Catalytic Converter Rattles
#1
08-11-2012, 11:45 PM
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Catalytic Converter Rattles
Hi everybody, I crawled under the AeroRetard the other day while it was parked and idling to find out where the rattling noise was coming from.
It seems to be coming from the rear catalytic converter.
I was wondering if this is the case, would it also cause a lack of power, as in driving up a steep hill or driving up a steep inclined bridge?
Thanks in advance!
It seems to be coming from the rear catalytic converter.
I was wondering if this is the case, would it also cause a lack of power, as in driving up a steep hill or driving up a steep inclined bridge?
Thanks in advance!
#2
08-12-2012, 10:04 AM
Yes, if indeed the rattling is from a breakdown of the internal catalytic bead matrix. A meltdown would partially clog the exhaust, creating exhaust backpressure and driveability problems such as you mention.
Catastrophic catalyst failure is the end result of a larger problem upstream. Improper rich fuel mixtures cause the catalyst to overheat and eventual damage if not corrected. You could have the same driveability issues from incorrect fuel mixture. How? The engine control system (ECS) relies on several air/temperature/flow sensors to determine optimal fuel injector settings. If one or more of these sensors does not work, the engine stays in a 'cold start up' mode, i.e. a rich mixture. While it will run, it produces very poor fuel economy and performance issues.
It is also probable the rattle is coming from the heat shield or it could be a broken exhaust bracket mount. Cross your fingers it is one of these, as new catalyst(s) are rather pricey items.
Most of us around here rather enjoy our old vans and would take exception to anyone labeling them as "mechanically challenged". Aerostars are only as bad as those entrusted to care for them. You get out what you put into them.
Catastrophic catalyst failure is the end result of a larger problem upstream. Improper rich fuel mixtures cause the catalyst to overheat and eventual damage if not corrected. You could have the same driveability issues from incorrect fuel mixture. How? The engine control system (ECS) relies on several air/temperature/flow sensors to determine optimal fuel injector settings. If one or more of these sensors does not work, the engine stays in a 'cold start up' mode, i.e. a rich mixture. While it will run, it produces very poor fuel economy and performance issues.
It is also probable the rattle is coming from the heat shield or it could be a broken exhaust bracket mount. Cross your fingers it is one of these, as new catalyst(s) are rather pricey items.
Most of us around here rather enjoy our old vans and would take exception to anyone labeling them as "mechanically challenged". Aerostars are only as bad as those entrusted to care for them. You get out what you put into them.
#3
08-12-2012, 09:54 PM
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Thanks for the info AeroC.
Today I lightly tapped the rear cat with a rubber mallet and sure enough there is a loose chunk of something inside. I also tapped on the front cat but it seemed to be solid. I am not sure why only the rear cat melted down. Also, the vehicle passed our government Air Care testing about two months ago. It almost seems as if the previous owner planted a secretive deconstruct time bomb on the vehicle (just kidding).
The front exhaust heat shield has detached, but it is currently held tightly in place utilizing two stainless steel gear clamps. The cat shields seem to be ok. Also, the muffler appears to have been recently replaced by the previous owner. All of the exhaust clamps seem to be ok, although on a side note, I am a little concerned about how near the tailpipe is to the rear suspension spring (but that's another topic).
As a courier driver, I keep a daily log of gasoline consumption and mileage. My current 1993 Aerostar 3.0L has almost the exact same MPG as my previous 1997 Aerostar 3.0L.
It looks like I will have to get new cats installed (crying). When I got a new cat installed on my previous 1997 Aerostar, they installed one combo type of cat. By that I mean, the muffler shop installed one new cat to replace the old two cats. I was wondering if this is ok to do again with the 1993 Aerostar? Also, my 1993 Aerostar has only one front upstream O2 Sensor. I am not sure what that means in regards to performance and the engine computer sensor thingys.
Today I lightly tapped the rear cat with a rubber mallet and sure enough there is a loose chunk of something inside. I also tapped on the front cat but it seemed to be solid. I am not sure why only the rear cat melted down. Also, the vehicle passed our government Air Care testing about two months ago. It almost seems as if the previous owner planted a secretive deconstruct time bomb on the vehicle (just kidding).
The front exhaust heat shield has detached, but it is currently held tightly in place utilizing two stainless steel gear clamps. The cat shields seem to be ok. Also, the muffler appears to have been recently replaced by the previous owner. All of the exhaust clamps seem to be ok, although on a side note, I am a little concerned about how near the tailpipe is to the rear suspension spring (but that's another topic).
As a courier driver, I keep a daily log of gasoline consumption and mileage. My current 1993 Aerostar 3.0L has almost the exact same MPG as my previous 1997 Aerostar 3.0L.
It looks like I will have to get new cats installed (crying). When I got a new cat installed on my previous 1997 Aerostar, they installed one combo type of cat. By that I mean, the muffler shop installed one new cat to replace the old two cats. I was wondering if this is ok to do again with the 1993 Aerostar? Also, my 1993 Aerostar has only one front upstream O2 Sensor. I am not sure what that means in regards to performance and the engine computer sensor thingys.
#4
08-13-2012, 04:54 AM
hi,
unless you want to have a second cat, just eliminate the second bad one and replace it with a straight-thru pipe, something which you can probably do yourself or with the help of a muffler shop, I'm sure the van will pass inspection with just one converter. You might get a little better fuel mileage and a little more horsepower since you will end up with one less obstruction in the exhaust system.
Also replacing the stock Air Filter with a K & N Air filter helps the engine breathe better and helps improve mileage and horsepower too, K&N are expensive filters but you will never have to replace the air filter again.
unless you want to have a second cat, just eliminate the second bad one and replace it with a straight-thru pipe, something which you can probably do yourself or with the help of a muffler shop, I'm sure the van will pass inspection with just one converter. You might get a little better fuel mileage and a little more horsepower since you will end up with one less obstruction in the exhaust system.
Also replacing the stock Air Filter with a K & N Air filter helps the engine breathe better and helps improve mileage and horsepower too, K&N are expensive filters but you will never have to replace the air filter again.
#5
08-13-2012, 07:51 PM
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Hi Jose,
I was also thinking of replacing the rear cat with a straight-thru pipe as a temporary solution, but now I am thinking it will be a long term solution.
About the air filter, I was thinking a high air flow filter achieves this because it captures less particles because it has bigger holes in the filter material. But for the time being, I am going to be using WIX air filters for at least two reasons (flow compromise and half the price of a Ford Motorcraft air filter).
I was also thinking of replacing the rear cat with a straight-thru pipe as a temporary solution, but now I am thinking it will be a long term solution.
About the air filter, I was thinking a high air flow filter achieves this because it captures less particles because it has bigger holes in the filter material. But for the time being, I am going to be using WIX air filters for at least two reasons (flow compromise and half the price of a Ford Motorcraft air filter).
#6
08-14-2012, 04:32 AM
hi CourierYVR,
you can always argue that there are no replacement cats available
also, there are people who buy old cats for their (supposed) platinum content, so the whole job could cost you zero, nada. Make sure you don't leave the old rattler at the muffler shop!
the best price I've found for a K & N Air Filter is $38.00 delivered. I'm still looking.
you can always argue that there are no replacement cats available
also, there are people who buy old cats for their (supposed) platinum content, so the whole job could cost you zero, nada. Make sure you don't leave the old rattler at the muffler shop!
the best price I've found for a K & N Air Filter is $38.00 delivered. I'm still looking.
#7
08-14-2012, 08:51 AM
Don't waste your time on a K&N filter. The reason you have an air filter is to protect the engine. The stock paper filter, when new can flow more than twice the amount of air the engine needs, but protects the engine better. K&N filters don't need to be replaced, but they do require their cleaning kit, and the filter needs to be cleaned far more often than K&N claims. This means any savings will first get blown on the cost of cleaning the filter.
Then secondly, you have a fine balancing act. Too little oil and you get inadequate protection. Too much and it damages the MAF that is located just inches away. The MAF can not always be restored by cleaning, so if you run a K&N, factor the cost of replacing the MAF sensor into your budget, and you will soon find that a K&N is about the most expensive filter you could possibly run.
Stick with a good quality paper filter, it gives you all the performance you can get out of the engine, plus it is inexpensive, and protects the engine.
On the subject of a failed cat, while a rich mixture could be responsible, physical damage is also a possibility, all it takes is driving through a field with a pointing rock sticking up, hitting a piece of blown tire on the highway, etc. A sufficiently hard shock can fracture the catalyst. But even without it, other factors can affect it and break it too. One example is the catalyst is at full operating temperature, and gets cold water splashed on it. A sufficient amount could thermally shock the catalyst and break it.
But possible fuel mixture issues must be addressed and corrected. It is standard procedure to replace the O2 sensors when replacing the converter. An Aerostar will have a single O2 sensor where the y-pipe comes together, and '96 and '97 models will have a second sensor after the second cat. Only the front one needs to be addressed.
Make sure the vehicle has had all other proper tune up items. Here is an excellent article defining what a tune up on a fuel injected vehicle is, and how to proceed. Some of the techniques seem old school, but you get better results in doing them, most modern technicians have not learned how to do a tune up properly.
Bear River Converters Forum - So what is a tune up anyway?
Notice they begin with using a vacuum gauge. It is an inexpensive tool, and many mechanics don't even have one. But its diagnostic function even on newer cars is indispensable. It is even more useful on fuel injected vehicles that are pre-OBD-II ('95 and older), since those vehicles often lack advanced on-board diagnostics.
On 1996 and newer, you must retain the two cat setup. Firstly from a legal standpoint, EPA law spells out that any converter that is removed must be replaced. Secondly, both cats are monitored. So removing one decreases the total efficiency, and on a '96 or newer, can trigger CELs. Many inspection stations will also visually fail a vehicle that is missing smog equipment, so check with your local emissions stations.
On '95 and older, the above doesn't apply, but there are still benefits to running dual cats. Aerostars tend to get obnoxiously loud with a single converter, yes, the design is partially acoustical. And if the remaining cat is damaged or not functioning correctly, the vehicle may not pass an emissions test. Again, check with your local emissions station. Other than that, there are no major drawbacks. So if your are in a non-emissions area, and you can live with a louder exhaust tone, then you are fine.
Check to make sure the back converter is not filled with broken pieces of the front cat.
Then secondly, you have a fine balancing act. Too little oil and you get inadequate protection. Too much and it damages the MAF that is located just inches away. The MAF can not always be restored by cleaning, so if you run a K&N, factor the cost of replacing the MAF sensor into your budget, and you will soon find that a K&N is about the most expensive filter you could possibly run.
Stick with a good quality paper filter, it gives you all the performance you can get out of the engine, plus it is inexpensive, and protects the engine.
On the subject of a failed cat, while a rich mixture could be responsible, physical damage is also a possibility, all it takes is driving through a field with a pointing rock sticking up, hitting a piece of blown tire on the highway, etc. A sufficiently hard shock can fracture the catalyst. But even without it, other factors can affect it and break it too. One example is the catalyst is at full operating temperature, and gets cold water splashed on it. A sufficient amount could thermally shock the catalyst and break it.
But possible fuel mixture issues must be addressed and corrected. It is standard procedure to replace the O2 sensors when replacing the converter. An Aerostar will have a single O2 sensor where the y-pipe comes together, and '96 and '97 models will have a second sensor after the second cat. Only the front one needs to be addressed.
Make sure the vehicle has had all other proper tune up items. Here is an excellent article defining what a tune up on a fuel injected vehicle is, and how to proceed. Some of the techniques seem old school, but you get better results in doing them, most modern technicians have not learned how to do a tune up properly.
Bear River Converters Forum - So what is a tune up anyway?
Notice they begin with using a vacuum gauge. It is an inexpensive tool, and many mechanics don't even have one. But its diagnostic function even on newer cars is indispensable. It is even more useful on fuel injected vehicles that are pre-OBD-II ('95 and older), since those vehicles often lack advanced on-board diagnostics.
On 1996 and newer, you must retain the two cat setup. Firstly from a legal standpoint, EPA law spells out that any converter that is removed must be replaced. Secondly, both cats are monitored. So removing one decreases the total efficiency, and on a '96 or newer, can trigger CELs. Many inspection stations will also visually fail a vehicle that is missing smog equipment, so check with your local emissions stations.
On '95 and older, the above doesn't apply, but there are still benefits to running dual cats. Aerostars tend to get obnoxiously loud with a single converter, yes, the design is partially acoustical. And if the remaining cat is damaged or not functioning correctly, the vehicle may not pass an emissions test. Again, check with your local emissions station. Other than that, there are no major drawbacks. So if your are in a non-emissions area, and you can live with a louder exhaust tone, then you are fine.
Check to make sure the back converter is not filled with broken pieces of the front cat.
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#8
08-14-2012, 12:34 PM
Don't waste your time on a K&N filter. The reason you have an air filter is to protect the engine. The stock paper filter, when new can flow more than twice the amount of air the engine needs, but protects the engine better. K&N filters don't need to be replaced, but they do require their cleaning kit, and the filter needs to be cleaned far more often than K&N claims. This means any savings will first get blown on the cost of cleaning the filter.
Then secondly, you have a fine balancing act. Too little oil and you get inadequate protection. Too much and it damages the MAF that is located just inches away. The MAF can not always be restored by cleaning, so if you run a K&N, factor the cost of replacing the MAF sensor into your budget, and you will soon find that a K&N is about the most expensive filter you could possibly run.
Stick with a good quality paper filter, it gives you all the performance you can get out of the engine, plus it is inexpensive, and protects the engine.
On the subject of a failed cat, while a rich mixture could be responsible, physical damage is also a possibility, all it takes is driving through a field with a pointing rock sticking up, hitting a piece of blown tire on the highway, etc. A sufficiently hard shock can fracture the catalyst. But even without it, other factors can affect it and break it too. One example is the catalyst is at full operating temperature, and gets cold water splashed on it. A sufficient amount could thermally shock the catalyst and break it.
But possible fuel mixture issues must be addressed and corrected. It is standard procedure to replace the O2 sensors when replacing the converter. An Aerostar will have a single O2 sensor where the y-pipe comes together, and '96 and '97 models will have a second sensor after the second cat. Only the front one needs to be addressed.
Make sure the vehicle has had all other proper tune up items. Here is an excellent article defining what a tune up on a fuel injected vehicle is, and how to proceed. Some of the techniques seem old school, but you get better results in doing them, most modern technicians have not learned how to do a tune up properly.
Bear River Converters Forum - So what is a tune up anyway?
Notice they begin with using a vacuum gauge. It is an inexpensive tool, and many mechanics don't even have one. But its diagnostic function even on newer cars is indispensable. It is even more useful on fuel injected vehicles that are pre-OBD-II ('95 and older), since those vehicles often lack advanced on-board diagnostics.
On 1996 and newer, you must retain the two cat setup. Firstly from a legal standpoint, EPA law spells out that any converter that is removed must be replaced. Secondly, both cats are monitored. So removing one decreases the total efficiency, and on a '96 or newer, can trigger CELs. Many inspection stations will also visually fail a vehicle that is missing smog equipment, so check with your local emissions stations.
On '95 and older, the above doesn't apply, but there are still benefits to running dual cats. Aerostars tend to get obnoxiously loud with a single converter, yes, the design is partially acoustical. And if the remaining cat is damaged or not functioning correctly, the vehicle may not pass an emissions test. Again, check with your local emissions station. Other than that, there are no major drawbacks. So if your are in a non-emissions area, and you can live with a louder exhaust tone, then you are fine.
Check to make sure the back converter is not filled with broken pieces of the front cat.
Then secondly, you have a fine balancing act. Too little oil and you get inadequate protection. Too much and it damages the MAF that is located just inches away. The MAF can not always be restored by cleaning, so if you run a K&N, factor the cost of replacing the MAF sensor into your budget, and you will soon find that a K&N is about the most expensive filter you could possibly run.
Stick with a good quality paper filter, it gives you all the performance you can get out of the engine, plus it is inexpensive, and protects the engine.
On the subject of a failed cat, while a rich mixture could be responsible, physical damage is also a possibility, all it takes is driving through a field with a pointing rock sticking up, hitting a piece of blown tire on the highway, etc. A sufficiently hard shock can fracture the catalyst. But even without it, other factors can affect it and break it too. One example is the catalyst is at full operating temperature, and gets cold water splashed on it. A sufficient amount could thermally shock the catalyst and break it.
But possible fuel mixture issues must be addressed and corrected. It is standard procedure to replace the O2 sensors when replacing the converter. An Aerostar will have a single O2 sensor where the y-pipe comes together, and '96 and '97 models will have a second sensor after the second cat. Only the front one needs to be addressed.
Make sure the vehicle has had all other proper tune up items. Here is an excellent article defining what a tune up on a fuel injected vehicle is, and how to proceed. Some of the techniques seem old school, but you get better results in doing them, most modern technicians have not learned how to do a tune up properly.
Bear River Converters Forum - So what is a tune up anyway?
Notice they begin with using a vacuum gauge. It is an inexpensive tool, and many mechanics don't even have one. But its diagnostic function even on newer cars is indispensable. It is even more useful on fuel injected vehicles that are pre-OBD-II ('95 and older), since those vehicles often lack advanced on-board diagnostics.
On 1996 and newer, you must retain the two cat setup. Firstly from a legal standpoint, EPA law spells out that any converter that is removed must be replaced. Secondly, both cats are monitored. So removing one decreases the total efficiency, and on a '96 or newer, can trigger CELs. Many inspection stations will also visually fail a vehicle that is missing smog equipment, so check with your local emissions stations.
On '95 and older, the above doesn't apply, but there are still benefits to running dual cats. Aerostars tend to get obnoxiously loud with a single converter, yes, the design is partially acoustical. And if the remaining cat is damaged or not functioning correctly, the vehicle may not pass an emissions test. Again, check with your local emissions station. Other than that, there are no major drawbacks. So if your are in a non-emissions area, and you can live with a louder exhaust tone, then you are fine.
Check to make sure the back converter is not filled with broken pieces of the front cat.
#9
08-14-2012, 01:04 PM
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Have still the Factory mounted Cats on mine. They do gargle for the first minutes after start while water condensates dripping out of endpipe. I suggested a rattle in the first time but closer inspection revealed the mentioned gargle.
I'm awaiting two different new Oxygene-Sensors to be delivered. Hope i will get it right with which is where (Bosch 15717 and Bosch 15719). Had terrible swiss-cheese from Flex-Pipe to Tail-Pipe - all new now, except the two Sensors, economic AP-Exhaust Parts brought through Rock directly to my door (howdy, is that Stuff cheap compared to EU-Resellers Prices!). Catalysts must wait to be renewed, major investment consideration, bulky to ship.. Perhaps cleaning inside would help, there is a thread how to do.
To do list: Spark-Plugs, Ignition Wires, Radiator Pressure Cap, Brake Fluid Reservoir Cap, Oil Filler Cap, Thermostat. (- besides the Spark-Plugs, all Parts are Original St.Louis Plant) Coolant Flush will be Fun next week!
Now reading Bear Rivers article next..
97' XLT RWD 3.0L
I'm awaiting two different new Oxygene-Sensors to be delivered. Hope i will get it right with which is where (Bosch 15717 and Bosch 15719). Had terrible swiss-cheese from Flex-Pipe to Tail-Pipe - all new now, except the two Sensors, economic AP-Exhaust Parts brought through Rock directly to my door (howdy, is that Stuff cheap compared to EU-Resellers Prices!). Catalysts must wait to be renewed, major investment consideration, bulky to ship.. Perhaps cleaning inside would help, there is a thread how to do.
To do list: Spark-Plugs, Ignition Wires, Radiator Pressure Cap, Brake Fluid Reservoir Cap, Oil Filler Cap, Thermostat. (- besides the Spark-Plugs, all Parts are Original St.Louis Plant) Coolant Flush will be Fun next week!
Now reading Bear Rivers article next..
97' XLT RWD 3.0L
Last edited by waterbear; 08-14-2012 at 01:06 PM. Reason: spell check
#10
08-14-2012, 01:58 PM
yes indeed, parts in Europe are very expensive, I ship hard to find Jaguar parts to UK, Spain, and AU to friends who I've met through 23 years of owning a Jag. They say it's a lot cheaper in the US. And then I end up buying Aerostar parts from Brazil because they are not available in the US. It is like the magnetic Poles have shifted in the auto parts business!
#11
08-14-2012, 03:13 PM
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Yeah, the U.S.A are a great Place for doing Business!
Reseller here in Germany order Shiploads of Parts from the U.S. to decrease Costs. But Storage Costs do increase. No Benefit for Customers. CreditCard Payment Solutions are not so widely used by the Society as it is the Case in the States and Order Procedures are somewhat Tricky for the many not practiced in English language (i'm still working on it).
I had never problem to find the right Part from U.S. sources, since decades. The only Part i actualy cannot find is the PCV Grommet for the Valvecover. Mine has dried out and does not hold the PC Valve securely anymore. The PCV is wrapped with Teflon-Tape now to get a tight Fit.
Doing Cold Calls is Fun!
Reseller here in Germany order Shiploads of Parts from the U.S. to decrease Costs. But Storage Costs do increase. No Benefit for Customers. CreditCard Payment Solutions are not so widely used by the Society as it is the Case in the States and Order Procedures are somewhat Tricky for the many not practiced in English language (i'm still working on it).
I had never problem to find the right Part from U.S. sources, since decades. The only Part i actualy cannot find is the PCV Grommet for the Valvecover. Mine has dried out and does not hold the PC Valve securely anymore. The PCV is wrapped with Teflon-Tape now to get a tight Fit.
Doing Cold Calls is Fun!
#12
08-14-2012, 05:07 PM
you can also use "O" rings to enlarge the diameter of the plastic PCV port, but if the grommet is dried out, it might cause more damage. Better to get a new grommet made of better rubber.
#14
08-14-2012, 05:26 PM
#15
08-14-2012, 08:50 PM
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Waterbear,
It is similar situation in Canada about prices. I order all of my parts from the USA. Some of them are even manufactured in my home country of Canada!
Even after paying FedEx's highest shipping rates, they are still way cheaper.
I think FedEx and UPS have a secretive policy, that if the buyer pays the premium shipping rate, they will forgive you of all or any import excise taxes.
It is similar situation in Canada about prices. I order all of my parts from the USA. Some of them are even manufactured in my home country of Canada!
Even after paying FedEx's highest shipping rates, they are still way cheaper.
I think FedEx and UPS have a secretive policy, that if the buyer pays the premium shipping rate, they will forgive you of all or any import excise taxes.