Ok I posted a couple weeks ago about my comp g dying after further inspection we think it could the fly wheel or crank shaft. As I stated in my other post. I was driving the car when it was as if I put the car in neutral and after turning off rhe car it no longer cranks. The serpentine belt is not turning. When the car broke it was making some rattling before I cut it off. I have not had a chance to fully inspect the car as it sat for a week on the side of the road and I work full time. I'm just looking for some tips on what it might could be wrong. I was nor flooring rhe car the rpms was around 3500 at time of breaking.
2004 Comp G fly wheel? or crankshaft?
- Thread starter cpsmith92
- Start date
MonzaRacer
New member
You might want a regular mechanic to check it out. IF the crank broke or you have serious internal issues, being a Comp G all you would need is a good low miles shortblock, THIS is all the bottom end parts, then have heads,intake, blower etc swapped on and either find local tuner or as its being repaired or doing the repairs your self get a "topswap" tune. The more expensive route is locating a new/used supercharged engine complete. The reason for computer needing a "topswap" tune is that non supercharged bottom ends or shortblocks have higher compression and it can "knock" or KR its self to death if you beat on it or get bad (low octane)gas even. The shortblock will basically be everything below the heads/intake. Most people with NA cars are doing "topswaps". I have an 04 I picked up with rod knock, still trying to figure out getting it home, then I need new engine/rebuild and see how it drives. Hoping I can have it ready for winter! Mainly cause car I have now has no heater! and I am putting off pulling dash(I am a tech by trade so as they say mechanics car gets worked on last) to replace and car needs so much more work. My mom gave it to me and hope to be able to drop driving it and start repairing it.
Oh well back to your issues, Get it properly diagnosed. Then make plans/decide on course of action. AND WATCH OUT ,DONT LET MECHANIC TELL YOU IT ISNT WORTH FIXING WITH OUT DOING RESEARCH. Because unless the car is rusted out underneath or has major damage somewhere N/A engines can be found for very little cash. Heck you can get N/A complete engines off ebay for $300-$400 shipped just watch ads cause some are super high miles engines.
OH and any 3800 Series 2 or 3 shortblock will work. up to the year GM discontinued them. The only changes were minor. And 3800s from Bonnevilles, Lucernes, etc all work you may just need to swap oil pan/pickup. and of course your top end id its N/A engine.
OH and IF your engine broke and a piston hit a head get the valve checked before bolting it on different shortblock.
OH yeah, 2004 and up with throttle by wire are using GEN V superchargers so if you picked up older L67 supercharged engine you still need to swap on your lower intake, and supercharger but wont need "topswap tune" as all S/C cars have lower compression engine from factory, makes up for blower.
Oh well back to your issues, Get it properly diagnosed. Then make plans/decide on course of action. AND WATCH OUT ,DONT LET MECHANIC TELL YOU IT ISNT WORTH FIXING WITH OUT DOING RESEARCH. Because unless the car is rusted out underneath or has major damage somewhere N/A engines can be found for very little cash. Heck you can get N/A complete engines off ebay for $300-$400 shipped just watch ads cause some are super high miles engines.
OH and any 3800 Series 2 or 3 shortblock will work. up to the year GM discontinued them. The only changes were minor. And 3800s from Bonnevilles, Lucernes, etc all work you may just need to swap oil pan/pickup. and of course your top end id its N/A engine.
OH and IF your engine broke and a piston hit a head get the valve checked before bolting it on different shortblock.
OH yeah, 2004 and up with throttle by wire are using GEN V superchargers so if you picked up older L67 supercharged engine you still need to swap on your lower intake, and supercharger but wont need "topswap tune" as all S/C cars have lower compression engine from factory, makes up for blower.
I have very little money to work with so a mechanic is completely out of the question. My dads mechanic friend was able to look at it for a second and told me he thinks its the fly wheel or crank shaft my thing is I need to know what to do to check these items. The car only has 135k on it and I have never driven the rpms past 3500 I only have had it for two months though. I'm looking for thoughts on what could be wrong and how to check them. You have certainly been more helpful than the people on my other post about it. But basically I'm looking for direction on what to check to I can diagnose the car myself without having it towed to a mechanic or paying one to come to the car.
Fivefingerdeathpunch
New member
An easy test is to remove the spark plugs to let the motor spin freely, then manual turn the motor over by the crank bolt.
If you can't even do that in either direction and it won't even move, the motor is likely locked up.
If you can't even do that in either direction and it won't even move, the motor is likely locked up.
MonzaRacer
New member
Well flywheel or crank your pulling big pieces like engine or trans, just sayin. You MIGHT be able to pull plastic cover down by starter between engine/trans. Bad flexplate=pull engine or trans. Which if you do it gives you change to clean,reseal and paint things.
IF engine cranks over ,IE you can verify rear of crank is being turned by starter/flywheel, this helps. IF engine is locked you will probably need to drop whole cradle as you cant reach all flexplate to converter bolts.
Honestly, knowing what I do popping an engine out isnt hard. small bracket on end of trans, knock sensors, starter, flexplate bolts. motor mount bolts to cradle, all the top wiring, exhaust manifolds , crossover, plugs(plug holes against debris) drain coolant/oil, remove fans/rad to avoid damage and with lots of blankets lay hood on roof of car or floor(I prefer to NOT sand them on end, ask me why)once all bellhousing bolts are out floor jack and wood under trans and cherry picker to pull it out using floor jack to help tip trans up and hold it as engine is lifted then as you raise it up prying block/trans apart.
IF engine has to come out, its great time to reseal pan and timing cover, rear cover,replace rear main seal.
OH if you can source engine tilter tool it helps in lining things up going back in. Me I always had to guess angles but Im good at engine swaps as I am a tech by trade. I had old video of me yanking warranty engine on Lumina/Cosicas when I used to work at dealership. 18.6 book hours, set them on jackstands and swap engines in a day. I was so good at it.
IF engine cranks over ,IE you can verify rear of crank is being turned by starter/flywheel, this helps. IF engine is locked you will probably need to drop whole cradle as you cant reach all flexplate to converter bolts.
Honestly, knowing what I do popping an engine out isnt hard. small bracket on end of trans, knock sensors, starter, flexplate bolts. motor mount bolts to cradle, all the top wiring, exhaust manifolds , crossover, plugs(plug holes against debris) drain coolant/oil, remove fans/rad to avoid damage and with lots of blankets lay hood on roof of car or floor(I prefer to NOT sand them on end, ask me why)once all bellhousing bolts are out floor jack and wood under trans and cherry picker to pull it out using floor jack to help tip trans up and hold it as engine is lifted then as you raise it up prying block/trans apart.
IF engine has to come out, its great time to reseal pan and timing cover, rear cover,replace rear main seal.
OH if you can source engine tilter tool it helps in lining things up going back in. Me I always had to guess angles but Im good at engine swaps as I am a tech by trade. I had old video of me yanking warranty engine on Lumina/Cosicas when I used to work at dealership. 18.6 book hours, set them on jackstands and swap engines in a day. I was so good at it.
This is just rude, replys like this should make nobody want to help you.
Thank you you have been very helpful I'm telling me what needs to be done to check it all out. I made a post two weeks ago and was being told to reset the computer to get it to crank which makes no sense at all. Hence making a new post and actually getting somewhere this time. As soon as I get the chance to look at it and see what's wrong I will post updates.
MonzaRacer
New member
Well most of the newer cars the ignition switch doesnt crank engine directly like older car. The switch tells computer to energize the start relay which actuates the starter. This way the computer and oem security can control starting.
I can tell you if its not cranking the starter motor/engine take a look at the security light IF its cranking but not starting, again check the light.
If the starter isnt spinning the flywheel you should know, if its broken, loose ,etc its pretty evident. Not sure why everyone has issues with 3800 rebuilds. We just finished assembling one with experimental forged piston/rod combo (off shelf stroker piston for a Ford 4 cyl and narrowed 4.3 rods for cheaper combo over current offerings). I loaned them flycutting kit to clearance for valves as boy wanted big Comp cam going back. He had spare car harness so built a run stand. He has already put something like 100 hrs on it, him and father have bunch of parts engines laying around and just picked up an HPTuner, I personally have a DHP.
Anyway paying attention to sounds. Could be loose flywheel, lost the crank bolts.
OR something else. As for crank breakage, doubtful but not impossible. And if it didnt damage block or rods fairly straightforward fix. Just dropped crank in one of these the other day at work as car had low oil pressure and new front cover failed to fix it. Boss drove it for three days, ran great.
Weird I buy my GP, start working towards getting it running and I start seeing lots of 3800 stuff!
Good luck
I can tell you if its not cranking the starter motor/engine take a look at the security light IF its cranking but not starting, again check the light.
If the starter isnt spinning the flywheel you should know, if its broken, loose ,etc its pretty evident. Not sure why everyone has issues with 3800 rebuilds. We just finished assembling one with experimental forged piston/rod combo (off shelf stroker piston for a Ford 4 cyl and narrowed 4.3 rods for cheaper combo over current offerings). I loaned them flycutting kit to clearance for valves as boy wanted big Comp cam going back. He had spare car harness so built a run stand. He has already put something like 100 hrs on it, him and father have bunch of parts engines laying around and just picked up an HPTuner, I personally have a DHP.
Anyway paying attention to sounds. Could be loose flywheel, lost the crank bolts.
OR something else. As for crank breakage, doubtful but not impossible. And if it didnt damage block or rods fairly straightforward fix. Just dropped crank in one of these the other day at work as car had low oil pressure and new front cover failed to fix it. Boss drove it for three days, ran great.
Weird I buy my GP, start working towards getting it running and I start seeing lots of 3800 stuff!
Good luck