My vehicle: 1985 300CD-T

Issue:
I suspect that the vehicle has an exhaust leak.
Why?
In recent months, when I have gotten out of the vehicle either when idling or having just shutoff the engine, I smell a strong exhaust odor (no visible smoke though). I've had the vehicle for around 19 years and it is my second W123.153-617.952 and this is a new situation that I've never encountered with either car.

History:
4.5 years and 16,000 miles ago, I replaced the center and rear mufflers as the originals had developed holes due to rust.

Diagnosis work thus far:
I have ever so meticulously (and repeatedly) examined the entire exhaust system from the manifold to the tailpipe looking for holes, cracks, loose assemblies, etc. and found no obvious points of failure.

My suspicion:
A small but smellable amount of exhaust gases are escaping at the joint where the two muffler assemblies connect (attached picture). During my latest inspection, I *was* able to use my hand at the joint to create and observe a small amount of movement between the two pipes.

My question:
What is the typical best practice when connecting the two exhaust pipes? Stated another way: Is there an exhaust-specific sealant/adhesive that is applied before connecting the two pipes and then tightening the clamp? Disassembling the old joint when I replaced both assemblies, there did not seem to be any sealant/adhesive residue though after 30 years that wouldn't be a surprise.

Of course, I could just tighten the clamp more but I'd like to get some feedback before resorting to applying additional torque. The clamp itself is not loose.

I'd appreciate any advice on this. Thanks-

Attached Thumbnails

 

They're usually easy to spot by the soft flat black soot that accumulates wherever the leak is .

Some decades ago I decided to use only welded up exhausts, this stopped hose pesky joint leaks cold and eliminated the rattles squeaks too .

I', sure you already know about the R107 exhaust hangers ? they have a tiny bicycle chain loop embedded in the rubber do nut so they'll never fail and drop your exhaust when you're wearing a nice suit in the rain.....

__________________
-Nate
1982 240D 408,XXX miles
Ignorance is the mother of suspicion and fear is the father

I did then what I knew how to do ~ now that I know better I do better

Muffler Cement has been around as long as I can remember since back in the early 1960's. Go to the Autozone and other auto part chain store sites and see.

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84 300D, 82 Volvo 244Gl Diesel

Yes, that was one of the first things that I thought to look for. I was disappointed that I didn't find anything obvious.

Hadn't thought of that. Something to consider.

Yes, when I did the original job of replacing the two mufflers, I also replaced all of the rubber pieces associated with the exhaust system.

Thanks for your response.

In the early 1970's we were out bashing a poor old VW dune buggy to death in the desert and broke the exhaust from vibration, all we had was a roll of tape ~ some sort of duct tape IIRC, we lt it cool a bit, wrapped it and hoped it'd last back to camp ~

The tape melted then hardened and never did fail, I used to remember the brand of duct tape but no longer .

As mentioned, there are muffler / exhaust cements that work pretty well .

__________________
-Nate
1982 240D 408,XXX miles
Ignorance is the mother of suspicion and fear is the father

I did then what I knew how to do ~ now that I know better I do better

I'll check it out. Thank you.

Permatex makes several muffler/tailpipe sealants, and there are exhaust sealants for sale at Pelican too. When I used to work on Lotus cars we had very good success using the exhaust sealants made for the task.

Yes, of the four exhaust system repair products that Permatex offers, the Muffler & Tailpipe Sealer appears to be the appropriate one for my application. Thanks for the information.