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05-24-2016
My 02 Grand Prix has a slight knock coming from the engine on cold start but goes away after 2-5 minutes. im assuming its the rotational assembly but my question is can I change out that assembly (new crank or bearings or pistons) without changing the engine. vehicle has 205000 miles on it. any ideas?
05-24-2016
sounds like lifter tick. my old 230,000 engine would do this right about 3,000 miles on a oil change. changed the oil it stopped every time.
05-24-2016
Oil has been changed recently, it just started on me about 300 miles after a change. we use 10w-30 oil in it.
05-24-2016
I'd try adding some transmission fluid to the oil to maybe free up a sticky lifter.
You couldn't just swap out a crank/pistons/rods without costing yourself 1000-1500 in machine work. You could buy 3 used motors for that price. Rebuilt 3800's never last.
05-24-2016
Lol you guys that say rebuilt 3800's never last is about the dumbest thing ever.... It's a motor it has nothing to do with it being a 3800 if you don't have a retard build it then you shouldn't have any issues.Originally Posted by Fivefingerdeathpunch
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05-24-2016
your so far off. so many fail at re building this engine. it needs shop work and that cost more then a whole used engine, why its not worth it to rebuild one.
even shops f up rebuilds. so odds are far less in your favor of it staying together for more then 200 miles. thats what we call a back yard rebuild here, a 200 mile engine. thats all they last.
yes its been done and they live, but is it worth 2500 bucks to you? not me.
05-24-2016
Knocking is coming from the lower end of the motor, from the rod area
05-24-2016
and it stops? rod knocks tend to be quiet cold, as the oil warms and thins, you hear it knocking way more.
05-24-2016
it starts making noise when cold then goes away when it warms up.
05-24-2016
what your describing sounds more like a lifter, causing rocker clap in the valve cover.
time to get a stethoscope and listen close.
05-24-2016
Ok, but how would a lifter make a lower engine sound? I put my head to the left side of the motor (There the drive belt is) and it sounds like its coming from the bottom of the vehicle?
05-24-2016
put the scope on the oil pan, and the valve cover. you'll know whats louder.
you can also use a wood dowel, or a large screw driver to your ear.
typically, rod knock gets worse aka louder as the engine warms up, lifter tick goes away.
05-24-2016
Pry bar from covers to ear... Works everytime
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05-24-2016
If it sounds like this, it's a rod knock.
If it doesnt sound like this, it's a lifter/valvetrain.
05-24-2016
I will listen to the engine later tonight. The noise does not sound like that, its alot quieter than that noise is. I will pinpoint that later
05-24-2016
Say that to all the folks that have done all the machine work to a 3800 only to have it break in under 200 miles again.
Sure some last a little longer but most will just grenade again.
05-24-2016
It is to me mine is completely rebuilt by a local guy that builds race motors for our dirt track. The 3800 is basically a 350 with 2 less cylinders set up identical. Anyone that does it for a living and is pretty good at it shouldn't have any issues. Yeah if you take it to a back yard mechanic then I can see that happening but it's not the 3800's fault it's the idiot working on it.
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05-24-2016
its not a 350, no matter what you say, this block will twist when the crank comes out, its not a simple tear it down, clean it up with new bearings and run with it rebuild.
it needs machine work or its a fail from the start.
jamesivey here had a shop re build his, it lasted all of 50 feet. same deal, thats what they do all day, rebuild engines.
so whats the friend price for a rebuild at your place there? everyone seem to be charged over 2 grand.
hell one guy who had the shop work done, then re built it himself with his dad, it cost him 2500, his own labor thats shop and parts cost only. lucky for that guy, hes one of the few we know of that are still running strong.
05-24-2016
Oh my fvcking god, a 3800 is not a 350 with 2 cylinders shaved off. That would be the 4.3 liter engine. I would know because I used to work at an engine shop and still occainsionally do work there.
These guys are telling you the complete truth about getting a used engine over a rebuilt one. When my motor blew on my 97 GP, the owner of the shop I worked at even told me I was better off getting one from a junkyard with a warranty and he's been doing this for over 35 years. He's even done NASCAR engines which are extremely technical. Listen to guys like Scott, Bill, Jason, etc, they know what they are talking about.
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05-25-2016
Yeah my GT is not worth 2500. I was planning anyways to convert it into a GTP so just getting another engine makes sense from the start. Im just trying to band-aide this motor until my SC motor is built. That engine is being machined and tuned since Im trying to turn it into a high performance vehicle. But the NA motor is not worth all that time and effort in my opinion. Thanks guys for all the infos and tips. Maybe once I get the SC motor started you guys can give me some tips?
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