I was under car (85 300D) and noticed the main front pipe is heavily rusted and flaking. The next section up the muffler is also rusted, but not as much. I think this is just the second set op pipes since car was new. They are OEM pipes and very heavy duty compared with most aftermarket stuff.

At the moment, nothing is broken. But no doubt days are numbered for at least front pipe.

I was thinking of wire brushing the pipes and coating with POR heat resistant manifold paint. I used it on my rusty R107's manifolds and after many years still looks good. On those, I first treated with rust converter.

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Graham
85 300D,72 350SL, 98 E320, Outback 2.5

Rustoleum may also be a good choice. There isn't enough heat in the exhaust to burn it off. I did that to my signature car eight years ago when I replaced the system and it still looks like new.

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'83 300D, 126K miles.

I wish I would have done it when I bought my exhaust system 6 years ago. My rear most muffler just developed a huge rust hole

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Eugene

10 E63 AMG
93 300te 4matic
07 BMW X3
14 Ford F-150 Fx2

If you plan on keeping it more than a year, and the car sees salt, paint the exhaust.

My '98 has a painted exhaust, and it's rust free

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$60 OM617 Blank Exhaust Flanges
$110 OM606 Blank Exhaust Flanges
No merc at the moment

High temp BBQ paint.
http://i.imgur.com/9N6W8p8.jpg

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CENSORED due to not family friendly words

There are quite a number of high temperature paints available. However, my pipes are old and already rusted and rough. That is why I was thinking about the POR-20.

On my R107 manifolds, I first degreased, then treated with a phosphoric acid type rust converter. Washed that with water after drying and then applied POR15. Very good long term results.

Not sure if wood stove/bbq paint or the like would work as well at preventing rust from coming back. same for some of the other paints like this one, which might work better on new pipes.

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Graham
85 300D,72 350SL, 98 E320, Outback 2.5

I have found that wood stove paint has poor rust prevention capabilities.

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1977 240D turbo

Prior to painting, you need to wire brush down to bare metal, wash with alcohol, and then preheat the metal until it's dry with a propane torch or heat gun-you will know by watching the condensation form then disappear on the metal. This method has worked great for me on everything from brake drums to exhaust parts.

Yes, the rear drums on my truck are still black and rush-free using BBQ paint and it has been 2 years. It really makes you smile when you check the rear brakes and the drum isn't crusty

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$60 OM617 Blank Exhaust Flanges
$110 OM606 Blank Exhaust Flanges
No merc at the moment

I painted the 300D's exhaust from the expansion joint right to the rear muffler (but not including the mufflers). It "looks" a lot better! I used DOM16 (a POR15 equivalent), Like POR, you can just paint after wirebrushing off any loose rust.

The pipes are OE Mercedes installed in 1998. Despite having lived in a harsh environment and having surface rust they still seem solid. Only think I replaced was rear muffler and that just last year. From what I recall, the OE exhaust only cost about $50 more than Speedy Muffler back then.

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Graham
85 300D,72 350SL, 98 E320, Outback 2.5

If its really rusty then it can't be saved. Just replace the front pipe. They are not even that expensive. Especially considering it takes $20+ of paint to cover the exhaust anyways.

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-diesel is not just a fuel, its a way of life-
'15 GLK250 Bluetec 118k - mine - (OC-123,800)
'17 Metris(VITO!) - 37k - wifes (OC-41k)
'09 Sprinter 3500 Winnebago View - 62k (OC - 67k)
'13 ML350 Bluetec - 95k - dad's (OC-98k)
'01 SL500 - 103k(km) - dad's (OC-110,000km)
'16 E400 4matic Sedan - 148k - Brothers (OC-155k)

I saw a youtube video (so it must be true) showing the benefits of plasti dip and this geezer had done the end of his tail pipe with the stuff. Amazingly he said it had been on there for a year and he was driving the extra macho Audi Nintendo powwwwwerrrrr blah blah blahhhhhh edition!

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1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!

painted mine with por 20 when i put new exhaust in 5 years ago silver high heat still looks like new one small can does all exhaust with small paint brush wear rubber gloves or you will have to wear that paint off your hands, recommended.

Thats a lot different situation than trying to salvage a 75% rusted through pipe though.

I painted a W123 full exhaust with a few coats of grill paint when it was new before I put it on my bro's car, after 2 years only a couple minor surface rust spots where debris knocked the paint off. a light brushing/re-paint and it would be all set again.

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-diesel is not just a fuel, its a way of life-
'15 GLK250 Bluetec 118k - mine - (OC-123,800)
'17 Metris(VITO!) - 37k - wifes (OC-41k)
'09 Sprinter 3500 Winnebago View - 62k (OC - 67k)
'13 ML350 Bluetec - 95k - dad's (OC-98k)
'01 SL500 - 103k(km) - dad's (OC-110,000km)
'16 E400 4matic Sedan - 148k - Brothers (OC-155k)

Not sure if you were talking to me. But I was not "saving" my pipes and they were not "really" rusty. Nothing wrong with front pipe.

Just wire brushed and painted with DOM-16 to make them "pretty" and perhaps last a little longer than not painting. I could have used POR20 because I have some, But I was under there painting with black DOM16 anyway.

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Graham
85 300D,72 350SL, 98 E320, Outback 2.5