3800SC engine,(not mine)- "RUNS" fine. Has 1.9 rockers and Headers so has a non stock idle (but not lumpy). The noise, that sounds almost like a Loud "spark jumping", coming from around #6,( but looked in the dark, no spark). Went over the "entire engine" top to bottom with a "stethescope", (belts off) not a sound ! Not in bottom end, not lifters, not rockers( everything sounds like a sewing machine running). Gets louder when put in gear and not moving. I almost suspect either a leaking Header gasket or a cracked Flywheel. (Trans was replaced about 500 miles ago) The header is almost impossible to get to because of it's location. I really don't want to drop the cradle. Any Ideas ??? Thanks
I said in the post, "Belts off". the "sound"( is the same with the belt off", everything "Inside" the engine is silent (sewing machine), but somewhere there is that noise, not clacking, not knocking (I am familiar with those noises). sounds just like a huge spark jumping.
[This message has been edited by Lou6t4gto (edited 11-04-2019).]
Does it sound like its coming from the trans area since that was just replaced? Fly wheel cover rubbing or just the clutch making noise? Hard to make guesses without knowing where its coming from or hearing what it sounds like.
------------------ "America is all about speed, hot nasty bad-ass speed" - Eleanor Roosevelt
Start car. Put up on lift. Then use a 3/4" 30" long hose taped to a funnel as your stethoscope. Listen around the bottom area where the transmission joins to the engine (flexplate area). I found that the starter gear on my engine was not fully retracting and hitting against the flexplate. It was a loud ringing noise and on first thought believed it to be a rod bearing but it wasn't. The flexplates on these engines can occasionally fail as well.
------------------ " THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, P-log Manifold, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, Champion Radiator, S10 Brake Booster, HP Tuners VCM Suite. "THE COLUSSUS" 87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H " ON THE LOOSE WITHOUT THE JUICE "
[This message has been edited by Dennis LaGrua (edited 11-06-2019).]
further inspection, not trans/ flywheel. Took belts off again, removed all rockers and push rods and checked all, put back together, with no belts, no noise ! put belts on, NOISE, took belts off, STILL NOISE ! the sound seems to be coming from "dead center",but cannot pinpoint it. used both a stethescope, a piece of rubber tube, and a long screwdriver. the only way to describe "the sound" is, if i a lifter collapsed, and the roller is Bouncing on the cam lobe, a metal to metal Tap. does not do it 100% of the time, sometimes will stop for 10 seconds. exhaust is all tightened. going to order new LIFTERS and pray ! LOL
installed new ls7 lifters, same noise. push rods perfect, 1.9 rockers perfect, 65 psi oil at an idle 75-80 at 1500. is a wrist pin or piston going bad a Normal malady of a 3800 ??? absolutely no exhaust leaks. don't want to scrap the engine for something I cannot find thanks
if it was a head gasket, there would be SOME compression, correct ? nothing(combustion or oil) into the water jacket/radiator. no steam from the tail pipes, losing no coolant., no water in the oil. (runs right at 180 degrees.) just no compression and a rapping noise. should have mentioned, this is IN a 97 GTP, and getting to the rear bank is a REAL hand cutting experience. I've dealt with a bunch of 3800SC in fieros (installed, rebuilt), alot easier in a Fiero than the GTP with headers !
when I said runs fine, I thought it was just a lumpy idle from the 1.9 rockers and 3" exhaust. what I meant was it has 65psi oil at idle and goes to 80 at 1500 (Not in the crank). it is only running on 5 cyl (obviously)
Before you start tearing it down, get a Endoscope/inspection camera that will attach to your phone, pull the plug and take a peek inside. You can get them for $20 or so off Amazon and have it tomorrow.