• The site migration is complete! Hopefully everything transferred properly from the multiple decades old software we were using before. If you notice any issues please let me know, thanks! Also, I'm still working on things like chatbox, etc so hopefully those will be working in the next week or two.

2003 Grand Prix GTP Motor Knock

N

NvMySi83

New member
Alright guys so im looking to buy this grand prix of a guy in alberta its a 2003 GTP , 65,000 KMS so thats ver ylow KMS (not miles) but it knocks, the guy changed the spark plugs and wires and still same, he said he starts it it knocks loud and then stalls after 10-15 seconds, is the motor toast? hope you guys can let me know thanks,

if it is do the 98 GTP motors all the same up to 2003 incase i gotta change the motor.
 


Motor...yes.

Transmission...no.

If it is knocking it is pretty much done unless you want to totally rebuild it. Get a new short block, reuse the heads and everything else and be done.
 
How do you know its the motor forsure?some people problems with knocking were harmonic dampener, Supercharger coupler, a simplevacuum hose to the Supercharger, flex plate, etc... how can i go and find out that its the motor forsure, the guy told me on the phone that the knocking sound is coming from the passenger side, around the supercharger, but when he starts it it knocks and then stalls after 10 seconds of running.
 
You can check the oil pressure with a manual gauge to confirm that once the motor warms up the pressure tanks to nearly 0.

However the knocking, then upon warming up stalling ...kinda closes the deal if you ask me. That's a bad motor.

And well..Blue has a bit of experience in killing motors. :D Don'tcha Blue.
 
Yeah...hence why everyone who has toasted something in the past couple weeks I've called it on the first post. 5 motors of experience does that to you.
 
bluegtp91 said:
Yeah...hence why everyone who has toasted something in the past couple weeks I've called it on the first post. 5 motors of experience does that to you.
Click to expand...



hey, i wanted to know if a 1999 pontiac grand prix gtp supercharged, motor will be a straight swap with the 2003? all sensors and harness all the same or no? is tehre anything different that i should know about ? i'll be getting the parts car this friday and would want to know as much info as possible, after i take out what i need i will be parting it out, also is it easier to take the motor with the transmission from the top or bottom? i only worked on hondas and acuras and their motors arent so big i always took them out from the bottom. hope you can warn me lol. thanks alot i appreciate it.
 


Yep, straight forward swap.

Leave the trans in the car. I find it easiest to pull the motor after removing the oil filter adapter. Gives you about 4 more inches of clearnance. If not..leave an old filter on there and yank away.
 
how do you pull the motor out with the transmission in the engine bay still? dont you have to unscrew all the mounts, and the tranny has 1 mount holding it doesnt it? how do you seperate the tranny from the engine before pulling the motor? seems ackward, hmmm im confused. and im use to doing manual transmissions. never did an automatic. more difficult? any steps you guys can give me.
 
Why? He is just swapping blocks...you don't need to change squat but old to new gaskets and oil/fluids.
 
the reason i say this is because the guy i bought my GTP from put a 99 PCM in my 2002 to gain performance shift... it ended up costing me 3 transmissions.
 


gtpinsc said:
the reason i say this is because the guy i bought my GTP from put a 99 PCM in my 2002 to gain performance shift... it ended up costing me 3 transmissions.
Click to expand...

How the hell? All Perf shift does is raise the shift points? If you have a tuned PCM than there's your perf shift. Only difference is you have the benefit of being able to turn it off so your trans isn't always running on higher shift points and raised pressured trans lines

NvMySi83 said:
how do you pull the motor out with the transmission in the engine bay still? dont you have to unscrew all the mounts, and the tranny has 1 mount holding it doesnt it? how do you seperate the tranny from the engine before pulling the motor? seems ackward, hmmm im confused. and im use to doing manual transmissions. never did an automatic. more difficult? any steps you guys can give me.
Click to expand...

I've pulled the motor by itself and with the trans attached. From my experience, it is FAR easier pulling everything. Remove the dog bones (13mm), motor and transmounts (15mm) downpipe (13mm), harness, power steering (13mm), ac compressor(15mm), and master cylinder (13mm) slide this to the side rather then disconnecting any brake lines, and axles (32mm or 35mm depending on trans). After that and a few other things it's pretty much ready to pull.

Pulling only the motor is a bit more difficult. Same basic steps except the master cylinder, trans mount, and axles are not needed. There's 4 17mm bolts on the front of the bellhousing and 1 in the rear. You need to remove the passenger wheel and have a few extensions to access it. It's right behind the rear exhaust manifold so tons of fun getting to! (sarcasm). After that, hop under the car and unbolt the 3 bolts holding the flexplate to the tq converter (18mm). Now for the fun part. Wedging a pry bar or giant screwdriver in between the bellhousing and engine. Once you get a decent amount of seperation, start hoisting up the motor. Make sure to keep prying the motor away from the trans until you clear the flexplate.
 
Last edited:
actually i might be swapping the whole motor instead of playing around to change the blocks, more time consuming, so is there anything i should know? why cant i use my old pcm?
 
NvMySi83 said:
actually i might be swapping the whole motor instead of playing around to change the blocks, more time consuming, so is there anything i should know? why cant i use my old pcm?
Click to expand...

You can use your stock PCM. Not sure what the hell he's talking about with all that nonsense
 
gtpinsc said:
the reason i say this is because the guy i bought my GTP from put a 99 PCM in my 2002 to gain performance shift... it ended up costing me 3 transmissions.
Click to expand...

Something else was wrong. I ran slicks...got down to nearly a 1.7 60 foot on a stock transmission running a shift kit and 100% line pressure...no stupid performance shift upgrade is going to do that. Swapping blocks has nothing to do with the PCM.
 
got 1 more question as i got offered a good deal for a whole grand prix gt car, 3.8 litre no supercharger of course, will that block worl with the supercharged motor? as i rather buy the whole car and let you guys have an opportunity to buy parts off it if you wanted.
 


You must log in or register to reply here.
Back
Top