Like I already said, the 3.3L exhaust manifolds are known to leak, make sure they check the flange for warpage on both manifolds… And be warned, the bolts/studs are probably going to break in the process, so they may have an extra charge for that… unless somewhat already factored in…
Yes, I recall what you wrote about the exhaust manifolds. I even forwarded your note to the service manager. But my questions – which are probably due to my lack of understanding about how it all works – still remain.
Namely: if the exhaust manifold warped or cracked, causing a leak, then that would be an issue with the manifold itself that would need repair. But the shop is saying it’s the gasket that needs replacing. So I don’t see how the manifold’s tendency to warp or crack would cause a rubber gasket to need replacing.
Also: the noise didn’t happen for a day or two after I picked up the car after they changed the cat. Seems that if the manifold got damaged when the cat was replaced, then the noise would have happened right away, no? So that doesn’t make sense either.
And if it’s just the rubber gasket, and not the manifold, then that makes even less sense about why it would happen a day or two after the cat was replaced.
I’m not trying to be argumentative here. I’m sincerely trying to understand the situation because, as I said, with my limited knowledge about how all of this works, it’s not clear to me.
Thanks!
An Exhaust Gasket is not made from rubber; it is usually made from multi-layered embossed steel with layers of high-temperature fiber material, graphite, ceramic composites, or a combination of those materials.
If the exhaust manifold came lose or the gasket was slightly damaged during assembly or any other countless reasons, the exhaust gases could start escaping and that would slowly erode the composite material to be eaten or blown away leaving a defective gasket and the resultant exhaust leak.
As for it occurring just a day or two after replacing the cat, the exhaust system was probably the “wiggling and rangling” around of the exhaust system to get the cat to slip in place.
You may never know the exact reason this happened. The path between cause and effect is not always a straight line.
Here is an extreme example of “cause and effect.” Many, many years ago, I bought gas at an Esso (now Exxon…) station that I knew practiced shady repair practices. It was full service then and the attendant asked if I wanted him to check the oil and I replied no (I knew better than let anyone from that station under my hood) so he finished cleaning the windshield. When I started the car, the battery blew up. The whole side of the battery blew out, leaking acid all over the engine. I can’t imagine what I would have done if I had let the attendant check the oil…
So, what was the cause of the battery blowing up, me getting gasoline, was it having the windshield cleaned, or was it just coincidence?
If I asked the membership which of these two seemingly innocent acts caused the battery to blow, you can be darn sure, that every member would write “Neither” it was just “bad luck!”
You didn’t have any Black “Cats” walk in front of your car recently, did you? L 
L . . .
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LoudThunder pretty much summed it up… 
what he said…
Ever walked in a room and flipped the light switch and the bulb blew?? If you had not flipped the switch the bulb would not have blown, now was it your fault the bulb blew?
Sometimes 
happens… 
The (alleged) warped/cracked manifold was already weakening the gasket and it was probably about to blow sooner or later anyway…
BTW Black cats are the best, had a few over the years…
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Thanks, guys. I appreciate you helping to educate me and to clear that up.
The (alleged) warped/cracked manifold was already weakening the gasket and it was probably about to blow sooner or later anyway…
If the manifold was warped or cracked, and that, therefore, weakened the gasket, then wouldn’t that imply that the manifold needed repair as well?
Or, if the manifold was not warped or cracked, then how would the gasket have gotten damaged?
Again, just curious and trying to understand here.
That may be what happened, given how things have gone. Here’s a summary of the situation from the start.
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Needed to pass inspection. Two codes: leak from fuel tank and bad cat.
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Shop orders new fuel tank from salvage yard. I provide 3rd party cat. Also new 3rd party fuel pump (which needed to be replaced)
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Fuel tank arrives, it also has a leak. Shop decides to just repair existing tank instead. They drop the tank and repair leaks. New cat is also installed.
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Shop realizes they forgot to install the new fuel pump when they repaired the tank. So they have to drop the tank again and install the fuel pump.
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After leaving, I notice that my fuel gauge isn’t working. Shows Full when engine is on; shows 3/8 tank when engine is off.
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After a day or two car starts making the noise we’re discussing.
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I bring the car back to the shop. They say they have no idea how the fuel gauge would have been damaged. They drop the tank again and check the output from the fuel pump as well as other items and determine that everything is working properly. Must be the instrument cluster that’s bad (for some unknown reason). They order new used instrument cluster from ebay.
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They also check the noise which was presumed to be coming from the cat, since the noise wasn’t there before the cat was installed. They run a smoke test, can’t find any leaks. Check all connections on the cat, replace gaskets. Nothing changes. They determine it’s a bad cat.
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I submit to the 3rd party for a warranty replacement of the cat. They require a mechanic’s diagnoses and a bunch of pictures of the cat. So they put the car up on the lift and take some pictures. Only the guy misunderstood, so he removed the cat to take pictures (wasn’t necessary), and they had to reattach the cat afterwards.
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I then notice that some of the light bulbs in the newly-replaced instrument cluster are out and tell the shop.
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I receive the replacement cat and bring it to the shop. They replace the burnt out light bulbs. They install the new cat, but noise remains. They eventually determine the noise was from the manifold gasket and look to replace it.
And that’s where we’re at! LOL
You are talking thousands of an inch here, might just need new gaskets, or sometimes you can double gasket an exhaust manifold to the cylinder head… Other times it requires new manifolds…
Will need a long (as the manifold anyway) straight edge and feeler gauge to know for sure against the spec… If you have a hard, perfectly flat surface and a large piece of sand paper stuck to the flat surface, you can run the exhaust manifold across it to check for high and low spots…
Worsts case Rock auto has both for under $110 each plus shipping, I’m sure other parts houses do as well…
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I expect your shop is presuming at this point the only problem causing the exhaust sound is the gasket. No way to tell without measuring it. They’ll measure the flatness of the exhaust manifold mating surface as part of the job. If it is warped you’ll be getting another phone call saying they’ll have to replace the manifold as well as installing a new gasket.
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I am so surprised that the Shop took in your “3rd Party Catalytic Converter.” How does one deal with warranty issues? And since you had warranty issues, who paid for the replacement labor? I am sure the Shop did not say it’s free on us… then, I have to question the skill and knowledge of the technicians "forgetting’ to install the new fuel pump. Then the “new, used” dash, didn’t they check it out before or even after installation? And then finally, after that, the noise remains, in spite of the new catalytic converter. You wrote that the warranty replacement required a “mechanic’s diagnoses and a bunch of pictures,” who provided the “mechanic?”
I do not believe that throwing good money after bad will ever resolve you problems, you either have a car that has the embodiment of “Christine” or there are no “mechanics” at that shop…
In case you missed the reference, Christine…
I think that garage also had a bad “cat…” L o L . . .
The shop said they were discontinuing allowing customers to bring their own parts the following week, because it created too many problems.
They were going to charge me for replacing the cat. But then, since the problem turned out to not be the cat; and since we only replaced it because they diagnosed it as defective; they didn’t charge me for replacing it.
They forgot to install the new fuel pump I guess because it was sitting on the front seat of my car. They were focused on repairing the fuel tank, and the fuel pump was just an additional thing.
They did check out the dash after installing it and made sure everything was working OK. But I guess they forgot to check the lights.
They provided the mechanics diagnosis, which was just a statement of what they did to troubleshoot it and why they felt the cat was bad. They didn’t charge me for doing that, nor for the pictures.
You write “you were sitting on the front seat of my car” while they were working on your fuel tank??? Did you watch that video of the movie, that was gasoline, no respectable shop should allow a customer to sit in the vehicle at a time like that.
You also wrote, that they "did check out the dash after installing it and made sure everything was working OK. But I guess they forgot to check the lights. So, what you are saying is they did not really check the dash. I wonder how these technicians performed the testing… They turned on the car and hoped for the best.
I hope you have another shop to go to in the future, perhaps one where the “Customer’s Waiting Room” is not in the vehicle itself…
I am sorry about coming down on this shop, but it sure sounds like they took you for a ride without ever leaving the shop…
No, I wrote “IT” was sitting in the front seat of my car. 
Opps, my bad… but my recommendations remain the same…
Both the movie and the book were fun 
It is quite possible the gasket would have failed when it did without anyone touching the exhaust system. That van is way past its expiration date. You need to expect expensive, frequent repairs going forward.
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Yeah, you’re probably right. Here’s a chart of my repair & maintenance costs for the past 7 years, both yearly cost (blue), as well as 3 year average at each year (orange). I detect an upward trend…
(Graph is backwards, with most recent year on the left.)
I predict that within the next year or two you’ll need to expand the “Y” axis scale on that graph.
ha! You’re WRONG!! I WON’T need to expand the “Y” axis on that graph because the software expands it automatically!!! ha!!
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That’s a helpful graph presentation of your repair expenses over time. It would be interesting to compare it to the average car owner who use shops for all of their R&M . Or to other owners of this same make/model.
That would definitely be interesting! Especially the latter.
For me, I’ve been comparing it to my expenses if I bought a new used car.
Car payments would be about $300 a month for 5 years. Plus full coverage insurance (which I don’t currently have). Plus some repairs and maintenance.
So I figured, if I got a new used car, it would be maybe $3600 a year for car payments; maybe $500 a year in repairs and maintenance; plus $800 maybe for the insurance full coverage.
So that would be about $4900 a year for a new used car, as opposed to an average of $500 to $1000 in repairs and maintenance, plus about $400 for the insurance I have. So $4900 for a new used car vs maybe $1400 a year for my current car.
With the current repairs, which are more than usual, the 3 year average has gone up to $1300. Even if it increases more and goes up to maybe $1500 or even $2000, I’m still ahead.
Couple all that with the fact that I work at home and drive my car maybe 3000 miles a year, so I don’t put a lot of wear and tear on it, and I think I’ll still come out ahead with this car for a while.
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