Mondial 3.2 exhaust noise

Sounds like the muffler (silencer) may have an issue...

EXHAUST SYSTEM (FOR US AND SA VERSION) - Ricambi America, Inc.

Good luck finding the problem.

Mike

 

All 3,2 exhausts (notably 328s) discharge more gases at idle from the driver's side pipes, this is due to the internal disposition of tubes in the exhaust box, notably the "Euro" variant (no catalysator; or is it catalycist?).

Rgds
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This picture is worth a thousand words. Thanks for posting it.

 

Hard to believe the muffler is a problem with the low mileage. I would first take a look under there and see any signs of perished "doughnut" gaskets at the various cat and tube junctions, make sure the O2 sensor and slow down light thermistor on the muffler are tight (assuming its a US model with the single entry pipe and cat, not the euro catless model pictured in this thread), etc. i.e. check for system leaks. Also make sure the exhaust "spring" hangers and brackets are all in good order and tight, could be the muffler or tips are hitting the grill or something while vibrating with the engine on.

I also note that looking in from the engine bay there is a check valve (# 3in pic) on each bank which is part of the air injection system, these can rot away and fail /leak and sound like an exhaust leak. Wiggle them around as they may look ok at a glance, they corrode from the inside out. Other items relating to the air injection (#4) or test pipes that are on each exhaust manifold (#30 and 52 in second pic) might also have corroded, usually where they join the manifold. Should be able to tell with a visual inspection, or might use a stethescope to pinpoint a noise source for greater certainty while the engine is running.

More remote issues could be a cracked exhaust manifold, and leak at the manifold gasket, but this is so uncommon I would think not likely but anything's possible with a car this age. My bet is the check valves or test port corrosion.

Beyond that, most people complain the Mondial is not loud enough in stock cat/muffler form!
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I bet one of the exhaust gas sensor sampling ports is broken/rusted off the manifold. Part 22 or 30 on the diagram. Design weak spot.

 

Mine started getting noisy, doughnut joint leaking, lots of popping when going down hill in 3Rd gear and off the throttle is a good indication. Also a huge loss in power with these engines when the exhaust leaks.
I fixed it and power was restored. Good luck, Bell

 

Does anyone actually use the exhaust gas analyzer ports to diagnose anything? Seems like a good idea to have but in practical terms who has actually used or benefited from this type of refined testing? Anyone removed/replaced them without busting things? Mine are fine but do look rusty where they attach at the manifold, and I always wondered whether these things would be a future problem and would be best to proactively replace?

 

Those pipes are a convenient test point for misfiring cylinders. Run the engine from cold for a few minutes, then try to hold your finger on the test pipes. If you can, then that cylinder is not firing.

If your pipes are rusty, you could soak them in Metal Rescue, then paint with VHT.

 

Per Andy's comment above. I had a check valve fail on mine. At that point it is an exhaust leak and quite loud.

 

Assuming that the engine appears to be running well, the mixture test I do is as follows.
To check fuel air mix and engine running I do a plug colour check. This check I do on hot idle, then at 30 mph at 50mph and at 70+mph these tests I do at those steady speeds in turn, I pull over at a set spot and instantly shut down the engine, pull the plugs and note the colours. This I do 3 times for each of the speeds. It normally takes me an hour and I have a good quiet road to do it on. The alternative is to but a rolling road or hire one.
Regards Bell

 

And you are sure it's not an after market sports exhaust?

 

Before you reinvent the wheel, look up Russ (snj5) and his hot rod 3.2 Coupe. He designed and developed an exhaust or two.

For example:

http://www.ferrarichat.com/forum/mondial/192175-carb-mondial-update-bit-technical.html

http://www.ferrarichat.com/forum/mondial/127652-mondial-modification-upgrade-list-also-308-328-a.html

 

My 88 1/2 Mondial 3.2 has exactly the same characteristic of what appears to be more exhaust discharge from one side of the muffler. Furthermore, it's done it w/ 2 different exhaust systems. Two experts on these cars have told me it's normal.

 

My 87 mondial box was welded back together 3 times before i junked it, the original ANSAs were not very good and rust away.

 

Check the pipe connections as the 3 sided flanges tend to rust away and the firerings become a bit loose and leak when cold