Strange Pinholes in Exhaust

[94GLX]

Hi all,

New user here. Just moved to Brisbane, Australia and picked up an 1994 1FZ 80 series. The truck has a few exhaust leaks which I found kind of strange. Has anyone ever seen holes like these? These are at the vertical kick up past the muffler.

In my experience, rust usually forms where water pools, but these are very small holes in the side of the pipe on a vertical section.

Thanks

 

[Rifleman]

Water is a natural by product of combustion, some rust inside your exhaust system is normal. You could drop that section of exhaust pipe, and have a muffler shop weld a patch over those holes. Problem is, with a 25 year old exhaust system, you'll just be prolonging the inevitable.

Since you've got that many holes in one of your exhaust pipes, for your safety you might want to Climb under your truck and take a real good look at your muffler, more then likely it's rusting out too. I think the best thing to do at this point, break out your check book, and buy a new exhaust system.

One last thing, seeing as you live in Brisbane you probably like driving on the beach, so I'd think about spending the extra money for a stainless steel exhaust system if you can find one.

 

[BILT4ME]

Water is a natural by product of combustion, some rust inside your exhaust system is normal. You could drop that section of exhaust pipe, and have a muffler shop weld a patch over those holes. Problem is, with a 25 year old exhaust system, you'll just be prolonging the inevitable.

Since you've got that many holes in one of your exhaust pipes, for your safety you might want to Climb under your truck and take a real good look at your muffler, more then likely it's rusting out too. I think the best thing to do at this point, break out your check book, and buy a new exhaust system.

One last thing, seeing as you live in Brisbane you probably like driving on the beach, so I'd think about spending the extra money for a stainless steel exhaust system if you can find one.

The LC exhaust systems are 409SS from the factory. When welded they SHOULD use 308 or 309 SS wire but carbon steel wire works for repairs on old systems.

 

[94GLX]

Thanks for the replies. Yes, I did have a good look, and there are some holes in the y-pipe as well. I have sourced a good used exhaust which I will install.

I've just never seen an exhaust rust this way, so I figured I'd post it up to see if I was missing something.

I noticed the 1FZ idles a bit high when cold (perhaps rich as well), and the comes down as it warms up.

I've only been in Brisbane a few months. Seeing as how I'm in LandCruiser country and we never got them in Canada, I jumped on a real solid example. Needs the aforementioned exhaust work and some basic seals. Currently looking for a decent place to buy maintenance items.

I read that the coolant hoses at the firewall can be a pain, so I may look into doing those while I have the valve cover off.

 

[inkpot]

Cold/high idle is normal. Likely it goes down as engine warms up without touching the throttle?

 

[Rifleman]

The LC exhaust systems are 409SS from the factory. When welded they SHOULD use 308 or 309 SS wire but carbon steel wire works for repairs on old systems.

Built4me thanks for the heads up that the Land Cruiser uses 409 SS for their exhaust system, i didn't know that. If i need to repair my LC exhaust system I've got all my bases covered, I've got a 310 amp tig welder, along with a good stock of 308, and 309 rod. When i was recommending a Stainless steel exhaust system to the OP, i was thinking about a system made out of 304 Stainless steel, it stands up great to salt.

 

[BILT4ME]

Built4me thanks for the heads up that the Land Cruiser uses 409 SS for their exhaust system, i didn't know that. If i need to repair my LC exhaust system I've got all my bases covered, I've got a 310 amp tig welder, along with a good stock of 308, and 309 rod. When i was recommending a Stainless steel exhaust system to the OP, i was thinking about a system made out of 304 Stainless steel, it stands up great to salt.

A 304SS system would be great...but expensive. Most of the street rod builders use 304SS because it can be polished and look good with minimal heat issues. It's just expensive. The polished 304SS will discolor a bit near the heads (blue to straw-color) but that gives it character.

The 409SS is common among most auto manufacturers (my 95 Jeep GC and Chrysler T&C both have SS Exhaust from the factory) because it is cheap and resists corrosion. Mind you, it rusts and LOOKS like carbon steel, but once it oxidizes, it maintains the level and the rate slows down. Eventually, the heating/cooling cycles will kill it.

Any vehicle that does not come up to full temperature and driven long enough to burn the moisture out of the oil, exhaust, cat's, differentials, will get "damaged" due to the moisture in the system causing corrosion, whether it's on bearings, inside the exhaust, or on the oil filler cap.

This is why dis-use is harder on a car than mis-use. I have recovered cars that had 20,000 miles on them, only to get them running and have the exhaust fall off, the engine start leaking, hoses rupture, start running very poorly, all because they have sat for so long and the moisture has worked its magic. Once you start heat/cool cycles, things break down quickly and fall apart.

My 59 Studebaker has been through multiple exhaust systems in its life of 101K miles.
My 95 Jeep GC, 98 Chry T&C, 98 Dodge Grand Caravan, 96 Toyota Land Cruiser all have their original factory exhaust. All have lots of miles respectively: 257K, 178K, 201K, 273K

I had a 69 Chevy K1500 that I went through 3-4 exhaust systems in 300K because they were all carbon steel "aluminized" exhaust. They don;t rust on the "aluminized" part, they rust on the weld seams and the joints in the Heat Affected Zone (HAZ) of the welds because the metallurgy is different there.

I would be willing to be on the OP's post about strange holes that the spots where it rusted through are where weld spatter globs landed either inside or outside the exhaust and caused a change in the metallurgy and inviting the corrosion.

When we build pressure vessels or industrial equipment, we have to grind off any arc strikes and fill weld and grind them back smooth again to help prevent some of this. I am not a metallurgist, but someone here can probably tell us why, for real.

 

[artech]

Possibly from inclusions in the base metal? Getting a bed batch of alloy happens sometimes and there's really not much anyone can do about it. AFAIK inclusions can't be detected without x-raying the part, although it seems like magnetic particle inspection should also show it.

That's why good gun barrels are MPI'd during manufacture, to find flaws.

 

[Rifleman]

A 304SS system would be great...but expensive. Most of the street rod builders use 304SS because it can be polished and look good with minimal heat issues. It's just expensive. The polished 304SS will discolor a bit near the heads (blue to straw-color) but that gives it character.

The 409SS is common among most auto manufacturers (my 95 Jeep GC and Chrysler T&C both have SS Exhaust from the factory) because it is cheap and resists corrosion. Mind you, it rusts and LOOKS like carbon steel, but once it oxidizes, it maintains the level and the rate slows down. Eventually, the heating/cooling cycles will kill it.

Any vehicle that does not come up to full temperature and driven long enough to burn the moisture out of the oil, exhaust, cat's, differentials, will get "damaged" due to the moisture in the system causing corrosion, whether it's on bearings, inside the exhaust, or on the oil filler cap.

This is why dis-use is harder on a car than mis-use. I have recovered cars that had 20,000 miles on them, only to get them running and have the exhaust fall off, the engine start leaking, hoses rupture, start running very poorly, all because they have sat for so long and the moisture has worked its magic. Once you start heat/cool cycles, things break down quickly and fall apart.

My 59 Studebaker has been through multiple exhaust systems in its life of 101K miles.
My 95 Jeep GC, 98 Chry T&C, 98 Dodge Grand Caravan, 96 Toyota Land Cruiser all have their original factory exhaust. All have lots of miles respectively: 257K, 178K, 201K, 273K

I had a 69 Chevy K1500 that I went through 3-4 exhaust systems in 300K because they were all carbon steel "aluminized" exhaust. They don;t rust on the "aluminized" part, they rust on the weld seams and the joints in the Heat Affected Zone (HAZ) of the welds because the metallurgy is different there.

I would be willing to be on the OP's post about strange holes that the spots where it rusted through are where weld spatter globs landed either inside or outside the exhaust and caused a change in the metallurgy and inviting the corrosion.

When we build pressure vessels or industrial equipment, we have to grind off any arc strikes and fill weld and grind them back smooth again to help prevent some of this. I am not a metallurgist, but someone here can probably tell us why, for real.

Built4me, the only reason why i suggested 304 SS to the OP, he lives close to the Ocean. I've seen, and worked on rigs that have spent alot of time driving on the beach, and in the surf. Their undercarriage and body looks alot like rigs that come out of the rust belt. If proper maintenance* is not performed each time they return from the beach, all that salt exposure can, and will cause extensive rust damage to their undercarriage, and body over time.

Yes 304 SS would be more money, but if he's going to be operating in that type environment, it could be money well spent, but he's the only one who can determine if that's of value to him. *Proper maintenance to me after returning from the beach, thoroughly rinsing the undercarriage, and body of my truck with fresh water, to remove as much salt residue, and beach sand as possible. YMMV

 

[BILT4ME]

If I could do mine in 304, I would it would last the rest of my lifetime......

Great idea being next to the ocean. May be money well spent.