Why does used fork oil smell like sewage?

[LuciferMutt]

Originally Posted by wsmc831

'Relatively sealed' is not completely sealed. Five years is too long. Replace it in a year as it should be on a bike ridden somewhat often and it will look and smell like new, and ride like new...or better.

Yeah I know. I'd been ignoring it because I don't really ride that bike hard these days, it's mostly a commuter and errand bike now. Did make a very positive difference of course -- front end is much more solid, planted and less harsh again. Feels great for being totally stock.

Now that it's done, I've changed the fork oil on both of my bikes and both are on a 10K change schedule from now on. The VFR is actually due in about 2K again, but I'm probably going to have RaceTech rebuild them for me with some better valving at the time.

[Laconic]

Originally Posted by Tosh Togo

Not really, and even if it were, how would water get in?....

Water will get into anything.

[SikDMAX]

Originally Posted by Tosh Togo

Not really, and even if it were, how would water get in?....

Dunno about the Eurocrap, but OEM Japanese fork oil always smells like bait that's way past its' pull date, and if you wait a few years it just gets worse.

Water and brake dust are the two biggest contaminates in forks.

[ragtoplvr]

Bugs end their lives on the fork tube, and some bug residue gets past the seals and dissolves into the oil. There will be some water too.The bacteria eat it. Bacterial farts are pretty nasty.

Rod

[Tosh Togo]

Originally Posted by ragtoplvr

Bugs end their lives on the fork tube, and some bug residue gets past the seals and dissolves into the oil. There will be some water too.The bacteria eat it. Bacterial farts are pretty nasty.

Rod

No shit?...

That's why cleaning all the debris from the sealing surfaces of your fork legs every time you ride prevents that from happening.

I change fork oil frequently, by the calendar (2 years max), and have never had any funky odor or debris once the OEM fork oil was replaced. The fork seals on my primary ride are about 15 years old, and they're both very happy.

I live in Orygun, and ride in the rain a LOT. I've yet to see any evidence of water in any fork oil removed from my bikes once the OEM swill has been replaced. There are always a few tiny bug bits, but no milkiness or any other indication of H2O in the wrong place.

[Bill the Bong]

Originally Posted by Tosh Togo

No shit?...

That's why cleaning all the debris from the sealing surfaces of your fork legs every time you ride prevents that from happening.

Maybe in my next life

[mhevezi]

I was working on my old 1975 Kawasaki KZ400, and when I ripped apart the forks on that bike, you can only imagine the stench from that fluid. 30+ years of riding on the same fluid.... oy.

[PeterW]

Originally Posted by ragtoplvr

Bugs end their lives on the fork tube, and some bug residue gets past the seals and dissolves into the oil. There will be some water too.The bacteria eat it. Bacterial farts are pretty nasty.

Rod

That's the one.

And just a comment, there's the lazy way to change fork oil - and if it' ain't smelling like sewage it saves a LOT of time. (If it's sewage you need to strip the forks down and clean them)

Just take the caps off, drain what you can ( use a transfer pump from the top if need be) and top up to the correct level with fresh oil, but do it OFTEN. Takes about 5 minutes compared with several hours needed to strip the forks down properly - well worth $10 spent on extra oil.

Pete

[wsmc831]

Yes, that is a fast way to replace fork oil. Though you won't ever get it all out, and there is no way to determine proper and equal amounts in each fork unless you remove springs and measure air gap.

Once the forks are off taking the caps and springs off takes and addition few minutes, so why not?

[PeterW]

Originally Posted by wsmc831

Yes, that is a fast way to replace fork oil. Though you won't ever get it all out, and there is no way to determine proper and equal amounts in each fork unless you remove springs and measure air gap.

Once the forks are off taking the caps and springs off takes and addition few minutes, so why not?

Proper and equal is easy. I have a bamboo skewer in the garage with tape around it I use as a refill marker. Do it properly once, measure and mark it once with the front fully down and the springs poking out.

Next time loosen the top clamp bolts, undo the caps, push the front of the bike down, pump the oil out that you can get at from the top (~2/3) (my forks don't have lower drain holes) and refill with fresh to the mark. Put it back together.

5 minutes every six months is a LOT less effort than several hours every two years, and I'll bet on average my oil is in better condition than yours. It's not engine oil (where this would be a bad idea) it ages totally differently.

Pete

[wsmc831]

Originally Posted by PeterW

Proper and equal is easy. I have a bamboo skewer in the garage with tape around it I use as a refill marker. Do it properly once, measure and mark it once with the front fully down and the springs poking out.

Next time loosen the top clamp bolts, undo the caps, push the front of the bike down, pump the oil out that you can get at from the top (~2/3) (my forks don't have lower drain holes) and refill with fresh to the mark. Put it back together.

5 minutes every six months is a LOT less effort than several hours every two years, and I'll bet on average my oil is in better condition than yours. It's not engine oil (where this would be a bad idea) it ages totally differently.

Pete

You won't ever get all the contaminents out that are sitting on the bottom.

I had a neighbor for several years in San Jose by the name of Jim Lindeman. I talked to him several times about replacing fork oil. He argued very affectively that there is no way to get the proper amount of fork oil in each fork unless you remove the springs and let gravity and piston action drain as much as possible, then remove damper rod and compress forks with hand over open end to use air pressure for force in new fluid. He seemed to know what he was doing.

You bet your fork oil is in better condition than mine? It's not a competition. There is a right way and an easy way to do things. I can, and do, change fork oil in my bikes in about an hour, start to finish, and the experts say this is the correct way to do it. I will spend an hour every year at (least) to know my front suspension is fresh.

of course, I'm nobody to argue with bamboo and tape.

[Kjharn]

Originally Posted by wsmc831

of course, I'm nobody to argue with bamboo and tape.

[PeterW]

Originally Posted by Kjharn

Me too

Pete

(Anything works better than waiting until it smells like a swamp though)

[Voidrider]

Ever work in a machine shop? Any machine using cutting fluid can end up stinking like rancid butter in a very short time. There are additives that are supposed to kill off bacteria, but even that doesn't totally solve the problem.

At one facility I worked at there was a sudden shut down, and despite the machinist's advice to clean up and drain the machines, they were told to leave things and get out. After a month long shut down the entire place smelled like a cross of rancid butter and rotting fish...and that aroma would bond to everything...and hair in particular. It got better after a while, but never really vanished entirely.

There are some pretty strange anaerobic bacteria that can grow and multiply in some pretty bizarre environments. Anaerobic bacteria tend to give off methane as a waste product. (Aerobic bacteria tend to give off carbon dioxide. Facultative bacteria can live in either aerobic or anaerobic conditions and can give off either gas - tricky!)

I always figured that heat and fluid/mechanical action killed off bacteria, but a few always survived, and they would just feast on the dead ones and the population would explode again. Even the original oil isn't added to the forks in a "clean room". Always going to be a few little critters getting into the system somewhere.

[Benesesso]

Originally Posted by Voidrider

There are some pretty strange anaerobic bacteria that can grow and multiply in some pretty bizarre environments. Anaerobic bacteria tend to give off methane as a waste product. (Aerobic bacteria tend to give off carbon dioxide. Facultative bacteria can live in either aerobic or anaerobic conditions and can give off either gas - tricky!)

I always figured that heat and fluid/mechanical action killed off bacteria, but a few always survived, and they would just feast on the dead ones and the population would explode again. Even the original oil isn't added to the forks in a "clean room". Always going to be a few little critters getting into the system somewhere.

Not that I think they're involved with "Original Jap Fork Oil Horrible Stench", but one real nasty anaerobe, a sulfate-reducing bacteria (SRB, formally known as Desulfovibrio desulfuricans), makes H2S (hydrogen sulfide). Methane gas in farts may ignite, but the strong "aroma" is H2S.

Take a look:


Abstract

The corrosion of sewers and the control of odor are the major operational and maintenance problems in wastewater collection systems. The generation of hydrogen sulfide and subsequent sulfuric acid results from microbially mediated reactions, by sulfate‐reducing bacteria (SBR) and sulfide‐oxidizing bacteria. This review covers pertinent information about sulfate reduction‐induced problems in general and SBR in particular. Metabolism with respect to carbon, energy, and sulfur sources, ecology, growth factors (dissolved oxygen, temperature, pH, and sulfide), and the competitive effects of methane‐producing bacteria on SBR are discussed. Because metals react with sulfide to form metal sulfide precipitates with extremely low solubilities, metal interactions in sulfate reduction environments are discussed.

http://www.tandfonline.com/doi/abs/1...43389609388489