I have used WMI for many years. On a rebuild back in 2018, I added braided steel internal Teflon coated methanol friendly lines to replace my plastic lines. After 6 months, I happened to notice a very small amount of rust developing in the connector on the internal steel and even along the Teflon coating itself, possibly some iron containment in the Teflon coating. At that time, I was running 50/50 mix of methanol/distilled water. I didn't at the time think it was a problem since it was minimal. The car then sat for 4 years waiting for me to replace the engine, where the new engine sat under my car lift in a crate for 3 1/2 years.

Fastforward to this summer, when I started installing the new engine. I started hooking up the WMI lines and noticed the rust problem was significant now. Makes sense, since they sat for 4 years. I found tow major lines were complete clogged. Not just the connector metal orifices, but even the inside Teflon coated sections. I replaced all the lines with new steel braided Teflon coated lines form a quality manufacturer on Summit Racing's website. I switch to water only this time, since I thought the methanol may have reacted with something in the Teflon coating and may have helped corrode the metal connectors too. I installed the lines in July-August. I just took one of the connectors off the pump two weeks ago and the flared metal orifice is rusted so bad, the that the orifice is half closed already. Looking done the line, the Teflon coating is rusting again on straight water. What is going on here? Has anyone had the same experience?

I am going to remove the lines from the engine and hook the ends on hoses going to a bucket. My plan is to run household type CLR, the best for rust removal, through the lines and let it sit for several days to eat the rust away. Then flush, since this CLR is not safe for aluminum or rubber. This rust will obviously return. Should I plan on using a small amount of CLR radiator flush in the distilled water to stop further rust? This type of CLR is safe for aluminum, metals and rubber. Will it hurt anything in the combustion chamber for the little time used during boost episodes?

Mike

 

Teflon/PTFE doesn't rust as it has no iron to oxidize

I'd be investigating the AN fittings you're using. You haven't mentioned the size but most WMI plumbing is -3 or -4 - and most of those fittings are steel. Double check that they're actually stainless steel fittings.

 

They are 6an coming from a rear tank and then there is a three-port small 4an manifold that separates into three sprayers (I am still twin turbo). I use one on the air intake elbow, one on the pre primary turbo and one on the pre secondary turbo, with that last one controlled by a solenoid and small vacuum switch which senses very minor vacuum so as to come on only when the secondary turbo is spooling. The turbo sprayers are #2, quite small, and the elbow I believe is #5.

The 6 an and 4 an are indeed steel fittings, it thought stainless (minimal to no iron), but obviously not. The Teflon coating is indeed showing some rusting. I know it's not the Teflon itself but there must be some iron impurity mixed in the coating. This is the second set over the last 5 years that the Teflon is probably compromised. When I cut open one of my old lines this summer, the entire Teflon coated internal hose was completely rusted shut. Not rust coming for the fitting, it was far away from the fitting.

My main question still is how to prevent the rust in the future. Can I run a very small amount of radiator flush or other rust preventor in the system and not worry about any effect on the engine combustion chambers (side seal, oil control rings, etc.)? Again, this would be the type that is safe for aluminum, rubber etc, not the household CLR type, I am currently using to clean the lines now, when disconnected for the engine.

Mike

 

I believe I may just add a very small amount of radiator antifreeze safe for our cars, as a corrosion inhibitor. It will also lubricate my check valves and the aqua pump.

Here are the lines I removed this summer. All the lines were similar. One is completely closed on one end. On the other, you can look down the bore and see the Teflon coated internal hose is rusted also. Again, not the Teflon itself but likely some iron impurity. Sorry about the fuzzy pictures. It's very hard to get clear due to the small size of the bore.




Here is the CLR cleaning of the current lines. I only used distilled water for my WMI injection this time, and the all-new lines were put in this summer/fall. Look at the rust residue. Quite a bit for these small lines for only several months.


Mike

 

I don't doubt that there is rust on them, but Teflon just does not rust. And Teflon/PTFE lines aren't a coating, they're an extruded piece of PTFE with an overbraid of stainless and/or fabric or whatever else is there. The rust is coming from somewhere else such as the inner compression portion of the fittings that the (aluminum or brass) olive is compressed against. There's also the innards of the pump that should be investigated as well - not all are Methanol-able.


You build it as a system that is corrosion resistant - methanol/alcohol being hygroscopic will cause localized oxidization no matter the additives you use - somehow you've built in something that is oxidizing to the system. If you don't have anything that will create iron oxide, you wont have rust.

 

I understand the Teflon/PTFE lines aren't a coating, they're an extruded piece of PTFE. I still truly believe there is some type of iron impurity in the extruded line. When I cut open a piece of hose last spring, the entire internal hose was completely corroded shut. This was nowhere near the fittings. The 6 an piece I cut was 12 feet long coming from my rear tank. I could be some other oxidizing impurity but looks like typical iron oxide inside the line.

You bring up a very good point about the system. Could I have type of electrical potential in the steel braided lines causing a galvanic type of reaction in the line leading to accelerated oxidation of the fittings and potentially some impurity in the Teflon/PTFE lines? Should I ground the lines to stop this possible electrical potential? This would be similar to copper water piping in a home needing to be grounded to stop a galvanic type process.

Mike

 

There is mineralisation in the water, methanol, or the tank or pump is corroding in your system. There is no way there is anything more than parts per million trace amounts of iron or minerals in the Teflon, it's specifically used to store and transfer highly reactive chemicals.

 

I totally agree, there is obviously something in my system causing the rust. The tank is actually a molded black polyethylene chemical tank. The water is distilled and even if it has some contaminate, it cannot believe it could help cause that must rust as to completely or near completely clog up all the lines. The pump is a typical aqua pump, from a company Devil's Own in the UK. The methanol I used last time is from a chemical supply house and in a typical 5-gallon pale. I am not using methanol this time and i am still rusting.

I agree that true Teflon cannot do this, but what if it's not really true Teflon/PTFE? Could some producers be selling these lines as pure Teflon and they are not? There are so many other fakes out there, even in our RX7 community. Look at the fake Walbro fuel pumps and the fake IGN1-A coils we have seen others buy.

My main question still remains on how to stop it or slow it down. I have added some typical Asian Zerex anti-freeze to the fluid, which I hope will help. I also an adding a grounding strap and clamp to the line. The majority of the line from the back to the front, over around10-12 feet, is ungrounded since it connects to the plastic pump fitting in the rear and in the front to a plastic flow sensor for my AEM failsafe flow meter. Again, this could set up some low-level electrical current in the line/fluid, similar to a ground loop in audio systems.

Mike

 

Have you pressure tested the system? Stripped the pump head? I'd think if you have been getting deposits like that the pump may have corroded to the point it can't deliver as expected.

 

I didn't internally inspect the pump head. It would be very difficult with my setup to get to the pump head off unless I absolutely had to. I did for two days run CLR (which eats rust and mineralization) through the entire system by hitting the test button on my AEM controller several times and repeating this every couple of hours during the day and early evening. The fluid running through the lines and then into a milk containers (one shown in the picture above) started out as very black and after two days was completely clear. I didn't directly check the pump pressure but did watch the AEM flow meter output, which steadily improved over the cleaning period. I ran the car today, careful not to over boost, and the measured flow (as seen on the AEM flow meter) now through the nozzles matches the setting I had set for pump several years ago. Therefore, empirically using flow only, it seems fine. Also, these Aguatec pumps have only a few very small metallic parts in the pump head. Mostly, the rubber diaphragms and the plastic components. I hope I am OK for now, but I will be monitoring closely and will not get into any higher boost until I am relatively sure the system continues to work as expected on the flow meter. I can actually download the plotted flow charts to make sure they are good.

Thanks for your help.
Mike
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@mikejokich I know this is an old thread, but I'm scheming a new AI setup, had a similar problem in years past, and was wondering if you ever figured out a resolution on this?

My bet is that it's galvanic corrosion like mentioned a few posts back, aluminum and stainless steels particularly don't play well together; the further apart they are on the galvanic series the worse off it is: https://en.wikipedia.org/wiki/Galvanic_series

 

It did have some galvanic corrosion at the ends, but the majority was just plain rust. It clogged the Teflon coated lines with rust, which was almost completely clogged in some areas. I now believe it was from a ground loop that was sending current down the line. The reason for the rust must have been some contaminant.
Mike

 

Interesting, thanks. Did it ever come back or did you figure out how to stop it?

 

I replaced all the lines when I first found the problem. Within 3-4 months, the process started again and started clogging the new lines. That's when I was also having some other questions of ground loops, so I used a ground strap on the main braided line coming from my rear hatch tank. I then cleaned the lines with CLR(the rust dissolver) by disconnecting all the lines, pouring it into my tank and using the pump on test mode, and dumping the liquid into a bucket. I then purged the tank and lines with distilled water using the same method. I did this several months ago and the line fluid has a slightly red tone but has not yet reclogged. I also added a small amount of coolant to my WMI tank with the distilled water as a rust preventer to help prevent further rusting. It is still very strange that this occurred and occurred twice, even with the new lines.
Mike

 

Because it's not the lines themselves that are causing the problem, it's something else in the system such as pump internals or fittings

Antifreeze may be a good solution as an anti corrosion additive, I believe either Volvo or Saab (blanking on which) released a paper back in the 80s or 90s on water injection using standard (I think) fuel injectors instead of modern high pressure pumps and nozzles - they ended up using water soluble cutting fluid/coolant as their anti-corrosion additive.

 

The pump is your typical pump sold by AEM, etc. Mine is from Devil's Own, but they are all the same aqua pumps. These do not rust. My connecting adapters are all aluminum. The only steel is in the braided hose connectors and the flared metal of the ends at the connections. These did rust some, but I literally cut several of the lines in half, very far from the connectors, and they were completely clogged shut by rust. This was the Teflon lined internal portions of the hose. This made no sense but was real. That's why I thought it was some type of metal (iron) containment. Look down into the hose, you can see rust beyond the metal connector even on these poorly focused photos.
Mike



Mike