Hi all, in 2003 my mom's 97 Bonneville was t-boned by a red light runner and they found themselves back in the Pontiac showroom looking at the new models. For some reason they sprang for the new for 2004 GXP. I always liked the car and was proud of my mom for getting something more than the standard V6. Fast forward 20 years and the car has fell into a certain state of disrepair. It has a leaky roof, the headliner needs to be redone, and she has moved on to a Toyota SUV. I am taking ownership of the car because I need a new project and it's just cool!

The good: CA car, no rust, paint is still good, less than 100k miles, one owner.

The bad: interior needs work, been sitting for a few years, rubber seals are all probably shot, located about 1500 miles from where I live.

My plan is to fly down and give the car a tune up, then drive it back where I can do the more extensive repairs at home. I'm now researching what I need to prepare for. It hasn't been driven since Dec 2021 so it def needs a battery, oil change, some fuel system work, brake fluid flush, possibly coolant as well. I know that my dad put Stabil in the tank last year. I plan on at least a fuel filter, and I'm hoping I don't have to go down the rabbit hole of a pump, new injectors, cleaning out the lines with an air compressor my parents don't own, etc etc.

What kind of service intervals do these engines have as far as cooling system ie water pumps etc? Tensioners? What should I be replacing as far as preventative maintenance before I make the trip from the south up to my home in New England?

Thanks for any insight. I've been across the country multiple times but I've always had the fortune of making sure my car is in top shape before the journey. I'd like to be able to do that with this one as well.

With this thing being powered by the Northstar engine, it is inherently a gamble as these had head gasket/head bolt issues well past the end of the Bonneville's production run. You at a minimum should be aware of the possibility of this failure. It requires removing the engine from the vehicle and costs thousands to repair. The only possible saving grace is the rust free body, if it is truly rust free.

If it has a sunroof, you'll want to clear the drains and replace all of the door water shields as those are definitely shot. I would pull up all the carpet and see what is waiting for you under there.

Knowing its history of sitting around, collecting dust and water, I think I would be prepared for failure on this road trip.

_________________
-Car Guy Carl
"Penelope" - 2003 SLE - 250k Miles
"Sydney" - 2000 Honda S2000 - 101k miles

^ I went thru the same thing re: alu block & head bolts with a bmw in the past. A Time sert kit solved that problem. Did it all in my driveway and garage.

Finally flew out to see the car and the interior, specifically headliner needs attention. I changed the oil and fuel filter, brought water pump/hoses/tstat but the car recently had some work done there so I left it alone for now. 80k miles on the clock.

Drove 9 hours to Atlanta to spend some time with my family and then 16 hours back home to CT. It rained the entire day on the second leg of the trip and I had no water intrusion from the sunroof. There may be water underneath but the day after there is no musty smell. I'm no stranger to leaks, having owned an 80's bmw convertible for 10 years.

The brakes were definitely terrible so I changed them out while at my uncle's house. I hadn't planned on this and had to get whatever o'rielly's had in stock but the rotors ended up being the coated type I prefer here in the northeast and I was able to get semi metallic pads. Normally I use performance brakes like EBC. The car has no rust at all and working on the brakes was much easier than anything I've had to do with local cars, despite a prior mechanic using red lock tite on the caliper mounting bolts.

The car has always since new had an issue losing a small amount coolant. While I was driving I noticed a distinct smell of coolant when the A/C was on anything but full cold, which means the heater core or valve is the cause of the slow coolant loss issue. Considering I'll likely have the interior torn apart for the water intrution & headliner repairs, it's not a big deal.

The motor seems down on power. My little 328i is much faster than this car. I'm going to see if there's anything obvious like a rats nest in the air filter box and go from there.

The car definitely needs shocks. From a quick glance it looks like KYB is the way to go. I've used those in the past on a Subaru and they were fine once they were broken in.

And lastly the paint is faded on the hood, roof, and trunk. I recently bought an HVLP spray setup & compressor for another project so I may try that out here.

I'd actually love the opportunity to pull the motor and do a deep clean of the engine bay, but I want to get the car to a point where it's more deserving of that kind of treatment.

Keep in mind, the car weighs 3,800 pounds... I am sure your 328 doesn't.

_________________


Retired Bonneville Owner and former GM Tech:
2004 Pontiac Bonneville GXP: Black/Ebony *SOLD*

Summer Toys: Combined 827 RWHP / 877lb/ft RWTQ
2004 Pontiac GTO: Impulse Blue Metallic/Black/M6: lots 'o mods, 415 RWHP / 405lb/ft RWTQ!
2006 Cadillac STS-V: Light Platinum Metallic/Light Gray/A6 - Spectre CAI, Magnaflow exhaust, Speed Inc. tune, 412 RWHP / 472lb/ft RWTQ

Daily Drivers:
2019 Chrysler Pacifica Limited: Mommy's new RGC
2015 Chrysler Town & Country Limited Platinum: Kids new RGC
2007 Chrysler Town & Country Limited: Sold to neighbor
2009 Pontiac G8 GT: L76, Sport Red Metallic
2003 Chevrolet Suburban 2500: Doeskin Tan - 8.1L Big Block... new plow truck
1999 Chevrolet Suburban: Sunset Gold Metallic - Daddy's winter beater and plow truck

Yes, it's such a weird feeling because I remember this car feeling so fast when I was younger! The bmw also has a close ratio manual trans and low gearing. But the big car is a nice cruiser, and it's so relaxing to drive an automatic.


We had a pretty good rain storm last week and I ended up with a spare tire well full of water. I had pulled all the stuff out of it prior to be able to track down the leak. I traced the water stream to a spot on the trunk seal, on the left side about halfway between the latch and the tail light. I pulled the seal up and the adhesive was not at all sticky, and the seal channel was full of water. It was super gross. It was like that all along the horizontal part between the taillights. I pulled the seal up and found good adhesive about halfway up once the seal started going vertical, about the height of the reverse lights.

Where the water had been coming thru the seal, there was about a quarter sized rust spot. It wasn't rotted but was pitted. I got out my angle grinder with the wire brush fitting and took off all the surface rust to see how bad the pitting was. It wasn't great so I got in with the flap disc and removed the pitting. This left the metal quite thin so I primered the surface with Krylon bonding primer which works great on metal, followed up with Bondo "plastic metal" which looks and smells like seam sealer, and once that was dry, sanded it smooth. Then I went again with the primer and finished with a color matched aerosol can because why not. While that was drying I scraped all the old adhesive off along the seal lip with a plastic razor blade and followed up with a healthy wiping (lol) of isopropyl alcohol. Over to the seal, I opened up the channel and scraped the adhesive out with a small screwdriver, then rinsed it out with water and did another round of scraping and rinsing. I didn't want to use alcohol to combat the adhesive bc it doesn't like rubber all that much. After I was done I blew out the seal channel with garage air (like shop air but at home) and let it dry over night. The next day I crimped the seal shut and applied 3m weatherstripping adhesive to the car and put the seal back on the car. I let it sit for a day with the car in the garage and I think we are good!


The passenger front door had a couple issues: the leather/vinyl material was coming off the top of the panel and there was a leak coming from somewhere in the door. I took the panel off and discovered the vapor barrier butyl tape had failed at the bottom of the door. I had some left over from a previous project so I used it to redo the seal, but first I had to pull all the old stuff off of both the door and the plastic vapor barrier. Once that was done I used a plastic razor blade and isopropyl alcohol to clean the rest of it off the door. I put the vapor barrier back on and smushed it down and that was done.

On the door panel itself I had to remove the metal lip at the top of the panel and half the plastic bosses that hold the metal strip's retaining screws broke off. I used superglue to put them back on and drilled out the bores so the screws would go in a bit easier and lessen the chance of the plastic snapping again when tightening the screws. I then used the same glue to get the leather back around the door panel backing and taped it up over night. Now it's back on the car and looks much better. There is some creasing in the leather material (is it real leather?) but I'm thinking that will sort itself out in the summer heat.


My next job is the headliner. I ordered a swatch from somewhere online and will pick a color I like. I'd like to go with a factory light gray but I'm not married to it. My plan is to recover the headliner, sunroof panel, and sunvisors together. I've never done a headliner and I'm excited for it!


I ordered a set of new headlights and I think I'm just going to put them in and not worry about them not being GXP specific. I'll hold onto the originals just in case.

Nice. Post some pics for us to follow along.

_________________

95 SLE... a keeper. 241k miles. Low and Slow.
97 BMW 528i
98 Infiniti vq35'd i30: 13.3@104mph, 30MPG Hwy (RIP)
02 Jag X-type
03 BMW M5
05 Chevy Cobalt LS
07 Infiniti G35s 6MT (Sold)
07 Ducati Monster S2R 800 with DS1000 swap
83 Yamaha IT175K
72 Yamaha DS7: '74 RD250 swap, JL chambers

Info on dropping a 92-99: Here.

Typical water leaks on this car. This place has a dearth of info about it. Darcy (ddalder) is a good source on it. He made his GXP water tight IIRC.

_________________


Retired Bonneville Owner and former GM Tech:
2004 Pontiac Bonneville GXP: Black/Ebony *SOLD*

Summer Toys: Combined 827 RWHP / 877lb/ft RWTQ
2004 Pontiac GTO: Impulse Blue Metallic/Black/M6: lots 'o mods, 415 RWHP / 405lb/ft RWTQ!
2006 Cadillac STS-V: Light Platinum Metallic/Light Gray/A6 - Spectre CAI, Magnaflow exhaust, Speed Inc. tune, 412 RWHP / 472lb/ft RWTQ

Daily Drivers:
2019 Chrysler Pacifica Limited: Mommy's new RGC
2015 Chrysler Town & Country Limited Platinum: Kids new RGC
2007 Chrysler Town & Country Limited: Sold to neighbor
2009 Pontiac G8 GT: L76, Sport Red Metallic
2003 Chevrolet Suburban 2500: Doeskin Tan - 8.1L Big Block... new plow truck
1999 Chevrolet Suburban: Sunset Gold Metallic - Daddy's winter beater and plow truck

I'll try to get some pictures. It's hard because when I'm working I like to keep the momentum going.

Last week the new headliner material showed up so I pulled the headliner out of the car. It wasn't hard, but definitely scary. I reclined the seats all the way and took it out through the rear passenger door. I should have just pulled the passenger seat but I'd read that it wasn't necessary. Well, it would have made me feel better about squeezing the fragile headliner through the door opening! I left the car outside while I had the headliner set up on a bench to remove the material. We had another rain storm, much bigger than last time, and the car's interior leaks were finally exposed. I had a small puddle on the drivers seat underneath the sunroof drain tube where it attaches to the sunroof tray, so I pulled off the hose and found that it was halfway clogged and there was more water inside! I went to the passenger side to check and found a very substantial puddle in the rear floor board. I traced the water and it seemed to be coming from a rubber gasket that surrounds the rear door brake, the piece that holds the door in position when it's open. I'll have to take off the panel and sort that out but for now I removed the front seats so I could get the rear carpet out. I was ecstatic to find NO rust underneath the carpet and butyl sound deadening. This was a California car but still, to have no rust at all with all that trapped water is unheard of here in the north east. I even picked off all the sound deadening to make sure. I had to move the car back into the garage with the seats unplugged so I have an airbag light now, but from my understanding that will clear itself after 3 drive cycles. I left the carpet out in the sun for a few hours and a few days later it seems to be dry. I'd like to get it back in asap.

Today I disconnected the sunroof drains from the sunroof cassette, removed it, and blew the drain holes out with compressed air. The sunroof does this thing when closing where it will pop into place but then lower slightly, like the motor isn't stopping in the right place. I was trying to work out how the system works but given that there is a module in line with the motor and no microswitches I'm not exactly sure how to adjust it. The four torx screws that attach the sunroof to the tray are already set to allow the rear of the sunroof to be as far up as it can go. Again, when I watch the sunroof do its closing cycle, it pops up into place, but then comes down about 1/8 of an inch, like the motor isn't stopping the cycle in time. It's hard to explain.

Back to the sunroof drains, I'm reading up on the "kazoo" style drain openings and how compressed air isn't the best way to clear them out. I would ideally like to remove the pipes from the car entirely and ensure they are all clear, which means pulling the dash I suppose. It's not a big deal because my heads up display stepper motor is out of sync, but I wasn't planning on doing all this work at this time. I have a four day weekend coming up so I'm hoping the weather will stay cool and I'll be able to get a lot done.

My method with cleaning the headliner is using a plastic razor blade to scrape the foam off, then spray the leftover goo with iso alcohol in a spray bottle, which makes the goo less gooey, then use the plastic scraper again to get the remnants, and finally blow it off with compressed air. That gets most of the solid goo but leaves a sticky residue, so I think I'll follow up with dawn dish soap and a sponge.

I believe there is some information Andrew posted about adjusting the sunroof home position. Do a search on the forum...its in there somewhere.

_________________

Resident Tightwad

Screw you, Photobucket.

Looking down into the sunroof drain tube



Found the pursed lip style openings



I straightened out the end and cleaned out the muck. After this I cut the end off so it would be round


This was under the rear carpet. The sound insulation was full of water. I scraped all it off looking for rust but by some miracle there was none. The staining is from the underside of the carpet


Removing the center console


My mom brought the car to someone to have them fix something and they couldn't figure out how to remove the center console. They ended up prying up the fabric here and broke almost all the plastic pieces where it attaches to the dash




Here I'm pulling out the 8mm bolts that hold the upper dash in. I had to take this out to get to the head up display unit, which wasn't adjusting correctly


Using my grabber tool


And the pad is out! I had to pull up on it and from dealing with older cars I felt like it was going to break but it was fine.

For the rear sunroof drains I took out the rear seat and parcel shelf


Which was completely unnecessary, but gave me a chance to vacuum the parcel shelf. The drain runs from the sunroof tray opening into the trunk. If you pull up the side trunk fabrics you can see it quite easily. It feeds into this rubber grommet which goes thru the body and also houses an electrical passage, which is a new one. Water + electricity are good friends


There is a hard plastic L shaped hose that the sunroof drain fits into, which then fits into the rubber grommet. There's also a round hole in a bit of sheet metal right near where the rubber grommet is located, and even unused clips, so I completed what was very obviously a design implement


I shoved the L shaped plastic all the way thru the rubber grommet so it forced open the "pursed lip" shape of the exterior side of the grommet drain. Then I clamped everything and zip tied it up

I ended up taking the front carpet out after finding some water under there as well. By this point I'd taken out everything so all that was left was to literally pull the carpet out. While I was in there I wanted to look for the piece where the front sunroof drains transition into the hard tube. People online say they like to separate from the tubes at this point leading the water under the carpet. I got up in there and removed half the underside of the dash. Once I had room I cut thru the soft rubber sound insulation and found the drain but it was all one piece on mine. It didn't look at all like the photos I've seen. My car is an 04 and they may have updated the design. It was all one piece and there was nothing to separate or clamp. Kind of a bummer since I did this in a heat wave and I died doing the work, all for nothing, but I was able to replace a clicking HVAC mode actuator and blower motor. I wasn't sure if the blower was bad but it seemed to be blowing air weakly at max speed and a new one was only 50 bucks. no pics because I was dead at that time from heat exhaustion

Got the carpets back in and vacuumed

My heads up display wouldn't adjust vertically. When I first got the car it was out of alignment and would only turn one way. I tried maxing it out to see if I could wake the mechanism up but it only made the problem worse. I took the module out of the car and opened it up. It only too a few torx screws. I love that this entire car seems to be held together with torx. I found the motor housing and removed it. Here is the gearset


I found that one of the gears had a crack and would bind, causing the mechanism not to turn in one direction


I superglued it and held it together with a pair of pliers with a rubberband on the handles


I let it dry and put it back together with some lube to help it turn in the future. After everything I windexed the mirror glass and plastic lens of the unit


And it works! Adjustment works perfectly and the display is a bit brighter. I'd read about old solder joints under the photocell causing dimming of the display but I checked mine and the solder was good. This wasn't a problem I was experiencing but I wanted to take a look at it while the unit was apart.

Nice progress!

_________________

95 SLE... a keeper. 241k miles. Low and Slow.
97 BMW 528i
98 Infiniti vq35'd i30: 13.3@104mph, 30MPG Hwy (RIP)
02 Jag X-type
03 BMW M5
05 Chevy Cobalt LS
07 Infiniti G35s 6MT (Sold)
07 Ducati Monster S2R 800 with DS1000 swap
83 Yamaha IT175K
72 Yamaha DS7: '74 RD250 swap, JL chambers

Info on dropping a 92-99: Here.

Good work, right up there with something Mike (95naSTA) would do.

Stupid plastic gear in the HUD is reminiscent of the accursed splitting gear in the HVAC actuator motors. Grrr.

_________________

Resident Tightwad

Screw you, Photobucket.

Thanks, it's been fun the past few weeks.

This was putting the center console back together. I vacuumed all around it and cleaned it best I could. It went back in easily.


Then this thing


What a massive pain. When I took it out both front seats were in the car but reclined all the way. I had to bow it to get it out thru the back door, but didn't crease it or anything. The material fell off but I was left with the foam. To get that off I put isopropyl alcohol in a spray bottle and misted the foam to loosen the glue, then it very easily scraped off. I used a plastic razor blade but you could use anything really. I let it try then I installed the new fabric


I followed a couple youtube tutorials. What worked for me was laying the fabric over then folding it back halfway, then using 3m headliner spray glue on both the backing board and the fabric. Then I would lay the fabric onto the headliner board about 8" at a time and repeat. I sprayed two layers on the board and a third around the corners and edges. Once the fabric was on I worked it around all the corners and cut out the relief holes. Then I went around the perimeter and trimmed it to fit. The whole thing wasn't difficult, but was definitely stressful. I used 2 yards for the headliner and a third for the sunroof tray. That was more of the same but the glue was adhered much better to its plastic backing so I had to break out the angle grinder with wire brush attachment.


Getting it back into the car was as difficult as removing it, even though I'd removed the front passenger seat by that point. I still had to bow it to get it in but we got her there. Finding the holes for the roof handles and sun visors was "fun" but eventually we prevailed. Just not in this pic


I forgot to plug in the rear view mirror so I have to get back in there.

The car is a car again. Still on the list is replacing the shocks (I have the rears in a box ready to go) and redoing the butyl for the door vapor barriers. Both doors on the passenger side are leaking. I got a new set of headlights for a standard model and I don't know how I feel about them yet. I'd like to pull apart the original lights and move the original lenses over at some point.

Today I was graced with the "low engine coolant" warning message, always a fun time. I believe it's a failing heater core. When the heater is on I can usually hear air bubbles behind the dash, in addition to a funky rubbery-old pipe smell emitting from the front of the interior. At first I thought it was my feet! The car has always had a slight coolant leak, but being that it previously lived in the temperate California climate, the problem never progressed enough to definitively lead to the heater core.

What's interesting is I got the "low coolant" message after starting the car that morning and driving down the block, so I was able to turn around and park the car before the engine fully warmed up. I opened the coolant res and saw that there was still coolant in the tank, so it must be a very slow leak that had been happening for some time before finally triggering the message.

I looked up how to do a heater core and found some answers from this board. It doesn't look that bad, there is access from under the dash. The car is going to go to sleep for the winter so I can budget some time to tackle it then. I have a new water pump and some other stuff I may do while the coolant is drained.

I've spent more time with an eye on the coolant res etc and have narrowed the coolant leak down to a specific set of circumstances. I've had my bmw in the garage the past week waiting on some parts to replace the valve cover gasket and it's been getting colder, which has allowed me the opportunity to explore the pontiac's coolant leak.

It seems that when I run the heater, the car will leak coolant out from the expansion tank overflow hose after the car has been sitting for a while. For example, after I get home from work, an hour later there will be traces of a puddle underneath the rad exp tank. Not enough of a puddle to build up surface tension, but enough to wet the ground. There will be wet coolant traces on the top of the control arm (directly under the overflow hose) and the coolant level in the tank will be elevated. I've experimented with this over the course of a few days and the size of the puddle will be related to how hot I run the heater. For example, if I set it to 90, the puddle will be bigger than if I set it to 74. Before this adventure running the heater, the coolant tank for maybe a month had been about 3/4" over the horizontal line on the side of the tank and now it's about 1/4" above it. So despite this overflow business, the car is still not low on coolant.

Outside of this, the car doesn't leak coolant at all. The inside of the reservoir does not smell like oil or exhaust. The car does not overheat or even go above half on the temp gauge. From what I can tell by doing research and poking around the engine bay, the heater core does not have a valve to shut off coolant flow and is always circulating. I believe what is happening is there is a small leak in the heater core circuit and when the heater is on and the blower motor is cooling the coolant inside the heater, the airflow and temp change condenses the coolant and pulls air in thru some tiny leak in an o ring etc. Then, when the car sits after a drive and heat soaks, the coolant expands again but this time there is an air bubble in the circuit which causes the coolant res to slightly overboil and then the coolant steam condenses back into liquid again once it drips out from the overflow hose.

On top of this, the rad cap fitted to the car is 16 lbs rather than 18 lbs. Was this done in the past to mask a coolant leak elsewhere and relocate the leak to the highest point in the cooling system allowing the system to self bleed? Or maybe someone installed the cap from a 3.8 not knowing there is a difference. All the coolant/heater hoses have date codes tracing back to 2004 so that's fun.

I bought a new heater core, a pair of heater door servos (replaced the mode one already), and a full outfit of heater hoses, as well as rad hoses, water pump and t stat. Now I'm thinking it would be a good idea to take care of the coolant cross over pipe, and while I'm at it the valve covers could be done as well.

I have a small single car garage, inside which the pontiac barely fits, so my strategy will be to put the car in the driveway and remove the interior components necessary to get the heater core out, then once it's just about ready to come out, back the car into the garage and drain the coolant etc and get ready for a three week project so I can take my time and make sure it's done right.

Yesterday I got underneath the dash and removed the panels covering the heater core. I also removed the center console, which came out pretty easily. Both lower bolts are accessible with the seats and backrests all the way forward. The rest is just a bunch of torx screws and electrical connections.

Here's what it looks like with the drivers side kick panel removed. This was easy, just a couple screws on either side and a push button clip on the pass side.


I removed the accordion vent thing in the middle and found all the brass plated 5.5mm screws holding both plastic heater core coverings in place. There are two of them and the come out independently.

Here is the passenger side w/kick panel removed. The center vent piece with the L shaped foam is supposed to come out but on my car the right hand side retaining bolt is placed directly in front of the cash metal lower dash bracket. It's impossible to get it out w/o a u joint socket, which I don't have in 1/4" drive, and getting the bolt back in would have been a chore as well, so I left it in.


This is a pic of the right hand side clip that holds that vent in. You just push it in with your fingers and it will come loose. Just to the left of the red connector.


Here's a shot of the brass plated screws that come out


There must have been 10 or 12 of these. They are all over in weird places, like just above where the flashlight is focused in this pic.


Lastly, the inner plastic covering is adhered to the firewall and I had to pry it off with a screwdriver. You can see the foam that makes the seal in the above pic.

Now that everything is ready on the inside of the car, I backed the car into the garage and will drain the coolant from the radiator and spend some time replacing the heater hoses etc etc and whatever else needs doing. I'll likely spend on hour on it each day in between other projects.

Hope the heater core solves it.
I'm in a similar situation with the garage. There's some strategy involved since the car needs to be outside if the doors have to be open on both sides.

_________________

95 SLE... a keeper. 241k miles. Low and Slow.
97 BMW 528i
98 Infiniti vq35'd i30: 13.3@104mph, 30MPG Hwy (RIP)
02 Jag X-type
03 BMW M5
05 Chevy Cobalt LS
07 Infiniti G35s 6MT (Sold)
07 Ducati Monster S2R 800 with DS1000 swap
83 Yamaha IT175K
72 Yamaha DS7: '74 RD250 swap, JL chambers

Info on dropping a 92-99: Here.