Exhaust rustproofing

[Vilan]

After my last exhaust system rusted out within 4-5 years, I'm looking at ideas on making the new one last longer. Seems like someone must make a protective coating.

I was checking out some high-temperature paint at the auto store. Says it's good up to 1500 F and they have a clear coat version so it'd be darn near invisible. Has anyone tried this as a rustproofer? Will it have to be reapplied every so often? Seems like it'd be worthwhile even if it just gives me an extra year or two. Obviously it won't stop interior rust, but something is better than nothing.

 

[river_rat]

Originally Posted By: Vilan
Has anyone tried this as a rustproofer? Will it have to be reapplied every so often?

Yes and yes.
Make sure you follow the directions for curing it exactly. It does really help.

 

[Jim 5]

I've been told by the owner of a muffler shop that the best thing you can do is drill a 1/8" hole in the lowest point of the exhaust can. This allows collected condensation to drain if your trip is short enough that there isn't enough heat to evaporate it.

I'd probably just give that hole a poke every time I changed the oil just to make sure it was still clear.

 

[Eddie]

+1 for drilling a small hole at the back lowest part of the muffler.

 

[Johnny248]

buy stainless exhaust

 

[tomcat27]

it may slow rust from starting on the outside, but exhaust systems also rust from the inside out.

 

[StevieC]

Originally Posted By: Vilan
After my last exhaust system rusted out within 4-5 years, I'm looking at ideas on making the new one last longer. Seems like someone must make a protective coating.

I was checking out some high-temperature paint at the auto store. Says it's good up to 1500 F and they have a clear coat version so it'd be darn near invisible. Has anyone tried this as a rustproofer? Will it have to be reapplied every so often? Seems like it'd be worthwhile even if it just gives me an extra year or two. Obviously it won't stop interior rust, but something is better than nothing.
Pay the money and get a stainless steel exhaust system... Will last a very long time.

 

[bepperb]

I've never heard anything to work. You're taking it from both directions, inside and out. Not sure a full stainless exhaust is cost-effective either.

Here's to retiring to Hawaii.

 

[RISUPERCREWMAN]

Best rustproofing you can obtain is to have a system made from T-304 Stainless Steel!......I have one, & not a trace of rust on over 3 years!

 

[mechtech2]

I have an exhaust cat back from Trubenz made out of that 304 stainless, and it is like the day I put it in 5 years ago.

But paint? It may help if the substrate is perfect first [not corroded, dirty, rusted, etc]. Count on yearly or more frequent touch ups.

 

[Corvette Owner]

Tailpipe and muffler life went up when they eliminated lead from gas.

Unless you rustproof from the inside of the pipe, you are kidding yourself.

Most stock systems already have a hole in the lowest point of the muffler.

Stainless steel IS THE ANSWER. My Corvette has it and it will last forever.

 

[StevieC]

The stainless steel pipe I have on my Santa Fe which is going on 4 years old and 200K KM (120K miles) is like brand new. It has a rusty colour from the heat and the impurities in the exhaust metal but it's rock solid like the day it was built.

If it so much as looks cold outside they salt our roads so I think that is pretty good for the mileage.

 

[eljefino]

My exhaust parts come with this oily goo (cosmolene?) so it would take an additional step to degrease them before applying any paint.

This is starting to sound like work. My parts store gave me a free walker muffler after the first one rusted out, warranties are good for something. Paint it and you're on your own.

 

[onion]

Originally Posted By: Jim 5
I've been told by the owner of a muffler shop that the best thing you can do is drill a 1/8" hole in the lowest point of the exhaust can. This allows collected condensation to drain if your trip is short enough that there isn't enough heat to evaporate it.

I'd probably just give that hole a poke every time I changed the oil just to make sure it was still clear.


Originally Posted By: Eddie
+1 for drilling a small hole at the back lowest part of the muffler.


+1 for giving that hole a poke.

 

[Vilan]

I agree that good stainless is the answer, but was wondering if there's hope for the rest of us. $10 of paint for an extra couple years of life sounds like a good deal.

Drilling a hole in the muffler is good too, but what about the rest of the system? My driving is mostly highway so it gets up to full temp pretty much every day.

 

[Shannow]

Even cheap stainless is a good answer.

Hole in the lowest point is good as well.

I remember an old mech ilustrated mag where they showed welding a zerk fitting onto the exhaust, and pumping some grease into it every oil change... Allegedly (I'll bet) smoked some on first highway run.

Had a neighbour who used to put fish oil down the interior (and spray the exterior). His argument was that yes, most of it burned off, but the point at which it stopped burning off was hot enough not to collect moisture/acid anyway...his logic was a tad flawed, but it seemed to work some (and stink)

 

[Kestas]

Originally Posted By: Corvette Owner
Tailpipe and muffler life went up when they eliminated lead from gas.
How would lead reduce the life of muffler metal? It's mainly the sulfur that corrodes mufflers. The sulfur became a serious problem when they introduced catalytic converters. The sulfur in the fuel converts to sulfur dioxide during combustion. This is converted to sulfur trioxide by the catalytic converter, which then converts to sulfuric acid when it meets moisture. The sulfuric acid really does a number on the exhaust system, especially during short trips when the muffler system hasn't fully warmed up to drive off the moisture. The tailpipe is last to heat up.

The same converter technology that is used in cars is also used in plants that manufacture sulfuric acid.

 

[mechtech2]

Unleaded gas was one thing that helped with exhaust life, for sure.
But for a left handed reason. The additives[scavengers] that helped keep the lead from accumulating in the engine attacks other metals downstream.

Nowadays, it is my experience that exhausts rust from the outside, rather than the inside - by far.
But I live in a salted winter area.

 

[JTK]

Regardless, exhaust systems do last far longer today than they did ~30yrs ago. I recall cars in the 1970's needing exhaust work at 30Kmi. It seemed almost like a yearly occurrence back then. Nowadays, it ~8-10yrs and well over 100Kmi even in the rust belt.

Joel

 

[Corvette Owner]

Originally Posted By: mechtech2
Unleaded gas was one thing that helped with exhaust life, for sure.
But for a left handed reason. The additives[scavengers] that helped keep the lead from accumulating in the engine attacks other metals downstream.


This is the reason unleaded gas is easier on exhaust life (and spark plugs, and piston rings and engines).