engine internal Damage

[Bart001]

Soooo I pulled the engine out.... Everything went perfect until I started to take out the pistons..... Every single Top compression ring came out in pieces like 50 pieces in all.....lol....

Then the last piston I took out, looked like someone took a hammer to it, or shot it with a gun.... and just imagine the damage to the cylinder wall.....Theres a nice lil grove that has formed in the wall....

and only 1 rod bearing was spinning and machined the crankshaft down...

Any Ideas what to do, Scrap it, fix it, new block and crank? lol

[Windsplitter]

2 things

1. Scrap it and get a new one OR
2. Rip it apart and u got urself a SWEET!!! do it urself Engine, on less its ur daly driver...

[matts]

if the gouge in the wall is too bad you dont have a whole lot of choices other than get a new block. im not sure how much a new block (rebuildable block i should say) will cost ya though. i know my 350 block i built was $175, then the cost to get it machined.


unless you're just wanting a new car it's gonna be cheaper in the long run to just build an engine and put it back in the car. you're talking $1500 compared to at least $4-5,000.

[Bart001]

I guess unless I post a few pics you cant really know... Its not that deep of a groove, its just noticeable when your paying attention, I was thinking of taking 0.010 out and buying a new piston and 0.010 over piston rings for just that piston.
And honing them all.....

And maybe a new crank, One of the Connecting rod surfaces must have been milled down like 0.03 unevenly, so i'm sure its scrap...

Wondering if anyone knows if that option is viable???

[Colin]

was thinking of taking 0.010 out and buying a new piston and 0.010 over piston rings for just that piston.All cylinders must be bored the same amount . You don't want one to displace more than the others . :roll2:

[matts]

:lol: yeah, you dont wanna do that. if you do one you gotta do them all.

[Bart001]

Actually i'm thinking now that i'll just resleeve that cylinder and get a new piston...

[Colin]

If the cylinders can be cleaned up with an overbore , just do the entire 6 and get new pistons and rings . If not get a different block and bore it . Or if you don't want to spend any $$ , hone it if it's in great condition , clean up the pistons and ring lands & re ring ( not recommended ) You don't wanna cheap out here or you'll regret it ... ;)

[Bart001]

yeah I talked with the machine shop today and they said the same thing as you with boring them all 0.030 and new pistons and rings,..... but...

I already bought the rings a week ago, all standard size, so I wanna keep them all....lol.. considering I already spent 450 on, Main and Rod Bearings, Rings, Head Gaskets, Crank seals, Timing cover gaskets...

Can I just hone them all, and resleeve that one cylinder, so everything can keep standard???

[Colin]

Can I just hone them all, and resleeve that one cylinder, so everything can keep standard???Waste of time , just bore it and fit new pistons/rings . The 3100-3400 are prone to piston slap already and honing will only make it worse . Why do you want a stock bore size ? you're gonna get more power from the increased displacement anyway ... Take the rings back and exchange them for a piston & ring set . :thumbup2:

[Bart001]

Yeah Colin... bastard...lmao... lol.. you convinced me... I'm gonna take the pitson rings back, and get 30 over and pistons, then bore 30thou, and hone it.....

another good question would be, HOw much will the compression go up?? lol... and a good answer would be, look at a compression calculator, or get a regular calculator out and figure it out....lol...

thanks again Colin... I will go with 30 overs.... Guess theres not too many GA's out there with 30 overs..... and I gotta deciede how much to take off the heads.... maybe just 10 thou, seeing as compression is already goin up with displacement enlargment

[Colin]

:thumbup:

[TA^Guy]

Well I'm just seeing this thread now but I agree with Colin.

Do not just bore one cylinder, and if the scrape isn't that deep and the cylinder walls can handle it I would try to bore is .030 over. Not that it will provide that much more displacement, but you may have easier luck finding piston and rings for it. You can always start by honing it and seeing what the results are and if it even needs a overbore.

Also if you have piston damage (from your discription sounds like you had some denotation at one point or running too lean) you might want to go ahead and check the heads for trueness, cracks, or burnt valves and valve seats. A fresh valve job usually isn't that expensive, or you can have a machine shop redo the seats and install fresh valves, springs, etc. IMO, if your going to build the bottom end might as well redo the top end. Nothing like a healthly motor that floats the valves in the higher RPMs due to old crappy springs.

[matts]

actually wont compression go down with the increased displacement? there's more volume in the cylinder.

anyway, i'd take the motor out and take it to a machine shop and ask them what they think. just cause you want .010 over doesnt necissarily mean you'll get .010.

[Colin]

Originally posted by matts
actually wont compression go down with the increased displacement? there's more volume in the cylinder.
No , unless you change the cylinder head chamber volume , your compressing more volume into the same space .

[matts]

well that makes sense, but wouldn't it be the same principle as putting a dished piston instead of a dome piston? the dish is going to lower compression and the dome is going to increase it.

[bowdenjeffery]

I would personally say sell that engine once its fixed...and buy a 3400

[Colin]

Originally posted by matts
well that makes sense, but wouldn't it be the same principle as putting a dished piston instead of a dome piston? the dish is going to lower compression and the dome is going to increase it. Again your changing the size of the combustion chamber volume . The domed piston makes it smaller and the dish makes it larger .

[ENGGUY]

By the time you spend $ for all the parts and machine work, you could get a new engine from the dealer.
And it comes with a warranty of sorts, and is already assembled.
Time is money too.

[Bart001]

Well everythings sent out.... 30 thou over pistons, 10 thou off the heads, New Cam, Valve Job, P&P and used from the 3400 will be the Oil Pump, Lifters, Rockers, Balancer..... I guess thats all...lol

Suprising fact... I'm using the Crank outta a 2003 3400...lol
Both are 981 casting numbers... and the 3400 crank actually says 3.1L on it.. Damn GM bastards saving money... thats ok now I dont gotta buy a new one..... This new engine better run like new.....lol... and with a lil more power....



ON Compression
theres two factors with two sub factors..... When Changing the Volume you will change the compression, Depending on where you change the volume heads or cylinder determines + or - compression....

If you increase the Volume of the Cylinder or decrease the volume of the combustion space compression will go UP.. remember this combustion space is when piston is at TDC

If you Decrease Cylinder Volume or Increase the Combustion space you will have compression go DOWN...

Pistons, domed increases, dished decreases.... and these at TDC change the volume of the combustion space and not cylinder volume. Only way to change the cylinder volume is with boring or resleving with a smaller bore....