New exhaust has surface rust?

[UVB76]

Hey all.

Picked up a new 3" exhaust last week, aluminised mild steel, nothing fancy just wanted to replace the factory exhaust because it's pretty beat.
Inside the new exhaust pipes there's some surface rust along a seam running the length of the pipes. I'm wondering if this is normal or a sign of a defective product? I've attached some pics and would appreciate advice. It's the first exhaust I've bought so not sure if this is to be expected.

Cheers all.

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[mudnut]

I would say it has been sitting around for a very long time. I would also expect that flange to have a complete weld around the pipe.

[4bye4]

I deal with replacement exhausts at my workshop here all the time, and what that appears to be is just where they have heated it during manufacture cooling and picking up moisture causing a bit of surface rust. That can happen in a day. Having said that, it doesn't take a second to spray these things with protector, even WD40 during manufacture. Depends on the quality of workmanship you like to portray I guess. Summare - probably ok product to use but sloppy manufacturer.

[UVB76]

I would say it has been sitting around for a very long time.
Yeah, that's my thought, too - it's been sitting for a while in the warehouse.


I would also expect that flange to have a complete weld around the pipe.
Good point - the 3rd pic doesn't show it but there's a full weld of the flange on the inside of the pipe. The other flanges are welded on the outside of the pipe so not sure why this one's different.

Even though it was a cheaper exhaust, things like this ^ don't give me much confidence about the overall quality.


I deal with replacement exhausts at my workshop here all the time, and what that appears to be is just where they have heated it during manufacture cooling and picking up moisture causing a bit of surface rust. That can happen in a day. Having said that, it doesn't take a second to spray these things with protector, even WD40 during manufacture. Depends on the quality of workmanship you like to portray I guess. Summare - probably ok product to use but sloppy manufacturer.
Good to know about the moisture after manufacture.
The inside of the exhaust has a residue, oily feel to it, so I suspect something has been applied - doesn't have a smell, though. It's only surface rust from what I can see so I'm not heaps worried, but it does make me question how the welds will hold up, rust around the welds, etc.

[UVB76]

What do you reckon if I sprayed some Penetrol on the surface rust areas, and around the welds? Would this cause a problem when heating up or with the aluminised mild steel?

[threedogs]

Hit it with a wire brush and spray with HT paint
Once fitted soot will take care of the inside
Not sure why its not fully welded but an exhaust shop
can weld that up for you if you feel it should

[4bye4]

What do you reckon if I sprayed some Penetrol on the surface rust areas, and around the welds? Would this cause a problem when heating up or with the aluminised mild steel?

I wouldn't worry about it, especially on the inside. Penetrol will only burn off anyway. Spray the nuts and bolts with Penetrol about an hour before you want to undo them. Spray the outside after you have fitted it with HT paint as suggested by TD's.
The welding is probably just a couple of tacks to hold the flange in position while the main weld was done, assuming it is welded on the other side of the flange.

[Sir Roofy]

Yeah, that's my thought, too - it's been sitting for a while in the warehouse.


Good point - the 3rd pic doesn't show it but there's a full weld of the flange on the inside of the pipe. The other flanges are welded on the outside of the pipe so not sure why this one's different.

Even though it was a cheaper exhaust, things like this ^ don't give me much confidence about the overall quality.


Good to know about the moisture after manufacture.
The inside of the exhaust has a residue, oily feel to it, so I suspect something has been applied - doesn't have a smell, though. It's only surface rust from what I can see so I'm not heaps worried, but it does make me question how the welds will hold up, rust around the welds, etc.
If your worried about it take it back and show them and exchange it

[threedogs]

I wouldn't worry about it, especially on the inside. Penetrol will only burn off anyway. Spray the nuts and bolts with Penetrol about an hour before you want to undo them. Spray the outside after you have fitted it with HT paint as suggested by TD's.
The welding is probably just a couple of tacks to hold the flange in position while the main weld was done, assuming it is welded on the other side of the flange.

would you recommend applying some "never seize" or similar to the bolts closer to the motor

[4bye4]

would you recommend applying some "never seize" or similar to the bolts closer to the motor

I never have bothered mainly because the temps in an exhaust will burn off just about anything you can apply when assembling. May as well just give them a good soak with penetrine or similay before removing. Really difficult stuff in the workshop we have sprayed then heated with a heat gun then sprayed again. A good thing to have for this job IMO is a metrinch set as the bolts on exhausts are often rounded or rusted. If all else fails buy a nut splitter. Works better than the hair splitter on the other thread.:smile:

[UVB76]

Appreciate all the input, guys :)
The exhaust has a 3 yr warranty so if it rusts out it's covered, and I don't live near the beach so there's no chance for salt water to get in and speed up the process.

How important is some silicone sealant on the gaskets, like RTV? And the heat shield on the factory exhaust is completely rooted, do I really need to replace it?

[BigRAWesty]

Appreciate all the input, guys :)
The exhaust has a 3 yr warranty so if it rusts out it's covered, and I don't live near the beach so there's no chance for salt water to get in and speed up the process.

How important is some silicone sealant on the gaskets, like RTV? And the heat shield on the factory exhaust is completely rooted, do I really need to replace it?
Again silicone will just burn away..
If it didn't come with gaskets then you'll either need to find some or make some..

[UVB76]

Again silicone will just burn away..
If it didn't come with gaskets then you'll either need to find some or make some..

Yeah, it came with gaskets but there's a note in the packaging that says to use high-temp silicone gasket stuff with the gaskets... :confused:

[threedogs]

it came with silver perforated 3 hole gasket
pretty sure I dont have the heat shield on mine, they are a PITB at the best of times
Any HT rtv should do the job for you. lol

[ando89]

If you are really worried about it i would put some heavy duty high temp anti seize on the bolts as threedogs suggested. Wire brush it and paint it with high temp paint. But remember it is an exhaust and the first time you go off read half the paint will be scratched off.
If you really wanted a exhaust that wasn't going to rust you should have got a 316SS exhaust. Nothing wrong with mild steel 90% of exhaust around the world are made from mild steel.

[4bye4]

Appreciate all the input, guys :)
The exhaust has a 3 yr warranty so if it rusts out it's covered, and I don't live near the beach so there's no chance for salt water to get in and speed up the process.

How important is some silicone sealant on the gaskets, like RTV? And the heat shield on the factory exhaust is completely rooted, do I really need to replace it?

Sorry missed the bit about the heat shield before - yes replace it. It helps to stop your exhaust cooking all the other stuff in the engine bay. There is a thread here somwhere about batteries getting overheated.

[BigRAWesty]

Sorry missed the bit about the heat shield before - yes replace it. It helps to stop your exhaust cooking all the other stuff in the engine bay. There is a thread here somwhere about batteries getting overheated.
I'm personally going to wrap all my stuff when the time comes

[Cuppa]

I'm personally going to wrap all my stuff when the time comes

I question the value of wrapping exhausts for everyday use when ceramic coating is more effective & isn't overly expensive, particularly on mild steel exhausts where one occasionally reads of 'wrap- induced rust'.

[threedogs]

Have to agree on wrapping a daily driver I think more benefits would come from ceramic coating it,
A daily driver will condensate too much, a lot of negitives written about it.
I had some block huggers had and made a huge improvement to under bonnet temps.
Do some more reading if you really want to wrap the dump pipe. some with plenty of $$
probably wouldnt give a shite and tell you to do it

[mudski]

I wrapped the dump pipe on my pipe. Did it to the old 3ltr too. Worked a treat, i could put my hand on the pipe while the motor is running so it works. As for rusting. No issues there. The heat of the pipe quickly dries. The dump pipe on my 3ltr was wrapped for 2 years and the pipe was like new under it when i removed it. You can buy a sealing spray to coat the wrap too if you want.
My 2c.

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[BigRAWesty]

Was only going to wrap manifold, and dump. And then run a Bennie on the turbo.

[ando89]

Every bolt i take out i put never seize on. wouldn't hurt but as 4bye4 said the heat from the exhaust will dry out any moisture.

[threedogs]

Was only going to wrap manifold, and dump. And then run a Bennie on the turbo.

Do You mean beanie, if so If had mine on for well over a year now
Ive found no down sides to it just positives only. Thermal dynamics oh yeah

http://www.nissanpatrol.com.au/forums/showthread.php?32023-INFO-ON-TURBO-BLANKET-beanie&highlight=turbo+beanie

[UVB76]

Thanks for all the replies and just thought I'd update.

It took about 3hrs of knuckle-busting to remove the factory exhaust and an hour to get the new one in. Probably should have washed the underside first but I didn't and ended up with plenty of dirt and dust dropping into my face.

I didn't reinstall the heatshield around the dump pipe because I'll need to take it off again soon: one of the bolt holes in the flange that joins to the turbo won't let a factory bolt fit into it so I'll need to resize the hole a bit or find a stubbier bolt, and the pyro bung (1/8 npt) is too small for the VDO EGT thermocouple fitting (1/4 nptf) so I'll need to get the VDO bung welded on or find a new fitting.
I figure I'll look more into the heatshield / wrap / turbo beanie once the dump pipe is all sorted.

Also, the larger diameter of the exhaust meant it was now high enough to touch the dangling wiring for a reversing light I added a while back. The fuse for the dash/OBD II/etc was blowing and I couldn't figure out why! Spent some time under the Patrol to look for any wiring I might have knocked loose from fitting the exhaust, and eventually found the reversing light wiring sitting on the top of the exhaust and the insulation had melted through and the wire was touching! :( :(

All in all the small (but noticeable) change in low-rev responsiveness is nice for the RD28. The exhaust note is nice and even though it's quite loud under throttle, I like it. I can get some audio/video if anyone's interested.
It was a cheaper exhaust (http://www.factorydirect4x4exhausts.com.au/nissan-patrol-gu-2-8l-3-aluminised-exhaust-system-no-muffler-with-pyro/) and the quality is what I'd expect for the price range, so we'll see how it fares over the next few months.