Hello -

I stumbled upon this forum while researching a problem I'm having with a Eaton m62 blower (gen 2). I have this supercharger on a 1997 BMW 318ti (4 banger, hatchback).

I was running alchoo/water injection before the supercharger, for about 5 months last summer. After I stopped running the spray, I noticed my boost was less than normal, it dropped from 7.5psi to 5.5psi max. From the research that I've done, I'm pretty sure I have a problem with the rotor coating, on the gen 2 superchargers I guess it'* a teflon coating (?) that isn't compatible with water or alcohol.

I haven't removed the supercharger to inspect it yet, but I'm pretty sure the coating is gone, as all the signs point to that. The supercharger only has 30k miles on it, the bearings, and everything else are in perfect shape (no noise, vibration), it'* just the rotors that are bad. What is the best way to take care of this issue? Is there anywhere that does rotor re-coating? The supercharger is from a Downing Atlanta supercharger kit, so it'* not a production type blower, so I can't just buy a replacement off ebay.

Let me know what you think. I'm open to suggestion and/or ridicule. Here are some pics to look at:


http://180customs.net/v-web/gallery/...dom_009?full=1

http://180customs.net/v-web/gallery/BMW/BMW_029?full=1

Follow up question (as I do more research): Is it possilbe for me to replace the rotor pack? I see you have many pics of disassembed superchargers and I'm just curious I this is a serviceable part, or if it'* too complex for a DIYer to tackle. If the rotor packs are replaceable, where could I buy them.

Thanks for the help in advance, I know I'm not a Bonneville owner, but I share the same love for boost you guys do!

Not sure how different the coating on your SC is from the ones on our cars. Our M62 from 92-93 had no coating, 94-95 had a coating, but unsure what type off the top of my head, and the M90 from 96+ had the teflon coating I believe. If your rotors have the same coating at the 94-95 and the internal size is the same, you might be able to get rotors from a 94-95 SC and place them into yours. If they have the same as the 96+. thein you might have an issue since I think they are different rotor (pretty sure they are) but i think there are places to get them recoated, but that costs.

You can also check as the new Cobalt SS with the Supercharged motor uses the M62 and you might be able to get rotors from one of those.

just some thoughts./

Ok thanks! Can anyone confirm that the rotors changed in 96? I think the actuall rotors are the same on all m62s (this would make sense anyways), is this correct? I think finding a SC off ebay might be my best bet.

How hard is it to swap rotor packs? Does anyone have a write up on it?

Thanks again!

Water Injection should raise the amount of boost you see.

It did until I stopped using it. Once the WI stripped the coating off the rotors, it basically relied on the water to seal it up. Again, I believe my supercharger is a Gen 2, does anyone know what kind of coating the Gen 2s used?

Thanks!

no coating.



at least I think thats correct :?

There is definately some kind of coating on the rotors. It'* a light gray colored coating, someone thought it might be telfon? I guess the Epoxy coated rotors can handle WI, while the Teflon ones cannot.

gen 2s which were used in 92/93 did not have coating..I believe the 94/95 did have epoxy based coating. 96+ bonnevilles started using the M90s

If it is not a 'production' supercharger we can tell if they came with a coating or not (epoxy not teflon). Their was never a 'gen 2' made that was a 'production' peice. If it does (did) have epoxy coated rotors you can get them recoated for about $100 but I don't think that your rotors are coated.