04' Bonneville GXP antifreeze leak
 

Hi all....I'm new to the list. I've wanted to own a Bonneville GXP since they came out, but couldn't afford one new. Even knowing about their typical problems after 4/5 years of reading about them, I was finally able to get my hands on one WITH a full warranty. I bought an 04' Diamond White GXP with 34K miles on it. I love this car!!!
Even though I have a warranty, I'm a hands on kind of guy and at least want to investigate my antifreeze leak problem before I take it to a dealership and blindly trust what they tell me is the problem.
Description of problem: Before I purchased the car, I placed it on a rack and checked the underside for leaks of any type. The car was bone dry. I checked all fluid levels EXCEPT the coolant level before the car went up on the rack. The car was hot and I didn't want to mess with the coolant cap and the pressure. When I got the car home and cooled, I filled up a coolant reservoir that was about a 1/3 of a gallon low. The next day I see a puddle of antifreeze under the car, almost center, favoring the drivers side by about 10" past center.
The car DOESN'T leak while running. It doesn't leak while hot and parked. It only leaks after I have parked the car for the evening and it has been allowed to get bone cold.

Am I looking at a water pump issue or a water pump gasket issue? I'm thinking gasket issue. If that's the case, can I simply try tightening the bolts to rid my leak, or can I even get to the bolts?

Thanks,
Gary

The engine is so new to us here, and me as a GXP owner, very little has been done mechanically. And as you mentioned, most of us have the full/extended warranty. That makes you a pioneer! LOL (Doesnt help,..... did it.) Some users have mentioned an erratic coolant light (including me) but when checked(always later for me), nothing is wrong/low. I suspect enough is going into the coolant bottle at might to trigger the alarm and it returns as the engine warms. But you say coolant is on the drive. Did you fill the Bottle beyond the mark? One member reported a crossover leak in the rear of his enginem but had it fixed by Dealer Service. Havent had a report of the waterpump housing leak, but it's always a possibility. And can be checked without a big hassle. Pleased keep us informed, as I mentioned, most of our engines are still under warranty, and the way they crammed this V8 in there, not alot of actually owner service for us to refer to yet. If you have the chance to get the GMPP extended warranty, It's a good idea and more than half here have it. Aftermarket warranty's are nothing but trouble.

Try filling the overflow again. Then at night, stick a few paper towels around where you think it's leaking. Then in the morning pull them back out and make a note of any coolant on the towels. This will at least give you a much better idea where it's leaking.

I did have a coolant leak. The problem turned out to be my water pump. Since it was replaced, I haven't had a single problem (I estimate about a year ago). Of course there are any number of different possibilities. If you have a full warranty, a dealer visit may be in order (even if you'd like to know ahead of time). Keep in mind that "blindly" trusting the dealer isn't as bad with a warranty as without. I'm sure you know this already, but the water pump is on the driver side. This of course doesn't mean that's the side the leak is actually on. I've had several cars in the past that have had antifreeze leak, drip down onto other parts to be carried to a completely unrelated area before dropping to the ground.

Thanks for the input guys. I'll be taking it to the dealer and find out what they say. Like you mentioned, the warranty will pay for the replacement of the pump or whatever it may be.
I'm sure I'll be back with many other questions related to this car and it's goofy traits :)
Gary

I have this same leak/symptoms. Hopefully it is the water pump so my extended warranty,(not GMPP) will pay. Please post when you find out.

me to these cars have many problems

Yes they do. I must have a factory freak for sure. I have the extended GMPP but haven't had to use it for anything. (Knock on wood). 38k miles, WOT all the time, nitrous injected, and yet not a problem so far other than the IM shaft. My warranties up @ 70,000 miles and I have a feeling the engine will fall off it's cradle at 70,001. :eek:

Well, I had the leak diagnosed and it's the crossover pipe. This is the gasket between the water pump housing plate and the block. My extended warranty IS going to cover job. Estimate was for $595. My car now just turned over 29K in mileage. This is a disgrace that at this mileage, I've had almost $2K in repairs done. 80% of it under warranty. My last Poncho, '95 Grand AM GT, was nowhere near this unreliable. I really like the car, but am uncertain if I can continue with these headaches. GM has basically said F U to all my inquires [sic]. All these problems don't give me a warm feeling inside about doing business with GM in the future.

GM has told me to screw myself over enough times already. I bought an aftermarket warranty (Nissan Quality Guard Plus Deluxe), which has covered everything so far. Here's a short list to give you an idea of what you should expect. I now have nearly 60k miles.

- Front left and right wheel hubs
- Coolant crossover pipe
- Water pump housing gasket
- Steering shaft (typical)
- Gauge cluster (temp gauge fell)
- Front engine mount
- Fog light wiring harness (ended up installing HIDs)
- Steering gear (expensive as hell job)
- Ignition coil assembly (blown while WOT from 0-50)

I'm going to assume for now that the owner who had the car before me abused the hell out of it. Serviced at a Chevy and Cadillac dealership, my warranty has forked over $5400 in repairs so far, and I still need to spend $65 to replace the oil cooler lines.

I still haven't taken the car to the dealership yet. I was hoping that the overflow tank was burping out the extra fluid I put in. It's been three days now and I haven't seen a drop of antifreeze on the driveway. My low coolant level light isn't illuminating and the fluid level is still visible/acceptable according to the overflow tank callouts. I'm sure hoping that my problem is corrected now, but if not, I'll be taking it in for sure for a thorough check and repair.
I feel for you owners that have had a bad experience with these GXP's. Had I bought one brand new, I'd be having a cow over all of the problems that have been mentioned. I bought mine just recently, fully knowing of all these issues, but tried to be prepared by getting a full warranty on the car. I don't know if buying the car makes me an idiot, or an avid Bonneville GXP fan! All I know is that I love the car's looks, it's comfort, it's ride, and the exhaust tone! I've owned it now for about 2 1/2 weeks and my wife hasn't driven it until tonight. She couldn't understand why I wanted one of these cars so bad. She thought it was another one of my "cool car" dreams. After her first trip down the drive way and onto the freeway, she called me to let me know she now understands why I bought the car :) Now...if anything breaks and it has to be fixed, not only will the warranty take care of me, but my wife will be more understanding of why I purchased the car!

If my leak reappears, I'll let everyone know what has happened and what the fix is.

By the way, who can help me with my production numbers and finding out anything specific about my car in comparison to all the other GXP's out there? I don't even know how many were made for 2004. Was it 2034?

I've had some problems with mine but things seem to have settled quite nicely over the past 6 - 9 months. Nothing lately but routine maintenance. I hope things turn out well for you too. I do believe these are very nice cars, otherwise I wouldn't own one.

As for production numbers... I can't speak for the US but for the 2004 model year, there were 232 imported into Canada for sale. 47 of them were Graystone Metallic and 136 were equipped with HUD. Mine was built April 26, 2004 :D

being on of the few owners in Canada, Im happy to say Im the ONLY owner of a GXP in the Northwest Territiries....I kinda like that...I still have my Grand Prix and even up here I see them all the time...Sure the car can be a PITA...but to me...all the frustrations aside...its sucha sweeet ride....

I have an appointment to take my car into the dealer on Monday to have it checked out. I smell antifreeze whenever I pull it into the garage when it's hot. I haven't seen any leaks on the floor, but the smell is strong. I hope it's just the cross over since many of you have had that fixed. Even if it's the water pump, it's still under warranty until 3/26. I want to get the GMPP extended warranty since I can't see buying a new car. This one just turned 13k this month. Can some of you give me an idea of what you paid for the extended warrany so I'll know what to expect when I go to the dealer on Monday. I though I might as well sign up for it while I'm there. Thanks

Mine was thrown in the "mix" when I bought the car new. There were alot of adds and subtractions, as I bought the car "new" but had been in the showroom for 14 months. But I think it was 70K miles for $1600. I'll have to dig for the paperwork in the glovebox and get back to ya.

Well Gentlemen, here is the culprit. The dreaded water crossover gaskets. I received my car back from the service facility today and these are the gaskets that failed. If you look at the one in the upper LH corner, you'll see a small abnormality in the top of the gasket where the water flows.. This is where it cracked, hence having the anti-freeze leak and smell. The single photo shows it with more detail, I hope. The technician said the job wasn't that bad, just the lower gasket bolts had to be wrenched off by hand. No air tools there.

Thanks for sharing the photos. It looks like this crossover gasket is becoming a common issue here. Like we need another one. Grrrrrrrrrrrr.

I asked them If they could replace the GM supplied gaskets with better ones such as Fel-pro. He said that was not an option, as Fel-pro probably made the ones for GM. I felt that I was getting gaskets replaced with the same ones that failed. It was covered under my extended warranty, which cost $700.70. It also came with a 12 mo/12K warranty on the repairs. BTW, those gaskets are hard like they are made of a phenolic material, so I was surprised to see them crack as they did. Unlike others here, I baby this car. No racing or excessive speed, so I'm a little dismayed at how it's been holding up.

GM went to alot of trouble rethinking gaskets and Coolant content after the first Dexcool catastrophe. It makes me wonder is there is a casting problem, heat warpage, or a guy in Detroit, Michigan who is used to steel blocks, overtorqueing on an all aluminum engine. Hammer down Bill. It's works for me. Wait,..... whats that hissing I hear.

Thanks Bill. I've got the exact same symtoms. Can you or anyone else tell me where these gaskets are located? I can see that apparently the water pump is at the front driver's side of the engine. I see a black metal line running forward, but it is connected by a rubber tube.

Well, I got the car back from the dealer and the work order claimed the problem was a gasket that was mis-aligned. I still smell antifreeze when I park the car in the garage, but I don't get the small puddles I was getting right before I took it into service. I purchased the GMPP extended warranty for an additional 3 years/ 36k miles since I can't see buying a new car as this one only has 13k on it now. The extended warranty cost me $1180, but that's chump change compared to a major repair on this engine or trans. I hope my problem is resolved!

There may still be some traces of anti-freeze that you'll smell for a little while. Let's hope it's all good. IMO, you definitely made the right choice in purchasing the GMPP warranty! It seems like a few hundred dollars to even open the hood these days. If it makes you feel any better, mine was over $2K and extended it to 5 years or 120,000 km. Welcome to Canada!

Well, seen as how I started this post, I'll finish it up by saying my cross over gaskets were leaking. The dealer charged $741 for the repair, with it only costing me $100 with my warranty. I knew it was a good idea to buy that warranty! I'm hoping that nothing will go wrong now for a while. The steering shaft is starting to "pop", but I know how to lube or "maintain" it as GM puts it. It will be quiet for another 15K miles. It's already been replaced once. I don't see messing with another trip to the shop to replace my bad part with another bad part.

Thanks all!!
Gary

Hopefully all remains well. Not to deviate from the original topic, but I had my intermediate steering shaft replaced almost 50,000km ago (approx. 30,000mi) and I haven't had even a hint of a problem since. Just hoping it stays this way.

The gaskets are between the waterpump housing and the block. The crossover allows water to circulate from one head to the other. The Tech had to remove the cover over the belt that drives the water pump to see it. They said that whole assembly had to be removed.

Gary! Good to see you on here....I pop in and out of the forums every few months to see what's new or check on a problem with GXP. Fortunately mine has been great for 5 years and almost 140,000 miles! I had it in for minor warranty stuff in the first year (fogs, steering shaft), but haven't visited a shop since then. I have the gauge cluster issue and now it looks like i have the oil cooler line leak, but otherwise this has been the most trouble-free car I've owned. We'll have to get together for that beer and swap GXP stories sometime soon.
Sean

It is probably a freeze plug in the block, most likely the back of the block. You cannot see it as the transaxle only allows about a 1/4 inch of space between it and the engine itself. But if you follow it (it's easier when the engine is cold), you'll see it eventually flows down the crossover exhaust pipe and down to the ground.

Your best bet, without removal of the engine is to go to NAPA and pick up some Block Seal. You will need to be able to let the car sit for 24 hours also. So plan accordingly.

Essentially drain the cooling system. Once drained, refill with water and a can of this Block Seal. Run the motor until it fully warms, cooling system purges water is topped off, and it runs at normal operating temps. I'd let it run for 20 minutes or so, so that this Block Seal product can circulate thoroughly through the engine.

Drain this water/block seal out, letting the cooling system comepletely drain, and leave drainc-o-c-k open for at least 24 hours. This will allow the Block Seal to set up and do it's job.

After 24 hours, refill with a mix of DexCool just like normal, purge, top-off, etc...

It'll probably be a good time to do hoses while you're doing the system flush. :D The upper radiator hose may be a pain in the butt to locate as they aren't commonly stocked items.