Thread: 2005 Pontiac Grand Prix GT Rebuild/Restoration

We have a 2005 Pontiac Grand Prix GT with approximately 150k miles on it. I've posted in the past on some modification ideas but am now ready to do some serious work. I would like to rebuild/restore it. Before I post my questions, let me provide some background on the car and clarify what I'd like to do:

- We have owned the car from day 1. I have done all the work on it. It runs well for the most part. Here is a list of what has been done to it:

• Regular oil changes (although not as often as I probably should have) using Pennzoil oil and AC Delco filters
• Tuneup including spark plugs and wires at approximately 100k
• Transmission fluid change (dropped pan and replaced filter) around 100k. Transmission has slipped on occasion since. I added some additive (I think it was Lubeguard High Friction Modification Supplement) last year and it seemed to help a lot. I did notice a slip a week ago....maybe low level.
• Regularly changed brakes and rotors
• Flushed coolant at around 100k
• The body is in good condition, a couple of small dents and scratches....no rust that I've seen.
• Interior is in good condition. Leather seats are okay (some leather cracking), carpets need to be cleaned but not worn, buttons are worn.

Some issues I know of:

• I believe it leaks oil but not sure exactly where from. I know I see oil when I change it.
• Ride is very rough. I would imagine struts need to be changed (seem expensive and complicated to do).
• Transmission slippage I mentioned above.
• Wheels are original. I know when I had tires replaced last, Discount Tire said there was corrosion on rims and they should be replaced.

My questions are:

• Mechanically what should I do next to the car? Assuming just over 150k, should the engine be rebuilt? What about the transmission? What would the cost and time (I've never done either of these) be?
• How much would it be to have the car repainted? I was thinking orange but not sure how that would look with a gray interior.
• What other exterior upgrades could I do to set it apart from every other old Grand Prix you see on the streets. What about interior mods?
• I would like to gain some speed/horsepower (wish we had bought the GTP). What mods could be done? It seems more sluggish then when was new, but it's hard to compare.

We would love a new car (wanted a Dodge Charger R/T) but it's not in the budget right now. We still like the Grand Prix and realized that it might be worthwhile putting some work into it when someone told us that someday it will be a collector like the 60's Chevys. I'd really like to breath some new life into and give it a new car feel if that's possible. Plus, make sure it's reliable going forward. Thanks in advance!

I'd start w/ checking to see if the LIM gaskets are the black plastic ones. If so, change em out to the new metal ones. Oil leak is most likely valve covers. Change gaskets and bolt grommets. Get a set of quick-struts and call it a day for the suspension. Might also look into replacing the lower control arms as they will come w/ new ball joints as well (get the Moog ones).

Don't bother the engine if it isn't having issues. These motors are known to go well beyond 200K. Trans is the weak link and will probably need a rebuild at some point.

A good paint job that is a color change is probably in the 3-5K range. Shop around on that one.

For more power, I'd go turbo. Before that, I would buy a built transmission as the stocker will die with the increased output. You "could" top-swap (meaning put the supercharger on from a GTP), but the cost to do that is just about the same as turbo, and turbo's seem to make better useable power.

These cars are most likely never going to be collectors items, unless its a special edition. Even then you'd be hard pressed to get more than blue book from it. Millions were made and for many years. I'd just enjoy it for what it is, make your own improvements and be happy with a faster grocery-getter. Besides, cops will look at a gray GP less often than the dude in the red T/A or Mustang, ya know- sleeper look.

Thanks FordMan!

• Is there somewhere I can see pictures of where the gaskets you are talking about are located?
• How much does a transmission rebuild cost? Is it something I can do myself?
• Paint job is out if it's that much. I didn't realize they were so expensive.
• I believe turbo is out too. I think they are a couple grand, right?
• Any other cheaper mods or replacements I could do to increase hp?
• Any exterior and/or interior mods/upgrades I'm missing?

LIM gasket ID- http://www.grandprixforums.net/threa...hlight=gaskets

A good trans rebuild will probably run around 2K. If you can deinstall/reinstall yourself check out tripleedgeperformance.com Dave is a well known builder of these transmissions and offers many different levels of build, not just all out race trans.

Used turbo kits can be pieced together over time for less than 3K, but yea, once you get it all done you still have to have it tuned, so that adds a few hundred. You could get some headers and HV3 insert for a bit of extra getup, but in the end some type of boost is really the best thing.

Exterior there are a few options. Inferno Hood, SE spoiler, dual outlet tips, larger rims, lowering springs, tint. Search around in the Visual/Body modificatrions forum here for better ideas.

I'll offer up my opinons in red:

Originally Posted by pmsmith2032

Thanks FordMan. I will check out the gaskets again this weekend. By the way, the car only has 129k on it (I checked last night). When I did the tune-up around 100k, I remember doing the following:

• Changed the spark plugs and spark plug wires (I'm not sure what I replaced them with but I know I bought them at Autozone) As long as the plugs were irridium and not Platinums, you're good. These cars hate Platinum plugs.
• Replaced the air filter
• Cleaned the throttle body
• Replaced the thermostat (when I changed the coolant)

Now I'm wondering what I missed/what I need to inspect. Here is a list of things I can think of:

• Transmission fluid - should I change it again (it's only been changed once)? Add Lubeguard High Friction Modification Supplement again?- Check the color by wiping dipstick on a white towel. If it's still red, I'd wait a bit.
• Drive belt - Has never been changed- Inspect it for cracks. If found, I'd replace it. Use a Gates or Goodyear Gatorback belt.
• Cooling System - Hoses never been changed. Coolant changed once. How often should it be replaced? As long as hoses are still firm then should be ok. If using the orange Dexcool, then I'd replace it every 50K or so.
• Brakes - Rotors and pads have been changed a number of times but lines have never been replaced and lines have never been bled- As long as there are no braking issues, visible cracks in the rubber lines when flexed and the system isn't leaking fluid, leave it be. If you relly want to, you can suck the old fluid from the master cyl, refill with fresh and then bleed the entire system until you get clear fluid. Probably kinda dirty looking by now.
• Boots, joints, seals - I've never had any problems and no work has been done. I'm not sure if anything needs to be done on this.- As long as the boots aren't slinging grease or leaking PS fluid, leave it be.
• Emissions - Oxygen sensor and PCV have never been replaced. MAF valve?- I'd pull the PCV valve and see if it rattles. If so, put it back in. If not, replace it. O2 sensor should be fine. Could clean the MAF sensor (not valve) with MAF cleaner (do NOT use brake or carb cleaner- get the approved cleaner for it.)
• Oil - Should I upgrade to synthetic or high mileage? Replace gaskets? Anything else I should do while I'm replacing the LIM gaskets and valve color gaskets?- Oil is your call. I've run nothing but regular Valvoline in my cars and my 00 GT has 320K, 95 Bonne has 200+,etc.. I feel as long as you change it on time and use a quality filter (e.g.- not Fram) then any oil should work. I do run semi-syn in my 03 Vic, but it came that way stock. While doing the LIM (if needed) then install the upgraded aluminum coolant elbows. Can be found in the "Help" section at most parts stores. As long as nothing else is leaking, leave it be. Not sure if the 05 motors have coolant ports in the LIM to pass it through the throttle body, but if they do you could plug those as well. I know BillBoost on here has a how-to.
• Exhaust - No work has been done on it. Not sure if anything needs to be replaced.- Leave it be until it rusts out.
• Fuel filter - Never replaced and not sure if it can be.- IIRC the 05's don't have a filter.
• Air filter - Stock system- Replace with a standard paper filter if needed. The K&N kits can throw oil on the MAF and kill it. Might want to check the cabin air filter (if equipped).
• A/C - Never been charged. Not sure if it needs to be.- If A/C is cold, leave it alone.
• Ignition - Not sure if I need to upgrade to premium spark plugs or wires- Standard Autozone lifetime wires will work. What is important is the spark plug type.
• Power steering - Should fluid be replaced?- Unless you are having issues, then no. Besides, sooner or later the rack will go and then you can replace the fluid, lol...
• Suspension - Struts need to be replaced (looks like they come as an assembly for rear but not front....certain brand). Lower control arms replaced (looks like they are just on front, correct) R-Series or Problem Solver; Control Arm w/Ball Joint? Front end alignment (never had one)?- At that mileage the stock struts are probably shot. See if KYB makes a quick-strut for the rear. If your front swaybar attaches to the strut and not the lower arm, I think there is a way to switch it to the older style. Either way, I'd go with Moog lower arms with the greaseable ball joint. This way you get all new bushings (because they come installed in the arms already) and a new ball joint. Swap it in and go. If you replace the front end parts you will need an alignment.
• Fuel injection - Cleaning?- Could dump a can of Seafoam into the gas tank at next fillup.

I'm sure I'm missing so feel free to let me know. Thanks in advance and have a great weekend!