I'm not sure what to make of this.

[CarlaValentine]

It's beginning to sound more like a clogged cat. If so, you will likely eventually have a cat code. This may be an opportunity to get an OBD-compliant high-flow cat for about $125, but I wouldn't spring for it until I was sure that you were fixing a problem.

Both mufflers being clogged can also be a source of both overheating and accumulation of carbon. As adillac said, make sure that the muffler drain holes aren't plugged.

I'll crawl under it tomorrow and have a look at them.

[Cadillac Jim]

How about starting the car and a second person listening and looking at the exhaust behind the car, and listen for a hissing sound or other evidence of clogging? After you do a visual check of the mufflers -- with the car cold for your personal comfort and safety -- you can look at the exhaust in action with the car cold, then after a drive, look at it with the car warmed up.

One symptom of exhaust clogging that shows up early on is a drop in gas mileage. This usually appears about the same time as a change in the torque curve, with a little more bottom-end oomph but running out of breath early. I had this once and it turned out to be a slightly clogged cat. I found it much later due to a P0420 code (Catalyst System Low Efficiency).

[CarlaValentine]

My gas mileage on the highway hasn't changed much. Dropped maybe 2mpg or so. In the city there is a significant difference of about 7-8 mpg. Accelerating from a stop, it feels a little sluggish. Almost as if I were towing something. It's get-up-and-go seems to have got up and went... Once it gets to about 20mph though, it picks up speed just fine and there is no noticeable loss of power. It runs great on the highway, but in the city...yeah, not so much.

I'm waiting for my boyfriend to get up so I can have him give me a hand with checking out the exhaust.

[BodybyFisher]

No way that the WOT solved your high temps. As a matter of fact, if I was sitting along side of you, at 228, I would have recommended against doing WOT at that time, especially since you are thinking head gasket.

More likely your water pump tensioner is not applying tension, and the WOT broke it loose, look at your water pump belt for shine indicating that it was slipping, and check your tensioner for binding, use some typy of lube ONLY a drop on the tensioner pivot point, you dont want lube flying up on the belt.

I may have an old tensioner in my box of parts Ill check

The clogged CAT is a good point also

[Cadillac Jim]

I'm thinking of poor low-end torque, slightly lower gas mileage on the road, lots lower gas mileage around town, and I'm thinking it just might be a bad load of gas. If it's down to 1/2 a tank or lower, try a tank of premium gas and 15 minutes of 55 mph or faster cruise to clean out the engine and mufflers, followed by a little around-town driving to recalibrate the knock sensor and see if that fixes it, or at least helps.

I you are looking at wildly improbable things, it could be a mix-up on the plug wires. That would likely get you a code or two with a Northstar, though.

[CarlaValentine]

Sorry I haven't been around in a little while. I had a really bad flare up with my Fibromyalgia and have been pretty much stuck in bed the last few days.

I finally got a chance to check on the exhaust this morning. The muffler drains seem to be fine...actually they are starting to develop some soft-ish rust spots around them and there are a few other rust spots on the mufflers that look like they are about to break through. I plan on putting new mufflers on this summer anyhow, so it's not a crisis.

When the car was first started, there was nothing from the exhaust. It didn't make any hissing noises or anything, but sounded extremely muffled and labored, as if there was a rag stuck in it or something. After a few seconds, there was quite a bit of steam from the pipes, but the muffled sound was still there. After about a minute, I had Carlos hit the throttle and out came a small cloud of dark grey/black smoke that had a funny smell to it. I can't put my finger on the smell. After that though, the labored/muffled sound went away and the exhaust sounded and looked normal.

[PAUL T]

Sorry I haven't been around in a little while. I had a really bad flare up with my Fibromyalgia and have been pretty much stuck in bed the last few days.

I finally got a chance to check on the exhaust this morning. The muffler drains seem to be fine...actually they are starting to develop some soft-ish rust spots around them and there are a few other rust spots on the mufflers that look like they are about to break through. I plan on putting new mufflers on this summer anyhow, so it's not a crisis.

When the car was first started, there was nothing from the exhaust. It didn't make any hissing noises or anything, but sounded extremely muffled and labored, as if there was a rag stuck in it or something. After a few seconds, there was quite a bit of steam from the pipes, but the muffled sound was still there. After about a minute, I had Carlos hit the throttle and out came a small cloud of dark grey/black smoke that had a funny smell to it. I can't put my finger on the smell. After that though, the labored/muffled sound went away and the exhaust sounded and looked normal.

If it smells like rotten eggs or sulfur then your cat is probably bad or going bad.

[jackc]

I thought about doing a coolant pressure test, but it would lose pressure regardless of whether or not it's a hg because I have that stupid nuisance leak on the water pump cover.... Is there any other (fairly simple) test I can try that wouldn't involve pressurizing the cooling system?

You need to fix the pressure leak if you haven't already - you won't get maximum cooling without maximum pressure. Pressure test the cap too. Ones that fail can look fine. I'd probably put a fresh stat in it too.

The exhaust crud makes me wonder if she's getting enough exercise.

[Cadillac Jim]

Sorry you're not feeling well. I tend to go with jackc. In fact, over the years, I've "fixed" so many cars by putting a fresh tank of top-tier gas and getting out on the road for an hour or two that I had a bit of a reputation as a wizard in my youth, partly because I never told anyone. I got to drive a lot of nice cars for rides in the country that way.

This helps a modern car several ways, including, but not limited to:

• Runs the cat so that it burns off any carbon or other stuff that may accumulate from running the car cold with not all of the cat burning.
• Heats up the exhaust system clear to the tailpipe and drys out all the condensed moisture that accumulates when all you do is short trips for awhile, particularly in the winter.
• Lets the EVAP system purge, so that it can operate normally.
• Cleans out the combustion chambers and other areas that can have buildups of carbon or gunk during cold starts, like the backs of the exhaust valves.
• Gives the pistons a chance to heat up and circulate oil through the rings normally for a period of time, reducing or eliminating any shellac buildup in the ring lands.

[CarlaValentine]

JackC, she gets plenty of exercise . I've been a little more careful lately though because I have an idler pulley that is rattling and I need to get that changed. As for the cooling system nuisance leak, I patched that a few days ago. I sanded down the surface around it, which was very hard because of where it is, and I patched it with JB Weld. So far, no more leaking. And I'm not worried about the JB getting into the cooling system because of how small of a leak it is, and it was only leaking under full system pressure. I also made sure not to run the car until it was totally dry and set. My temps are still remaining in the normal.

I can say the smell from the exhaust was like a mix between sulfur and hot metal, such as you would smell using a blow torch. The smell is there even after driving it on the highway for a while. I'm guessing my cat is a little polluted. A friend of mine suggested hollowing it out, but I'm not going to do that. If it needs to be fixed I am going to do it the right way and change it out. I still have to look at prices but something tells me it won't be cheap. First and foremost though, I need to change that idler pulley before it explodes on me. I also need a new ISC motor. My high idle is very intermittent, and only happens maybe one out of every 15 trips with it, but it's still something that needs tending to.

Also, there isn't a gas station anywhere near me that has "top tier gas" but I only use 93, and I only go to Hess or Sunoco.

I've had a lot of little problems with this car, but it's still worth it to me to keep fixing it and keep it on the road. I love my car.

[BodybyFisher]

If you smell eggs it is indicative of a rich mixture, check the FPR and injectors for leaking

Have you cleaned your throttle body plates? And have you disassembled the ISC and cleaned and lubed it?, along with cleaning the contacts?

[CarlaValentine]

If you smell eggs it is indicative of a rich mixture, check the FPR and injectors for leaking

Have you cleaned your throttle body plates? And have you disassembled the ISC and cleaned and lubed it?, along with cleaning the contacts?

Mike, I will check the injectors and the FPR tomorrow.

As for the other questions: yes, yes, and yes. I cleaned the throttle body and the plate shortly after I got the car. I re-cleaned it when I put in a new air filter about a month ago, and it hadn't really developed any buildup on it. I had also taken apart and cleaned the ISC in Feb, and it worked then, but not this time. The contacts were cleaned with a piece of paper and electronics cleaner. I know better than to use anything rough on an electrical connection. It seems to be sticking open. I have watched it when the idle acts up, and the pindle on the ISC isn't retracting all the way when it happens, then after a minute or a good revving, it goes back to normal. I am just going to get a new one and see if it makes a difference. If not, then I return it and figure out if there is something else causing it.

[Cadillac Jim]

If you're running 92 or 93 octane from a name brand gasoline company, you're running top tier gasoline.

An OBD-compliant cat can be had for under $100 that needs welding. Moving the flanges over from your old cat, inclding HO2 sensor bungs, and installation should be on the order of $125. I would consider new HO2 sensors unless you know that your old ones are good.

[CarlaValentine]

If you're running 92 or 93 octane from a name brand gasoline company, you're running top tier gasoline.

An OBD-compliant cat can be had for under $100 that needs welding. Moving the flanges over from your old cat, inclding HO2 sensor bungs, and installation should be on the order of $125. I would consider new HO2 sensors unless you know that your old ones are good.

I will be doing the work myself so the labor cost isn't an issue. According to my car's CarFax report, HO2 sensors were replaced at a dealership in 2007. They also aren't throwing any codes, so I am guessing those are fine.

[Cadillac Jim]

Well, then, use welding rod appropriate for stainless steel and you're good to go. I use a low-restriction 49-state OBD compliant cat that I recommend; I got the part number from another Caddyinfo user who also liked it. It's a MagnaFlow 94109 (do a search on "94109" here and you will see that I recommend it whenever the topic comes up), available for $69 from Summit Racing:

http://www.summitrac...arts/MPE-94109/

You won't get the full benefit from the lower restriction with the stock mufflers. You will see a return of the stock performance, with perhaps a very slight improvement in off-idle throttle response. If you put on Turbo mufflers or straight-through mufflers (again, welding required, stainless steel) you will in addition see the improved off-idle performance continue through the RPM range and the torque continue a few hundred RPM higher than the stock roll-off point.

You will need some additional 2 14" stainless steel piping to weld in the new mufflers. You should be able to get that locally. If not, Summit Racing has that stuff, too. They also have welding supplies, if you need stainless steel welding rod or gases or whatever.

The Borla "Super Turbo" general replacement muffler used by many here, and sometimes added as a dealer option to new cars is part number 40658, are $135 each at Summit Racing:

http://www.summitrac...arts/BOR-40658/

The straight-through mufflers that I run, which are a tad noisier, particularly at full throttle, give perhaps slight improvement at high RPM, are $100 each at Summit Racing:

http://www.summitrac...arts/BOR-40357/

When I needed mufflers in September 2006, Borla was the only game in town if you wanted stainless steel to match the rest of the Cadillac exhaust system. Not being willing to go back to the old days of mufflers rusting out (or off, if non-stainless welding rod is used on a stainless steel exhaust system) every couple of years, I went Borla. At this late date, you have several alternatives. Magnaflow, Flowmaster, and others now make stainless steel mufflers because even their favorite aftermarket demographic, hot trucks and SUVs, have been coming with stainless steel exhaust systems for a few years now. My feeling is that you can't go wrong with Borla, but there will be people where who recommend one or more of the other brands too.

[CarlaValentine]

This has me wondering if my mufflers are indeed stock. They are starting to rust through in a few small spots, while the rest of the exhaust is in pristine condition... or were the mufflers not stainless as the rest of the exhaust seems to be?

[Cadillac Jim]

Even stainless steel in the grade used in exhaust systems will rust a little bit. In climates where salt slush can accumulate on a cold muffler that is then parked with the salt slush caked on, this can be enough to eventually rust out the muffler. A little rust at the seams or drain holes is normal in an old system. It shouldn't rust out unless you are in really worst-case conditions, cake the underside of your car in salt slush, and park it overnight in subzero temperatures with the slush still caked up under there.

[CarlaValentine]

It's not rusted out. Just a few small spots near the drains and around the rear seam. They must have developed over this past winter because there wasn't any rust anywhere when I first got the car last summer. Shame on me for not giving it a good washing during the winter...

I'll be headed out shortly to check the FPR and the injectors. I'll post back my findings.

[CarlaValentine]

Well, I haven't been doing too well physically these last couple weeks, so I handed my car off to my brother to have him check things out. He had it over the weekend. He said the fuel system checked out fine (FPR and injectors). He put some type of pressure tester in the oxygen sensor bung in front of the catalytic converter and said that there seems to be too much pressure there (forgive me, I can't remember what the reading was. I'm in such a fog lately) but he thinks my cat is the problem. I will be getting a new one as soon as I can afford it. Medical bills have been eating up most of our money lately.

As for the idler pulley...it's not the idler pulley. I started the car yesterday and the clanking/grinding sound got worse then the car started to sputter, and eventually stalled. I started thinking it may be the crankshaft pulley, since the car stalled. I had my brother help me check things out, and it turned out to be the AC compressor clutch/pulley/bearing assembly. It's seizing up, and was shaking badly enough to rattle one of the compressor's mounting bolts right out. I don't know how I overlooked that but I did. I don't have the money for a new one right now, so I am just going to get a bypass for it until I do. I can forgo having air conditioning for a little while. I'm wondering if that pulley seizing up could have anything to do with my erratic idle since they both became noticeable around the same time. I'll find out once I get it changed.

It's been one thing after another, but I am not going to let it get me down. I will get this car back into great shape if it kills me.

[KHE]

The compressor pulley bearing can be changed without removing the compressor from the car or messing with the refrigerant charge. The bearing is less than $10.00 at a bearing supply house. GM sells the pulley with a new bearing installed also.

[CarlaValentine]

The compressor pulley bearing can be changed without removing the compressor from the car or messing with the refrigerant charge. The bearing is less than $10.00 at a bearing supply house. GM sells the pulley with a new bearing installed also.

Well, unfortunately, while removing the compressor to put the bypass pulley in, we discovered why the AC won't hold pressure. One of the steel lines attached to the compressor was completely broken off. It wasn't too bad of a job to change everything. The compressor is still good so I am holding onto it and will get a new clutch for it when I can afford it, and replace the broken lines. The clutch and pulley were pretty much shredded from being lose for a while, so saving them and replacing the bearing isn't really an option. At least that god awful scraping/rattling/grinding noise is gone now!

The down side is, changing that pulley didn't help with the sputtering/stalling problem. My brother wanted to take the car for a drive, so we went on the highway for a little bit to see if it would clear up with some more "hearty" driving. It didn't. When we got back to the garage, we quickly figured out the problem. I believe without a shadow of a doubt the cat is the problem. There was smoke pouring out from under the car, and everything from the cat forward was red (literally) hot. The smoke was from oil burning off the exhaust. We hosed the exhaust to cool it down. I'm sure my cat is clogged. I am getting a new one tomorrow and will hopefully get it put in either tomorrow or Thursday.

The car's coolant temps have remained pretty normal, but I did find another small coolant leak. It's leaking from what I believe is called a freeze plug? It's on the engine underneath where the water pump is and from what I gather there isn't really a way to fix it.

[KHE]

There was smoke pouring out from under the car, and everything from the cat forward was red (literally) hot. The smoke was from oil burning off the exhaust. We hosed the exhaust to cool it down. I'm sure my cat is clogged. I am getting a new one tomorrow and will hopefully get it put in either tomorrow or Thursday.

This sounds like a too rich condition/unmetered fuel entering the mix to me but if the exhaust backpressure test showed the backpressure too high, it may well be the cat-con.

[Cadillac Jim]

The freeze plug leak is likely fixable, depending on the size and cause of the leak, with a new freeze plug, a cement designed for the purpose, the sealant pellets, or some combination of these.

[BodybyFisher]

NEVER hose a hot car off like that, if you hit the block or heads you could crack it

You have been complaining of a lack of power, check your CAT/muffler system for clogging and as KHE stated a bad FPR

[CarlaValentine]

NEVER hose a hot car off like that, if you hit the block or heads you could crack it

You have been complaining of a lack of power, check your CAT/muffler system for clogging and as KHE stated a bad FPR

The FPR was checked last weekend and was fine. I didn't hose off the car, just the cat. I was EXTREMELY careful not to hit anything else as I am aware of the damage it could cause. Thank you for the warning though. =)

For the heck of it yesterday I removed the oxygen sensor closest to the cat-con (only temporarily) just to see if it would make any difference in the drive-ability of the car. Aside from the SES light coming on (for obvious reasons...no sensor) it drove significantly better. I ordered a new cat yesterday which should be in tomorrow morning. I'm hoping that will take care of the issue.

As for what caused the cat to decease, I have a few thoughts... maybe I'm right, maybe I'm not. My car had a very high idle problem for a couple months due to the ISC before I got it taken care of. It had a misfire on 3 cylinders as well before the plugs and wires were changed. It also had a bad MAP sensor for over a month before I figured out that was the problem and fixed it. Added to that list is the fact that the oil was overfilled not long ago and it was driven that way for about 30 miles. Could any of these, or a combination thereof, have caused my cat to go into early retirement?

I've also recently discovered a pretty bad case-half oil leak. I'm not going to bother with trying to fix that though...not unless I have to tear the engine apart for some other reason as well. It's not leaving puddles...it's just annoying.

I'll let everyone know how she's doing after a new cat is installed. I'm keeping my fingers crossed!