04compg Posted February 17, 2018 Report Share Posted February 17, 2018 Ok so I work at a parts store and a lady brings her Grand Prix I’m with a P0300 and I notice it has original wires and assuming plugs so I send her on her way with plugs and wires. Motor was quiet at this time. Then a week later she comes in and says her son changed them and it’s still missing and told me I could have it for $100 so I picked it up and drove it 15 miles home. Get home and it’s ticking bad. I find that 2 plug wires were crossed and fired it up. Still misses and still ticks. Changed the oil thinking it was washed out with fuel from her driving it so much missing and no change. I’m having a hard time tracking down the miss as it doesn’t sound like a rocker, the sound is best heard from the top of intake. Car has the 3100 any suggestions? Quote Link to comment Share on other sites More sharing options...
04compg Posted February 17, 2018 Author Report Share Posted February 17, 2018 Quote Link to comment Share on other sites More sharing options...
Imp558 Posted February 17, 2018 Report Share Posted February 17, 2018 L67 swap, fixes a 60* every time. rich_e777 and wstefan20 2 Quote Link to comment Share on other sites More sharing options...
wstefan20 Posted February 17, 2018 Report Share Posted February 17, 2018 I'd start with a compression test. This will fairly reliably tell you if the miss is due to worn piston rings, valve issues, etc. Then if you can do a wet compression test to rule out rings, then you can do a leak down test to isolate the issue. Course, if all tests come back good, I'd change the lower intake manifold gaskets and rebuild/ check the lifters as this sounds kind of like lifter tick. Quote Link to comment Share on other sites More sharing options...
04compg Posted February 17, 2018 Author Report Share Posted February 17, 2018 L67 swap, fixes a 60* every time. lol no way would I invest the time or money into a sub 1k car. Although I do have a spare Eaton in the garage lol Quote Link to comment Share on other sites More sharing options...
04compg Posted February 17, 2018 Author Report Share Posted February 17, 2018 I'd start with a compression test. This will fairly reliably tell you if the miss is due to worn piston rings, valve issues, etc. Then if you can do a wet compression test to rule out rings, then you can do a leak down test to isolate the issue. Course, if all tests come back good, I'd change the lower intake manifold gaskets and rebuild/ check the lifters as this sounds kind of like lifter tick. should I replace the rockers and pushrods too? Done a few lim gaskets before but never have replaced lifters in a engine before Quote Link to comment Share on other sites More sharing options...
wstefan20 Posted February 17, 2018 Report Share Posted February 17, 2018 As long as they look good I keep them, but I would verify good compression before you go tearing into them. Also, the orientation of the push rods and the order of both rockers and rods are EXTREMELY important. You can't switch them up because of how they wear. I usually cut holes in a closed small cardboard box and label it with each cylinder and place them as I go. There's a few videos on inspecting and rebuilding gm lifters on YouTube, but if you have any questions, let me know. However, with it ticking like this, I'd prepare bare minimum to replace at least one, and at worst the cam since the roller can damage the lobe. You can inspect the cam by manually turning the engine and looking down each lifter hole. Good luck! Quote Link to comment Share on other sites More sharing options...
bluegtp91 Posted February 17, 2018 Report Share Posted February 17, 2018 Well, that sounds healthy. It's a GM V6. You can toss junkyard parts on any of these cars and they'll work just fine. However, if it's misfiring like that and all you're getting is a P0300, I'd venture to think something in the valvetrain let go. Sounds like a broken valvespring or failed/stuck lifter. Time to rip into it. Plus, the 3100/3400's suck because of the goofy offset rockers/pushrods. Quote Link to comment Share on other sites More sharing options...
55trucker Posted February 17, 2018 Report Share Posted February 17, 2018 I’m having a hard time tracking down the miss as it doesn’t sound like a rocker, the sound is best heard from the top of intake. Car has the 3100 any suggestions? Pick yourself up one of these........and start listening seeing as you are employed by an auto parts store there should be one hanging on the wall Imp558 and wstefan20 2 Quote Link to comment Share on other sites More sharing options...
Galaxie500XL Posted February 17, 2018 Report Share Posted February 17, 2018 What year? My mother’s ‘03 Grand Am has had THREE rocker arm studs pull the threads completely out of the heads, because GM wanted to save 2 cents by using smaller diameter bolts, which puts greater stress on the threads. Quote Link to comment Share on other sites More sharing options...
55trucker Posted February 17, 2018 Report Share Posted February 17, 2018 '97-'99 L82 car Quote Link to comment Share on other sites More sharing options...
04compg Posted February 17, 2018 Author Report Share Posted February 17, 2018 This one is a 03 as well, I’ll probably just drive the car up to the crusher if it is more than a rocker stripped out Quote Link to comment Share on other sites More sharing options...
04compg Posted February 17, 2018 Author Report Share Posted February 17, 2018 Pick yourself up one of these........and start listening seeing as you are employed by an auto parts store there should be one hanging on the wall I have one and can’t seem to track it down other than the top of the intake, which leads me to think lifters, maybe from it missfiring for so long it washed out a lifter with fuel? Is that possible? Quote Link to comment Share on other sites More sharing options...
wstefan20 Posted February 17, 2018 Report Share Posted February 17, 2018 I have one and can’t seem to track it down other than the top of the intake, which leads me to think lifters, maybe from it missfiring for so long it washed out a lifter with fuel? Is that possible? I'd be surprised, but I have dealt with these lifters collapsing and not wanting to refill. Course, that was because of the dexkill and the lower intake gasket leak gummed things up. I was able to just take apart the lifter, soak it in acetone for a day, inspect the surfaces, and re-assemble and it's been fine since. Quote Link to comment Share on other sites More sharing options...
04compg Posted February 17, 2018 Author Report Share Posted February 17, 2018 I'd be surprised, but I have dealt with these lifters collapsing and not wanting to refill. Course, that was because of the dexkill and the lower intake gasket leak gummed things up. I was able to just take apart the lifter, soak it in acetone for a day, inspect the surfaces, and re-assemble and it's been fine since. do the lifters have to go back to the same spot they came from or can they get mixed up? Was going to just pull all of them and let them sit in parts cleaner then oil for a day Quote Link to comment Share on other sites More sharing options...
rich_e777 Posted February 17, 2018 Report Share Posted February 17, 2018 Lim gasket is probably sucking in coolant and lifters might be full of gunk from it all mixing, It is a 3100 after all. Unless its been maintained right which most are not, the LIMG has probably been leaking awhile. If it looks wet behind/below the P/S pump or TB its a good chance the gasket has failed. They also like to go bad internally on the other side of the coolant passage where the plastic part separates from the sealing part. Happens just as bad on the 3400 too but since using a copper based RTV on the valley seals I have had better luck. Defanitly do not use the crap that comes in the gasket set, get Permatex everytime. Once you get the pushrods out a magnetic tool will pull the lifters right out. After you take the plastic pushrod guide off Im recollecting, its easy. Quote Link to comment Share on other sites More sharing options...
55trucker Posted February 18, 2018 Report Share Posted February 18, 2018 This one is a 03 as well, I’ll probably just drive the car up to the crusher if it is more than a rocker stripped out aaaah.....it's an LG8 engine, somewhat more stout than the older L82. do the lifters have to go back to the same spot they came from or can they get mixed up? Was going to just pull all of them and let them sit in parts cleaner then oil for a day preferably.....even tho one is not dealing with a flat tappet cam try to return the lifters from where you found them. Have you narrowed down the location of the clattering to either the front bank or rear bank? Quote Link to comment Share on other sites More sharing options...
Galaxie500XL Posted February 18, 2018 Report Share Posted February 18, 2018 All that’s required to fix the thread issue is Helicoil...you’ll spot the problem right away with the valve covers removed. Imp558 1 Quote Link to comment Share on other sites More sharing options...
Imp558 Posted February 18, 2018 Report Share Posted February 18, 2018 do the lifters have to go back to the same spot they came from or can they get mixed up? Was going to just pull all of them and let them sit in parts cleaner then oil for a day I put fuel injectors in my ultrasonic tank, to tell them apart I use colored zip ties. If I mix them up I won't know how much improvement was made on them individually. Quote Link to comment Share on other sites More sharing options...
cutlassdude96 Posted February 18, 2018 Report Share Posted February 18, 2018 sounds just like my engine Quote Link to comment Share on other sites More sharing options...
04compg Posted February 18, 2018 Author Report Share Posted February 18, 2018 aaaah.....it's an LG8 engine, somewhat more stout than the older L82. preferably.....even tho one is not dealing with a flat tappet cam try to return the lifters from where you found them. Have you narrowed down the location of the clattering to either the front bank or rear bank? I can’t tell at all, the noise is loudest on top of intake Quote Link to comment Share on other sites More sharing options...
55trucker Posted February 18, 2018 Report Share Posted February 18, 2018 with the stethoscope one should be able to distinguish at what point the clatter is the loudest.....put the end of the scope on various points of each valve cover.....listen.......which cover produces that loudest sound? the clatter will resonate up the pushrod to the rocker arm. Quote Link to comment Share on other sites More sharing options...
04compg Posted February 18, 2018 Author Report Share Posted February 18, 2018 Changed the oil and added a quart of marvel. Quieted it down a lot, now only makes the noise when revving down, to me this confirms lifters since I wouldn’t think any oul additive would quiet a rocker noise Quote Link to comment Share on other sites More sharing options...
04compg Posted February 18, 2018 Author Report Share Posted February 18, 2018 Should I use mahle or Fel-Pro intake gaskets? And do I need to replace the intake bolts Quote Link to comment Share on other sites More sharing options...
55trucker Posted February 18, 2018 Report Share Posted February 18, 2018 Changed the oil and added a quart of marvel. Quieted it down a lot, now only makes the noise when revving down, to me this confirms lifters since I wouldn’t think any oul additive would quiet a rocker noise You're mistaking the sound you're hearing at the rocker for being a faulty rocker. That's not the case, when the lifter collapses you won't hear a clattering at the lifter, you'll hear the clattering at the rocker arm where the arm contacts the valve stem. Since there is a lack of pressure there to keep the clearances tight the end of the rocker now has a gap between it & the valve stem & that's the clattering one hears. Quote Link to comment Share on other sites More sharing options...
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