Exhaust Corrosion Protection: Tips & Solutions

Hello fellow mechanics!

I replaced the entire exhaust system on my Škoda Octavia TDI because it was rusted in several places.
Notably, the weld seams were the areas where corrosion was most prevalent.
The rest was probably galvanized.
Upon unpacking the new exhaust system, I noticed that some corrosion had already begun to affect the welds on the new part.

Is it somehow possible to protect these areas from corrosion?

Are there any sprays (zinc chloride) or other chemicals?
Home remedies?

Any ideas or experiences?

Do you also protect the underside of your vehicles in any other way?

Thank you in advance. KYLIE

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Are there any sprays (Kaltzink) or other chemicals??? Home remedies?

Yes, there is, but you can probably skip it because, in this case, the mufflers/pipes tend to rust from the inside out, mainly at the welds. Maybe it will extend their lifespan by 20%, if you're lucky. In my opinion, spray-on wax is best for the underbody and engine components.

Based on my previous experiences, I have never (!) encountered a diesel exhaust system that was completely rusted through. In every case, the failure has been due to a vibration fracture. While the fracture points were corroded, they were never actually rusted through. The breaking of the exhaust system components always occurred before they could completely rust through.

For gasoline engines where exhaust system components were very expensive, we used to completely fill the mufflers with Altoil, rotate them in all directions to ensure it reached every corner, then pour out the excess oil and install the system. Afterwards, it's important to carefully warm up the system to burn in the oil without burning it. Even years later, the burned-in layer showed that condensation would bead up on it. Although some people might disapprove now, the exhaust systems lasted significantly longer after this treatment.

Old diesel exhaust systems often appeared to be in excellent condition from the inside. Tests with a few drops of water confirmed what was expected: the water droplets beaded up on the layer of soot.

Sure.

My exhaust muffler on my G3 failed after 10 years, right before the welding seam gave way.

"Some astronauts have pushed something past a hose clamp... it's likely that the exhaust pipe then acts as a sacrificial electrode for the clamp..."

m;

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Based on my previous experiences, I have never (!) encountered a diesel exhaust system that was completely rusted through. In every case so far, the failure has been due to a vibration fracture. While the fracture points were corroded, they were never actually rusted through. The breaking of the exhaust system components always occurred before they could completely rust through.

For example, the good old 123 from Mercedes-Benz had problems with its diesel engine. Most often, the rear muffler would break right at the front weld seam, getting wedged between the road surface and the rear panel, which often caused the rear panel to be torn off by the muffler (which acted as a wedge brake) .

Since the use of flexible pipes, the vibration problem has essentially been resolved.
Considering that the lifespan of exhaust systems in premium vehicles can sometimes reach 10 years or more.

Hutfahrer wrote:

Based on my previous experiences, I have never (!) encountered a diesel exhaust system that was completely rusted through.

In every case so far, the failure has been due to a vibration fracture. }

Hi,

I'm also very familiar with rusted exhaust systems on diesel vehicles; it's a common problem in our area.

After 5 years and 150,000 km, mine was due for replacement. The middle section of the exhaust had a hole, about 1 cm in diameter, located on the curve above the rear axle. This hole could be expanded to roughly double its size by removing the rust. Additionally, the outermost layer of the metal on the tailpipe had peeled off.

It should be noted that recently, while loosening the clamp in front of the exhaust pipe to make modifications to the backpressure system, I removed a salt crust that was approximately 5mm thick. Yes, even in the low mountain range, they salt the roads twice a day, even without snowfall. And anything that isn't stainless steel will eventually be corroded by the salt solution.

Sure, for gasoline engines, additional assistance comes from within due to exhaust emissions.

I am familiar with the sad images of shattered rear panels of the W123 models – unfortunately! Mercedes-Benz had numerous exhaust-related issues; just remember the self-igniting rear aprons of the penultimate E-Class models, which would often smolder or even catch fire after a fast drive on the highway. For the W123, a steel cable attached to the underbody helped prevent the muffler from falling off and getting stuck. At least, that was the retrofit solution used by a friend who owned a W123.

It's just as frustrating for me to see salt solutions being applied so liberally and unnecessarily as it is to see the increased use of crushed rock to roughen up road surfaces. Both of these things are causing lasting damage to our vehicles. What's even worse is that even on nights when there's no frost, the salt trucks are still out there in the evening and morning.

It seems that for relatively recent vehicles from the Volkswagen Group, removing the silencer from the exhaust system is a common practice. Is there a sound-dampening layer between the outer metal casing and the silencer housing, or is it just metal on metal?

What are the experiences regarding the durability of mufflers that are now often manufactured using shell construction techniques?

A few astronauts got something stuck behind a hose clamp... probably the exhaust pipe is then a sacrificial electrode for the clamp...

Ahhh.
We had the exact same problem with our Golf 2, whose exhaust system had to be replaced once in 10 years and 300,000 km for the same reason.
By the way, the clamp we had was an original OEM part.

IMA, it must have been intentional.
At least, it seems like they haven't learned anything new in this generation of Golf, or even the one before it .

Or perhaps it was a 'give-away' to the exhaust supplier, and the reason for the discount when purchasing .
*duck and cover*

Best regards, Jochen.

It also depends on how much you drive, even with a diesel engine.
At that time, I had a Golf with approximately 210,000 kilometers on the odometer and 11 years old, and it still had the original exhaust system.
And now, the A4 with approximately 260,000 kilometers and nearly 12 years, also with the original equipment.

I drive about 100 km on the highway every day, and that's definitely taking its toll.

The exhaust system on my VW Jetta 16V has had the longest lifespan. The original factory system lasted for 6 years. A replacement muffler (a cheap aftermarket product) that was installed 2 years prior had to be replaced again after 2 years. After that, the vehicle received an exhaust system from the manufacturer Walker, which was similar to the standard system used on the SEAT Toledo 2.0 16V, and which we preferred due to its pipe diameter and dual exhaust pipes. Same chassis, same suspension... The exhaust system was purchased from an independent parts dealer.

Before installing the system, the parts were treated according to the Altoel method, as described above. The weld seams were previously treated with zinc oxide spray from the welding equipment. And here's the interesting part: The system, which was installed in 1998, is still in good condition under the car body, which has now reached 450,000 km! It must have seen approximately 300,000 km of that. The Jetta has been driven by a friend since 2001, was converted to LPG in 2005, and has been used almost exclusively for long-distance driving.

I have a Bosal DPF... let's just say it doesn't really cope well with the harsh conditions where it's located. After only 10 months, it already has a significant amount of surface rust.

Well, as is often the case, the quality of exhaust systems varies greatly. There's nothing against Renault (just as an example), but I know of systems that struggle to last even 3 years.

My exhaust system is still the original one, and it has already covered over 250,000 km and is 15 years old . Only one bracket on the middle section has fallen off once.
And that's despite the fact that we in Austria tend to use a lot of salt!
I don't believe there's much that can be done to prevent corrosion. It's either luck, or it's not.