PontiacBonnevilleClub.com

I just joined your club after researching some of my issues. I drive a silver 2002 Bonneville SE but I'm having some issues now that I'm at 95k miles driving the beaten roads of New Jersey.

1. Rust areas at the bottom of the passenger door. Any ways to treat and cover it?
2. The car is sucking down coolant, just changed it at the end of June and put DexCool in.
3. Driving on the road and hitting bumps, I hear a loud clunk from the trunk area on the passenger side and the back end shimmies. I'd like to know what to look for when I take off the wheel so I can identify the problem and fix it myself (if possible).

Any feedback is appreciated. I love my car and want it to last. It drives well and it's the biggest sedan on the road these days. Happy to be aboard.

Welcome I have a similar mileage car to yours. If you would have come here first you may have replaced the coolant with conventional instead of DEX. That is on my list for before winter!!! You probably have a bad rear shock mount or shock pretty common on these cars. Rust is rust after it starts theres not much you can do besides cut it out and replace.

Does the car have a recall sticker on the radiator support from a recall to replace the nuts on the throttle body to hold it tighter against the gasket and the throttle body. My 03 was seeping coolant there and taking it into the combustion chamber so I would lose coolant slowly especially when the car was driven in temps where the pressure was higher. If you have NOT had the recall done, it might be worth taking off just the throttle body and replacing the gasket with an after market which has a thicker gasket layer making it able to seal against the distortion of the end of the UIM. This might be a stopgap check until you're sure you're ready to do the upper and lower.

Also at that recall it would have had several GM sealer pellets put into the radiator. These are ground organic material that seals seeps, hopefully.

But your real solution would be to have the upper intake manifold UIM removed and replace the gaskets under the metal lower intake with the GM metal-framed gaskets. Myself, I had the UIM replaced with my APN (ineedparts.com) UIM which has a metal sleeve in the EGR tube. That helps keep the plastic cooler.

When that was done, the mechanic showed me the throttle body seep. I also had coolant seeping up around the threads of the lower intake bolt and one part of the gasket between the lower and the head was slightly distorted. This was all at 110K mi and had started at maybe 85K mi to show slight coolant loss which I thought was probably a water pump.

DCJREDLINE wrote: If you would have come here first you may have replaced the coolant with conventional instead of DEX. That is on my list for before winter!!!

If by conventional, you mean a coolant that doesn't protect the various metals including aluminum in the system, I'd stick with the correct type of coolant. If you mean, Mixes with All Colors and Types coolant, that's the same formula as Dexcool: check the labels. The early Dexcool used an antioxidant that deteriorated under some conditions, but that formula was changed, probably about 1999 when GM changed the EGR chimney size on the lower intakes because of all the leak problems.

marcv wrote: 3. Driving on the road and hitting bumps, I hear a loud clunk from the trunk area on the passenger side and the back end shimmies. I'd like to know what to look for when I take off the wheel so I can identify the problem and fix it myself (if possible).

Besides worn rubber mounts around the upper end of the shock in the trunk, take a good look at the tie rods that hold the rear wheel in position. I saw pictures of one that had rusted off, so it was free to move and bump, and the wheel was not held in place so the rear wheel could change toe.

My Monroe MA822 rear shocks came with new upper mounts.

imidazol97 wrote:

DCJREDLINE wrote: If you would have come here first you may have replaced the coolant with conventional instead of DEX. That is on my list for before winter!!!

If by conventional, you mean a coolant that doesn't protect the various metals including aluminum in the system, I'd stick with the correct type of coolant. If you mean, Mixes with All Colors and Types coolant, that's the same formula as Dexcool: check the labels. The early Dexcool used an antioxidant that deteriorated under some conditions, but that formula was changed, probably about 1999 when GM changed the EGR chimney size on the lower intakes because of all the leak problems.

Then why do all 00+ Bonnevilles with Dex-Cool still have issues with deteriorated plastic LIM gaskets?

All coolant is Propylene Glycol based, that's a given. The difference is the additives. "Mixes-With-Any" isn't the same as dex, it just has additives that don't sludge with dex like normal green coolant does.

Yes sorry I did mean "mixes with any" My bad on that one.

Thank you all so much for your input. I'm currently out of work so I'll be tinkering with my Bonny in the meantime. I did have a major issue with one of the major gaskets blowing which sent coolant shooting all over the place. I had an auto repair shop replace the gasket but that had to be about 2 years ago. I'm gonna look around underneath and see if I can spot any leaks. Thanks again all.

So I've managed to fix problem # 2 which was the rear wheel. Took it off and found the strut had rotted out. With the help of my neighbor and his tools we replaced it with the Monroe MA822. I took it for a test drive and smooth as can be. Thanks for the feedback.

Here is an update with the coolant leak: I jacked up the car and see coolant dripping down onto the oil filter and see some fluid on the sensor above it. I almost think it's a gasket above that area, hopefully not the head gasket. I checked my oil level and I could probably add a quart. I'm going to jack it up tomorrow and get some pictures. Any comments or suggestions would be great. I have nothing better to do at this point than work on my Bonny.

There are two black plastic pipes ("coolant elbows") that crack over time. From the location you described, one of these could be leaking. Inspect them to find out.

You can purchase the elbows (a set of two) for around $5 bucks at most auto parts stores (under the Dorman HELP brand). If you do some searches of past posts here at the Club, you can get more info on these elbows, including the part number, replacement procedures, and tips. (Learn to use the search function -- it is your biggest benefit from the Club.)

The elbows connect the water pump with something on the back of the engine, on the passenger side, above the power steering reservoir and below the alternator.

You should be able to inspect these elbows visually and perhaps with a tissue or paper towel (to see if they get wet). If these are not the source of your leak, look carefully for other signs of coolant on this side of the engine, in various nooks and crannies. The location of any pooling is significant and should be noted.

Look also in your oil fill neck, and check your oil. If you see signs of something that resembles a chocolate milkshake, report it back here immediately. This would indicate that one of your intake manifold gaskets has failed, and coolant is getting into your oil, which is a serious problem (but correctable if you act quickly).

Ken_W

Ken_W wrote:There are two black plastic pipes ("coolant elbows") that crack over time. From the location you described, one of these could be leaking. Inspect them to find out.

You can purchase the elbows (a set of two) for around $5 bucks at most auto parts stores (under the Dorman HELP brand). If you do some searches of past posts here at the Club, you can get more info on these elbows, including the part number, replacement procedures, and tips. (Learn to use the search function -- it is your biggest benefit from the Club.)

The elbows connect the water pump with something on the back of the engine, on the passenger side, above the power steering reservoir and below the alternator.

You should be able to inspect these elbows visually and perhaps with a tissue or paper towel (to see if they get wet). If these are not the source of your leak, look carefully for other signs of coolant on this side of the engine, in various nooks and crannies. The location of any pooling is significant and should be noted.

Look also in your oil fill neck, and check your oil. If you see signs of something that resembles a chocolate milkshake, report it back here immediately. This would indicate that one of your intake manifold gaskets has failed, and coolant is getting into your oil, which is a serious problem (but correctable if you act quickly).

Ken_W

Don't get the Dorman brand ones. I personally had Dorman elbows crack and blow out on me this week. They were not even 2 months/3,000 miles old. Get elbows from the dealer. I have heard of this same thing happening to many other people that have bought the Dorman ones too.

I have used the Dorman on 4 different motors and 2 different cars with no issues. Getting ready to do another one next weekend. No issues at all.

You guys were correct. The leak is coming from that plastic L piece. So what do I have to remove in order to pull that stupid L piece out? Also, if this is a job that you think should be left to an experienced mechanic, please say so. I can have an uncle help me with it.

You have to drain the coolant, remove the alternator and the aluminum bracket the alternator connects to, the tensioner bracket.

Got it. Thanks Beast.

If you look around using the board's Search function, you can find other discussions about these elbows that may include some installation tips. I'm pretty sure I recall seeing some.

Ken_W

I took off a bunch of bolts around the alternator and it didn't even budge. Gonna call in my wife's uncle for this since I get what needs to be done but lack the skill. Bought the two elbows and notice the both the upper and lower appear to be leaking but mostly the upper. Also bought some silicone heat resistent sealer for the install. Thanks for all of the tips but this rookie can't do it. I did change the rear shocks this weekend with very little assistance and some borrowed tools. Car rides great over bumps now. I've also noticed some oil on top of the engine towards the rear. Is this the dreaded manifold gasket defect that everyone talks about? I'm at 94k miles now.

You did remove the alternator first, correct? You also took off the belt? There should be 3-15mm headed bolts that hold that tensioner bracket in.

most likely valve cover leak im assuming

marcv wrote:I've also noticed some oil on top of the engine towards the rear. Is this the dreaded manifold gasket defect that everyone talks about? I'm at 94k miles now.

Is it around the LIM bolts? Have you ever done the UIM and LIM gasket change?

Sounds like it is time especially with 94k on it. Plus you will get to do these coolant elbows again.


As for the elbows, as Ed says, remove alternator and belt. Then remove bolts holding the bracket on and both elbows come off.