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Discussion Starter #1
Hello everyone.

I wonder if anyone can help pinpoint what the cause of a rattle that started after getting an Oil/filter change last Friday.

Unfortunately a new (to me) garage carried out the Oil change. Since then there is a rattle which seems to be coming from the front left/middle of the car. Not coming from the engine as far as I can tell.
Recently moved to a new area, so had to use different garage/mechanic. Had to wait to go back there this morning after them being closed over the weekend. He stood by the car and listened to the noise/rattle and said it was nothing to do with the oil/filter change he carried out. Said he would take a look at it next week when he next had time.
Don't think I will be taking him up on the offer, as now don't trust him.

100% the rattle was not there prior to his work on the car last Friday.

Could be a coincendence, but it is strange timing to hear it on the way home from his garage within a mile or so.
Anyhow I need to work out what's wrong and get it fixed, if I can afford the expense.

The rattle is easily heard when stationary in Park and setting RPM's at around 2000. Can also be heard when driving.

I wonder if anyone has any ideas or experienced this before.

Will try an post a video of the sound tomorrow.
Thanks
 

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2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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The 3.6 engine with VVT (Variable Valve Timing) is EXTREMELY sensitive to oil type and viscosity used and also to the filter brand used. Oil level also.

Google "cadillac forums 3.6 vvt engine oil problems" or some variant.
 

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Discussion Starter #3
Thanks Submariner409 for taking the time to reply.

Here is oil/filter info for the car, owned car since 2008 @19000 miles now 94000 miles .....

Last Friday (3 days ago). Used the same filter (K&N) as always, however different oil this time, Mobil 1 ESP 5w30. Mobil technical team recommended this oil after I contacted them directly.

Oil I used before this (for some years 4/5 years) was Shell AG Professional 5w 30. (Shell no longer recommended this oil, which is why I changed to the Mobil 1 ESP 5w 30 after their recommendation.

Before that Mobil 1 x1 5w30 until no longer available in the UK

Do you or anyone think I should drain the Mobil 1 ESP and fill with the Shell AG professional 5w 30 to fix the rattle/ noise issue ?
 

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Discussion Starter #4 (Edited)
Here is a link to a video I made of the rattle/noise, it cannot be heard from under the bonnet/hood. But can be heard from the side of the car, hope video sound is clear enough for you to hear the rattle.

 

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I'd be inclined to think it's a rattling heat shield somewhere on the exhaust. Get a jack and a jack stand and I would imagine you could find the issue in a matter of a few minutes.
 

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I agree with @AAIIIC it sounds like a loose heat shield. Total PIA to replace all the little bolts that hold them on, but at least you can get to some of them. IMO it would be worth taking it back to the mechanic if he will look at it next week. Much easier to do this on a lift than on jack stands.
 

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Discussion Starter #7
Thanks AAIIIC and RyanY for taking the time to reply. I have an appointment on Thursday with another garage/mechanic, will certainly let them know what you have said. Unfortunately there is no one anywhere near me that has any experience of the CTS, so any info I can get from those with knowledge here is great.

I am also thinking of also getting this new garage to drain out the new Mobil 1 ESP and fill with the Shell AG professional I had used in the car for some years before. Never used the ESP before and only changed because I was informed that Shell no longer recommended the AG version I had been using, but a different AG version that I could not source here. Would be shame to discard the newly changed Mobil oil, but obviously will do if advised by someone who knows it is the cause of the rattle.
 

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Mobil 1 is fine, and I would just leave it until next oil change. However I would ask them to take a look at it and determine the source of the rattle...they may even tighten up the shield bolts while they are in there.
 

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Discussion Starter #9
Okay thanks Ryan, I will ask them to have a good look around. Don't know how helpful they will be as not used them before. From googling I found there are heat shields around the catalytic converters, not sure if there are any in other places?
 

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My CTS only has them at the manifold/cat area, so I don't think they are supposed to be anywhere else. The only other shield is at the transmission but this item is more of a foil shield than metal.
 

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I am also thinking of also getting this new garage to drain out the new Mobil 1 ESP and fill with the Shell AG professional I had used in the car for some years before. Never used the ESP before and only changed because I was informed that Shell no longer recommended the AG version I had been using, but a different AG version that I could not source here. Would be shame to discard the newly changed Mobil oil, but obviously will do if advised by someone who knows it is the cause of the rattle.
The oil you're using is not the cause of that sound. If an oil was so shitty as to make an engine sound like that, the engine would tear itself to pieces in short order. Not to mention that the sound isn't audible in the engine bay, but is coming from under the car somewhere.
 

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Discussion Starter #12
Hi guys. Thanks again to you for taking the time to reply. Glad to hear you don't think it's anything to do with the new oil AAIIIC.
Update...Just had an exhaust shop look at it, a chain called Halfords. (Only place near me that could look at it.) They have diagnosed it as a baffler loose in the centre silencer. They won't fix this, so I am inclined to believe it is an accurate diagnosis. (As they won't do the work)

Only happened a few mins ago, so will try to search for the part. Hopefully it's not an expensive fix/repair.
 

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Unfortunately, the exhaust has no serviceable parts - it's all one part from downstream of the cats back to the mufflers. (See 2005 Cadillac CTS HF EXHAUST SYSTEM.) The resonator is also a crossover.

I would imagine the chances of finding a used exhaust system are pretty slim, since the pool of CTSs to draw from is so small over there. Your best bet would probably be to have a shop cut out the factory resonator and weld in an H or X crossover plus a resonator in each "leg" of the mid-pipe section of the exhaust. That won't be cheap, but it'll be cheaper than sourcing an entire new exhaust, I imagine!

Actually, I just found this - Walker 21532 - which it shows is a vehicle-specific fit for 2004-2007 CTSs. You can see the details if you search for that part number here - Exhaust Parts Lookup | Walker Exhaust Systems. There's a decent diagram here - Walker® - Quiet-Flow™ Stainless Steel Oval Aluminized Exhaust Muffler. So rather than having a shop fabricate something, they can just chop out the old part and weld this baby in. It's stainless steel, too, so probably better than whatever a shop would try to install.
 

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Discussion Starter #14
I can't thank you enough for your help AAIIIC. Great news about the Walker part, coincidentally I came across that just as I read your message.
Hopefully I can source one here in the UK. Otherwise I will maybe buy from RockAuto as I think they will ship to UK. (Never used them)

The car is my Dad's he purchased it 11-12 years ago. Unfortunately he recently had a stroke so cannot drive anymore. I want to keep it going as long as I can as he loves it and our rides out together in it with Mum and Brother.

Again thanks so much for your kind help.
 

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Discussion Starter #15
Just been to the guys that were going to fit the Walker 21532, they wanted to check it over. Unfortunately their diagnosis is the left side (passenger as RHD) catalytic converter is the source of the noise/rattle. So now I have two different opinions. This wouldn't be so bad if I didn't have to order parts from USA as there is not much if any choice of supply here. Going to try and get further opinions to try and get 100% certain opinion of what part(s) to look for.

I think I read somewhere, can't remember where that if a cat is broken, there is another reason for it to break. So to find that issue first, before replacing it as it will just happen again, anyone heard of this? or am I remembering wrongly?

Does anyone have any ideas for good quality inexpensive catalytic converters?
 

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It's a 15yo car with nearly 100k miles on it, I wouldn't say there's any way to know what specifically caused the cat to fail (if that's in fact what the issue is). I would be inclined to just install a new cat pipe and see what happens. Hopefully it'll go another almost 100k without issue.
 

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2007 CTS 3.6 >131k miles
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Thank, Will do.

I have no idea of what is a good aftermarket direct fit catalytic converter to buy, and where from. Found these For 2004-2007 for Cadillac CTS Catalytic Converter Set 2.8L & 3.6L A & B | eBay

Also passenger side on RHD is same as buying left side cat, correct. No difference because it's RHD?
I usually check Rock Auto prices before I go elsewhere. I don't know if they ship to UK but prices are much better than GM.

Walker is a reputable brand in the USA; I have used them in the past with no problems. The other brands listed may also be good but I have no experience with them.

Left and right cats have different part numbers so you would need the correct side. A call to a dealer may help you decide which part is correct for the RHD model.
 

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Discussion Starter #19
Thanks RyanY

Will check them out, although after having a quick look their reviews look iffy. Worried they make an error and accidentally send the wrong part. (My Luck) Then me sending it back to them, may not be an easy return from the UK I am guessing.

Will also try to find something here but options are limited.

One thing I noticed on RockAuto, on some of the listings it mentions Engine Family Numbers. How do I identify this, or do I need to?

Also with regard to confirming which side is the correct part to order on a RHD... I can't contact a dealer here as there are none. Cadillac closed their dealers some years ago. Will maybe randomly email a dealer in the USA and hope they will get back to me. Although I think the left side cat (passenger side here), would be the same as the left side in the US, correct?

Thanks again for your kind help
 

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Thanks RyanY

Will check them out, although after having a quick look their reviews look iffy. Worried they make an error and accidentally send the wrong part. (My Luck) Then me sending it back to them, may not be an easy return from the UK I am guessing.

Their service has always been great for my orders, but I would certainly hesitate for international orders. Maybe give them a call to verify accuracy of you plan to order there(?) Or perhaps the eBay units you linked are sufficient (?)

Will also try to find something here but options are limited.

One thing I noticed on RockAuto, on some of the listings it mentions Engine Family Numbers. How do I identify this, or do I need to?

if you click the info button under the Walker improved design units, it will tell you how to find this info.

Also with regard to confirming which side is the correct part to order on a RHD... I can't contact a dealer here as there are none. Cadillac closed their dealers some years ago. Will maybe randomly email a dealer in the USA and hope they will get back to me. Although I think the left side cat (passenger side here), would be the same as the left side in the US, correct?

i would not expect the driver location to affect the exhaust routing, but cannot confirm this.

Thanks again for your kind help
 
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