3rd motor swap in car

[learnAsUGo]

First off i have a grand prix gtp 3.8 s/c which originally was my brothers car. I decided to buy it from him after he had put a boat load of money into it and he threw a rod. I got an engine from pick n pull and swapped it out. Drove it for 3 days then i heard tapping, a day later on my way home from worked rod went out. when i finally got engine out of car n looked in the oil pan my next door neighbor (who has worked on this car since my brother had it) says the piston slipped out of the pin or something of that nature, which is exactly the same thing that happened to the original engine. As i had a warranty i took the engine back and got another one pulled out....this time we checked the rods a little more for play than the last time and noticed this has the same problem it seems. We were thinking about doing a sorta engine rebuild, but wanna see if anyone has had this problem with the engine and the pistons and if just changing the bearing and <there was something else> out would stop this from happening. If you have any questions on what i have explained feel free to ask. Any and all help is appreciated.

[FordMan77]

No, you broke a piston. They break around the skirts and let the rod/wrist pin pull out of it. Let me guess, #1 or #5??

No, changing the bearings would not avoid this. I'm not 100% sure but I think the GTP's got floating wrist pins which may be mistaken for the "play" you are feeling.

To properly rebuild the bottom end on one of these motors you have to align bore the block, then hone everything. If not then the chances of the motor surviving for long is questionable at best.

You need to find out why you broke the piston on the old motor before installing another one. Was there excessive spark knock (detonation, KR)? Did it go lean during boost (as in not enough fuel pressure, too small a pulley on the SC)?

[BillBoost37]

Yeah..L67 is a floater pin. I've seen pistons disintegrate etc.. nothing to do with the pin.

Putting bearings in yourself is a mistake unless you have a machine shop and understand the nuiances of the 3800.

[learnAsUGo]

sounds like a bigger problem than i thought. Yea this last motor was number 1 and the first motor was either 5 or 6. As for why it happened, the engine that just went didnt have any lean during boost (if by that you mean like a delay after you pushing the gas pedal down) as for excessive spark the only thing i know is that there was the tapping then a final thud sound and the engine died. I will let my next door neighbor know about the whole floating pins like you guys said and as far as i know he is pretty familiar with rebuilding engines hopefully he understands this. if changing just the bearings won't help would it help to rebuild the engine along with pistons and everything if they were all stock components or should i upgrade the size of the pistons.

[FoSHO99]

These motors are pretty hard to blow up stock, but if you mod them from stock and aren't scanning or aware of what the motor is doing or reacting to those mods, they are easy to blow. These motors have been pushed 600whp+ on stock bottom ends with no problems and the right tune.

When you got the car was anything done to the pcm beforehand?

[learnAsUGo]

no everything was stock on the car. The only thing my brother had done before the motor went on him was changed lifters, rebuilt oil pump, new fuel pump, timing chain, and some other work like shocks and such. as for the pcm that was never touched to my knowledge. just to make sure pcm is the main computer correct (the one in the air filter housing). if so does that need to be reprogrammed or whatever?

[thunder71173]

probably running less than 92 octane in it and getting kr and improper cylinder detonation. DONT RUN )(*&&^ gas in these cars or they will blow up.

[learnAsUGo]

yes i was running 87 octane in it which is what my brother was running in it for 2 years before it blew on him. but i did just read something that sounds relevant wanted to run it by the forum. right before i heard the knocking i had scanned the car to check the codes. the one that came up was that i had a bad egr valve...don't remember the exact code but regardless it was bad. I didn't have 140 bucks to change it so i decided to wait until i got paid...obviously i didn't make it that far lol. but i read a bad egr valve could cause excessive spark knock...is this most likely my problem?

[thunder71173]

If you put 87 octane in a car with compression and boost the cylinders detonate early which puts massive pressure on the crank, Rods and everything in the lower end of the engine. The number one cause of these engines blowing is running low octane fuel. You have blown two motors the same way running the same fuel it doesnt matter if your brother drove it that way for twoyears he just got lucky that it lasted as long as it did. You can throw as many L67s in it as you want if you keep running low octane fuel you will continue to blow engines may be a day week or even two years but it will eventually happen. I know higher octane fuel is expensive but there is a trade off. Put high octane fuel in and get better fuel mileage while keeping your engine clean and running strong or save a few bucks at the pump get crappy fuel mileage and blow motors. I hope you dont take offense to what im saying I am just telling you the truth the manufacturer wouldnt call for premium fuel only if it was ok to run 87 octane in anL67.

[learnAsUGo]

no I got u...u know more than me lol...thanks for the info...wat bout the egr valve

[thunder71173]

all the egr does is return some of the un burned fuel from the exhaust back into the intake manifold most people delete the egr all together by plugging it off. There are two copper hses that attach to the egr that have brackets on the end of themyou caut the tubes off and put a penny in one bracket that goes to the exhaust manifold seal it up with copper rtv and bolt it back up. the one that goes to the intake you plug up with a nickel I believe and seal it up withthe same copper rtv and bolt it shut. If you dont get the egr code deleted with a pcm tune I believe it will cause a check engine light and a little less fuel mileage but thats the extent of it. That bieng said I cant see how the egr bieng bad would cause your motor to blow? Put good 92 + octane in the tank and change the oil regularly and you will be suprised at how long your engine lasts! I dont know that much The only reason I know the things I do about fuels and cylinder detonation is from building race engines for my mx quads, they will run but they are a ticking time bomb. 87 octane fuel actually ignites easier than 93 does so the plug starts to fire the piston back down quicker which the pcm can only compensate timing so much so in a nut shell the explosion inside the cylinder happens too fast which is the knock you hear and the rod gets fored back down asplit second before it is supposed to and puts hella stress on the piston rod rod bearing and crank. So moral of the story is run the best gas you can and your supercharged engine will last much longer!!

[BillBoost37]

Ok...motor's are an issue that exists between the seat and steering wheel.

You can run a motor on 87 octane, but lemme tell you. If you rev the rpm, or drive it.. you are asking for another dead motor. How much fuel is in the car? How close is your nearest paint store? I realize that seems like an odd question but you want to find tolulene or Xylene. Based on the amount of fuel in the tank...we'll tell you about how much you need to add to bring the octane up to a safish level.

Put your next motor in and don't touch the bearings or bottom end. Your problems appear to be easy to fix.

[Bio248]

i run premium in everything i own for a reason.

[TLSheff]

Not to sound like a tool, and it IS possible it was removed, but most every GP Ive seen has a sticker on the inside of the fuel door that reads Premium Unleaded Only.

In the words of Bill Engvall, Here's your sign

EDIT: LOL W/E they're both funny and I hadn't had coffee yet :P

[blueguy]

Not to sound like a tool, and it IS possible it was removed, but most every GP Ive seen has a sticker on the inside of the fuel door that reads Premium Unleaded Only.

In the words of BILL ENGVALL, Here's your sign

I fixed it ya noob.

[BillBoost37]

In the words of BillBoost:
It's more costly to change engines than use super unleaded, more work too

[learnAsUGo]

thanks for all the info guys. sounds like my huge problem turns out to be a pretty easy one. learn new stuff everyday cuz i never knew the difference between the different gases now i know a lot more than i ever did. now my next question i know everyone is saying use premium (93 octane) gas, but i really don't have the money to pay 4/gallon...which soon will prolly be more like 5 or close to 6/gallon. what if i used 89 octane fuel, mainly would it get me through the next month or so until i get my money situated with fixing this car. Or is there an octane booster that actually works to help boost it at least up to a safer level to run the car.

also i was told as a rough estimate basically 4 cylinders you use 87, v6 use 89, and v8 use 93 is that true?

[GOTIT4CHEAP16]

Yea basically. Your car is boosted (Supercharger) you HAVE to use 91 or better or you will just keep putting in a new motor. You either learn your lesson or you dont.

[thunder71173]

Ok...motor's are an issue that exists between the seat and steering wheel.

You can run a motor on 87 octane, but lemme tell you. If you rev the rpm, or drive it.. you are asking for another dead motor. How much fuel is in the car? How close is your nearest paint store? I realize that seems like an odd question but you want to find tolulene or Xylene. Based on the amount of fuel in the tank...we'll tell you about how much you need to add to bring the octane up to a safish level.

Put your next motor in and don't touch the bearings or bottom end. Your problems appear to be easy to fix.

He said it right here

[BillBoost37]

The problem is detonation. In your motor, this is controlled by the pcm. There's other forces in the system that can make the detonation happen at the wrong time. This is called predetonation/pinging/knock. All are very bad to a motor. They blow holes in pistons, destroy bearings etc.

The octane rating of fuel can be considered to be knock resistant. The higher the rating, the better the resistance to the fuel igniting on it's own when you don't want it to happen. This is much more noticable in a boosted engine. You add extra fuel for the extra air and then compress it much more than a typical engine. ... Kinda like a diesel that doesn't have spark plugs. Too much compression (supercharging) and low octane (aka easy to ignite) fuel and you'll have problems.

Guys going to the track will typically dump in the highest rated octane of lead free fuel they can to ensure they don't hurt the motor and get the most power at the track.

If you want to run lower octane fuel like your saying. Don't put on the supercharger belt. Run the car NA and it'll handle it much better. Not having a belt on the motor, your right foot won't be able to whisper "it'll be ok if I just do it quick, it'll be ok to give it just a little more". Pull the belt and you'll be fine to drive around on lower octane fuel.