Catylitic Converter/exhaust manifold Leaks?

[jsudaria]

Hello all I have a 2003 Infiniti M45,
2.5 yrs ago I had a cracked exhaust manifold and cat converters were bad. I had both exhaust manifolds replaced at that time. Now cat converters breaking apart and exhaust manifold gasket leak. I just had both exhaust manifolds replaced again and also a new Y pipe installed. When I picked up my car from the auto shop I noticed upon ignition the car sounded louder and rough. Lots of vibration coming from area around the new manifolds and making my dashboard vibrate and rattle. During idle, my car is so rough I can feel it through the floor board and gets louder when I accelerate from a stop (vibration and engine noise.) Any ideas to help me out??

Thanks,
Jason.

[EdBwoy]

Any idea if they re-installed flex joints when the Y-pipe was replaced? My understanding is that those are meant to take up vibrations from the exhaust headers close to the engine.
I know the precats can get damaged and dislodged in there, but I expect a rattling sound, not anything to shake your dash. Do you remember what it sounded like when you first had damaged cats?
Third guess would be the motor mounts. Some people might jack up the motor for ease of removing the headers, damaging the motor mounts in the process.

[jsudaria]

Thanks Ed for your reply. To answer your questions, I don't know if they used flex joints. When I first noticed something was not right is when I could hear what sounded like loud air flow when accelerating and I had a huge loss of power. I could also hear raw engine noise from around the exhaust manifolds. So I assumed the gaskets were bad. When the shop inspected it, they said they could hear a rattling coming from the cat converters.

Interesting that you mentioned the motor mounts. I went back to the shop late this afternoon and with my car on their rack, they showed me my motor mounts were bad. When he stepped on the accelerator with his foot on the brake, I could see the engine really tilt and move a lot. So I guess the engine moving could cause the vibration while driving and possibly when its idling when parked, but don't know why the engine sounds "throaty" and very noticeable sputtering sound coming from under the hood or under the engine. Almost sounds kinda like an exhaust leak. Any other ideas? I saw a picture of the exhaust manifold gasket and it looks like it could be installed with the engine block side facing the manifold. Do you know if the gasket is supposed to be installed facing in only 1 direction. In other words if the wrong side is facing the engine block, could that cause a problem such as a gasket leak?

Thanks.

[EdBwoy]

Thanks Ed for your reply. To answer your questions, I don't know if they used flex joints. When I first noticed something was not right is when I could hear what sounded like loud air flow when accelerating and I had a huge loss of power. I could also hear raw engine noise from around the exhaust manifolds. So I assumed the gaskets were bad. When the shop inspected it, they said they could hear a rattling coming from the cat converters.

Interesting that you mentioned the motor mounts. I went back to the shop late this afternoon and with my car on their rack, they showed me my motor mounts were bad. When he stepped on the accelerator with his foot on the brake, I could see the engine really tilt and move a lot. So I guess the engine moving could cause the vibration while driving and possibly when its idling when parked, but don't know why the engine sounds "throaty" and very noticeable sputtering sound coming from under the hood or under the engine. Almost sounds kinda like an exhaust leak. Any other ideas? I saw a picture of the exhaust manifold gasket and it looks like it could be installed with the engine block side facing the manifold. Do you know if the gasket is supposed to be installed facing in only 1 direction. In other words if the wrong side is facing the engine block, could that cause a problem such as a gasket leak?

Thanks.

For the flex joints, if you can just crawl/lay under the car and check. From the factory, they are located behind the secondary catalytic converters. M45s sit quite low, but I believe I can just feel around under there.

Motor mounts: They do wear with time, and if you snap the throttle you will notice the engine sort of jump up on the right side (my experience with conventionally turning crankshafts). Some motion is normal, unless you can visibly see the engine jump around while idling. Is this the only proof they had of bad motor mounts? Maybe post a video of your engine for comparison.

The exhaust gaskets should be reversible in terms of engine vs. header surfaces, although they have a right-side-up

When the bad cats were addressed, did they put OEM headers and precats back on? Were they brand new or used? Do you have a check engine light? Because these might point to gutted cats, high flow cats (not very easily sourced for your car) or even an exhaust leak as you say. Those make an exhaust throaty. The one bad gasket I replaced only had a low sputtering sound, certainly not noticeably unless you were right next to the flange. If you really have a leak, the o2 sensor one should detect that and throw a code. Also, if you have a leak, the some performance parameters might be retarded (I will check the manual again to see if this is done uniformly across all cylinders or if it only affects one bank - which could cause sputtering)

My big questions at this point would be: do you have any OBD codes coming up & also, are you having an issue with the exhaust on one bank or are both of them giving you trouble?

[jsudaria]

Thanks agian for your most recent reply. Currently I am not getting a service engine light. Also, no codes coming up. I was told last week when the "new" exhaust manifolds and Y pipe were installed, all parts cam from infiniti. I was also told the cat converters are part of the manifiold assembly. He didn't say anything about headers. Initially I was just having trouble on the left manifold. I was told I needed to replace both. Ath this point I can't tell if the noise is more on the right or left. I just hear it in the vicinity of the back part of the engine like its coming from manifold area.

I remember when both manifolds were replaced over 2 years ago because of the left one being cracked, the car was nice and quiet after the work was done and no vibrations. Now with this new set of manifolds installed last week (under warranty) the power has returned but the car vibrates and is noisy when idle and when accelerating. And the shop has no explanation for the noisy rough feeling, other than the motor mounts. I'll try to post a video. Can I do that on this website?

Thanks.

[EdBwoy]

You're welcome. Always glad to help.

Mostly, I post videos on my youtube account and just link them here. I've seen people link videos from photobucket and the other picture hosting sites as well.

Pardon my use of the term "header". I was really referring to the manifolds, and those do come with the primary catalytic converters in them.

And I asked if you bought them new because some 03 and 04 m45 owners have reported issues with cracked manifolds, especially the left one (me included). Also for whatever reason the left one costs hundreds more than the right one from Infiniti.

If the vibration did start right after the work was done, then I would point that out to them and have the installers correct it.

The 2 exhaust things that would cause vibration close to the back of the engine would be lack of flex pipes or failure to install the support brackets. This bracket bolts to both of the manifold- flanges and is secured to the bottom of the transmission.

What is your RPM at idle?

[Double E]

Seems unusual that the shop doing the work would take it for a drive after. They would have noticed it. Was it a dealer?

[jsudaria]

How can I see a picture of what the bracket looks like and where it goes (the one you mentioned that is secured to the bottom of the transmission)
I ask this because yesterday, with my car on the rack, the sales manager pointed out to me that there is a bar of some sort that is missing and I could see where it would be bolted. Perhaps they forgot to put this part back on the car. It looked like it would go under the transmission area. I could see open threads on the left and right side where "something" should be bolted.

I think my rpm at idle is a little less than 1000. By the way, are the manifolds for my car only available through infiniti? An is that support bracket that bolts under the transmission available only through infiniti?
Thanks a bunch--your replies are helping to trouble shoot this problem. All information is greatly appreciated!

-Jason.

[jsudaria]

Unfortunately they're doing lazy work. They probably don't want to invest any more time into my issues since they had to replace the manifolds at their expense. Manifolds were installed at Goodyear automotive shop.

[jsudaria]

Is it customary to jack up the engine when removing/installing exhaust manifolds. I did not have broken motor mounts when I left my car at the shop for the installation of the new exhaust manifolds. I know for sure my car was not vibrating and rattling or I would have asked them to investigate that noise. When I turned my car on at the shop when I went to pick it up after the exhaust manifold work, it was rattling and vibrating and worse when I drive it. How can motor mounts go bad while at the auto shop??

Thanks.

[EdBwoy]

If your idle is steady as 650+/-50 with no load, then it seems normal. Just wanted to verify it wasn't an issue internal to the engine like misfiring.

For the schematic of the bracket I'm talking about, check page 3 of the manual: http://www.nicoclub.com/FSM/M/2003/ex.pdf The part has been aptly named "bracket" and it consists of #13 and 2 #12 units. #12 is bolted to the 2 flange bolts and 13 secures it to the trans.

For the removal steps: http://www.nicoclub.com/FSM/M/2003/em.pdf, page 22
Step 2 d) calls for the bottom of the engine to be jacked up, then mentions that the mount should be removed.
It would be poor practice to not unbolt the mounts from the subframe before raising the engine. An experienced mechanic would at least catch that. Also, the manual suggests removing the engine mount to be able to access the manifold bolts and IIRC, there's no real workaround to that.

Maybe an inexperienced person worked on the car this time around and messed up the mounts? All I know is if my engine was smooth when the car rolled in, but is now all iffy after only THEY touched it, then THEY would have to rectify the situation.


Off topic here, but what have you been doing with your old exhaust manifolds?

[jsudaria]

Thanks again Ed. You have given some great information and insight. Since our discussion, I've been able to call the shop and call them out on not replacing the bracket. In fact they never even told me it is needed and did not discuss with me the need to order a new one if mine in fact was damaged or "lost." He let me drive off with my car in that condition. The office manager told me they will order and pay for the bracket, unfortunately they wouldn't be doing it if I had never called them.
As far as the motor mounts, I know I'll have a hard time proving they were negligent and damaged my mounts. The estimate is $1400 to replace the mounts and I'm pissed to say the least. My car has 160,000 miles and I know the mounts go bad over time but they were fully in tact when I dropped my car off at the shop for the exhaust repairs.
The shop kept my old exhaust manifolds and gave them to the parts supplier for the core. That's what the shop told me. I'll look at the links today and post a question for you if I have any. I'm sure I will.

Thank You!

[EdBwoy]

You're welcome, and glad you're getting some resolution. Did you figure out the source of the throaty sound?

And this might be a stretch, but a stretch that could save you $1400. Can you personally or have someone check the nuts that secure the engine mounts to the subframe?
If they unbolted them, there will be obvious signs of tools on the surface (especially if they used an impact tool). If they didn't, then it might be a point of discussion as to how they even accessed the headers without damaging the mounts.

I did not think the motor mount job would be that expensive, either in parts or labor, but I'd preferably have a different shop do it this time. I would also request that they remove the old mounts as gently as they can then I'd do a quick examination to see where the point of failure is. Motor mounts are almost always in compression, so if it looks like someone pulled them apart, time for a discussion.

[jsudaria]

I had another shop inspect my car yesterday afternoon. They work on lots of infiniti. They confirmed the motor mounts are bad but I did not ask them if they checked to make sure the bolts were tight. I'll call them to ask this question. They also told me the throaty sound could be caused by the missing bracket and/or by the motor vibration as I accelerate. I did not have them replace the mounts yesterday although they suggested I get the "shotty" shop replace the missing bracket, then take the car back to them so they can run engine diagnostics, etc. I'll be having a discussion with the owner or general manager of the shop who likely damaged my mounts when they worked on the manifolds. Good call to ask about the motor mount bolts. Do these nuts get removed from the top or under the vehicle?

Thanks.

[EdBwoy]

2 nuts hold the mount. A 17mm at the bottom to the subframe, and a 14mm on top to the motor mount bracket.

Thanks for the updates. Let us know how it goes.

[jsudaria]

UPDATE: I HAD THE MOTOR MOUNTS REPLACED BUT THE VEHICLE STILL SHAKES A LOT DURING IDLE AND SHAKES AND VIBRATES MORE IN DRIVE WITH MY FOOT ON THE BRAKE. THE BRACKET THAT WE DISCUSSED EARLIER THAT WAS NOT INSTALLED IS STILL NOT ON MY CAR. I WAS TOLD THE NEW EXHAUST MANIFOLDS WITH CATS WHICH WERE INSTALLED HAVE A NEW "DESIGN" SO NOW THE BRACKET THAT ATTACHED TO THE FLANGE ON THE CATS DOES NOT FIT. I CONTACTED INFINITI AND I WAS TOLD THAT INFINITI HAS ISSUED A NEW PART NUMBER FOR THE BRACKET BUT THERE IS NO PART MADE THAT MATCHED THE NEW PART NUMBER. ANYONE HEAR OF THIS? COULD THE VIBRATION BE CAUSED BY THE M ISSING BRACKET OR HOW ABOUT THE HARMONIC BALANCER? HELP!!

THANKS.

[EdBwoy]

I haven't heard much about the redesigned manifolds, and I don't know the likelihood of that detail slipping the manufacturer after making such a change. Do they have pictures or part numbers for this setup?
At this point I don't think that bracket could cause vibration as bad as you're describing; at least not to the engine.
What recourse is the first shop offering, considering that your car was fine when you delivered it there but now has issues upon pickup?

[jsudaria]

The shop did not charge labor for the installation of the motor mounts. prior to the mounts getting installed, they told me the vibration is due to the broken motor mounts. I complained that the mounts were fine when I dropped off my car. That's why they did not charge labor. Now they tell me to take it to a muffler shop to see if someone can fabricate a bracket. The car still also makes a sputtering noise like a putt-putt sound when I accelerate from a stop and gets faster as I increase speed which sounds a lot like an exhaust manifold gasket is failing. So my car is still making the same noise and vibration ever since the manifolds were replaced and motor mounts replaced. I was told my valve covers are leaking oil. Could this cause the sputtering noise?

[EdBwoy]

If you go, ask the muffler shop what they can do to diagnose exhaust leaks around the header and see if that's your sputtering sound source.
I would also consider biting the bullet and taking it to a shop to get a proper diagnosis on it. See what the engine shake is all about. I cringe at the Infiniti and Nissan dealership diagnosis rates that I have been quoted ($140/diagnosis and also $140/hour), especially since they don't prorate them, but I believe no one knows a Nissan like Nissan themselves. Please get pictures whenever you get the car on a lift, or some form of video of the engine as is.
I ran my 03 m45 without that bracket and an almost fully unrestricted exhaust and my engine wasn't making any uncomfortable movements; and that's why I don't quite see what their fuss about the bracket is.

Another thing I thought of: Has the transmission mount been inspected as well?

[jsudaria]

Well the mystery is solved! I took it to another shop (thanks for the suggestion). They found that a lower bracket on the exhaust near the transmission was installed UPSIDE DOWN! The bracket was up against the transmission and this was the cause of all the vibration and sputtering noise. The car is so quiet now that it has been fixed by re-installing the bracket. I went to the shop who installed the exhaust manifolds and they will reimburse my the $106 I had to pay someone else to diagnose and fix it. Man, what a nightmare but I'm glad I had your help and ideas. You really did help me narrow things down. I was ready to sell the car.

Thanks ED!

[EdBwoy]

You're welcome partner! Always glad to help on this forum when I can. And thanks for coming back to post your resolution
Happy motoring.