out, but now I think it should take me no more than 2 to open it all up again. I just hated having to drain the power steering, coolant and the fuel lines. Oh yeah, and if I do have to tear into it again, is there anything you'd advise me to replace while half the engine is apart? Quote Link to comment Share on other sites More sharing options...
BIGBULS Posted August 1, 2008 Report Share Posted August 1, 2008 It's pretty common for lifters to stick afer doing the LIMG's. And damn do they make a racket. Also...........make sure no bolts made it down an intake passage or something...........I saw that happen once (my tech was lucky that *I* had a spare set of LG8 heads sitting in my garage that I got for free and hadn't gotten around to selling for a profit). Quote Link to comment Share on other sites More sharing options...
BXX Posted August 1, 2008 Report Share Posted August 1, 2008 It's pretty common for lifters to stick afer doing the LIMG's. And damn do they make a racket. Also...........make sure no bolts made it down an intake passage or something...........I saw that happen once (my tech was lucky that *I* had a spare set of LG8 heads sitting in my garage that I got for free and hadn't gotten around to selling for a profit). yup, and even more so if GMs TSB on proper torqueing isnt followed. I think it was release 2 years ago. So if you have torque specs older than that, they are more than likely incorrect. Quote Link to comment Share on other sites More sharing options...
GPX Posted August 1, 2008 Report Share Posted August 1, 2008 I think you can remove the rocker covers on the 3.1 and still have everything assembled enough to to run, but I'm not sure. What I do know is that if you try to run the engine with the covers off, you will send oil flying EVERYWHERE! I know that you used to be able to get little guide plates that would keep the oil in when you had the covers off and the engine was running, but that was back when you had to properly adjust valve lash. I don't know if you can get any that are suitable for the 3.1. My guess though is that if your knocking is very audible (and possibly caused a code to be set), you will be able to see it plainly when you pull the covers. x2You won't like it if you run your motor with no covers, but you may laugh about it someday if you do. Though it won't be that day. I wonder if you can get those deflectors. They do sort of work. My advice is try the screwdriver technique (you'll be surprised how effective it is if you've never tried it), locate the general area, pull covers and see what you see there. If you do pull the covers and run it, be sure to get some video! Quote Link to comment Share on other sites More sharing options...
genEus Posted August 3, 2008 Author Report Share Posted August 3, 2008 OK, well guess what. I just ran my motor without the back cover. Not a single drop of oil went anywhere, it stayed right where it was. And before I did that I did the screwdriver trick. The screwdriver told me the knocking came from the back cover because when I listened to the front cover the knock was muddy and not as pronounced. Then I opened the back cover and took a good long look at all the rockers, touched every single one, made sure it wasn't loose, made sure it had a push rod underneath it, and so on. Then I decided to be brave and put everything together leaving the cover off and started the engine. Again, there was no oil splattered anywhere... But also I didn't have any idea what was knocking. All the rockers were going up and down just dandy. WHAT AM I LOOKING FOR?? I did the screwdriver trick again and set the tip of the screwdriver on the plenum. The knocking was very pronounced there. Then I set it again on the front cover and the knocking was muddled... Right now I have no idea what to look for and I'm going to take off the front cover, maybe I'll see something there... Maybe someone can chime in? If anyone thinks he can tell by the sound of the knocking I can take a cell phone video and post it if it'll help. Thanks !!! I think you can remove the rocker covers on the 3.1 and still have everything assembled enough to to run, but I'm not sure. What I do know is that if you try to run the engine with the covers off, you will send oil flying EVERYWHERE! I know that you used to be able to get little guide plates that would keep the oil in when you had the covers off and the engine was running, but that was back when you had to properly adjust valve lash. I don't know if you can get any that are suitable for the 3.1. My guess though is that if your knocking is very audible (and possibly caused a code to be set), you will be able to see it plainly when you pull the covers. x2You won't like it if you run your motor with no covers, but you may laugh about it someday if you do. Though it won't be that day. I wonder if you can get those deflectors. They do sort of work. My advice is try the screwdriver technique (you'll be surprised how effective it is if you've never tried it), locate the general area, pull covers and see what you see there. If you do pull the covers and run it, be sure to get some video! Quote Link to comment Share on other sites More sharing options...
spiderw31 Posted August 3, 2008 Report Share Posted August 3, 2008 No oil at all? I dunno, but that just doesn't sound good to me. So the knocking is strongest from the plenum area? Collapsed or stuck lifter perhaps? If for whatever reason there wasn't enough oil to pump the lifters up (and I say that only because you saw no oil under the valve cover), that sure would make a nasty racket. Quote Link to comment Share on other sites More sharing options...
GPX Posted August 3, 2008 Report Share Posted August 3, 2008 No oil at all? I dunno, but that just doesn't sound good to me. So the knocking is strongest from the plenum area? Collapsed or stuck lifter perhaps? If for whatever reason there wasn't enough oil to pump the lifters up (and I say that only because you saw no oil under the valve cover), that sure would make a nasty racket. That was my feeling, but not being an engine expert, I thought I'd bow out. I know I was being a smart ass with all my advice, but oil should be squirting out pretty good if you have good oil pressure. There are plenty of folks here who know these motors inside and out. I'll let them speak. Quote Link to comment Share on other sites More sharing options...
genEus Posted August 3, 2008 Author Report Share Posted August 3, 2008 No, there is plenty of oil under the covers but nothing is squirting around. The rockers are rocking along in their happy beat, there is oil surrounding them and all but there is nothing squirting anything anywhere... Now I loosened and retightened all the rockers and NADA... same story, same knocking. I am thinking to pull rockers one by one and start the engine to see which one causes the knock. IS it safe to run the engine without one of the rockers? Thanks!! EDIT: Uploaded a video from my cell phone to YouTube... Dunno if it'll help. I would hate to tear into the engine again. I'm going to take out the pushrods and see if any of them are bent. By the way, in the video I have NO idea what the loud thuds are every few seconds. My cell phone is POS probably... Quote Link to comment Share on other sites More sharing options...
Brian P Posted August 4, 2008 Report Share Posted August 4, 2008 Okay, the engine is at idle (assume ~750 rpm) which is about 12.5 revolutions every second. The knocking is occuring about 6 times per second, which is about half the speed of the motor, so you can be assured it's a noise coming from the valvetrain (it spins half the speed of the motor). If it were me, I'd put a screwdriver against every rocker arm mounting bolt and try to hear where it's the loudest, that SHOULD pinpoint the offending component. How long have you ran the motor so far after doing the LIM job? Quote Link to comment Share on other sites More sharing options...
genEus Posted August 4, 2008 Author Report Share Posted August 4, 2008 Okay, the engine is at idle (assume ~750 rpm) which is about 12.5 revolutions every second. The knocking is occuring about 6 times per second, which is about half the speed of the motor, so you can be assured it's a noise coming from the valvetrain (it spins half the speed of the motor). If it were me, I'd put a screwdriver against every rocker arm mounting bolt and try to hear where it's the loudest, that SHOULD pinpoint the offending component. How long have you ran the motor so far after doing the LIM job? Brian, I have so far taken out every rocker except two and started up the engine every single time to see if the knock went away, to no avail. The two I didn't was because it was too late, I was getting discouraged and the knock came from the opposite side of the engine from where those last two were. The engine has always run like a champ - the car only has about 50,000 miles on it and I've had it since it had 27,000 on it. It's never had any knocks like that, so that leads me to think that I screwed something up just now. Except the problem is that I can't think of what I could have done wrong. I mean, once I took out the upper and lower manifolds, I put the gaskets in, put the rockers back - and I followed the Haynes manual suggestion to put all the rockers and push rods in their separate labeled holes in a cardboard box when I took them out, which I did... And other than those there weren't any moving components that I could have forgotten to screw in properly, right? Or, is there a chance that something else just happened to go wrong just as I was fixing the LIM gaskets and it's all just a coincidence? I'm afraid to take off the manifolds again because at least now I can run it with the covers off and listen to it. If I take off the manifolds I won't be able to do that, but I have no idea what I'm looking for anymore. I thought a loose rocker was to blame for sure... but I guess not. I have run the engine for a total of maybe 5-10 minutes so far... Argh this is driving me nuts!! Quote Link to comment Share on other sites More sharing options...
Brian P Posted August 4, 2008 Report Share Posted August 4, 2008 Well to be honest, I've had lifters get noisy on me, that would go away after a warm-up period and a brief drive, usually 20 minutes or more. It's usually only one or two lifters that take some time to "pump up". This also depends on how long the lifters were sitting without tension from the installed valvetrain. For example, when I did my last LIM job on my Olds, the engine sat for two days with the manifolds off and the pushrods out, and after reassembly and startup, I got a lot of valvetrain noise initially. I'm not saying you definitely have the same issues that I did, but just don't rule it out. I've never observed how a lifter sounds when the rocker arm/ pushrod is removed and the engine's started, so I don't know if it can be pinpointed that way. My other question is, did you change the oil after this job? Only because it's very difficult to avoid having any coolant spill into the lifter valley and then travel to the bottom of the motor when removing the LIM. Possibly if a lifter got saturated with coolant, this could take some time to work itself out, if at all, but it's very important that the rotating assembly doesn't get exposed to coolant-contaminated oil. Quote Link to comment Share on other sites More sharing options...
genEus Posted August 4, 2008 Author Report Share Posted August 4, 2008 Well to be honest, I've had lifters get noisy on me, that would go away after a warm-up period and a brief drive, usually 20 minutes or more. It's usually only one or two lifters that take some time to "pump up". This also depends on how long the lifters were sitting without tension from the installed valvetrain. For example, when I did my last LIM job on my Olds, the engine sat for two days with the manifolds off and the pushrods out, and after reassembly and startup, I got a lot of valvetrain noise initially. I'm not saying you definitely have the same issues that I did, but just don't rule it out. I've never observed how a lifter sounds when the rocker arm/ pushrod is removed and the engine's started, so I don't know if it can be pinpointed that way. My other question is, did you change the oil after this job? Only because it's very difficult to avoid having any coolant spill into the lifter valley and then travel to the bottom of the motor when removing the LIM. Possibly if a lifter got saturated with coolant, this could take some time to work itself out, if at all, but it's very important that the rotating assembly doesn't get exposed to coolant-contaminated oil. Yes, absolutely I changed the oil. Actually I did spill quite a bit of coolant inside as when I took out the pan bolt about 100cc of coolant first came out before the oil... As for the stuck lifter -- well, there was about a week in between disassembly of the motor and putting it back together, so it sat without rockers and pushrods for about a week. I am dead scared to put it together and drive it like that though... Anything else you (or anyone else) can think of? Quote Link to comment Share on other sites More sharing options...
Brian P Posted August 4, 2008 Report Share Posted August 4, 2008 I would at least rev the engine up in park and hold it (~2500 rpm) for maybe 30 seconds to build up substantial oil pressure in order to pump the lifters up. As long as you know for certain that all pushrods went to their correct locations, all rocker bolts are torqued to spec (sounds like you did all that) then you don't have anything to lose at this point. Quote Link to comment Share on other sites More sharing options...
Brian P Posted August 4, 2008 Report Share Posted August 4, 2008 additionally: It's not so much that the lifters are "stuck" more that it's lost some of the oil inside them since they are hydraulic. The older 2.8/3.1's had priority oiling to the valvetrain, secondary to the bottom of the motor. Those motors hardly ever had noise coming from that area, even after cam swaps. The gen 3 3100/3400 etc like you have gives priority oiling to the main bottom end, THEN to the valvetrain. It kind of explains how oil isn't squirting out and flying around as much at idle when you took the valve cover off. Quote Link to comment Share on other sites More sharing options...
GP1138 Posted August 4, 2008 Report Share Posted August 4, 2008 I thought you'd put a Nine Inch Nails song in the background of the video or something. It honestly doesn't sound terrible... I'd say lifters too. Quote Link to comment Share on other sites More sharing options...
genEus Posted August 4, 2008 Author Report Share Posted August 4, 2008 I thought you'd put a Nine Inch Nails song in the background of the video or something. It honestly doesn't sound terrible... I'd say lifters too. lol @ NIN comment. Now maybe if I were taking apart my LS1 (God forbid!) - then maybe... But, with the Lumina? ha. So... my next step is to just rev it up and keep it up and just pray that a lifter gets "unstuck?" I'll do it after work tonight... If that doesn't help, I'm at a loss. Quote Link to comment Share on other sites More sharing options...
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